chapter four

substances of that character:

Soda (_nitrum_). Lye. "Ashes which wool-dyers use." "Salt made from the ashes of musk ivy."

The last three are certainly potash, probably impure. While the first might be either potash or soda, the fact that the last three are mentioned separately, together with other evidence, convinces us that by the first is intended the _nitrum_ so generally imported into Europe from Egypt during the Middle Ages. This imported salt was certainly the natural bicarbonate, and we have, therefore, used the term "soda."

[11] In this chapter are mentioned seven kinds of common salt:

Salt _Sal._ Rock salt _Sal fossilis._ "Made" salt _Sal facticius._ Refined salt _Sal purgatius._ Melted salt _Sal liquefactus._

And in addition _sal tostus_ and _sal torrefactus_. _Sal facticius_ is used in distinction from rock-salt. The melted salt would apparently be salt-glass. What form the _sal tostus_ and _sal torrefactus_ could have we cannot say, however, but they were possibly some form of heated salt; they may have been combinations after the order of _sal artificiosus_ (see p. 236).

[12] "Stones which easily melt in hot furnaces and sand which is made from them" (_lapides qui in ardentibus fornacibus facile liquescunt arenae ab eis resolutae_). These were probably quartz in this instance, although fluorspar is also included in this same genus. For fuller discussion see note on p. 380.

[13] _Tophus_. (_Interpretatio_, _Toffstein oder topstein_). According to Dana (Syst. of Min., p. 678), the German _topfstein_ was English potstone or soapstone, a magnesian silicate. It is scarcely possible, however, that this is what Agricola meant by this term, for such a substance would be highly infusible. Agricola has a good deal to say about this mineral in _De Natura Fossilium_ (p. 189 and 313), and from these descriptions it would seem to be a tufaceous limestone of various sorts, embracing some marls, stalagmites, calcareous sinter, etc. He states: "Generally fire does not melt it, but makes it harder and breaks it into powder. Tophus is said to be a stone found in caverns, made from the dripping of stone juice solidified by cold ... sometimes it is found containing many shells, and likewise the impressions of alder leaves; our people make lime by burning it." Pliny, upon whom Agricola depends largely for his nomenclature, mentions such a substance (XXXVI, 48): "Among the multitude of stones there is _tophus_. It is unsuitable for buildings, because it is perishable and soft. Still, however, there are some places which have no other, as Carthage, in Africa. It is eaten away by the emanations from the sea, crumbled to dust by the wind, and washed away by the rain." In fact, _tophus_ was a wide genus among the older mineralogists, Wallerius (_Meditationes Physico-Chemicae De Origine Mundi_, Stockholm, 1776, p. 186), for instance, gives 22 varieties. For the purposes for which it is used we believe it was always limestone of some form.

[14] _Saxum fissile album._ (_The Interpretatio_ gives the German as _schifer_). Agricola mentions it in _Bermannus_ (459), in _De Natura Fossilium_ (p. 319), but nothing definite can be derived from these references. It appears to us from its use to have been either a quartzite or a fissile limestone.

[15] Argol (_Feces vini siccae_,--"Dried lees of wine." Germ. trans. gives _die wein heffen_, although the usual German term of the period was _weinstein_). The lees of wine were the crude tartar or argols of commerce and modern assayers. The argols of white wine are white, while they are red from red wine. The white argol which Agricola so often specifies would have no special excellence, unless it may be that it is less easily adulterated. Agricola (_De Nat. Fos._, p. 344) uses the expression "_Fex vini sicca_ called _tartarum_"--one of the earliest appearances of the latter term in this connection. The use of argol is very old, for Dioscorides (1st Century A.D.) not only describes argol, but also its reduction to impure potash. He says (V, 90): "The lees (_tryx_) are to be selected from old Italian wine; if not, from other similar wine. Lees of vinegar are much stronger. They are carefully dried and then burnt. There are some who burn them in a new earthen pot on a large fire until they are thoroughly incinerated. Others place a quantity of the lees on live coals and pursue the same method. The test as to whether it is completely burned, is that it becomes white or blue, and seems to burn the tongue when touched. The method of burning lees of vinegar is the same.... It should be used fresh, as it quickly grows stale; it should be placed in a vessel in a secluded place." Pliny (XXIII, 31) says: "Following these, come the lees of these various liquids. The lees of wine (_vini faecibus_) are so powerful as to be fatal to persons on descending into the vats. The test for this is to let down a lamp, which, if extinguished, indicates the peril.... Their virtues are greatly increased by the action of fire." Matthioli, commenting on this passage from Dioscorides in 1565, makes the following remark (p. 1375): "The precipitate of the wine which settles in the casks of the winery forms stone-like crusts, and is called by the works-people by the name _tartarum_." It will be seen above that these lees were rendered stronger by the action of fire, in which case the tartar was reduced to potassium carbonate. The _weinstein_ of the old German metallurgists was often the material lixiviated from the incinerated tartar.

Dried lees of vinegar (_siccae feces aceti_; _Interpretatio_, _die heffe des essigs_). This would also be crude tartar. Pliny (XXIII, 32) says: "The lees of vinegar (_faex aceti_); owing to the more acrid material are more aggravating in their effects.... When combined with _melanthium_ it heals the bites of dogs and crocodiles."

[16] Dried lees of _aqua_ which separates gold and silver. (_Siccae feces aquarum quae aurum ab argento secernunt_. German translation, _Der scheidwasser heffe_). There is no pointed description in Agricola's works, or in any other that we can find, as to what this material was. The "separating _aqua_" was undoubtedly nitric acid (see p. 439, Book X). There are two precipitates possible, both referred to as _feces_,--the first, a precipitate of silver chloride from clarifying the _aqua valens_, and the second, the residues left in making the acid by distillation. It is difficult to believe that silver chloride was the _feces_ referred to in the text, because such a precipitate would be obviously misleading when used as a flux through the addition of silver to the assays, too expensive, and of no merit for this purpose. Therefore one is driven to the conclusion that the _feces_ must have been the residues left in the retorts when nitric acid was prepared. It would have been more in keeping with his usual mode of expression, however, to have referred to this material as a _residuus_. The materials used for making acid varied greatly, so there is no telling what such a _feces_ contained. A list of possibilities is given in note 8, p. 443. In the main, the residue would be undigested vitriol, alum, saltpetre, salt, etc., together with potassium, iron, and alum sulphates. The _Probierbuechlin_ (p. 27) also gives this re-agent under the term _Toden kopff das ist schlam oder feces auss dem scheydwasser_.

[17] _Recrementum vitri_. (_Interpretatio_, _Glassgallen_). Formerly, when more impure materials were employed than nowadays, the surface of the mass in the first melting of glass materials was covered with salts, mostly potassium and sodium sulphates and chlorides which escaped perfect vitrification. This "slag" or "_glassgallen_" of Agricola was also termed _sandiver_.

[18] The whole of this expression is "_candidus, candido_." It is by no means certain that this is tin, for usually tin is given as _plumbum candidum_.

[19] _Sal artificiosus_. These are a sort of stock fluxes. Such mixtures are common in all old assay books, from the _Probierbuechlin_ to later than John Cramer in 1737 (whose Latin lectures on Assaying were published in English under the title of "Elements of the Art of Assaying Metals," London, 1741). Cramer observes (p. 51) that: "Artificers compose a great many fluxes with the above-mentioned salts and with the reductive ones; nay, some use as many different fluxes as there are different ores and metals; all which, however, we think needless to describe. It is better to have explained a few of the simpler ones, which serve for all the others, and are very easily prepared, than to tire the reader with confused compositions: and this chiefly because unskilled artificers sometimes attempt to obtain with many ingredients of the same nature heaped up beyond measure, and with much labour, though not more properly and more securely, what might have been easily effected, with one only and the same ingredient, thus increasing the number, not at all the virtue of the things employed. Nevertheless, if anyone loves variety, he may, according to the proportions and cautions above prescribed, at his will chuse among the simpler kinds such as will best suit his purpose, and compose a variety of fluxes with them."

[20] This operation apparently results in a coating to prevent the deflagration of the saltpetre--in fact, it might be permitted to translate _inflammatur_ "deflagrate," instead of kindle.

[21] The results which would follow from the use of these "fluxes" would obviously depend upon the ore treated. They can all conceivably be successful. Of these, the first is the lead-glass of the German assayers--a flux much emphasized by all old authorities, including Lohneys, Ercker and Cramner, and used even yet. The "powerful flux" would be a reducing, desulphurizing, and an acid flux. The "more powerful" would be a basic flux in which the reducing action of the argols would be largely neutralised by the nitre. The "still more powerful" would be a strongly sulphurizing basic flux, while the "most powerful" would be a still more sulphurizing flux, but it is badly mixed as to its oxidation and basic properties. (See also note 19 on _sal artificiosus_).

[22] Lead ash (_Cinis Plumbi_. Glossary, _Pleyasch_).--This was obviously, from the method of making, an artificial lead sulphide.

[23] Ashes of lead (_Nigri plumbi cinis_). This, as well as lead ash, was also an artificial lead sulphide. Such substances were highly valued by the Ancients for medicinal purposes. Dioscorides (V, 56) says: "Burned lead (_Molybdos cecaumenos_) is made in this way: Sprinkle sulphur over some very thinnest lead plates and put them into a new earthen pot, add other layers, putting sulphur between each layer until the pot is full; set it alight and stir the melted lead with an iron rod until it is entirely reduced to ashes and until none of the lead remains unburned. Then take it off, first stopping up your nose, because the fumes of burnt lead are very injurious. Or burn the lead filings in a pot with sulphur as aforesaid." Pliny (XXXIV., 50) gives much the same directions.

[24] Camphor (_camphora_). This was no doubt the well-known gum. Agricola, however, believed that camphor (_De Nat. Fossilium_, p. 224) was a species of bitumen, and he devotes considerable trouble to the refutation of the statements by the Arabic authors that it was a gum. In any event, it would be a useful reducing agent.

[25] Inasmuch as orpiment and realgar are both arsenical sulphides, the use of iron "slag," if it contains enough iron, would certainly matte the sulphur and arsenic. Sulphur and arsenic are the "juices" referred to (see note 4, p. 1). It is difficult to see the object of preserving the antimony with such a sulphurizing "addition," unless it was desired to secure a regulus of antimony alone from a given antimonial ore.

[26] The lead free from silver, called _villacense_, was probably from Bleyberg, not far from Villach in Upper Austria, this locality having been for centuries celebrated for its pure lead. These mines were worked prior to, and long after, Agricola's time.

[27] This method of proportionate weights for assay charges is simpler than the modern English "assay ton," both because of the use of 100 units in the standard of weight (the _centumpondium_), and because of the lack of complication between the Avoirdupois and Troy scales. For instance, an ore containing a _libra_ of silver to the _centumpondium_ would contain 1/100th part, and the same ratio would obtain, no matter what the actual weight of a _centumpondium_ of the "lesser weight" might be. To follow the matter still further, an _uncia_ being 1/1,200 of a _centumpondium_, if the ore ran one "_uncia_ of the lesser weight" to the "_centumpondium_ of the lesser weight," it would also run one actual _uncia_ to the actual _centumpondium_; it being a matter of indifference what might be the actual weight of the _centumpondium_ upon which the scale of lesser weights is based. In fact Agricola's statement (p. 261) indicates that it weighed an actual _drachma_. We have, in some places, interpolated the expressions "lesser" and "greater" weights for clarity.

This is not the first mention of this scheme of lesser weights, as it appears in the _Probierbuechlein_ (1500? see Appendix B) and Biringuccio (1540). For a more complete discussion of weights and measures see Appendix C. For convenience, we repeat here the Roman scale, although, as will be seen in the Appendix, Agricola used the Latin terms in many places merely as nomenclature equivalents of the old German scale.

Ozs. dwts. Troy gr. Grains. per short ton. 1 _Siliqua_ 2.87 Per _Centumpondium_ 0 3 9 6 _Siliquae_ = 1 _Scripulum_ 17.2 " " 1 0 6 4 _Scripula_ = 1 _Sextula_ 68.7 " " 4 1 0 6 _Sextulae_ = 1 _Uncia_ 412.2 " " 24 6 2 12 _Unciae_ = 1 _Libra_ 4946.4 " " 291 13 8 100 _Librae_ = 1 _Centumpondium_ 494640.0

However Agricola may occasionally use

16 _Unciae_ = 1 _Libra_ 6592.0 (?) 100 _Librae_ = 1 _Centumpondium_ 659200.0 (?)

Also

Oz. dwts. gr. per short ton. 1 _Scripulum_ 17.2 Per _Centumpondium_ 1 0 6 3 _Scripula_ = 1 _Drachma_ 51.5 " " 3 0 19 2 _Drachmae_ = 1 _Sicilicus_ 103.0 " " 6 1 15 4 _Sicilici_ = 1 _Uncia_ 412.2 " " 24 6 12 8 _Unciae_ = 1 _Bes_ 3297.6 " " 194 12 0

[28] The amalgamation of gold ores is fully discussed in note 12, p. 297.

[29] For discussion of the silver ores, see note 8, p. 108. _Rudis_ silver was a fairly pure silver mineral, the various coloured silvers were partly horn-silver and partly alteration products.

[30] It is difficult to see why copper scales (_squamae aeris_--copper oxide?) are added, unless it be to collect a small ratio of copper in the ore. This additional copper is not mentioned again, however. The whole of this statement is very confused.

[31] This old story runs that Hiero, King of Syracuse, asked Archimedes to tell him whether a crown made for him was pure gold or whether it contained some proportion of silver. Archimedes is said to have puzzled over it until he noticed the increase in water-level upon entering his bath. Whereupon he determined the matter by immersing bars of pure gold and pure silver, and thus determining the relative specific weights. The best ancient account of this affair is to be found in Vitruvius, IX, Preface. The story does not seem very probable, seeing that Theophrastus, who died the year Archimedes was born, described the touchstone in detail, and that it was of common knowledge among the Greeks before (see note 37). In any event, there is not sufficient evidence in this story on which to build the conclusion of Meyer (Hist. of Chemistry, p. 14) and others, that, inasmuch as Archimedes was unable to solve the problem until his discovery of specific weights, therefore the Ancients could not part gold and silver. The probability that he did not want to injure the King's jewellery would show sufficient reason for his not parting these metals. It seems probable that the Ancients did part gold and silver by cementation. (See note on p. 458).

[32] The Alchemists (with whose works Agricola was familiar--_vide_ preface) were the inventors of nitric acid separation. (See note on p. 460).

[33] Parting gold and silver by nitric acid is more exhaustively discussed in Book X. and note 10, p. 443.

[34] The lesser weights, probably.

[35] Lead and Tin seem badly mixed in this paragraph.

[36] It is not clear what is added.

[37] HISTORICAL NOTE ON TOUCHSTONE. (_Coticula_. _Interpretatio_,--_Goldstein_). Theophrastus is, we believe, the first to describe the touchstone, although it was generally known to the Greeks, as is evidenced by the metaphors of many of the poets,--Pindar, Theognis, Euripides, etc. The general knowledge of the constituents of alloys which is implied, raises the question as to whether the Greeks did not know a great deal more about parting metals, than has been attributed to them. Theophrastus says (78-80): "The nature of the stone which tries gold is also very wonderful, as it seems to have the same power with fire; which is also a test of that metal. Some people have for this reason questioned the truth of this power in the stone, but their doubts are ill-founded, for this trial is not of the same nature or made in the same manner as the other. The trial by fire is by the colour and by the quantity lost by it; but that by the stone is made only by rubbing the metal on it; the stone seeming to have the power to receive separately the distinct particles of different metals. It is said also that there is a much better kind of this stone now found out, than that which was formerly used; insomuch that it now serves not only for the trial of refined gold, but also of copper or silver coloured with gold; and shows how much of the adulterating matter by weight is mixed with gold; this has signs which it yields from the smallest weight of the adulterating matter, which is a grain, from thence a colybus, and thence a quadrans or semi-obolus, by which it is easy to distinguish if, and in what degree, that metal is adulterated. All these stones are found in the River Tmolus; their texture is smooth and like that of pebbles; their figure broad, not round; and their bigness twice that of the common larger sort of pebbles. In their use in the trial of metals there is a difference in power between their upper surface, which has lain toward the sun, and their under, which has been to the earth; the upper performing its office the more nicely; and this is consonant to reason, as the upper part is dryer; for the humidity of the other surface hinders its receiving so well the particles of metals; for the same reason also it does not perform its office as well in hot weather as in colder, for in the hot it emits a kind of humidity out of its substance, which runs all over it. This hinders the metalline particles from adhering perfectly, and makes mistakes in the trials. This exudation of a humid matter is also common to many other stones, among others, to those of which statues are made; and this has been looked on as peculiar to the statue." (Based on Hill's trans.) This humid "exudation of fine-grained stones in summer" would not sound abnormal if it were called condensation. Pliny (XXXIII, 43) says: "The mention of gold and silver should be accompanied by that of the stone called _coticula_. Formerly, according to Theophrastus, it was only to be found in the river Tmolus but now found in many parts, it was found in small pieces never over four inches long by two broad. That side which lay toward the sun is better than that toward the ground. Those experienced with the _coticula_ when they rub ore (_vena_) with it, can at once say how much gold it contains, how much silver or copper. This method is so accurate that they do not mistake it to a scruple." This purported use for determining values of _ore_ is of about Pliny's average accuracy. The first detailed account of touch-needles and their manner of making, which we have been able to find, is that of the _Probierbuechlein_ (1527? see Appendix) where many of the tables given by Agricola may be found.

[38] _De Natura Fossilium_ (p. 267) and _De Ortu et Causis Subterraneorum_ (p. 59). The author does not add any material mineralogical information to the quotations from Theophrastus and Pliny given above.

[39] In these tables Agricola has simply adopted Roman names as equivalents of the old German weights, but as they did not always approximate in proportions, he coined terms such as "units of 4 _siliquae_," etc. It might seem more desirable to have introduced the German terms into this text, but while it would apply in this instance, as we have discussed on p. 259, the actual values of the Roman weights are very different from the German, and as elsewhere in the book actual Roman weights are applied, we have considered it better to use the Latin terms consistently throughout. Further, the obsolete German would be to most readers but little improvement upon the Latin. For convenience of readers we set out the various scales as used by Agricola, together with the German:--

ROMAN SCALE. OLD GERMAN SCALE. 6 _Siliquae_ = 1 _Scripulum_ 3 _Grenlin_ = 1 _Gran_ 4 _Scripula_ = 1 _Sextula_ 4 _Gran_ = 1 _Krat_ 2 _Sextulae_ = 1 _Duella_ 24 _Kratt_ = 1 _Mark_ 24 _Duellae_ = 1 _Bes_ or 24 _Grenlin_ = 1 "_Nummus_" 12 "_Nummi_" = 1 _Mark_

Also the following scales are applied to fineness by Agricola:--

3 _Scripula_ = 1 _Drachma_ 4 _Pfennige_ = 1 _Quintlein_ 2 _Drachmae_ = 1 _Sicilicus_ 4 _Quintlein_ = 1 _Loth_ 2 _Sicilici_ = 1 _Semuncia_ 16 _Loth_ = 1 _Mark_ 16 _Semunciae_ = 1 _Bes_

The term "_nummus_," a coin, given above and in the text, appears in the German translation as _pfennig_ as applied to both German scales, but as they are of different values, we have left Agricola's adaptation in one scale to avoid confusion. The Latin terms adopted by Agricola are given below, together with the German:--

Number in one Value in Roman Term. German Term. Mark or Bes. _Siliquae_.

_Siliqua_ 1152 1

"Unit of 4 _Siliquae_" _Grenlin_ 288 4

_Pfennig_ 256 --

_Scripulum_ _Scruple_ (?) 192 6

_Semi-sextula_ _Gran_ 96 12

_Drachma_ _Quintlein_ 64 18

_Sextula_ _Halb Krat_ 48 24

_Sicilicus_ _Halb Loth_ 32 36

_Duella_ _Krat_ 24 48

_Semuncia_ _Loth_ 16 72

"_Unit of 5 Drachmae "_Nummus_" 12 96 & 1 Scripulum_"

_Uncia_ _Untzen_ 8 144

_Bes_ _Mark_ 1 1152

While the proportions in a _bes_ or _mark_ are the same in both scales, the actual weight values are vastly different--for instance, the _mark_ contained about 3609.6, and the _bes_ 3297 Troy Grains. Agricola also uses:

_Selibra_ _Halb-pfundt_ _Libra_ _Pfundt_ _Centumpondium_ _Centner_.

As the Roman _libra_ contains 12 _unciae_ and the German _pfundt_ 16 _untzen_, the actual weights of these latter quantities are still further apart--the former 4946 and the latter 7219 Troy grains.

[40] There are no tables in the Latin text, the whole having been written out _in extenso_, but they have now been arranged as above, as being in a much more convenient and expressive form.

[41] See note 39 above.

[42] See note 27, p. 242, for discussion of this "Assay ton" arrangement.

[43] _Agrippinenses_ and _Antuerpiani_.

## BOOK VIII.

Questions of assaying were explained in the last Book, and I have now come to a greater task, that is, to the description of how we extract the metals. First of all I will explain the method of preparing the ore[1]; for since Nature usually creates metals in an impure state, mixed with earth, stones, and solidified juices, it is necessary to separate most of these impurities from the ores as far as can be, before they are smelted, and therefore I will now describe the methods by which the ores are sorted, broken with hammers, burnt, crushed with stamps, ground into powder, sifted, washed, roasted, and calcined[2].

I will start at the beginning with the first sort of work. Experienced miners, when they dig the ore, sort the metalliferous material from earth, stones, and solidified juices before it is taken from the shafts and tunnels, and they put the valuable metal in trays and the waste into buckets. But if some miner who is inexperienced in mining matters has omitted to do this, or even if some experienced miner, compelled by some unavoidable necessity, has been unable to do so, as soon as the material which has been dug out has been removed from the mine, all of it should be examined, and that part of the ore which is rich in metal sorted from that part of it which is devoid of metal, whether such part be earth, or solidified juices, or stones. To smelt waste together with an ore involves a loss, for some expenditure is thrown away, seeing that out of earth and stones only empty and useless slags are melted out, and further, the solidified juices also impede the smelting of the metals and cause loss. The rock which lies contiguous to rich ore should also be broken into small pieces, crushed, and washed, lest any of the mineral should be lost. When, either through ignorance or carelessness, the miners while excavating have mixed the ore with earth or broken rock, the work of sorting the crude metal or the best ore is done not only by men, but also by boys and women. They throw the mixed material upon a long table, beside which they sit for almost the whole day, and they sort out the ore; when it has been sorted out, they collect it in trays, and when collected they throw it into tubs, which are carried to the works in which the ores are smelted.

[Illustration 268 (Sorting Ore): A--Long table. B--Tray. C--Tub.]

[Illustration 269 (Cutting Metal): A--Masses of metal. B--Hammer. C--Chisel. D--Tree stumps. E--Iron tool similar to a pair of shears.]

The metal which is dug out in a pure or crude state, to which class belong native silver, silver glance, and gray silver, is placed on a stone by the mine foreman and flattened out by pounding with heavy square hammers. These masses, when they have been thus flattened out like plates, are placed either on the stump of a tree, and cut into pieces by pounding an iron chisel into them with a hammer, or else they are cut with an iron tool similar to a pair of shears. One blade of these shears is three feet long, and is firmly fixed in a stump, and the other blade which cuts the metal is six feet long. These pieces of metal are afterward heated in iron basins and smelted in the cupellation furnace by the smelters.

[Illustration 270 (Spalling Ore): A--Tables. B--Upright planks. C--Hammer. D--Quadrangular hammer. E--Deeper vessel. F--Shallower vessel. G--Iron rod.]

Although the miners, in the shafts or tunnels, have sorted over the material which they mine, still the ore which has been broken down and carried out must be broken into pieces by a hammer or minutely crushed, so that the more valuable and better parts can be distinguished from the inferior and worthless portions. This is of the greatest importance in smelting ore, for if the ore is smelted without this separation, the valuable part frequently receives great damage before the worthless part melts in the fire, or else the one consumes the other; this latter difficulty can, however, be partly avoided by the exercise of care and

## partly by the use of fluxes. Now, if a vein is of poor quality, the

better portions which have been broken down and carried out should be thrown together in one place, and the inferior portion and the rock thrown away. The sorters place a hard broad stone on a table; the tables are generally four feet square and made of joined planks, and to the edge of the sides and back are fixed upright planks, which rise about a foot from the table; the front, where the sorter sits, is left open. The lumps of ore, rich in gold or silver, are put by the sorters on the stone and broken up with a broad, but not thick, hammer; they either break them into pieces and throw them into one vessel, or they break and sort--whence they get their name--the more precious from the worthless, throwing and collecting them separately into different vessels. Other men crush the lumps of ore less rich in gold or silver, which have likewise been put on the stone, with a broad thick hammer, and when it has been well crushed, they collect it and throw it into one vessel. There are two kinds of vessels; one is deeper, and a little wider in the centre than at the top or bottom; the other is not so deep though it is broader at the bottom, and becomes gradually a little narrower toward the top. The latter vessel is covered with a lid, while the former is not covered; an iron rod through the handles, bent over on either end, is grasped in the hand when the vessel is carried. But, above all, it behooves the sorters to be assiduous in their labours.

[Illustration 271 (Spalling Ore): A--Pyrites. B--Leggings. C--Gloves. D--Hammer.]

By another method of breaking ore with hammers, large hard fragments of ore are broken before they are burned. The legs of the workmen--at all events of those who crush pyrites in this manner with large hammers in Goslar--are protected with coverings resembling leggings, and their hands are protected with long gloves, to prevent them from being injured by the chips which fly away from the fragments.

[Illustration 272 (Spalling Ore): A--Area paved with stones. B--Broken ore. C--Area covered with broken ore. D--Iron tool. E--Its handle. F--Broom. G--Short strake. H--Wooden hoe.]

In that district of Greater Germany which is called Westphalia and in that district of Lower Germany which is named Eifel, the broken ore which has been burned, is thrown by the workmen into a round area paved with the hardest stones, and the fragments are pounded up with iron tools, which are very much like hammers in shape and are used like threshing sledges. This tool is a foot long, a palm wide, and a digit thick, and has an opening in the middle just as hammers have, in which is fixed a wooden handle of no great thickness, but up to three and a half feet long, in order that the workmen can pound the ore with greater force by reason of its weight falling from a greater height. They strike and pound with the broad side of the tool, in the same way as corn is pounded out on a threshing floor with the threshing sledges, although the latter are made of wood and are smooth and fixed to poles. When the ore has been broken into small pieces, they sweep it together with brooms and remove it to the works, where it is washed in a short strake, at the head of which stands the washer, who draws the water upward with a wooden hoe. The water running down again, carries all the light particles into a trough placed underneath. I shall deal more fully with this method of washing a little later.

Ore is burned for two reasons; either that from being hard, it may become soft and more easily broken and more readily crushed with a hammer or stamps, and then can be smelted; or that the fatty things, that is to say, sulphur, bitumen, orpiment, or realgar[3] may be consumed. Sulphur is frequently found in metallic ores, and, generally speaking, is more harmful to the metals, except gold, than are the other things. It is most harmful of all to iron, and less to tin than to bismuth, lead, silver, or copper. Since very rarely gold is found in which there is not some silver, even gold ores containing sulphur ought to be roasted before they are smelted, because, in a very vigorous furnace fire, sulphur resolves metal into ashes and makes slag of it. Bitumen acts in the same way, in fact sometimes it consumes silver, which we may see in bituminous _cadmia_[4].

[Illustration 274 (Stall Roasting Ore): A--Area. B--Wood. C--Ore. D--Cone-shaped piles. E--Canal.]

I now come to the methods of roasting, and first of all to that one which is common to all ores. The earth is dug out to the required extent, and thus is made a quadrangular area of fair size, open at the front, and above this, firewood is laid close together, and on it other wood is laid transversely, likewise close together, for which reason our countrymen call this pile of wood a crate; this is repeated until the pile attains a height of one or two cubits. Then there is placed upon it a quantity of ore that has been broken into small pieces with a hammer; first the largest of these pieces, next those of medium size, and lastly the smallest, and thus is built up a gently sloping cone. To prevent it from becoming scattered, fine sand of the same ore is soaked with water and smeared over it and beaten on with shovels; some workers, if they cannot obtain such fine sand, cover the pile with charcoal-dust, just as do charcoal-burners. But at Goslar, the pile, when it has been built up in the form of a cone, is smeared with _atramentum sutorium rubrum_[5], which is made by the leaching of roasted pyrites soaked with water. In some districts the ore is roasted once, in others twice, in others three times, as its hardness may require. At Goslar, when pyrites is roasted for the third time, that which is placed on the top of the pyre exudes a certain greenish, dry, rough, thin substance, as I have elsewhere written[6]; this is no more easily burned by the fire than is asbestos. Very often also, water is put on to the ore which has been roasted, while it is still hot, in order to make it softer and more easily broken; for after fire has dried up the moisture in the ore, it breaks up more easily while it is still hot, of which fact burnt limestone affords the best example.

[Illustration 275 (Heap Roasting Ore): A--Lighted pyre. B--Pyre which is being constructed. C--Ore. D--Wood. E--Pile of the same wood.]

By digging out the earth they make the areas much larger, and square; walls should be built along the sides and back to hold the heat of the fire more effectively, and the front should be left open. In these compartments tin ore is roasted in the following manner. First of all wood about twelve feet long should be laid in the area in four layers, alternately straight and transverse. Then the larger pieces of ore should be laid upon them, and on these again the smaller ones, which should also be placed around the sides; the fine sand of the same ore should also be spread over the pile and pounded with shovels, to prevent the pile from falling before it has been roasted; the wood should then be fired.

[Illustration 276 (Stall Roasting Ore): A--Burning pyre which is composed of lead ore with wood placed above it. B--Workman throwing ore into another area. C--Oven-shaped furnace. D--Openings through which the smoke escapes.]

Lead ore, if roasting is necessary, should be piled in an area just like the last, but sloping, and the wood should be placed over it. A tree trunk should be laid right across the front of the ore to prevent it from falling out. The ore, being roasted in this way, becomes partly melted and resembles slag. Thuringian pyrites, in which there is gold, sulphur, and vitriol, after the last particle of vitriol has been obtained by heating it in water, is thrown into a furnace, in which logs are placed. This furnace is very similar to an oven in shape, in order that when the ore is roasted the valuable contents may not fly away with the smoke, but may adhere to the roof of the furnace. In this way sulphur very often hangs like icicles from the two openings of the roof through which the smoke escapes.

[Illustration 277 (Hearths for roasting): A--Iron plates full of holes. B--Walls. C--Plate on which ore is placed. D--Burning charcoal placed on the ore. E--Pots. F--Furnace. G--Middle part of upper chamber. H--The other two compartments. I--Divisions of the lower chamber. K--Middle wall. L--Pots which are filled with ore. M--Lids of same pots. N--Grating.]

If pyrites or _cadmia_, or any other ore containing metal, possesses a good deal of sulphur or bitumen, it should be so roasted that neither is lost. For this purpose it is thrown on an iron plate full of holes, and roasted with charcoal placed on top; three walls support this plate, two on the sides and the third at the back. Beneath the plate are placed pots containing water, into which the sulphurous or bituminous vapour descends, and in the water the fat accumulates and floats on the top. If it is sulphur, it is generally of a yellow colour; if bitumen, it is black like pitch. If these were not drawn out they would do much harm to the metal, when the ore is being smelted. When they have thus been separated they prove of some service to man, especially the sulphurous kind. From the vapour which is carried down, not into the water, but into the ground, there is created a sulphurous or a bituminous substance resembling _pompholyx_[7], and so light that it can be blown away with a breath. Some employ a vaulted furnace, open at the front and divided into two chambers. A wall built in the middle of the furnace divides the lower chamber into two equal parts, in which are set pots containing water, as above described. The upper chamber is again divided into three parts, the middle one of which is always open, for in it the wood is placed, and it is not broader than the middle wall, of which it forms the topmost portion. The other two compartments have iron doors which are closed, and which, together with the roof, keep in the heat when the wood is lighted. In these upper compartments are iron bars which take the place of a floor, and on these are arranged pots without bottoms, having in place of a bottom, a grating made of iron wire, fixed to each, through the openings of which the sulphurous or bituminous vapours roasted from the ore run into the lower pots. Each of the upper pots holds a hundred pounds of ore; when they are filled they are covered with lids and smeared with lute.

[Illustration 278 (Heap Roasting): A--Heap of cupriferous stones. B--Kindled heap. C--Stones being taken to the beds of faggots.]

In Eisleben and the neighbourhood, when they roast the schistose stone from which copper is smelted, and which is not free from bitumen, they do not use piles of logs, but bundles of faggots. At one time, they used to pile this kind of stone, when extracted from the pit, on bundles of faggots and roast it by firing the faggots; nowadays, they first of all carry these same stones to a heap, where they are left to lie for some time in such a way as to allow the air and rain to soften them. Then they make a bed of faggot bundles near the heap, and carry the nearest stones to this bed; afterward they again place bundles of faggots in the empty place from which the first stones have been removed, and pile over this extended bed, the stones which lay nearest to the first lot; and they do this right up to the end, until all the stones have been piled mound-shape on a bed of faggots. Finally they fire the faggots, not, however, on the side where the wind is blowing, but on the opposite side, lest the fire blown up by the force of the wind should consume the faggots before the stones are roasted and made soft; by this method the stones which are adjacent to the faggots take fire and communicate it to the next ones, and these again to the adjoining ones, and in this way the heap very often burns continuously for thirty days or more. This schist rock when rich in copper, as I have said elsewhere, exudes a substance of a nature similar to asbestos.

[Illustration 284 (Stamp-mill): A--Mortar. B--Upright posts. C--Cross-beams. D--Stamps. E--Their heads. F--Axle (cam-shaft). G--Tooth of the stamp (tappet). H--Teeth of axle (cams).]

Ore is crushed with iron-shod stamps, in order that the metal may be separated from the stone and the hangingwall rock.[8] The machines which miners use for this purpose are of four kinds, and are made by the following method. A block of oak timber six feet long, two feet and a palm square, is laid on the ground. In the middle of this is fixed a mortar-box, two feet and six digits long, one foot and six digits deep; the front, which might be called a mouth, lies open; the bottom is covered with a plate of iron, a palm thick and two palms and as many digits wide, each end of which is wedged into the timber with broad wedges, and the front and back part of it are fixed to the timber with iron nails. To the sides of the mortar above the block are fixed two upright posts, whose upper ends are somewhat cut back and are mortised to the timbers of the building. Two and a half feet above the mortar are placed two cross-beams joined together, one in front and one in the back, the ends of which are mortised into the upright posts already mentioned. Through each mortise is bored a hole, into which is driven an iron clavis; one end of the clavis has two horns, and the other end is perforated in order that a wedge driven through, binds the beams more firmly; one horn of the clavis turns up and the other down. Three and a half feet above the cross-beams, two other cross-beams of the same kind are again joined in a similar manner; these cross-beams have square openings, in which the iron-shod stamps are inserted. The stamps are not far distant from each other, and fit closely in the cross-beams. Each stamp has a tappet at the back, which requires to be daubed with grease on the lower side that it can be raised more easily. For each stamp there are on a cam-shaft, two cams, rounded on the outer end, which alternately raise the stamp, in order that, by its dropping into the mortar, it may with its iron head pound and crush the rock which has been thrown under it. To the cam-shaft is fixed a water-wheel whose buckets are turned by water-power. Instead of doors, the mouth of the mortar has a board, which is fitted into notches cut out of the front of the block. This board can be raised, in order that when the mouth is open, the workmen can remove with a shovel the fine sand, and likewise the coarse sand and broken rock, into which the rocks have been crushed; this board can be lowered, so that the mouth thus being closed, the fresh rock thrown in may be crushed with the iron-shod stamps. If an oak block is not available, two timbers are placed on the ground and joined together with iron clamps, each of the timbers being six feet long, a foot wide, and a foot and a half thick. Such depth as should be allowed to the mortar, is obtained by cutting out the first beam to a width of three-quarters of a foot and to a length of two and a third and one twenty-fourth of a foot. In the bottom of the part thus dug out, there should be laid a very hard rock, a foot thick and three-quarters of a foot wide; about it, if any space remains, earth or sand should be filled in and pounded. On the front, this bed rock is covered with a plank; this rock when it has been broken, should be taken away and replaced by another. A smaller mortar having room for only three stamps may also be made in the same manner.

[Illustration 285 (Stamps): A--Stamp. B--Stem cut out in lower part. C--Shoe. D--The other shoe, barbed and grooved. E--Quadrangular iron band. F--Wedge. G--Tappet. H--Angular cam-shaft. I--Cams. K--Pair of compasses.]

The stamp-stems are made of small square timbers nine feet long and half a foot wide each way. The iron head of each is made in the following way; the lower part of the head is three palms long and the upper part the same length. The lower part is a palm square in the middle for two palms, then below this, for a length of two digits it gradually spreads until it becomes five digits square; above the middle part, for a length of two digits, it again gradually swells out until it becomes a palm and a half square. Higher up, where the head of the shoe is enclosed in the stem, it is bored through and similarly the stem itself is pierced, and through the opening of each, there passes a broad iron wedge, which prevents the head falling off the stem. To prevent the stamp head from becoming broken by the constant striking of fragments of ore or rocks, there is placed around it a quadrangular iron band a digit thick, seven digits wide, and six digits deep. Those who use three stamps, as is common, make them much larger, and they are made square and three palms broad each way; then the iron shoe of each has a total length of two feet and a palm; at the lower end, it is hexagonal, and at that point it is seven digits wide and thick. The lower part of it which projects beyond the stem is one foot and two palms long; the upper part, which is enclosed in the stem, is three palms long; the lower part is a palm wide and thick; then gradually the upper part becomes narrower and thinner, so that at the top it is three digits and a half wide and two thick. It is bored through at the place where the angles have been somewhat cut away; the hole is three digits long and one wide, and is one digit's distance from the top. There are some who make that part of the head which is enclosed in the stem, barbed and grooved, in order that when the hooks have been fixed into the stem and wedges fitted to the grooves, it may remain tightly fixed, especially when it is also held with two quadrangular iron bands. Some divide the cam-shaft with a compass into six sides, others into nine; it is better for it to be divided into twelve sides, in order that successively one side may contain a cam and the next be without one.

[Illustration 286 (Stamp-mill): A--Box. Although the upper part is not open, it is shown open here, that the wheel may be seen. B--Wheel. C--Cam-shaft. D--Stamps.]

The water-wheel is entirely enclosed under a quadrangular box, in case either the deep snows or ice in winter, or storms, may impede its running and its turning around. The joints in the planks are stopped all around with moss. The cover, however, has one opening, through which there passes a race bringing down water which, dropping on the buckets of the wheel, turns it round, and flows out again in the lower race under the box. The spokes of the water-wheel are not infrequently mortised into the middle of the cam-shaft; in this case the cams on both sides raise the stamps, which either both crush dry or wet ore, or else the one set crushes dry ore and the other set wet ore, just as circumstances require the one or the other; further, when the one set is raised and the iron clavises in them are fixed into openings in the first cross-beam, the other set alone crushes the ore.

[Illustration 287 (Handling stamped material): A--Box laid flat on the ground. B--Its bottom which is made of iron wire. C--Box inverted. D--Iron rods. E--Box suspended from a beam, the inside being visible. F--Box suspended from a beam, the outside being visible.]

Broken rock or stones, or the coarse or fine sand, are removed from the mortar of this machine and heaped up, as is also done with the same materials when raked out of the dump near the mine. They are thrown by a workman into a box, which is open on the top and the front, and is three feet long and nearly a foot and a half wide. Its sides are sloping and made of planks, but its bottom is made of iron wire netting, and fastened with wire to two iron rods, which are fixed to the two side planks. This bottom has openings, through which broken rock of the size of a hazel nut cannot pass; the pieces which are too large to pass through are removed by the workman, who again places them under stamps, while those which have passed through, together with the coarse and fine sand, he collects in a large vessel and keeps for the washing. When he is performing his laborious task he suspends the box from a beam by two ropes. This box may rightly be called a quadrangular sieve, as may also that kind which follows.

[Illustration 288 (Sifting Ore): A--Sieve. B--Small planks. C--Post. D--Bottom of sieve. E--Open box. F--Small cross-beam. G--Upright posts.]

Some employ a sieve shaped like a wooden bucket, bound with two iron hoops; its bottom, like that of the box, is made of iron wire netting. They place this on two small cross-planks fixed upon a post set in the ground. Some do not fix the post in the ground, but stand it on the ground until there arises a heap of the material which has passed through the sieve, and in this the post is fixed. With an iron shovel the workman throws into this sieve broken rock, small stones, coarse and fine sand raked out of the dump; holding the handles of the sieve in his hands, he agitates it up and down in order that by this movement the dust, fine and coarse sand, small stones, and fine broken rock may fall through the bottom. Others do not use a sieve, but an open box, whose bottom is likewise covered with wire netting; this they fix on a small cross-beam fastened to two upright beams and tilt it backward and forward.

[Illustration 289 (Sifting Ore): A--Box. B--Bale. C--Rope. D--Beam. E--Handles. F--Five-toothed rake. G--Sieve. H--Its handles. I--Pole. K--Rope. L--Timber.]

Some use a sieve made of copper, having square copper handles on both sides, and through these handles runs a pole, of which one end projects three-quarters of a foot beyond one handle; the workman then places that end in a rope which is suspended from a beam, and rapidly shakes the pole alternately backward and forward. By this movement the small

## particles fall through the bottom of the sieve. In order that the end of

the pole may be easily placed in the rope, a stick, two palms long, holds open the lower part of the rope as it hangs double, each end of the rope being tied to the beam; part of the rope, however, hangs beyond the stick to a length of half a foot. A large box is also used for this purpose, of which the bottom is either made of a plank full of holes or of iron netting, as are the other boxes. An iron bale is fastened from the middle of the planks which form its sides; to this bale is fastened a rope which is suspended from a wooden beam, in order that the box may be moved or tilted in any direction. There are two handles on each end, not unlike the handles of a wheelbarrow; these are held by two workmen, who shake the box to and fro. This box is the one principally used by the Germans who dwell in the Carpathian mountains. The smaller particles are separated from the larger ones by means of three boxes and two sieves, in order that those which pass through each, being of equal size, may be washed together; for the bottoms of both the boxes and sieves have openings which do not let through broken rock of the size of a hazel nut. As for the dry remnants in the bottoms of the sieves, if they contain any metal the miners put them under the stamps. The larger pieces of broken rock are not separated from the smaller by this method until the men and boys, with five-toothed rakes, have separated them from the rock fragments, the little stones, the coarse and the fine sand and earth, which have been thrown on to the dumps.

[Illustration 291 (Sifting Ore): A--Workman carrying broken rock in a barrow. B--First chute. C--First box. D--Its handles. E--Its bales. F--Rope. G--Beam. H--Post. I--Second chute. K--Second box. L--Third chute. M--Third box. N--First table. O--First sieve. P--First tub. Q--Second table. R--Second sieve. S--Second tub. T--Third table. V--Third sieve. X--Third tub. Y--Plugs.]

At Neusohl, in the Carpathians, there are mines where the veins of copper lie in the ridges and peaks of the mountains, and in order to save expense being incurred by a long and difficult transport, along a rough and sometimes very precipitous road, one workman sorts over the dumps which have been thrown out from the mines, and another carries in a wheelbarrow the earth, fine and coarse sand, little stones, broken rock, and even the poorer ore, and overturns the barrow into a long open chute fixed to a steep rock. This chute is held apart by small cleats, and the material slides down a distance of about one hundred and fifty feet into a short box, whose bottom is made of a thick copper plate, full of holes. This box has two handles by which it is shaken to and fro, and at the top there are two bales made of hazel sticks, in which is fixed the iron hook of a rope hung from the branch of a tree or from a wooden beam which projects from an upright post. From time to time a sifter pulls this box and thrusts it violently against the tree or post, by which means the small particles passing through its holes descend down another chute into another short box, in whose bottom there are smaller holes. A second sifter, in like manner, thrusts this box violently against a tree or post, and a second time the smaller

## particles are received into a third chute, and slide down into a third

box, whose bottom has still smaller holes. A third sifter, in like manner, thrusts this box violently against a tree or post, and for the third time the tiny particles fall through the holes upon a table. While the workman is bringing in the barrow, another load which has been sorted from the dump, each sifter withdraws the hooks from his bale and carries away his own box and overturns it, heaping up the broken rock or sand which remains in the bottom of it. As for the tiny particles which have slid down upon the table, the first washer--for there are as many washers as sifters--sweeps them off and in a tub nearly full of water, washes them through a sieve whose holes are smaller than the holes of the third box. When this tub has been filled with the material which has passed through the sieve, he draws out the plug to let the water run away; then he removes with a shovel that which has settled in the tub and throws it upon the table of a second washer, who washes it in a sieve with smaller holes. The sediment which has this time settled in his tub, he takes out and throws on the table of a third washer, who washes it in a sieve with the smallest holes. The copper concentrates which have settled in the last tub are taken out and smelted; the sediment which each washer has removed with a limp is washed on a canvas strake. The sifters at Altenberg, in the tin mines of the mountains bordering on Bohemia, use such boxes as I have described, hung from wooden beams. These, however, are a little larger and open in the front, through which opening the broken rock which has not gone through the sieve can be shaken out immediately by thrusting the sieve against its post.

[Illustration 292 (Sifting Ore): A--Sieve. B--Its handles. C--Tub. D--Bottom of sieve made of iron wires. E--Hoop. F--Rods. G--Hoops. H--Woman shaking the sieve. I--Boy supplying it with material which requires washing. K--Man with shovel removing from the tub the material which has passed through the sieve.]

If the ore is rich in metal, the earth, the fine and coarse sand, and the pieces of rock which have been broken from the hangingwall, are dug out of the dump with a spade or rake and, with a shovel, are thrown into a large sieve or basket, and washed in a tub nearly full of water. The sieve is generally a cubit broad and half a foot deep; its bottom has holes of such size that the larger pieces of broken rock cannot pass through them, for this material rests upon the straight and cross iron wires, which at their points of contact are bound by small iron clips. The sieve is held together by an iron band and by two cross-rods likewise of iron; the rest of the sieve is made of staves in the shape of a little tub, and is bound with two iron hoops; some, however, bind it with hoops of hazel or oak, but in that case they use three of them. On each side it has handles, which are held in the hands by whoever washes the metalliferous material. Into this sieve a boy throws the material to be washed, and a woman shakes it up and down, turning it alternately to the right and to the left, and in this way passes through it the smaller pieces of earth, sand, and broken rock. The larger pieces remain in the sieve, and these are taken out, placed in a heap and put under the stamps. The mud, together with fine sand, coarse sand, and broken rock, which remain after the water has been drawn out of the tub, is removed by an iron shovel and washed in the sluice, about which I will speak a little later.

[Illustration 293 (Sifting Ore): A--Basket. B--Its handles. C--Dish. D--Its back part. E--Its front part. F--Handles of same.]

The Bohemians use a basket a foot and a half broad and half a foot deep, bound together by osiers. It has two handles by which it is grasped, when they move it about and shake it in the tub or in a small pool nearly full of water. All that passes through it into the tub or pool they take out and wash in a bowl, which is higher in the back part and lower and flat in the front; it is grasped by the two handles and shaken in the water, the lighter particles flowing away, and the heavier and mineral portion sinking to the bottom.

[Illustration 294 (Mills for Grinding Ore): A--Axle. B--Water-wheel. C--Toothed drum. D--Drum made of rundles. E--Iron axle. F--Millstone. G--Hopper. H--Round wooden plate. I--Trough.]

Gold ore, after being broken with hammers or crushed by the stamps, and even tin ore, is further milled to powder. The upper millstone, which is turned by water-power, is made in the following way. An axle is rounded to compass measure, or is made angular, and its iron pinions turn in iron sockets which are held in beams. The axle is turned by a water-wheel, the buckets of which are fixed to the rim and are struck by the force of a stream. Into the axle is mortised a toothed drum, whose teeth are fixed in the side of the rim. These teeth turn a second drum of rundles, which are made of very hard material. This drum surrounds an iron axle which has a pinion at the bottom and revolves in an iron cup in a timber. At the top of the iron axle is an iron tongue, dove-tailed into the millstone, and so when the teeth of the one drum turn the rundles of the other, the millstone is made to turn round. An overhanging machine supplies it with ore through a hopper, and the ore, being ground to powder, is discharged from a round wooden plate into a trough and flowing away through it accumulates on the floor; from there the ore is carried away and reserved for washing. Since this method of grinding requires the millstone to be now raised and now lowered, the timber in whose socket the iron of the pinion axle revolves, rests upon two beams, which can be raised and lowered.

[Illustration 296 (Mills for Grinding Ore): A--First mill. B--Wheel turned by goats. C--Second mill. D--Disc of upright axle. E--Its toothed drum. F--Third mill. G--Shape of lower millstone. H--Small upright axle of the same. I--Its opening. K--Lever of the upper millstone. L--Its opening.]

There are three mills in use in milling gold ores, especially for quartz[11] which is not lacking in metal. They are not all turned by water-power, but some by the strength of men, and two of them even by the power of beasts of burden. The first revolving one differs from the next only in its driving wheel, which is closed in and turned by men treading it, or by horses, which are placed inside, or by asses, or even by strong goats; the eyes of these beasts are covered by linen bands. The second mill, both when pushed and turned round, differs from the two above by having an upright axle in the place of the horizontal one; this axle has at its lower end a disc, which two workmen turn by treading back its cleats with their feet, though frequently one man sustains all the labour; or sometimes there projects from the axle a pole which is turned by a horse or an ass, for which reason it is called an _asinaria_. The toothed drum which is at the upper end of the axle turns the drum which is made of rundles, and together with it the millstone.

The third mill is turned round and round, and not pushed by hand; but between this and the others there is a great distinction, for the lower millstone is so shaped at the top that it can hold within it the upper millstone, which revolves around an iron axle; this axle is fastened in the centre of the lower stone and passes through the upper stone. A workman, by grasping in his hand an upright iron bar placed in the upper millstone, moves it round. The middle of the upper millstone is bored through, and the ore, being thrown into this opening, falls down upon the lower millstone and is there ground to powder, which gradually runs out through its opening; it is washed by various methods before it is mixed with quicksilver, which I will explain presently.

[Illustration 299 (Stamp-mill): A--Water-wheel. B--Axle. C--Stamp. D--Hopper in the upper millstone. E--Opening passing through the centre. F--Lower millstone. G--Its round depression. H--Its outlet. I--Iron axle. K--Its crosspiece. L--Beam. M--Drum of rundles on the iron axle. N--Toothed drum of main axle. O--Tubs. P--The small planks. Q--Small upright axles. R--Enlarged part of one. S--Their paddles. T--Their drums which are made of rundles. V--Small horizontal axle set into the end of the main axle. X--Its toothed drums. Y--Three sluices. Z--Their small axles. AA--Spokes. BB--Paddles.]

Some people build a machine which at one and the same time can crush, grind, cleanse, and wash the gold ore, and mix the gold with quicksilver. This machine has one water-wheel, which is turned by a stream striking its buckets; the main axle on one side of the water-wheel has long cams, which raise the stamps that crush the dry ore. Then the crushed ore is thrown into the hopper of the upper millstone, and gradually falling through the opening, is ground to powder. The lower millstone is square, but has a round depression in which the round, upper millstone turns, and it has an outlet from which the powder falls into the first tub. A vertical iron axle is dove-tailed into a cross-piece, which is in turn fixed into the upper millstone; the upper pinion of this axle is held in a bearing fixed in a beam; the drum of the vertical axle is made of rundles, and is turned by the toothed drum on the main axle, and thus turns the millstone. The powder falls continually into the first tub, together with water, and from there runs into a second tub which is set lower down, and out of the second into a third, which is the lowest; from the third, it generally flows into a small trough hewn out of a tree trunk. Quicksilver[12] is placed in each tub, across which is fixed a small plank, and through a hole in the middle of each plank there passes a small upright axle, which is enlarged above the plank to prevent it from dropping into the tub lower than it should. At the lower end of the axle three sets of paddles intersect, each made from two little boards fixed to the axle opposite each other. The upper end of this axle has a pinion held by a bearing set in a beam, and around each of these axles is a small drum made of rundles, each of which is turned by a small toothed drum on a horizontal axle, one end of which is mortised into the large horizontal axle, and the other end is held in a hollow covered with thick iron plates in a beam. Thus the paddles, of which there are three sets in each tub, turn round, and agitating the powder, thoroughly mix it with water and separate the minute particles of gold from it, and these are attracted by the quicksilver and purified. The water carries away the waste. The quicksilver is poured into a bag made of leather or cloth woven from cotton, and when this bag is squeezed, as I have described elsewhere, the quicksilver drips through it into a jar placed underneath. The pure gold[13] remains in the bag. Some people substitute three broad sluices for the tubs, each of which has an angular axle on which are set six narrow spokes, and to them are fixed the same number of broad paddles; the water that is poured in strikes these paddles and turns them round, and they agitate the powder which is mixed with the water and separate the metal from it. If the powder which is being treated contains gold

## particles, the first method of washing is far superior, because the

quicksilver in the tubs immediately attracts the gold; if it is powder in which are the small black stones from which tin is smelted, this latter method is not to be despised. It is very advantageous to place interlaced fir boughs in the sluices in which such tin-stuff is washed, after it has run through the launders from the mills, because the fine tin-stone is either held back by the twigs, or if the current carries them along they fall away from the water and settle down.

Seven methods of washing are in common use for the ores of many metals; for they are washed either in a simple buddle, or in a divided buddle, or in an ordinary strake, or in a large tank, or in a short strake, or in a canvas strake, or in a jigging sieve. Other methods of washing are either peculiar to some particular metal, or are combined with the method of crushing wet ore by stamps.

[Illustration 301 (Buddles): A--Head of buddle. B--Pipe. C--Buddle. D--Board. E--Transverse buddle. F--Shovel. G--Scrubber.]

A simple buddle is made in the following way. In the first place, the head is higher than the rest of the buddle, and is three feet long and a foot and a half broad; this head is made of planks laid upon a timber and fastened, and on both sides, side-boards are set up so as to hold the water, which flows in through a pipe or trough, so that it shall fall straight down. The middle of the head is somewhat depressed in order that the broken rock and the larger metallic particles may settle into it. The buddle is sunk into the earth to a depth of three-quarters of a foot below the head, and is twelve feet long and a foot and a half wide and deep; the bottom and each side are lined with planks to prevent the earth, when it is softened by the water, from falling in or from absorbing the metallic particles. The lower end of the buddle is obstructed by a board, which is not as high as the sides. To this straight buddle there is joined a second transverse buddle, six feet long and a foot and a half wide and deep, similarly lined with planks; at the lower end it is closed up with a board, also lower than the sides of the buddle so that the water can flow away; this water falls into a launder and is carried outside the building. In this simple buddle is washed the metallic material which has passed on to the floor of the works through the five large sieves. When this has been gathered into a heap, the washer throws it into the head of the buddle, and water is poured upon it through the pipe or small trough, and the portion which sinks and settles in the middle of the head compartment he stirs with a wooden scrubber,--this is what we will henceforth call the implement made of a stick to which is fixed a piece of wood a foot long and a palm broad. The water is made turbid by this stirring, and carries the mud and sand and small particles of metal into the buddle below. Together with the broken rock, the larger metallic particles remain in the head compartment, and when these have been removed, boys throw them upon the platform of a washing tank or the short strake, and separate them from the broken rock. When the buddle is full of mud and sand, the washer closes the pipe through which the water flows into the head; very soon the water which remains in the buddle flows away, and when this has taken place, he removes with a shovel the mud and sand which are mixed with minute particles of metal, and washes them on a canvas strake. Sometimes before the buddles have been filled full, the boys throw the material into a bowl and carry it to the strakes and wash it.

Pulverized ore is washed in the head of this kind of a buddle; but usually when tin-stone is washed in it, interlacing fir boughs are put into the buddle, in the same manner as in the sluice when wet ore is crushed with stamps. The larger tin-stone particles, which sink in the upper part of the buddle, are washed separately in a strake; those

## particles which are of medium size, and settle in the middle part, are

washed separately in the same way; and the mud mixed with minute

## particles of tin-stone, which has settled in the lowest part of the

buddle below the fir boughs, is washed separately on the canvas strakes.

[Illustration 302 (Buddles): A--Pipe. B--Cross launder. C--Small troughs. D--Head of the buddle. E--Wooden scrubber. F--Dividing boards. G--Short strake.]

The divided buddle differs from the last one by having several cross-boards, which, being placed inside it, divide it off like steps; if the buddle is twelve feet long, four of them are placed within; if nine feet long, three. The nearer each one is to the head, the greater is its height; the further from the head, the lower it is; and so when the highest is a foot and a palm high, the second is usually a foot and three digits high, the third a foot and two digits, and the lowest a foot and one digit. In this buddle is generally washed that metalliferous material which has been sifted through the large sieve into the tub containing water. This material is continuously thrown with an iron shovel into the head of the buddle, and the water which has been let in is stirred up by a wooden scrubber, until the buddle is full, then the cross-boards are taken out by the washer, and the water is drained off; next the metalliferous material which has settled in the compartments is again washed, either on a short strake or on the canvas strakes or in the jigging sieves. Since a short strake is often united with the upper part of this buddle, a pipe in the first place carries the water into a cross launder, from which it flows down through one little launder into the buddle, and through another into the short strake.

[Illustration 303 (Washing material): A--Head. B--Strake. C--Trowel. D--Scrubber. E--Canvas. F--Rod by which the canvas is made smooth.]

An ordinary strake, so far as the planks are concerned, is not unlike the last two. The head of this, as of the others, is first made of earth stamped down, then covered with planks; and where it is necessary, earth is thrown in and beaten down a second time, so that no crevice may remain through which water carrying the particles of metal can escape. The water ought to fall straight down into the strake, which has a length of eight feet and a breadth of a foot and a half; it is connected with a transverse launder, which then extends to a settling pit outside the building. A boy with a shovel or a ladle takes the impure concentrates or impure tin-stone from a heap, and throws them into the head of the strake or spreads them over it. A washer with a wooden scrubber then agitates them in the strake, whereby the mud mixed with water flows away into the transverse launder, and the concentrates or the tin-stone settle on the strake. Since sometimes the concentrates or fine tin-stone flow down together with the mud into the transverse launder, a second washer closes it, after a distance of about six feet, with a cross-board and frequently stirs the mud with a shovel, in order that when mixed with water it may flow out into the settling-pit; and there remains in the launder only the concentrates or tin-stone. The tin-stuff of Schlackenwald and Erbisdorff is washed in this kind of a strake once or twice; those of Altenberg three or four times; those of Geyer often seven times; for in the ore at Schlackenwald and Erbisdorff the tin-stone particles are of a fair size, and are crushed with stamps; at Altenberg they are of much smaller size, and in the broken ore at Geyer only a few particles of tin-stone can be seen occasionally.

This method of washing was first devised by the miners who treated tin ore, whence it passed on from the works of the tin workers to those of the silver workers and others; this system is even more reliable than washing in jigging-sieves. Near this ordinary strake there is generally a canvas strake.

[Illustration 305 (Washing material): A--Upper cross launder. B--Small launders. C--Heads of strakes. D--Strakes. E--Lower transverse launder. F--Settling pit. G--Socket in the sill. H--Halved iron rings fixed to beam. I--Pole. K--Its little scrubber. L--Second small scrubber.]

In modern times two ordinary strakes, similarly made, are generally joined together; the head of one is three feet distant from that of the other, while the bodies are four feet distant from each other, and there is only one cross launder under the two strakes. One boy shovels, from the heap into the head of each, the concentrates or tin-stone mixed with mud. There are two washers, one of whom sits at the right side of one strake, and the other at the left of the other strake, and each pursues his task, using the following sort of implement. Under each strake is a sill, from a socket in which a round pole rises, and is held by half an iron ring in a beam of the building, so that it may revolve; this pole is nine feet long and a palm thick. Penetrating the pole is a small round piece of wood, three palms long and as many digits thick, to which is affixed a small board two feet long and five digits wide, in an opening of which one end of a small axle revolves, and to this axle is fixed the handle of a little scrubber. The other end of this axle turns in an opening of a second board, which is likewise fixed to a small round piece of wood; this round piece, like the first one, is three palms long and as many digits thick, and is used by the washer as a handle. The little scrubber is made of a stick three feet long, to the end of which is fixed a small tablet of wood a foot long, six digits broad, and a digit and a half thick. The washer constantly moves the handle of this implement with one hand; in this way the little scrubber stirs the concentrates or the fine tin-stone mixed with mud in the head of the strake, and the mud, on being stirred, flows on to the strake. In the other hand he holds a second little scrubber, which has a handle of half the length, and with this he ceaselessly stirs the concentrates or tin-stone which have settled in the upper part of the strake; in this way the mud and water flow down into the transverse launder, and from it into the settling-pit which is outside the building.

[Illustration 306 (Washing material): A--Trough. B--Platform. C--Wooden scrubber.]

Before the short strake and the jigging-sieve had been invented, metalliferous ores, especially tin, were crushed dry with stamps and washed in a large trough hollowed out of one or two tree trunks; and at the head of this trough was a platform, on which the ore was thrown after being completely crushed. The washer pulled it down into the trough with a wooden scrubber which had a long handle, and when the water had been let into the trough, he stirred the ore with the same scrubber.

[Illustration 307 (Washing material): A--Short strake. B--Small launder. C--Transverse launder. D--Wooden scrubber.]

The short strake is narrow in the upper part where the water flows down into it through the little launder; in fact it is only two feet wide; at the lower end it is wider, being three feet and as many palms. At the sides, which are six feet long, are fixed boards two palms high. In other respects the head resembles the head of the simple buddle, except that it is not depressed in the middle. Beneath is a cross launder closed by a low board. In this short strake not only is ore agitated and washed with a wooden scrubber, but boys also separate the concentrates from the broken rock in them and collect them in tubs. The short strake is now rarely employed by miners, owing to the carelessness of the boys, which has been frequently detected; for this reason, the jigging-sieve has taken its place. The mud which settles in the launder, if the ore is rich, is taken up and washed in a jigging-sieve or on a canvas strake.

[Illustration 308 (Washing material): A--Beams. B--Canvas. C--Head of strake. D--Small launder. E--Settling pit or tank. F--Wooden scrubber. G--Tubs.]

A canvas strake is made in the following way. Two beams, eighteen feet long and half a foot broad and three palms thick, are placed on a slope; one half of each of these beams is partially cut away lengthwise, to allow the ends of planks to be fastened in them, for the bottom is covered by planks three feet long, set crosswise and laid close together. One half of each supporting beam is left intact and rises a palm above the planks, in order that the water that is running down may not escape at the sides, but shall flow straight down. The head of the strake is higher than the rest of the body, and slopes so as to enable the water to flow away. The whole strake is covered by six stretched pieces of canvas, smoothed with a stick. The first of them occupies the lowest division, and the second is so laid as to slightly overlap it; on the second division, the third is similarly laid, and so on, one on the other. If they are laid in the opposite way, the water flowing down carries the concentrates or particles of tin-stone under the canvas, and a useless task is attempted. Boys or men throw the concentrates or tin-stuff mixed with mud into the head of the strake, after the canvas has been thus stretched, and having opened the small launder they let the water flow in; then they stir the concentrates or tin-stone with a wooden scrubber till the water carries them all on to the canvas; next they gently sweep the linen with the wooden scrubber until the mud flows into the settling-pit or into the transverse launder. As soon as there is little or no mud on the canvas, but only concentrates or tin-stone, they carry the canvas away and wash it in a tub placed close by. The tin-stone settles in the tub, and the men return immediately to the same task. Finally, they pour the water out of the tub, and collect the concentrates or tin-stone. However, if either concentrates or tin-stone have washed down from the canvas and settled in the settling-pit or in the transverse launder, they wash the mud again.

[Illustration 309 (Collecting concentrates): A--Canvas strake. B--Man dashing water on the canvas. C--Bucket. D--Bucket of another kind. E--Man removing concentrates or tin-stone from the trough.]

Some neither remove the canvas nor wash it in the tubs, but place over it on each edge narrow strips, of no great thickness, and fix them to the beams with nails. They agitate the metalliferous material with wooden scrubbers and wash it in a similar way. As soon as little or no mud remains on the canvas, but only concentrates or fine tin-stone, they lift one beam so that the whole strake rests on the other, and dash it with water, which has been drawn with buckets out of the small tank, and in this way all the sediment which clings to the canvas falls into the trough placed underneath. This trough is hewn out of a tree and placed in a ditch dug in the ground; the interior of the trough is a foot wide at the top, but narrower in the bottom, because it is rounded out. In the middle of this trough they put a cross-board, in order that the fairly large particles of concentrates or fairly large-sized tin-stone may remain in the forepart into which they have fallen, and the fine concentrates or fine tin-stone in the lower part, for the water flows from one into the other, and at last flows down through an opening into the pit. As for the fairly large-sized concentrates or tin-stone which have been removed from the trough, they are washed again on the ordinary strake. The fine concentrates and fine tin-stone are washed again on this canvas strake. By this method, the canvas lasts longer because it remains fixed, and nearly double the work is done by one washer as quickly as can be done by two washers by the other method.

[Illustration 311 (Jigging Sieve): A--Fine sieves. B--Limp. C--Finer sieve. D--Finest sieve.]

The jigging sieve has recently come into use by miners. The metalliferous material is thrown into it and sifted in a tub nearly full of water. The sieve is shaken up and down, and by this movement all the material below the size of a pea passes through into the tub, and the rest remains on the bottom of the sieve. This residue is of two kinds, the metallic particles, which occupy the lower place, and the particles of rock and earth, which take the higher place, because the heavy substance always settles, and the light is borne upward by the force of the water. This light material is taken away with a limp, which is a thin tablet of wood almost semicircular in shape, three-quarters of a foot long, and half a foot wide. Before the lighter portion is taken away the contents of the sieve are generally divided crosswise with a limp, to enable the water to penetrate into it more quickly. Afterward fresh material is again thrown into the sieve and shaken up and down, and when a great quantity of metallic particles have settled in the sieve, they are taken out and put into a tray close by. But since there fall into the tub with the mud, not only particles of gold or silver, but also of sand, pyrites, _cadmia_, galena, quartz, and other substances, and since the water cannot separate these from the metallic

## particles because they are all heavy, this muddy mixture is washed a

second time, and the part which is useless is thrown away. To prevent the sieve passing this sand again too quickly, the washer lays small stones or gravel in the bottom of the sieve. However, if the sieve is not shaken straight up and down, but is tilted to one side, the small stones or broken ore move from one part to another, and the metallic material again falls into the tub, and the operation is frustrated. The miners of our country have made an even finer sieve, which does not fail even with unskilled washers; in washing with this sieve they have no need for the bottom to be strewn with small stones. By this method the mud settles in the tub with the very fine metallic particles, and the larger sizes of metal remain in the sieve and are covered with the valueless sand, and this is taken away with a limp. The concentrates which have been collected are smelted together with other things. The mud mixed with the very fine metallic particles is washed for a third time and in the finest sieve, whose bottom is woven of hair. If the ore is rich in metal, all the material which has been removed by the limp is washed on the canvas strakes, or if the ore is poor it is thrown away.

I have explained the methods of washing which are used in common for the ores of many metals. I now come to another method of crushing ore, for I ought to speak of this before describing those methods of washing which are peculiar to ores of particular metals.

[Illustration 313 (Stamp-mill): A--Mortar. B--Open end of mortar. C--Slab of rock. D--Iron sole plates. E--Screen. F--Launder. G--Wooden shovel. H--Settling pit. I--Iron shovel. K--Heap of material which has settled. L--Ore which requires crushing. M--Small launder.]

In the year 1512, George, the illustrious Duke of Saxony[14], gave the overlordship of all the dumps ejected from the mines in Meissen to the noble and wise Sigismund Maltitz, father of John, Bishop of Meissen. Rejecting the dry stamps, the large sieve, and the stone mills of Dippoldswalde and Altenberg, in which places are dug the small black stones from which tin is smelted, he invented a machine which could crush the ore wet under iron-shod stamps. That is called "wet ore" which is softened by water which flows into the mortar box, and they are sometimes called "wet stamps" because they are drenched by the same water; and on the other hand, the other kinds are called "dry stamps" or "dry ore," because no water is used to soften the ore when the stamps are crushing. But to return to our subject. This machine is not dissimilar to the one which crushes the ore with dry iron-shod stamps, but the heads of the wet stamps are larger by half than the heads of the others. The mortar-box, which is made of oak or beech timber, is set up in the space between the upright posts; it does not open in front, but at one end, and it is three feet long, three-quarters of a foot wide, and one foot and six digits deep. If it has no bottom, it is set up in the same way over a slab of hard, smooth rock placed in the ground, which has been dug down a little. The joints are stopped up all round with moss or cloth rags. If the mortar has a bottom, then an iron sole-plate, three feet long, three-quarters of a foot wide, and a palm thick, is placed in it. In the opening in the end of the mortar there is fixed an iron plate full of holes, in such a way that there is a space of two digits between it and the shoe of the nearest stamp, and the same distance between this screen and the upright post, in an opening through which runs a small but fairly long launder. The crushed particles of silver ore flow through this launder with the water into a settling-pit, while the material which settles in the launder is removed with an iron shovel to the nearest planked floor; that material which has settled in the pit is removed with an iron shovel on to another floor. Most people make two launders, in order that while the workman empties one of them of the accumulation which has settled in it, a fresh deposit may be settling in the other. The water flows in through a small launder at the other end of the mortar that is near the water-wheel which turns the machine. The workman throws the ore to be crushed into the mortar in such a way that the pieces, when they are thrown in among the stamps, do not impede the work. By this method a silver or gold ore is crushed very fine by the stamps.

[Illustration 314 (Buddle): A--Launder reaching to the screen. B--Transverse trough. C--Spouts. D--Large buddles. E--Shovel. F--Interwoven twigs. G--Boards closing the buddles. H--Cross trough.]

When tin ore is crushed by this kind of iron-shod stamps, as soon as crushing begins, the launder which extends from the screen discharges the water carrying the fine tin-stone and fine sand into a transverse trough, from which the water flows down through the spouts, which pierce the side of the trough, into the one or other of the large buddles set underneath. The reason why there are two is that, while the washer empties the one which is filled with fine tin-stone and sand, the material may flow into the other. Each buddle is twelve feet long, one cubit deep, and a foot and a half broad. The tin-stone which settles in the upper part of the buddles is called the large size; these are frequently stirred with a shovel, in order that the medium sized

## particles of tin-stone, and the mud mixed with the very fine particles

of the stones may flow away. The particles of medium size generally settle in the middle part of the buddle, where they are arrested by interwoven fir twigs. The mud which flows down with the water settles between the twigs and the board which closes the lower end of the buddle. The tin-stone of large size is removed separately from the buddle with a shovel; those of medium size are also removed separately, and likewise the mud is removed separately, for they are separately washed on the canvas strakes and on the ordinary strake, and separately roasted and smelted. The tin-stone which has settled in the middle part of the buddle, is also always washed separately on the canvas strakes; but if the particles are nearly equal in size to those which have settled in the upper part of the buddle, they are washed with them in the ordinary strake and are roasted and smelted with them. However, the mud is never washed with the others, either on the canvas strakes or on the ordinary strake, but separately, and the fine tin-stone which is obtained from it is roasted and smelted separately. The two large buddles discharge into a cross trough, and it again empties through a launder into a settling-pit which is outside the building.

This method of washing has lately undergone a considerable change; for the launder which carries the water, mixed with the crushed tin-stone and fine sand which flow from the openings of the screen, does not reach to a transverse trough which is inside the same room, but runs straight through a partition into a small settling-pit. A boy draws a three-toothed rake through the material which has settled in the portion of the launder outside the room, by which means the larger sized

## particles of tin-stone settle at the bottom, and these the washer takes

out with the wooden shovel and carries into the room; this material is thrown into an ordinary strake and swept with a wooden scrubber and washed. As for those tin-stone particles which the water carries off from the strake, after they have been brought back on to the strake, he washes them again until they are clean.

[Illustration 315 (Buddle): A--First launder. B--Three-toothed rake. C--Small settling pit. D--Large buddle. E--Buddle resembling the simple buddle. F--Small roller. G--Boards. H--Their holes. I--Shovel. K--Building. L--Stove. (This picture does not entirely agree with the text).]

The remaining tin-stone, mixed with sand, flows into the small settling-pit which is within the building, and this discharges into two large buddles. The tin-stone of moderate size, mixed with those of fairly large size, settle in the upper part, and the small size in the lower part; but both are impure, and for this reason they are taken out separately and the former is washed twice, first in a buddle like the simple buddle, and afterward on an ordinary strake. Likewise the latter is washed twice, first on a canvas strake and afterward on an ordinary strake. This buddle, which is like the simple buddle, differs from it in the head, the whole of which in this case is sloping, while in the case of the other it is depressed in the centre. In order that the boy may be able to rest the shovel with which he cleanses the tin-stone, this sluice has a small wooden roller which turns in holes in two thick boards fixed to the sides of the buddle; if he did not do this, he would become over-exhausted by his task, for he spends whole days standing over these labours. The large buddle, the one like the simple buddle, the ordinary strake, and the canvas strakes, are erected within a special building. In this building there is a stove that gives out heat through the earthen tiles or iron plates of which it is composed, in order that the washers can pursue their labours even in winter, if the rivers are not completely frozen over.

[Illustration 317 (Workroom with settling-pit): A--Launder from the screen of the mortar-box. B--Three-toothed rake. C--Small settling-pit. D--Canvas. E--Strakes. F--Brooms.]

On the canvas strakes are washed the very fine tin-stone mixed with mud which has settled in the lower end of the large buddle, as well as in the lower end of the simple buddle and of the ordinary strake. The canvas is cleaned in a trough hewn out of one tree trunk and partitioned off with two boards, so that three compartments are made. The first and second pieces of canvas are washed in the first compartment, the third and fourth in the second compartment, the fifth and sixth in the third compartment. Since among the very fine tin-stone there are usually some grains of stone, rock, or marble, the master cleanses them on the ordinary strake, lightly brushing the top of the material with a broom, the twigs of which do not all run the same way, but some straight and some crosswise. In this way the water carries off these impurities from the strake into the settling-pit because they are lighter, and leaves the tin-stone on the table because it is heavier.

Below all buddles or strakes, both inside and outside the building, there are placed either settling-pits or cross-troughs into which they discharge, in order that the water may carry on down into the stream but very few of the most minute particles of tin-stone. The large settling-pit which is outside the building is generally made of joined flooring, and is eight feet in length, breadth and depth. When a large quantity of mud, mixed with very fine tin-stone, has settled in it, first of all the water is let out by withdrawing a plug, then the mud which is taken out is washed outside the house on the canvas strakes, and afterward the concentrates are washed on the strake which is inside the building. By these methods the very finest tin-stone is made clean.

[Illustration 318 (Streaming for Tin): A--River. B--Weir. C--Gate. D--Area. E--Meadow. F--Fence. G--Ditch.]

The mud mixed with the very fine tin-stone, which has neither settled in the large settling-pit nor in the transverse launder which is outside the room and below the canvas strakes, flows away and settles in the bed of the stream or river. In order to recover even a portion of the fine tin-stone, many miners erect weirs in the bed of the stream or river, very much like those that are made above the mills, to deflect the current into the races through which it flows to the water-wheels. At one side of each weir there is an area dug out to a depth of five or six or seven feet, and if the nature of the place will permit, extending in every direction more than sixty feet. Thus, when the water of the river or stream in autumn and winter inundates the land, the gates of the weir are closed, by which means the current carries the mud mixed with fine tin-stone into the area. In spring and summer this mud is washed on the canvas strakes or on the ordinary strake, and even the finest black-tin is collected. Within a distance of four thousand fathoms along the bed of the stream or river below the buildings in which the tin-stuff is washed, the miners do not make such weirs, but put inclined fences in the meadows, and in front of each fence they dig a ditch of the same length, so that the mud mixed with the fine tin-stone, carried along by the stream or river when in flood, may settle in the ditch and cling to the fence. When this mud is collected, it is likewise washed on canvas strakes and on the ordinary strake, in order that the fine tin-stone may be separated from it. Indeed we may see many such areas and fences collecting mud of this kind in Meissen below Altenberg in the river Moglitz,--which is always of a reddish colour when the rock containing the black tin is being crushed under the stamps.

[Illustration 320 (Stamp-mill): A--First machine. B--Its stamps. C--Its mortar-box. D--Second machine. E--Its stamps. F--Its mortar-box. G--Third machine. H--Its stamps. I--Its mortar-box. K--Fourth machine. L--Its stamps. M--Its mortar-box.]

But to return to the stamping machines. Some usually set up four machines of this kind in one place, that is to say, two above and the same number below. By this plan it is necessary that the current which has been diverted should fall down from a greater height upon the upper water-wheels, because these turn axles whose cams raise heavier stamps. The stamp-stems of the upper machines should be nearly twice as long as the stems of the lower ones, because all the mortar-boxes are placed on the same level. These stamps have their tappets near their upper ends, not as in the case of the lower stamps, which are placed just above the bottom. The water flowing down from the two upper water-wheels is caught in two broad races, from which it falls on to the two lower water-wheels. Since all these machines have the stamps very close together, the stems should be somewhat cut away, to prevent the iron shoes from rubbing each other at the point where they are set into the stems. Where so many machines cannot be constructed, by reason of the narrowness of the valley, the mountain is excavated and levelled in two places, one of which is higher than the other, and in this case two machines are constructed and generally placed in one building. A broad race receives in the same way the water which flows down from the upper water-wheel, and similarly lets it fall on the lower water-wheel. The mortar-boxes are not then placed on one level, but each on the level which is appropriate to its own machine, and for this reason, two workmen are then required to throw ore into the mortar-boxes. When no stream can be diverted which will fall from a higher place upon the top of the water-wheel, one is diverted which will turn the foot of the wheel; a great quantity of water from the stream is collected in one pool capable of holding it, and from this place, when the gates are raised, the water is discharged against the wheel which turns in the race. The buckets of a water-wheel of this kind are deeper and bent back, projecting upward; those of the former are shallower and bent forward, inclining downward.

[Illustration 321 (Stamp-mill): A--Stamps. B--Mortar. C--Plates full of holes. D--Transverse launder. E--Planks full of cup-like depressions. F--Spout. G--Bowl into which the concentrates fall. H--Canvas strake. I--Bowls shaped like a small boat. K--Settling-pit under the canvas strake.]

Further, in the Julian and Rhaetian Alps[15] and in the Carpathian Mountains, gold or even silver ore is now put under stamps, which are sometimes placed more than twenty in a row, and crushed wet in a long mortar-box. The mortar has two plates full of holes through which the ore, after being crushed, flows out with the water into the transverse launder placed underneath, and from there it is carried down by two spouts into the heads of the canvas strakes. Each head is made of a thick broad plank, which can be raised and set upright, and to which on each side are fixed pieces projecting upward. In this plank there are many cup-like depressions equal in size and similar in shape, in each of which an egg could be placed. Right down in these depressions are small crevices which can retain the concentrates of gold or silver, and when the hollows are nearly filled with these materials, the plank is raised on one side so that the concentrates will fall into a large bowl. The cup-like depressions are washed out by dashing them with water. These concentrates are washed separately in different bowls from those which have settled on the canvas. This bowl is smooth and two digits wide and deep, being in shape very similar to a small boat; it is broad in the fore part, narrow in the back, and in the middle of it there is a cross groove, in which the particles of pure gold or silver settle, while the grains of sand, since they are lighter, flow out of it.

In some parts of Moravia, gold ore, which consists of quartz mixed with gold, is placed under the stamps and crushed wet. When crushed fine it flows out through a launder into a trough, is there stirred by a wooden scrubber, and the minute particles of gold which settle in the upper end of the trough are washed in a black bowl.

So far I have spoken of machines which crush wet ore with iron-shod stamps. I will now explain the methods of washing which are in a measure peculiar to the ore of certain metals, beginning with gold. The ore which contains particles of this metal, and the sand of streams and rivers which contains grains of it, are washed in frames or bowls; the sands especially are also washed in troughs. More than one method is employed for washing on frames, for these frames either pass or retain the particles or concentrates of gold; they pass them if they have holes, and retain them if they have no holes. But either the frame itself has holes, or a box is substituted for it; if the frame itself is perforated it passes the particles or concentrates of gold into a trough; if the box has them, it passes the gold material into the long sluice. I will first speak of these two methods of washing. The frame is made of two planks joined together, and is twelve feet long and three feet wide, and is full of holes large enough for a pea to pass. To prevent the ore or sand with which the gold is mixed from falling out at the sides, small projecting edge-boards are fixed to it. This frame is set upon two stools, the first of which is higher than the second, in order that the gravel and small stones can roll down it. The washer throws the ore or sand into the head of the frame, which is higher, and opening the small launder, lets the water into it, and then agitates it with a wooden scrubber. In this way, the gravel and small stones roll down the frame on to the ground, while the particles or concentrates of gold, together with the sand, pass through the holes into the trough which is placed under the frame, and after being collected are washed in the bowl.

[Illustration 322 (Frames for Washing Ore or Alluvial): A--Head of frame. B--Frame. C--Holes. D--Edge-boards. E--Stools. F--Scrubber. G--Trough. H--Launder. I--Bowl.]

[Illustration 323 (Frames for Washing Ore or Alluvial): A--Sluice. B--Box. C--Bottom of inverted box. D--Open part of it. E--Iron hoe. F--Riffles. G--Small launder. H--Bowl with which settlings are taken away. I--Black bowl in which they are washed.]

A box which has a bottom made of a plate full of holes, is placed over the upper end of a sluice, which is fairly long but of moderate width. The gold material to be washed is thrown into this box, and a great quantity of water is let in. The lumps, if ore is being washed, are mashed with an iron shovel. The fine portions fall through the bottom of the box into the sluice, but the coarse pieces remain in the box, and these are removed with a scraper through an opening which is nearly in the middle of one side. Since a large amount of water is necessarily let into the box, in order to prevent it from sweeping away any particles of gold which have fallen into the sluice, the sluice is divided off by ten, or if it is as long again, by fifteen riffles. These riffles are placed equidistant from one another, and each is higher than the one next toward the lower end of the sluice. The little compartments which are thus made are filled with the material and the water which flows through the box; as soon as these compartments are full and the water has begun to flow over clear, the little launder through which this water enters into the box is closed, and the water is turned in another direction. Then the lowest riffle is removed from the sluice, and the sediment which has accumulated flows out with the water and is caught in a bowl. The riffles are removed one by one and the sediment from each is taken into a separate bowl, and each is separately washed and cleansed in a bowl. The larger particles of gold concentrates settle in the higher compartments, the smaller size, in the lower compartments. This bowl is shallow and smooth, and smeared with oil or some other slippery substance, so that the tiny particles of gold may not cling to it, and it is painted black, that the gold may be more easily discernible; on the exterior, on both sides and in the middle, it is slightly hollowed out in order that it may be grasped and held firmly in the hands when shaken. By this method the particles or concentrates of gold settle in the back part of the bowl; for if the back part of the bowl is tapped or shaken with one hand, as is usual, the contents move toward the fore part. In this way the Moravians, especially, wash gold ore.

The gold particles are also caught on frames which are either bare or covered. If bare, the particles are caught in pockets; if covered, they cling to the coverings. Pockets are made in various ways, either with iron wire or small cross-boards fixed to the frame, or by holes which are sunk into the sluice itself or into its head, but which do not quite go through. These holes are round or square, or are grooves running crosswise. The frames are either covered with skins, pieces of cloth, or turf, which I will deal with one by one in turn.

[Illustration 324 (Frames for Washing Ore or Alluvial): A--Plank. B--Side-boards. C--Iron wire. D--Handles.]

In order to prevent the sand which contains the particles of gold from spilling out, the washer fixes side-boards to the edges of a plank which is six feet long and one and a quarter wide. He then lays crosswise many iron wires a digit apart, and where they join he fixes them to the bottom plank with iron nails. Then he makes the head of the frame higher, and into this he throws the sand which needs washing, and taking in his hands the handles which are at the head of the frame, he draws it backward and forward several times in the river or stream. In this way the small stones and gravel flow down along the frame, and the sand mixed with particles of gold remains in the pockets between the strips. When the contents of the pockets have been shaken out and collected in one place, he washes them in a bowl and thus cleans the gold dust.

[Illustration 326 (Frames for Washing Ore or Alluvial): A--Head of the sluice. B--Riffles. C--Wooden scrubber. D--Pointed stick. E--Dish. F--Its cup-like depression. G--Grooved dish.]

Other people, among whom are the Lusitanians[16], fix to the sides of a sluice, which is about six feet long and a foot and a half broad, many cross-strips or riffles, which project backward and are a digit apart. The washer or his wife lets the water into the head of the sluice, where he throws the sand which contains the particles of gold. As it flows down he agitates it with a wooden scrubber, which he moves transversely to the riffles. He constantly removes with a pointed wooden stick the sediment which settles in the pockets between the riffles, and in this way the particles of gold settle in them, while the sand and other valueless materials are carried by the water into a tub placed below the sluice. He removes the particles of metal with a small wooden shovel into a wooden bowl. This bowl does not exceed a foot and a quarter in breadth, and by moving it up and down in the stream he cleanses the gold dust, for the remaining sand flows out of the dish, and the gold dust settles in the middle of it, where there is a cup-like depression. Some make use of a bowl which is grooved inside like a shell, but with a smooth lip where the water flows out. This smooth place, however, is narrower where the grooves run into it, and broader where the water flows out.

[Illustration 327 (Frames for Washing Ore or Alluvial): A--Head of the sluice. B--Side-boards. C--Lower end of the sluice. D--Pockets. E--Grooves. F--Stools. G--Shovel. H--Tub set below. I--Launder.]

The cup-like pockets and grooves are cut or burned at the same time into the bottom of the sluice; the bottom is composed of three planks ten feet long, and is about four feet wide; but the lower end, through which the water is discharged, is narrower. This sluice, which likewise has side-boards fixed to its edges, is full of rounded pockets and of grooves which lead to them, there being two grooves to one pocket, in order that the water mixed with sand may flow into each pocket through the upper groove, and that after the sand has partly settled, the water may again flow out through the lower groove. The sluice is set in the river or stream or on the bank, and placed on two stools, of which the first is higher than the second in order that the gravel and small stones may roll down the sluice. The washer throws sand into the head with a shovel, and opening the launder, lets in the water, which carries the particles of metal with a little sand down into the pockets, while the gravel and small stones with the rest of the sand falls into a tub placed below the sluice. As soon as the pockets are filled, he brushes out the concentrates and washes them in a bowl. He washes again and again through this sluice.

[Illustration 328 (Frames for Washing Ore or Alluvial): A--Cross grooves. B--Tub set under the sluice. C--Another tub.]

Some people cut a number of cross-grooves, one palm distant from each other, in a sluice similarly composed of three planks eight feet long. The upper edge of these grooves is sloping, that the particles of gold may slip into them when the washer stirs the sand with a wooden shovel; but their lower edge is vertical so that the gold particles may thus be unable to slide out of them. As soon as these grooves are full of gold

## particles mixed with fine sand, the sluice is removed from the stools

and raised up on its head. The head in this case is nothing but the upper end of the planks of which the sluice is composed. In this way the metallic particles, being turned over backward, fall into another tub, for the small stones and gravel have rolled down the sluice. Some people place large bowls under the sluice instead of tubs, and as in the other cases, the unclean concentrates are washed in the small bowl.

[Illustration 329 (Frames for Washing Ore or Alluvial): A--Sluice covered with canvas. B--Its head full of pockets and grooves. C--Head removed and washed in a tub. D--Sluice which has square pockets. E--Sluice to whose planks small shavings cling. F--Broom. G--Skins of oxen. H--Wooden scrubber.]

The Thuringians cut rounded pockets, a digit in diameter and depth, in the head of the sluice, and at the same time they cut grooves reaching from one to another. The sluice itself they cover with canvas. The sand which is to be washed, is thrown into the head and stirred with a wooden scrubber; in this way the water carries the light particles of gold on to the canvas, and the heavy ones sink in the pockets, and when these hollows are full, the head is removed and turned over a tub, and the concentrates are collected and washed in a bowl. Some people make use of a sluice which has square pockets with short vertical recesses which hold the particles of gold. Other workers use a sluice made of planks, which are rough by reason of the very small shavings which still cling to them; these sluices are used instead of those with coverings, of which this sluice is bare, and when the sand is washed, the particles of gold cling no less to these shavings than to canvas, or skins, or cloths, or turf. The washer sweeps the sluice upward with a broom, and when he has washed as much of the sand as he wishes, he lets a more abundant supply of water into the sluice again to wash out the concentrates, which he collects in a tub set below the sluice, and then washes again in a bowl. Just as Thuringians cover the sluice with canvas, so some people cover it with the skins of oxen or horses. They push the auriferous sand upward with a wooden scrubber, and by this system the light material flows away with the water, while the particles of gold settle among the hairs; the skins are afterward washed in a tub; and the concentrates are collected in a bowl.

[Illustration 330 (Washing material in spring): A--Spring. B--Skin. C--Argonauts.]

The Colchians[17] placed the skins of animals in the pools of springs; and since many particles of gold had clung to them when they were removed, poets invented the "golden fleece" of the Colchians. In like manner, it can be contrived by the methods of miners that skins should take up, not only particles of gold, but also of silver and gems.

[Illustration 331 (Frames for Washing Ore or Alluvial): A--Head of frame. B--Frame. C--Cloth. D--small launder. E--Tub set below the frame. F--Tub in which cloth is washed.]

Many people cover the frame with a green cloth as long and wide as the frame itself, and fasten it with iron nails in such a way that they can easily draw them out and remove the cloth. When the cloth appears to be golden because of the particles which adhere to it, it is washed in a special tub and the particles are collected in a bowl. The remainder which has run down into the tub is again washed on the frame.

[Illustration 332 (Frames for Washing Ore or Alluvial): A--Cloth full of small knots, spread out. B--Small knots more conspicuously shown. C--Tub in which cloth is washed.]

Some people, in place of a green cloth, use a cloth of tightly woven horsehair, which has a rough knotty surface. Since these knots stand out and the cloth is rough, even the very small particles of gold adhere to it; these cloths are likewise washed in a tub with water.

[Illustration 333 (Frames for Washing Ore or Alluvial): A--Head of frame. B--Small launder through which water flows into head of frame. C--Pieces of turf. D--Trough placed under frame. E--Tub in which pieces of turf are washed.]

Some people construct a frame not unlike the one covered with canvas, but shorter. In place of the canvas they set pieces of turf in rows. They wash the sand, which has been thrown into the head of the frame, by letting in water. In this way the particles of gold settle in the turf, the mud and sand, together with the water, are carried down into the settling-pit or trough below, which is opened when the work is finished. After all the water has passed out of the settling-pit, the sand and mud are carried away and washed over again in the same manner. The particles which have clung to the turf are afterward washed down into the settling-pit or trough by a stronger current of the water, which is let into the frame through a small launder. The concentrates are finally collected and washed in a bowl. Pliny was not ignorant of this method of washing gold. "The ulex," he says, "after being dried, is burnt, and its ashes are washed over a grassy turf, that the gold may settle on it."

[Illustration 334 (Trays for Washing Alluvial): A--Tray. B--Bowl-like depression. C--Handles.]

Sand mixed with particles of gold is also washed in a tray, or in a trough or bowl. The tray is open at the further end, is either hewn out of a squared trunk of a tree or made out of a thick plank to which side-boards are fixed, and is three feet long, a foot and a half wide, and three digits deep. The bottom is hollowed out into the shape of an elongated bowl whose narrow end is turned toward the head, and it has two long handles, by which it is drawn backward and forward in the river. In this way the fine sand is washed, whether it contains

## particles of gold or the little black stones from which tin is made.

[Illustration 335 (Trough for washing alluvial): A--Trough. B--Its open end. C--End that may be closed. D--Stream. E--Hoe. F--End-board. G--Bag.]

The Italians who come to the German mountains seeking gold, in order to wash the river sand which contains gold-dust and garnets,[19] use a fairly long shallow trough hewn out of a tree, rounded within and without, open at one end and closed at the other, which they turn in the bed of the stream in such a way that the water does not dash into it, but flows in gently. They stir the sand, which they throw into it, with a wooden hoe, also rounded. To prevent the particles of gold or garnets from running out with the light sand, they close the end with a board similarly rounded, but lower than the sides of the trough. The concentrates of gold or garnets which, with a small quantity of heavy sand, have settled in the trough, they wash in a bowl and collect in bags and carry away with them.

[Illustration 336 (Bowls for Alluvial Washing): A--Large bowl. B--Ropes. C--Beam. D--Other large bowl which coiners use. E--Small bowl.]

Some people wash this kind of sand in a large bowl which can easily be shaken, the bowl being suspended by two ropes from a beam in a building. The sand is thrown into it, water is poured in, then the bowl is shaken, and the muddy water is poured out and clear water is again poured in, this being done again and again. In this way, the gold particles settle in the back part of the bowl because they are heavy, and the sand in the front part because it is light; the latter is thrown away, the former kept for smelting. The one who does the washing then returns immediately to his task. This method of washing is rarely used by miners, but frequently by coiners and goldsmiths when they wash gold, silver, or copper. The bowl they employ has only three handles, one of which they grasp in their hands when they shake the bowl, and in the other two is fastened a rope by which the bowl is hung from a beam, or from a cross-piece which is upheld by the forks of two upright posts fixed in the ground. Miners frequently wash ore in a small bowl to test it. This bowl, when shaken, is held in one hand and thumped with the other hand. In other respects this method of washing does not differ from the last.

[Illustration 337 (Ground Sluicing): A--Stream. B--Ditch. C--Mattock. D--Pieces of turf. E--Seven-pronged fork. F--Iron shovel. G--Trough. H--Another trough below it. I--Small wooden trowel.]

I have spoken of the various methods of washing sand which contains grains of gold; I will now speak of the methods of washing the material in which are mixed the small black stones from which tin is made[20]. Eight such methods are in use, and of these two have been invented lately. Such metalliferous material is usually found torn away from veins and stringers and scattered far and wide by the impetus of water, although sometimes _venae dilatatae_ are composed of it. The miners dig out the latter material with a broad mattock, while they dig the former with a pick. But they dig out the little stones, which are not rare in this kind of ore, with an instrument like the bill of a duck. In districts which contain this material, if there is an abundant supply of water, and if there are valleys or gentle slopes and hollows, so that rivers can be diverted into them, the washers in summer-time first of all dig a long ditch sloping so that the water will run through it rapidly. Into the ditch is thrown the metallic material, together with the surface material, which is six feet thick, more or less, and often contains moss, roots of plants, shrubs, trees, and earth; they are all thrown in with a broad mattock, and the water flows through the ditch. The sand and tin-stone, as they are heavy, sink to the bottom of the ditch, while the moss and roots, as they are light, are carried away by the water which flows through the ditch. The bottom of the ditch is obstructed with turf and stones in order to prevent the water from carrying away the tin-stone at the same time. The washers, whose feet are covered with high boots made of hide, though not of rawhide, themselves stand in the ditch and throw out of it the roots of the trees, shrubs, and grass with seven-pronged wooden forks, and push back the tin-stone toward the head of the ditch. After four weeks, in which they have devoted much work and labour, they raise the tin-stone in the following way; the sand with which it is mixed is repeatedly lifted from the ditch with an iron shovel and agitated hither and thither in the water, until the sand flows away and only the tin-stone remains on the shovel. The tin-stone is all collected together and washed again in a trough by pushing it up and turning it over with a wooden trowel, in order that the remaining sand may separate from it. Afterward they return to their task, which they continue until the metalliferous material is exhausted, or until the water can no longer be diverted into the ditches.

[Illustration 338 (Sluicing Tin): A--Trough. B--Wooden shovel. C--Tub. D--Launder. E--Wooden trowel. F--Transverse trough. G--Plug. H--Falling water. I--Ditch. K--Barrow conveying material to be washed. L--Pick like the beak of a duck with which the miner digs out the material from which the small stones are obtained.]

The trough which I mentioned is hewn out of the trunk of a tree and the interior is five feet long, three-quarters of a foot deep, and six digits wide. It is placed on an incline and under it is put a tub which contains interwoven fir twigs, or else another trough is put under it, the interior of which is three feet long and one foot wide and deep; the fine tin-stone, which has run out with the water, settles in the bottom. Some people, in place of a trough, put a square launder underneath, and in like manner they wash the tin-stone in this by agitating it up and down and turning it over with a small wooden trowel. A transverse trough is put under the launder, which is either open on one end and drains off into a tub or settling-pit, or else is closed and perforated through the bottom; in this case, it drains into a ditch beneath, where the water falls when the plug has been partly removed. The nature of this ditch I will now describe.

[Illustration 340 (Sluicing Tin): A--Launder. B--Interlacing fir twigs. C--Logs; three on one side, for the fourth cannot be seen because the ditch is so full with material now being washed. D--Logs at the head of the ditch. E--Barrow. F--Seven-pronged fork. G--Hoe.]

If the locality does not supply an abundance of water, the washers dig a ditch thirty or thirty-six feet long, and cover the bottom, the full length, with logs joined together and hewn on the side which lies flat on the ground. On each side of the ditch, and at its head also, they place four logs, one above the other, all hewn smooth on the inside. But since the logs are laid obliquely along the sides, the upper end of the ditch is made four feet wide and the tail end, two feet. The water has a high drop from a launder and first of all it falls into interlaced fir twigs, in order that it shall fall straight down for the most part in an unbroken stream and thus break up the lumps by its weight. Some do not place these twigs under the end of the launder, but put a plug in its mouth, which, since it does not entirely close the launder, nor altogether prevent the discharge from it, nor yet allow the water to spout far afield, makes it drop straight down. The workman brings in a wheelbarrow the material to be washed, and throws it into the ditch. The washer standing in the upper end of the ditch breaks the lumps with a seven-pronged fork, and throws out the roots of trees, shrubs, and grass with the same instrument, and thereby the small black stones settle down. When a large quantity of the tin-stone has accumulated, which generally happens when the washer has spent a day at this work, to prevent it from being washed away he places it upon the bank, and other material having been again thrown into the upper end of the ditch, he continues the task of washing. A boy stands at the lower end of the ditch, and with a thin pointed hoe stirs up the sediment which has settled at the lower end, to prevent the washed tin-stone from being carried further, which occurs when the sediment has accumulated to such an extent that the fir branches at the outlet of the ditch are covered.

[Illustration 341 (Sifting Ore): A--Strakes. B--Tank. C--Launder. D--Plug. E--Wooden shovel. F--Wooden mallet. G--Wooden shovel with short handle. H--The plug in the strake. I--Tank placed under the plug.]

The third method of washing materials of this kind follows. Two strakes are made, each of which is twelve feet long and a foot and a half wide and deep. A tank is set at their head, into which the water flows through a little launder. A boy throws the ore into one strake; if it is of poor quality he puts in a large amount of it, if it is rich he puts in less. The water is let in by removing the plug, the ore is stirred with a wooden shovel, and in this way the tin-stone, mixed with the heavier material, settles in the bottom of the strake, and the water carries the light material into the launder, through which it flows on to a canvas strake. The very fine tin-stone, carried by the water, settles on to the canvas and is cleansed. A low cross-board is placed in the strake near the head, in order that the largest sized tin-stone may settle there. As soon as the strake is filled with the material which has been washed, he closes the mouth of the tank and continues washing in the other strake, and then the plug is withdrawn and the water and tin-stone flow down into a tank below. Then he pounds the sides of the loaded strake with a wooden mallet, in order that the tin-stone clinging to the sides may fall off; all that has settled in it, he throws out with a wooden shovel which has a short handle. Silver slags which have been crushed under the stamps, also fragments of silver-lead alloy and of cakes melted from pyrites, are washed in a strake of this kind.

[Illustration 342 (Sifting Ore): A--Sieve. B--Tub. C--Water flowing out of the bottom of it. D--Strake. E--Three-toothed rake. F--Wooden scrubber.]

Material of this kind is also washed while wet, in a sieve whose bottom is made of woven iron wire, and this is the fourth method of washing. The sieve is immersed in the water which is contained in a tub, and is violently shaken. The bottom of this tub has an opening of such size that as much water, together with tailings from the sieve, can flow continuously out of it as water flows into it. The material which settles in the strake, a boy either digs over with a three-toothed iron rake or sweeps with a wooden scrubber; in this way the water carries off a great part of both sand and mud. The tin-stone or metalliferous concentrates settle in the strake and are afterward washed in another strake.

[Illustration 343 (Sluicing Tin): A--Box. B--Perforated plate. C--Trough. D--Cross-boards. E--Pool. F--Launder. G--Shovel. H--Rake.]

These are ancient methods of washing material which contains tin-stone; there follow two modern methods. If the tin-stone mixed with earth or sand is found on the slopes of mountains or hills, or in the level fields which are either devoid of streams or into which a stream cannot be diverted, miners have lately begun to employ the following method of washing, even in the winter months. An open box is constructed of planks, about six feet long, three feet wide, and two feet and one palm deep. At the upper end on the inside, an iron plate three feet long and wide is fixed, at a depth of one foot and a half from the top; this plate is very full of holes, through which tin-stone about the size of a pea can fall. A trough hewn from a tree is placed under the box, and this trough is about twenty-four feet long and three-quarters of a foot wide and deep; very often three cross-boards are placed in it, dividing it off into compartments, each one of which is lower than the next. The turbid waters discharge into a settling-pit.

The metalliferous material is sometimes found not very deep beneath the surface of the earth, but sometimes so deep that it is necessary to drive tunnels and sink shafts. It is transported to the washing-box in wheelbarrows, and when the washers are about to begin they lay a small launder, through which there flows on to the iron plate so much water as is necessary for this washing. Next, a boy throws the metalliferous material on to the iron plate with an iron shovel and breaks the small lumps, stirring them this way and that with the same implement. Then the water and sand penetrating the holes of the plate, fall into the box, while all the coarse gravel remains on the plate, and this he throws into a wheelbarrow with the same shovel. Meantime, a younger boy continually stirs the sand under the plate with a wooden scrubber nearly as wide as the box, and drives it to the upper end of the box; the lighter material, as well as a small amount of tin-stone, is carried by the water down into the underlying trough. The boys carry on this labour without intermission until they have filled four wheelbarrows with the coarse and worthless residues, which they carry off and throw away, or three wheelbarrows if the material is rich in black tin. Then the foreman has the plank removed which was in front of the iron plate, and on which the boy stood. The sand, mixed with the tin-stone, is frequently pushed backward and forward with a scrubber, and the same sand, because it is lighter, takes the upper place, and is removed as soon as it appears; that which takes the lower place is turned over with a spade, in order that any that is light can flow away; when all the tin-stone is heaped together, he shovels it out of the box and carries it away. While the foreman does this, one boy with an iron hoe stirs the sand mixed with fine tin-stone, which has run out of the box and has settled in the trough and pushes it back to the uppermost part of the trough, and this material, since it contains a very great amount of tin-stone, is thrown on to the plate and washed again. The material which has settled in the lowest part of the trough is taken out separately and piled in a heap, and is washed on the ordinary strake; that which has settled in the pool is washed on the canvas strake. In the summer-time this fruitful labour is repeated more often, in fact ten or eleven times. The tin-stone which the foreman removes from the box, is afterward washed in a jigging sieve, and lastly in a tub, where at length all the sand is separated out. Finally, any material in which are mixed particles of other metals, can be washed by all these methods, whether it has been disintegrated from veins or stringers, or whether it originated from _venae dilatatae_, or from streams and rivers.

[Illustration 345 (Ground Sluicing): A--Launder. B--Cross trough. C--Two spouts. D--Boxes. E--Plate. F--Grating. G--Shovels. H--Second cross trough. I--Strake. K--Wooden scrubber. L--Third cross trough. M--Launder. N--Three-toothed rake.]

The sixth method of washing material of this kind is even more modern and more useful than the last. Two boxes are constructed, into each of which water flows through spouts from a cross trough into which it has been discharged through a pipe or launder. When the material has been agitated and broken up with iron shovels by two boys, part of it runs down and falls through the iron plates full of holes, or through the iron grating, and flows out of the box over a sloping surface into another cross trough, and from this into a strake seven feet long and two and a half feet wide. Then the foreman again stirs it with a wooden scrubber that it may become clean. As for the material which has flowed down with the water and settled in the third cross trough, or in the launder which leads from it, a third boy rakes it with a two-toothed rake; in this way the fine tin-stone settles down and the water carries off the valueless sand into the creek. This method of washing is most advantageous, for four men can do the work of washing in two boxes, while the last method, if doubled, requires six men, for it requires two boys to throw the material to be washed on to the plate and to stir it with iron shovels; two more are required with wooden scrubbers to keep stirring the sand, mixed with the tin-stone, under the plate, and to push it toward the upper end of the box; further, two foremen are required to clean the tin-stone in the way I have described. In the place of a plate full of holes, they now fix in the boxes a grating made of iron wire as thick as the stalks of rye; that these may not be depressed by the weight and become bent, three iron bars support them, being laid crosswise underneath. To prevent the grating from being broken by the iron shovels with which the material is stirred in washing, five or six iron rods are placed on top in cross lines, and are fixed to the box so that the shovels may rub them instead of the grating; for this reason the grating lasts longer than the plates, because it remains intact, while the rods, when worn by rubbing, can easily be replaced by others.

[Illustration 346 (Ground Sluicing): A--Pits. B--Torrent. C--Seven-pronged fork. D--Shovel.]

Miners use the seventh method of washing when there is no stream of water in the part of the mountain which contains the black tin, or

## particles of gold, or of other metals. In this case they frequently dig

more than fifty ditches on the slope below, or make the same number of pits, six feet long, three feet wide, and three-quarters of a foot deep, not any great distance from each other. At the season when a torrent rises from storms of great violence or long duration, and rushes down the mountain, some of the miners dig the metalliferous material in the woods with broad hoes and drag it to the torrent. Other miners divert the torrent into the ditches or pits, and others throw the roots of trees, shrubs, and grass out of the ditches or pits with seven-pronged wooden forks. When the torrent has run down, they remove with shovels the uncleansed tin-stone or particles of metal which have settled in the ditches or pits, and cleanse it.

[Illustration 347 (Ground Sluicing): A--Gully. B--Ditch. C--Torrent. D--Sluice box employed by the Lusitanians.]

The eighth method is also employed in the regions which the Lusitanians hold in their power and sway, and is not dissimilar to the last. They drive a great number of deep ditches in rows in the gullies, slopes, and hollows of the mountains. Into these ditches the water, whether flowing down from snow melted by the heat of the sun or from rain, collects and carries together with earth and sand, sometimes tin-stone, or, in the case of the Lusitanians, the particles of gold loosened from veins and stringers. As soon as the waters of the torrent have all run away, the miners throw the material out of the ditches with iron shovels, and wash it in a common sluice box.

[Illustration 348 (Trough for washing alluvial): A--Trough. B--Launder. C--Hoe. D--Sieve.]

The Poles wash the impure lead from _venae dilatatae_ in a trough ten feet long, three feet wide, and one and one-quarter feet deep. It is mixed with moist earth and is covered by a wet and sandy clay, and so first of all the clay, and afterward the ore, is dug out. The ore is carried to a stream or river, and thrown into a trough into which water is admitted by a little launder, and the washer standing at the lower end of the trough drags the ore out with a narrow and nearly pointed hoe, whose wooden handle is nearly ten feet long. It is washed over again once or twice in the same way and thus made pure. Afterward when it has been dried in the sun they throw it into a copper sieve, and separate the very small pieces which pass through the sieve from the larger ones; of these the former are smelted in a faggot pile and the latter in the furnace. Of such a number then are the methods of washing.

[Illustration 349 (Tin burning Furnace): A--Furnace. B--Its mouth. C--Poker. D--Rake with two teeth. E--Hoe.]

One method of burning is principally employed, and two of roasting. The black tin is burned by a hot fire in a furnace similar to an oven[21]; it is burned if it is a dark-blue colour, or if pyrites and the stone from which iron is made are mixed with it, for the dark blue colour if not burnt, consumes the tin. If pyrites and the other stone are not volatilised into fumes in a furnace of this kind, the tin which is made from the tin-stone is impure. The tin-stone is thrown either into the back part of the furnace, or into one side of it; but in the former case the wood is placed in front, in the latter case alongside, in such a manner, however, that neither firebrands nor coals may fall upon the tin-stone itself or touch it. The fuel is manipulated by a poker made of wood. The tin-stone is now stirred with a rake with two teeth, and now again levelled down with a hoe, both of which are made of iron. The very fine tin-stone requires to be burned less than that of moderate size, and this again less than that of the largest size. While the tin-stone is being thus burned, it frequently happens that some of the material runs together.

The burned tin-stone should then be washed again on the strake, for in this way the material which has been run together is carried away by the water into the cross-trough, where it is gathered up and worked over, and again washed on the strake. By this method the metal is separated from that which is devoid of metal.

[Illustration 350 (Stall Roasting Matte): A--Pits. B--Wood. C--Cakes. D--Launder.]

Cakes from pyrites, or _cadmia_, or cupriferous stones, are roasted in quadrangular pits, of which the front and top are open, and these pits are generally twelve feet long, eight feet wide, and three feet deep. The cakes of melted pyrites are usually roasted twice over, and those of _cadmia_ once. These latter are first rolled in mud moistened with vinegar, to prevent the fire from consuming too much of the copper with the bitumen, or sulphur, or orpiment, or realgar. The cakes of pyrites are first roasted in a slow fire and afterward in a fierce one, and in both cases, during the whole following night, water is let in, in order that, if there is in the cakes any alum or vitriol or saltpetre capable of injuring the metals, although it rarely does injure them, the water may remove it and make the cakes soft. The solidified juices are nearly all harmful to the metal, when cakes or ore of this kind are smelted. The cakes which are to be roasted are placed on wood piled up in the form of a crate, and this pile is fired[22].

[Illustration 351 (Matte Roasting): A--Cakes. B--Bundles of faggots. C--Furnaces.]

The cakes which are made of copper smelted from schist are first thrown upon the ground and broken, and then placed in the furnace on bundles of faggots, and these are lighted. These cakes are generally roasted seven times and occasionally nine times. While this is being done, if they are bituminous, then the bitumen burns and can be smelled. These furnaces have a structure like the structure of the furnaces in which ore is smelted, except that they are open in front; they are six feet high and four feet wide. As for this kind of furnace, three of them are required for one of those in which the cakes are melted. First of all they are roasted in the first furnace, then when they are cooled, they are transferred into the second furnace and again roasted; later they are carried to the third, and afterward back to the first, and this order is preserved until they have been roasted seven or nine times.

END OF BOOK VIII.

FOOTNOTES:

[1] As would be expected, practically all the technical terms used by Agricola in this chapter are adaptations. The Latin terms, _canalis_, _area_, _lacus_, _vasa_, _cribrum_, and _fossa_, have had to be pressed into service for many different devices, largely by extemporised combinations. Where the devices described have become obsolete, we have adopted the nomenclature of the old works on Cornish methods. The following examples may be of interest:--

Simple buddle = _Canalis simplex_ Divided buddle = _Canalis tabellis distinctus_ Ordinary strake = _Canalis devexus_ Short strake = _Area curta_ Canvas strake = _Area linteis extensis contecta_ Limp = _Radius_.

The strake (or streke) when applied to alluvial tin, would have been termed a "tye" in some parts of Cornwall, and the "short strake" a "gounce." In the case of the stamp mill, inasmuch as almost every mechanical part has its counterpart in a modern mill, we have considered the reader will have less difficulty if the modern designations are used instead of the old Cornish. The following are the essential terms in modern, old Cornish, and Latin:--

Stamp Stamper _Pilum_ Stamp-stem Lifter _Pilum_ Shoes Stamp-heads _Capita_ Mortar-box Box _Capsa_ Cam-shaft Barrell _Axis_ Cams Caps _Dentes_ Tappets Tongues _Pili dentes_ Screen Crate _Laminae foraminum plenae_ Settling pit Catchers _Lacus_ Jigging sieve Dilleugher _Cribrum angustum_

[2] Agricola uses four Latin verbs in connection with heat operations at temperatures under the melting point: _Calefacio_, _uro_, _torreo_, and _cremo_. The first he always uses in the sense of "to warm" or "to heat," but the last three he uses indiscriminately in much the same way as the English verbs burn, roast, and calcine are used; but in general he uses the Latin verbs in the order given to indicate degrees of heat. We have used the English verbs in their technical sense as indicated by the context.

It is very difficult to say when roasting began as a distinct and separate metallurgical step in sulphide ore treatment. The Greeks and Romans worked both lead and copper sulphides (see note on p. 391, and note on p. 403), but neither in the remains of old works nor in their literature is there anything from which satisfactory details of such a step can be obtained. The Ancients, of course, understood lime-burning, and calcined several salts to purify them or to render them more caustic. Practically the only specific mention is by Pliny regarding lead ores (see p. 391). Even the statement of Theophilus (1050-1100, A.D.), may refer simply to rendering ore more fragile, for he says (p. 305) in regard to copper ore: "This stone dug up in abundance is placed upon a pile and burned (_comburitur_) after the manner of lime. Nor does it change colour, but loses its hardness and can be broken up, and afterward it is smelted." The _Probierbuechlein_ casually mentions roasting prior to assaying, and Biringuccio (III, 2) mentions incidentally that "dry and ill-disposed ores before everything must be roasted in an open oven so that the air can get in." He gives no further information; and therefore this account of Agricola's becomes practically the first. Apparently roasting, as a preliminary to the treatment of copper sulphides, did not come into use in England until some time later than Agricola, for in Col. Grant Francis' "Smelting of Copper in the Swansea District" (London, 1881, p. 29), a report is set of the "Doeinges of Jochim Ganse"--an imported German--at the "Mynes by Keswicke in Cumberland, A.D., 1581," wherein the delinquencies of the then current practice are described: "Thei never coulde, nether yet can make (copper) under XXII. tymes passinge thro the fire, and XXII. weekes doeing thereof ane sometyme more. But now the nature of these IX. hurtfull humors abovesaid being discovered and opened by Jochim's way of doeing, we can, by his order of workeinge, so correct theim, that parte of theim beinge by nature hurtfull to the copper in wasteinge of it, ar by arte maide freindes, and be not onely an encrease to the copper, but further it in smeltinge; and the rest of the other evill humors shalbe so corrected, and their humors so taken from them, that by once rosteinge and once smeltinge the ure (which shalbe done in the space of three dayes), the same copper ure shall yeeld us black copper." Jochim proposed by 'rostynge' to be rid of "sulphur, arsineque, and antimony."

[3] _Orpiment_ and _realgar_ are the red and yellow arsenical sulphides. (See note on p. 111).

[4] _Cadmia bituminosa_. The description of this substance by Agricola, given below, indicates that it was his term for the complex copper-zinc-arsenic-cobalt minerals found in the well-known, highly bituminous, copper schists at Mannsfeld. The later Mineralogists, Wallerius (_Mineralogia_, Stockholm, 1747), Valmont De Bomare (_Mineralogie_, Paris, 1762), and others assume Agricola's _cadmia bituminosa_ to be "black arsenic" or "arsenic noir," but we see no reason for this assumption. Agricola's statement (_De Nat. Foss._, p. 369) is "... the schistose stone dug up at the foot of the Melibocus Mountains, or as they are now called the Harz (_Hercynium_), near Eisleben, Mannsfeld, and near Hettstedt, is similar to _spinos_ (a bituminous substance described by Theophrastus), if not identical with it. This is black, bituminous, and cupriferous, and when first extracted from the mine it is thrown out into an open space and heaped up in a mound. Then the lower part of the mound is surrounded by faggots, on to which are likewise thrown stones of the same kind. Then the faggots are kindled and the fire soon spreads to the stones placed upon them; by these the fire is communicated to the next, which thus spreads to the whole heap. This easy reception of fire is a characteristic which bitumen possesses in common with sulphur. Yet the small, pure and black bituminous ore is distinguished from the stones as follows: when they burn they emit the kind of odour which is usually given off by burning bituminous coal, and besides, if while they are burning a small shower of rain should fall, they burn more brightly and soften more quickly. Indeed, when the wind carries the fumes so that they descend into nearby standing waters, there can be seen floating in it something like a bituminous liquid, either black, or brown, or purple, which is sufficient to indicate that those stones were bituminous. And that genus of stones has been recently found in the Harz in layers, having occasionally gold-coloured specks of pyrites adhering to them, representing various flat sea-fish or pike or perch or birds, and poultry cocks, and sometimes salamanders."

[5] _Atramentum sutorium rubrum_. Literally, this would be red vitriol. The German translation gives _rot kupferwasser_, also red vitriol. We must confess that we cannot make this substance out, nor can we find it mentioned in the other works of Agricola. It may be the residue from leaching roasted pyrites for vitriol, which would be reddish oxide of iron.

[6] The statement "elsewhere" does not convey very much more information. It is (_De Nat. Fos._, p. 253): "When Goslar pyrites and Eisleben (copper) schists are placed on the pyre and roasted for the third time, they both exude a certain substance which is of a greenish colour, dry, rough, and fibrous (_tenue_). This substance, like asbestos, is not consumed by the fire. The schists exude it more plentifully than the pyrites." The _Interpretatio_ gives _federwis_, as the German equivalent of _amiantus_ (asbestos). This term was used for the feathery alum efflorescence on aluminous slates.

[7] Bearing in mind that bituminous cadmia contained arsenical-cobalt minerals, this substance "resembling _pompholyx_" would probably be arsenic oxide. In _De Natura Fossilium_ (p. 368). Agricola discusses the _pompholyx_ from _cadmia_ at length and pronounces it to be of remarkably "corrosive" quality. (See also note on p. 112.)

[8] HISTORICAL NOTE ON CRUSHING AND CONCENTRATION OF ORES. There can be no question that the first step in the metallurgy of ores was direct smelting, and that this antedates human records. The obvious advantages of reducing the bulk of the material to be smelted by the elimination of barren portions of the ore, must have appealed to metallurgists at a very early date. Logically, therefore, we should find the second step in metallurgy to be concentration in some form. The question of crushing is so much involved with concentration that we have not endeavoured to keep them separate. The earliest indication of these processes appears to be certain inscriptions on monuments of the IV Dynasty (4,000 B.C.?) depicting gold washing (Wilkinson, The Ancient Egyptians, London, 1874, II, p. 137). Certain stelae of the XII Dynasty (2,400 B.C.) in the British Museum (144 Bay 1 and 145 Bay 6) refer to gold washing in the Sudan, and one of them appears to indicate the working of gold ore as distinguished from alluvial. The first written description of the Egyptian methods--and probably that reflecting the most ancient technology of crushing and concentration--is that of Agatharchides, a Greek geographer of the second Century B.C. This work is lost, but the passage in question is quoted by Diodorus Siculus (1st Century B.C.) and by Photius (died 891 A.D.). We give Booth's translation of Diodorus (London, 1700, p. 89), slightly amended: "In the confines of Egypt and the neighbouring countries of Arabia and Ethiopia there is a place full of rich gold mines, out of which with much cost and pains of many labourers gold is dug. The soil here is naturally black, but in the body of the earth run many white veins, shining like white marble, surpassing in lustre all other bright things. Out of these laborious mines, those appointed overseers cause the gold to be dug up by the labour of a vast multitude of people. For the Kings of Egypt condemn to these mines notorious criminals, captives taken in war, persons sometimes falsely accused, or against whom the King is incens'd; and not only they themselves, but sometimes all their kindred and relations together with them, are sent to work here, both to punish them, and by their labour to advance the profit and gain of the Kings. There are infinite numbers upon these accounts thrust down into these mines, all bound in fetters, where they work continually, without being admitted any rest night or day, and so strictly guarded that there is no possibility or way left to make an escape. For they set over them barbarians, soldiers of various and strange languages, so that it is not possible to corrupt any of the guard by discoursing one with another, or by the gaining insinuations of familiar converse. The earth which is hardest and full of gold they soften by putting fire under it, and then work it out with their hands. The rocks thus soften'd and made more pliant and yielding, several thousands of profligate wretches break in pieces with hammers and pickaxes. There is one artist that is the overseer of the whole work, who marks out the stone, and shows the labourers the way and manner how he would have it done. Those that are the strongest amongst them that are appointed to this slavery, provided with sharp iron pickaxes, cleave the marble-shining rock by mere force and strength, and not by arts or sleight-of-hand. They undermine not the rock in a direct line, but follow the bright shining vein of the mine. They carry lamps fastened to their foreheads to give them light, being otherwise in perfect darkness in the various windings and turnings wrought in the mine; and having their bodies appearing sometimes of one colour and sometimes of another (according to the nature of the mine where they work) they throw the lumps and pieces of the stone cut out of the rock upon the floor. And thus they are employed continually without intermission, at the very nod of the overseer, who lashes them severely besides. And there are little boys who penetrate through the galleries into the cavities and with great labour and toil gather up the lumps and pieces hewed out of the rock as they are cast upon the ground, and carry them forth and lay them upon the bank. Those that are over thirty years of age take a piece of the rock of such a certain quantity, and pound it in a stone mortar with iron pestles till it be as small as a vetch; then those little stones so pounded are taken from them by women and older men, who cast them into mills that stand together there near at hand in a long row, and two or three of them being employed at one mill they grind a certain measure given to them at a time, until it is as small as fine meal. No care at all is taken of the bodies of these poor creatures, so that they have not a rag so much as to cover their nakedness, and no man that sees them can choose but commiserate their sad and deplorable condition. For though they are sick, maimed, or lame, no rest nor intermission in the least is allowed them; neither the weakness of old age, nor women's infirmities are any plea to excuse them; but all are driven to their work with blows and cudgelling, till at length, overborne with the intolerable weight of their misery, they drop down dead in the midst of their insufferable labours; so that these miserable creatures always expect the future to be more terrible than even the present, and therefore long for death as far more desirable than life.

"At length the masters of the work take the stone thus ground to powder, and carry it away in order to perfect it. They spread the mineral so ground upon a broad board, somewhat sloping, and pouring water upon it, rub it and cleanse it; and so all the earthy and drossy part being separated from the rest by the water, it runs off the board, and the gold by reason of its weight remains behind. Then washing it several times again, they first rub it lightly with their hands; afterward they draw off any earthy and drossy matter with slender sponges gently applied to the powdered dust, till it be clean, pure gold. At last other workmen take it away by weight and measure, and these put it into earthen pots, and according to the quantity of the gold in every pot they mix with it some lead, grains of salt, a little tin and barley bran. Then, covering every pot close, and carefully daubing them over with clay, they put them in a furnace, where they abide five days and nights together; then after a convenient time that they have stood to cool, nothing of the other matter is to be found in the pots but only pure, refined gold, some little thing diminished in the weight. And thus gold is prepared in the borders of Egypt, and perfected and completed with so many and so great toils and vexations. And, therefore, I cannot but conclude that nature itself teaches us, that as gold is got with labour and toil, so it is kept with difficulty; it creates everywhere the greatest cares; and the use of it is mixed both with pleasure and sorrow."

The remains at Mt. Laurion show many of the ancient mills and concentration works of the Greeks, but we cannot be absolutely certain at what period in the history of these mines crushing and concentration were introduced. While the mines were worked with great activity prior to 500 B.C. (see note 6, p. 27), it was quite feasible for the ancient miner to have smelted these argentiferous lead ores direct. However, at some period prior to the decadence of the mines in the 3rd Century B.C., there was in use an extensive system of milling and concentration. For the following details we are indebted mostly to Edouard Ardaillon (_Les Mines Du Laurion dans l'Antiquite_, Chap. IV.). The ore was first hand-picked (in 1869 one portion of these rejects was estimated at 7,000,000 tons) and afterward it was apparently crushed in stone mortars some 16 to 24 inches in diameter, and thence passed to the mills. These mills, which crushed dry, were of the upper and lower millstone order, like the old-fashioned flour mills, and were turned by hand. The stones were capable of adjustment in such a way as to yield different sizes. The sand was sifted and the oversize returned to the mills. From the mills it was taken to washing plants, which consisted essentially of an inclined area, below which a canal, sometimes with riffles, led through a series of basins, ultimately returning the water again to near the head of the area. These washing areas, constructed with great care, were made of stone cemented over smoothly, and were so efficiently done as to remain still intact. In washing, a workman brushed upward the pulp placed on the inclined upper portion of the area, thus concentrating there a considerable proportion of the galena; what escaped had an opportunity to settle in the sequence of basins, somewhat on the order of the buddle. A quotation by Strabo (III, 2, 10) from the lost work of Polybius (200-125 B.C.) also indicates concentration of lead-silver ores in Spain previous to the Christian era: "Polybius speaking of the silver mines of New Carthage, tells us that they are extremely large, distant from the city about 20 stadia, and occupy a circuit of 400 stadia, that there are 40,000 men regularly engaged in them, and that they yield daily to the Roman people (a revenue of) 25,000 drachmae. The rest of the process I pass over, as it is too long, but as for the silver ore collected, he tells us that it is broken up, and sifted through sieves over water; that what remains is to be again broken, and the water having been strained off, it is to be sifted and broken a third time. The dregs which remain after the fifth time are to be melted, and the lead being poured off, the silver is obtained pure. These silver mines still exist; however, they are no longer the property of the state, neither these nor those elsewhere, but are possessed by private individuals. The gold mines, on the contrary, nearly all belong to the state. Both at Castlon and other places there are singular lead mines worked. They contain a small proportion of silver, but not sufficient to pay for the expense of refining." (Hamilton's Translation, Vol. I., p. 222). While Pliny gives considerable information on vein mining and on alluvial washing, the following obscure passage (XXXIII, 21) appears to be the only reference to concentration of ores: "That which is dug out is crushed, washed, roasted, and ground to powder. This powder is called _apitascudes_, while the silver (lead?) which becomes disengaged in the furnace is called _sudor_ (sweat). That which is ejected from the chimney is called _scoria_ as with other metals. In the case of gold this _scoria_ is crushed and melted again." It is evident enough from these quotations that the Ancients by "washing" and "sifting," grasped the practical effect of differences in specific gravity of the various components of an ore. Such processes are barely mentioned by other mediaeval authors, such as Theophilus, Biringuccio, etc., and thus the account in this chapter is the first tangible technical description. Lead mining has been in active progress in Derbyshire since the 13th century, and concentration was done on an inclined board until the 16th century, when William Humphrey (see below) introduced the jigging sieve. Some further notes on this industry will be found in note 1, p. 77. However, the buddle and strake which appear at that time, are but modest improvements over the board described by Agatharchides in the quotation above.

The ancient crushing appliances, as indicated by the ancient authors and by the Greek and Roman remains scattered over Europe, were hand-mortars and mill-stones of the same order as those with which they ground flour. The stamp-mill, the next advance over grinding in mill-stones, seems to have been invented some time late in the 15th or early in the 16th centuries, but who invented it is unknown. Beckmann (Hist. of Inventions, II, p. 335) says: "In the year 1519 the process of sifting and wet-stamping was established at Joachimsthal by Paul Grommestetter, a native of Schwarz, named on that account the Schwarzer, whom Melzer praises as an ingenious and active washer; and we are told that he had before introduced the same improvements at Schneeberg. Soon after, that is in 1521, a large stamping-work was erected at Joachimsthal, and the process of washing was begun. A considerable saving was thus made, as a great many metallic particles were before left in the washed sand, which was either thrown away or used as mortar for building. In the year 1525, Hans Poertner employed at Schlackenwalde the wet method of stamping, whereas before that period the ore there was ground. In the Harz this invention was introduced at Wildenmann by Peter Philip, who was assay-master there soon after the works at the Upper Harz were resumed by Duke Henry the Younger, about the year 1524. This we learn from the papers of Herdan Hacke or Haecke, who was preacher at Wildenmann in 1572."

In view of the great amount of direct and indirect reference to tin mining in Cornwall, covering four centuries prior to Agricola, it would be natural to expect some statement bearing upon the treatment of ore. Curiously enough, while alluvial washing and smelting of the black-tin are often referred to, there is nothing that we have been able to find, prior to Richard Carew's "Survey of Cornwall" (London, 1602, p. 12) which gives any tangible evidence on the technical phases of ore-dressing. In any event, an inspection of charters, tax-rolls, Stannary Court proceedings, etc., prior to that date gives the impression that vein mining was a very minor portion of the source of production. Although Carew's work dates 45 years after Agricola, his description is of interest: "As much almost dooth it exceede credite, that the Tynne, for and in so small quantitie digged up with so great toyle, and passing afterwards thorow the managing of so many hands, ere it comes to sale, should be any way able to acquite the cost: for being once brought above ground in the stone, it is first broken in peeces with hammers; and then carryed, either in waynes, or on horses' backs, to a stamping mill, where three, and in some places sixe great logges of timber, bounde at the ends with yron, and lifted up and downe by a wheele, driven with the water, doe break it smaller. If the stones be over-moyst, they are dried by the fire in an yron cradle or grate. From the stamping mill, it passeth to the crazing mill, which betweene two grinding stones, turned also with a water-wheel, bruseth the same to a find sand; howbeit, of late times they mostly use wet stampers, and so have no need of the crazing mills for their best stuffe, but only for the crust of their tayles. The streame, after it hath forsaken the mill, is made to fall by certayne degrees, one somewhat distant from another; upon each of which, at every discent, lyeth a greene turfe, three or foure foote square, and one foote thick. On this the Tinner layeth a certayne portion of the sandie Tinne, and with his shovel softly tosseth the same to and fro, that, through this stirring, the water which runneth over it may wash away the light earth from the Tinne, which of a heavier substance lyeth fast on the turfe. Having so clensed one portion, he setteth the same aside, and beginneth with another, until his labour take end with his taske. The best of those turfes (for all sorts serve not) are fetched about two miles to the eastwards of S. Michael's Mount, where at low water they cast aside the sand, and dig them up; they are full of rootes of trees, and on some of them nuts have been found, which confirmeth my former assertion of the sea's intrusion. After it is thus washed, they put the remnant into a wooden dish, broad, flat, and round, being about two foote over, and having two handles fastened at the sides, by which they softly shogge the same to and fro in the water betweene their legges, as they sit over it, untill whatsoever of the earthie substance that was yet left be flitted away. Some of later time, with a sleighter invention, and lighter labour, doe cause certayne boyes to stir it up and down with their feete, which worketh the same effect; the residue, after this often clensing, they call Blacke Tynne."

It will be noticed that the "wet stampers" and the buddle--worked with "boyes feete"--are "innovations of late times." And the interesting question arises as to whether Cornwall did not derive the stamp-mill, buddle, and strake, from the Germans. The first adequate detailed description of Cornish appliances is that of Pryce (_Mineralogia Cornubiensis_, London, 1778) where the apparatus is identical with that described by Agricola 130 years before. The word "stamper" of Cornwall is of German origin, from _stampfer_, or, as it is often written in old German works, _stamper_. However, the pursuit of the subject through etymology ends here, for no derivatives in German can be found for buddle, tye, strake, or other collateral terms. The first tangible evidence of German influence is to be found in Carew who, continuing after the above quotation, states: "But sithence I gathered stickes to the building of this poore nest, Sir Francis Godolphin (whose kind helpe hath much advanced this my playing labour) entertained a Dutch Mynerall man, and taking light from his experience, but building thereon farre more profitable conclusions of his owne invention, hath practised a more saving way in these matters, and besides, made Tynne with good profit of that refuse which Tynners rejected as nothing worth." Beyond this quotation we can find no direct evidence of the influence of "Dutch Mynerall men" in Cornish tin mining at this time. There can be no doubt, however, that in copper mining in Cornwall and elsewhere in England, the "Dutch Mynerall men" did play a large part in the latter part of the 16th Century. Pettus (_Fodinae Regales_, London, 1670, p. 20) states that "about the third year of Queen Elizabeth (1561) she by the advice of her Council sent over for some Germans experienced in mines, and being supplied, she, on the tenth of October, in the sixth of her reign, granted the mines of eight counties ... to Houghsetter, a German whose name and family still continue in Cardiganshire." Elizabeth granted large mining rights to various Germans, and the opening paragraphs of two out of several Charters may be quoted in point. This grant is dated 1565, and in part reads: "ELIZABETH, by the Grace of God, Queen of England, France, and Ireland, Defender of the Faith, &c. To all Men to whom these Letters Patents shall come, Greeting. Where heretofore we have granted Privileges to Cornelius de Voz, for the Mining and Digging in our Realm of England, for Allom and Copperas, and for divers Ewers of Metals that were to be found in digging for the said Allom and Copperas, incidently and consequently without fraud or guile, as by the same our Privilege may appear. And where we also moved, by credible Report to us made, of one Daniel Houghsetter, a German born, and of his Skill and Knowledge of and in all manner of Mines, of Metals and Minerals, have given and granted Privilege to Thomas Thurland, Clerk, one of our Chaplains, and Master of the Hospital of Savoy, and to the same Daniel, for digging and mining for all manner of Ewers of Gold, Silver, Copper, and Quicksilver, within our Counties of York, Lancaster, Cumberland, Westmorland, Cornwall, Devon, Gloucester, and Worcester, and within our Principality of Wales; and with the same further to deal, as by our said Privilege thereof granted and made to the said Thomas Thurland and Daniel Houghsetter may appear. _And_ we now being minded that the said Commodities, and all other Treasures of the Earth, in all other Places of our Realm of England...." On the same date another grant reads: "ELIZABETH, by the Grace of God, Queen of England, France, and Ireland, Defender of the Faith, &c. To all Men to whom these our Letters Patents shall come, Greeting. Where we have received credible Information that our faithful and well-beloved Subject William Humfrey, Saymaster of our Mint within our Tower of London, by his great Endeavour, Labour, and Charge, hath brought into this our Realm of England one Christopher Shutz, an Almain, born at _St. Annen Berg_, under the Obedience of the Electer of Saxony; a Workman as it is reported, of great Cunning, Knowledge, and Experience, as well in the finding of the Calamin Stone, call'd in Latin, _lapis calaminaris_, and in the right and proper use and commodity thereof, for the Composition of the mix'd Metal commonly call'd _latten_, etc." Col. Grant-Francis, in his most valuable collection (Smelting of Copper in the Swansea District, London, 1881) has published a collection of correspondence relating to early mining and smelting operations in Great Britain. And among them (p. 1., etc.) are letters in the years 1583-6 from William Carnsewe and others to Thomas Smyth, with regard to the first smelter erected at Neath, which was based upon copper mines in Cornwall. He mentions "Mr. Weston's (a partner) provydence in bringynge hys Dutch myners hether to aplye such businys in this countrye ys more to be commendyd than his ignorance of our countrymen's actyvytyes in suche matters." The principal "Dutche Mineral Master" referred to was one Ulrick Frosse, who had charge of the mine at Perin Sands in Cornwall, and subsequently of the smelter at Neath. Further on is given (p. 25) a Report by Jochim Gaunse upon the Smelting of copper ores at Keswick in Cumberland in 1581, referred to in note 2, p. 267. The Daniel Hochstetter mentioned in the Charter above, together with other German and English gentlemen, formed the "Company of Mines Royal" and among the properties worked were those with which Gaunse's report is concerned. There is in the Record Office, London (Exchequer K.R. Com. Derby 611. Eliz.) the record of an interesting inquisition into Derbyshire methods in which a then recent great improvement was the jigging sieve, the introduction of which was due to William Humphrey (mentioned above). It is possible that he learned of it from the German with whom he was associated. Much more evidence of the

## activity of the Germans in English mining at this period can be adduced.

On the other hand, Cornwall has laid claims to having taught the art of tin mining and metallurgy to the Germans. Matthew Paris, a Benedictine monk, by birth an Englishman, who died in 1259, relates (_Historia Major Angliae_, London, 1571) that a Cornishman who fled to Germany on account of a murder, first discovered tin there in 1241, and that in consequence the price of tin fell greatly. This statement is recalled with great persistence by many writers on Cornwall. (Camden, _Britannia_, London, 1586; Borlase, Natural History of Cornwall, Oxford, 1758; Pryce, _Mineralogia Cornubiensis_, London, 1778, p. 70, and others).

[11] _Lapidibus liquescentibus_. (See note 15, p. 380).

[12] HISTORICAL NOTE ON AMALGAMATION. The recovery of gold by the use of mercury possibly dates from Roman times, but the application of the process to silver does not seem to go back prior to the 16th Century. Quicksilver was well-known to the Greeks, and is described by Theophrastus (105) and others (see note 58, p. 432, on quicksilver). However, the Greeks made no mention of its use for amalgamation, and, in fact, Dioscorides (V, 70) says "it is kept in vessels of glass, lead, tin or silver; if kept in vessels of any other kind it consumes them and flows away." It was used by them for medicinal purposes. The Romans amalgamated gold with mercury, but whether they took advantage of the principle to recover gold from ores we do not know. Vitruvius (VII, 8) makes the following statement:--"If quicksilver be placed in a vessel and a stone of a hundred pounds' weight be placed on it, it will swim at the top, and will, notwithstanding its weight, be incapable of pressing the liquid so as to break or separate it. If this be taken out, and only a single scruple of gold be put in, that will not swim, but immediately descend to the bottom. This is a proof that the gravity of a body does not depend on its weight, but on its nature. Quicksilver is used for many purposes; without it, neither silver nor brass can be properly gilt. When gold is embroidered on a garment which is worn out and no longer fit for use, the cloth is burnt over the fire in earthen pots; the ashes are thrown into water and quicksilver added to them; this collects all the particles of gold and unites with them. The water is then poured off and the residuum placed in a cloth, which, when squeezed with the hands, suffers the liquid quicksilver to pass through the pores of the cloth, but retains the gold in a mass within it." (Gwilt's Trans., p. 217). Pliny is rather more explicit (XXXIII, 32): "All floats on it (quicksilver) except gold. This it draws into itself, and on that account is the best means of purifying; for, on being repeatedly agitated in earthen pots it casts out the other things and the impurities. These things being rejected, in order that it may give up the gold, it is squeezed in prepared skins, through which, exuding like perspiration, it leaves the gold pure." It may be noted particularly that both these authors state that gold is the only substance that does not float, and, moreover, nowhere do we find any reference to silver combining with mercury, although Beckmann (Hist. of Inventions, Vol. I, p. 14) not only states that the above passage from Pliny refers to silver, but in further error, attributes the origin of silver amalgamation of ores to the Spaniards in the Indies.

The Alchemists of the Middle Ages were well aware that silver would amalgamate with mercury. There is, however, difficulty in any conclusion that it was applied by them to separating silver or gold from ore. The involved gibberish in which most of their utterances was couched, obscures most of their reactions in any event. The School of Geber (Appendix B) held that all metals were a compound of "spiritual" mercury and sulphur, and they clearly amalgamated silver with mercury, and separated them by distillation. The _Probierbuechlein_ (1520?) describes a method of recovering silver from the cement used in parting gold and silver, by mixing the cement (silver chlorides) with quicksilver. Agricola nowhere in this work mentions the treatment of silver ores by amalgamation, although he was familiar with Biringuccio (_De La Pirotechnia_), as he himself mentions in the Preface. This work, published at least ten years before _De Re Metallica_, contains the first comprehensive account of silver amalgamation. There is more than usual interest in the description, because, not only did it precede _De Re Metallica_, but it is also a specific explanation of the fundamental essentials of the Patio Process long before the date when the Spaniards could possibly have invented that process in Mexico. We quote Mr. A. Dick's translation from Percy (Metallurgy of Silver and Gold, p. 560):

"He was certainly endowed with much useful and ingenious thought who invented the short method of extracting metal from the sweepings produced by those arts which have to do with gold and silver, every substance left in the refuse by smelters, and also the substance from certain ores themselves, without the labour of fusing, but by the sole means and virtue of mercury. To effect this, a large basin is first constructed of stone or timber and walled, into which is fitted a millstone made to turn like that of a mill. Into the hollow of this basin is placed matter containing gold (_della materia vra che tiene oro_), well ground in a mortar and afterward washed and dried; and, with the above-mentioned millstone, it is ground while being moistened with vinegar, or water, in which has been dissolved corrosive sublimate (_solimato_), verdigris (_verde rame_), and common salt. Over these materials is then put as much mercury as will cover them; they are then stirred for an hour or two, by turning the millstone, either by hand, or horse-power, according to the plan adopted, bearing in mind that the more the mercury and the materials are bruised together by the millstone, the more the mercury may be trusted to have taken up the substance which the materials contain. The mercury, in this condition, can then be separated from the earthy matter by a sieve, or by washing, and thus you will recover the auriferous mercury (_el vro mercurio_). After this, by driving off the mercury by means of a flask (_i.e._, by heating in a retort or an alembic), or by passing it through a bag, there will remain, at the bottom, the gold, silver, or copper, or whatever metal was placed in the basin under the millstone to be ground. Having been desirous of knowing this secret, I gave to him who taught it to me a ring with a diamond worth 25 ducats; he also required me to give him the eighth part of any profit I might make by using it. This I wished to tell you, not that you should return the ducats to me for teaching you the secret, but in order that you should esteem it all the more and hold it dear."

In another part of the treatise Biringuccio states that washed (concentrated) ores may be ultimately reduced either by lead or mercury. Concerning these silver concentrates he writes: "Afterward drenching them with vinegar in which has been put green copper (_i.e._, verdigris); or drenching them with water in which has been dissolved vitriol and green copper...." He next describes how this material should be ground with mercury. The question as to who was the inventor of silver amalgamation will probably never be cleared up. According to Ulloa (_Relacion Historica Del Viage a la America Meridional_, Madrid, 1748) Dom Pedro Fernandes De Velasco discovered the process in Mexico in 1566. The earliest technical account is that of Father Joseph De Acosta (_Historia Natural y Moral de las Indias_, Seville, 1590, English trans. Edward Grimston, London, 1604, re-published by the Hakluyt Society, 1880). Acosta was born in 1540, and spent the years 1570 to 1585 in Peru, and 1586 in Mexico. It may be noted that Potosi was discovered in 1545. He states that refining silver with mercury was introduced at Potosi by Pedro Fernandes de Velasco from Mexico in 1571, and states (Grimston's Trans., Vol. I, p. 219): "... They put the powder of the metall into the vessels upon furnaces, whereas they anoint it and mortifie it with brine, putting to every fiftie quintalles of powder five quintalles of salt. And this they do for that the salt separates the earth and filth, to the end the quicksilver may the more easily draw the silver unto it. After, they put quicksilver into a piece of holland and presse it out upon the metall, which goes forth like a dewe, alwaies turning and stirring the metall, to the end it may be well incorporate. Before the invention of these furnaces of fire, they did often mingle their metall with quicksilver in great troughes, letting it settle some daies, and did then mix it and stirre it againe, until they thought all the quicksilver were well incorporate with the silver, the which continued twentie daies and more, and at least nine daies." Frequent mention of the different methods of silver amalgamation is made by the Spanish writers subsequent to this time, the best account being that of Alonso Barba, a priest. Barba was a native of Lepe, in Andalusia, and followed his calling at various places in Peru from about 1600 to about 1630, and at one time held the Curacy of St. Bernard at Potosi. In 1640 he published at Madrid his _Arte de los Metales_, etc., in five books. The first two books of this work were translated into English by the Earl of Sandwich, and published in London in 1674, under the title "The First Book of the Art of Metals." This translation is equally wretched with those in French and German, as might be expected from the translators' total lack of technical understanding. Among the methods of silver amalgamation described by Barba is one which, upon later "discovery" at Virginia City, is now known as the "Washoe Process." None of the Spanish writers, so far as we know, make reference to Biringuccio's account, and the question arises whether the Patio Process was an importation from Europe or whether it was re-invented in Mexico. While there is no direct evidence on the point, the presumption is in favour of the former.

The general introduction of the amalgamation of silver ores into Central Europe seems to have been very slow, and over 200 years elapsed after its adoption in Peru and Mexico before it received serious attention by the German Metallurgists. Ignaz Elder v. Born was the first to establish the process effectually in Europe, he having in 1784 erected a "quick-mill" at Glasshutte, near Shemnitz. He published an elaborate account of a process which he claimed as his own, under the title _Ueber das Anquicken der Gold und Silberhaeltigen Erze_, Vienna, 1786. The only thing new in his process seems to have been mechanical agitation. According to Born, a Spaniard named Don Juan de Corduba, in the year 1588, applied to the Court at Vienna offering to extract silver from ores with mercury. Various tests were carried out under the celebrated Lazarus Erckern, and although it appears that some vitriol and salt were used, the trials apparently failed, for Erckern concluded his report with the advice: "That their Lordships should not suffer any more expense to be thrown away upon this experiment." Born's work was translated into English by R. E. Raspe, under the title--"Baron Inigo Born's New Process of Amalgamation, etc.," London, 1791. Some interest attaches to Raspe, in that he was not only the author of "Baron Munchausen," but was also the villain in Scott's "Antiquary." Raspe was a German Professor at Cassel, who fled to England to avoid arrest for theft. He worked at various mines in Cornwall, and in 1791 involved Sir John Sinclair in a fruitless mine, but disappeared before that was known. The incident was finally used by Sir Walter Scott in this novel.

[13] _Aurum in ea remanet purum_. This same error of assuming squeezed amalgam to be pure gold occurs in Pliny; see previous footnote.

[14] George, Duke of Saxony, surnamed "The Bearded," was born 1471, and died 1539. He was chiefly known for his bitter opposition to the Reformation.

[15] The Julian Alps are a section east of the Carnic Alps and lie north of Trieste. The term Rhaetian Alps is applied to that section along the Swiss Italian Boundary, about north of Lake Como.

[16] Ancient Lusitania comprised Portugal and some neighbouring portions of Spain.

[17] Colchis, the traditional land of the Golden Fleece, lay between the Caucasus on the north, Armenia on the south, and the Black Sea on the west. If Agricola's account of the metallurgical purpose of the fleece is correct, then Jason must have had real cause for complaint as to the tangible results of his expedition. The fact that we hear nothing of the fleece after the day it was taken from the dragon would thus support Agricola's theory. Tons of ink have been expended during the past thirty centuries in explanations of what the fleece really was. These explanations range through the supernatural and metallurgical, but more recent writers have endeavoured to construct the journey of the Argonauts into an epic of the development of the Greek trade in gold with the Euxine. We will not attempt to traverse them from a metallurgical point of view further than to maintain that Agricola's explanation is as probable and equally as ingenious as any other, although Strabo (XI, 2, 19.) gives much the same view long before.

Alluvial mining--gold washing--being as old as the first glimmer of civilization, it is referred to, directly or indirectly, by a great majority of ancient writers, poets, historians, geographers, and naturalists. Early Egyptian inscriptions often refer to this industry, but from the point of view of technical methods the description by Pliny is practically the only one of interest, and in Pliny's chapter on the subject, alluvial is badly confused with vein mining. This passage (XXXIII, 21) is as follows: "Gold is found in the world in three ways, to say nothing of that found in India by the ants, and in Scythia by the Griffins. The first is as gold dust found in streams, as, for instance, in the Tagus in Spain, in the Padus in Italy, in the Hebrus in Thracia, in the Pactolus in Asia, and in the Ganges in India; indeed, there is no gold found more perfect than this, as the current polishes it thoroughly by attrition.... Others by equal labour and greater expense bring rivers from the mountain heights, often a hundred miles, for the purpose of washing this debris. The ditches thus made are called _corrugi_, from our word _corrivatio_, I suppose; and these entail a thousand fresh labours. The fall must be steep, that the water may rush down from very high places, rather than flow gently. The ditches across the valleys are joined by aqueducts, and in other places, impassable rocks have to be cut away and forced to make room for troughs of hollowed-out logs. Those who cut the rocks are suspended by ropes, so that to those who watch them from a distance, the workmen seem not so much beasts as birds. Hanging thus, they take the levels and trace the lines which the ditch is to take; and thus, where there is no place for man's footstep, streams are dragged by men. The water is vitiated for washing if the current of the stream carries mud with it. This kind of earth is called _urium_, hence these ditches are laid out to carry the water over beds of pebbles to avoid this _urium_. When they have reached the head of the fall, at the top of the mountain, reservoirs are excavated a couple of hundred feet long and wide, and about ten feet deep. In these reservoirs there are generally five gates left, about three feet square, so that when the reservoir is full, the gates are opened, and the torrent bursts forth with such violence that the rocks are hurled along. When they have reached the plain there is yet more labour. Trenches called _agogae_ are dug for the flow of the water. The bottoms of these are spread at regular intervals with _ulex_ to catch the gold. This _ulex_ is similar to rosemary, rough and prickly. The sides, too, are closed in with planks and are suspended when crossing precipitous spots. The earth is carried to the sea and thus the shattered mountain is washed away and scattered; and this deposition of the earth in the sea has extended the shore of Spain.... The gold procured from _arrugiae_ does not require to be melted, but is already pure gold. It is found in lumps, in shafts as well, sometimes even exceeding ten _librae_ in weight. These lumps are called _palagae_ and _palacurnae_, while the small grains are called _baluce_. The Ulex is dried and burnt and the ashes are washed on a bed of grassy turf in order that the gold may settle thereon."

[19] _Carbunculus Carchedonius_--Carthaginian carbuncle. The German is given by Agricola in the _Interpretatio_ as _granat_, _i.e._, garnet.

[20] As the concentration of crushed tin ore has been exhaustively treated of already, the descriptions from here on probably refer entirely to alluvial tin.

[21] From a metallurgical point of view all of these operations are roasting. Even to-day, however, the expression "burning" tin is in use in some parts of Cornwall, and in former times it was general.

[22] There can be no doubt that these are mattes, as will develop in

## Book IX. The German term in the Glossary for _panes ex pyrite_ is

_stein_, the same as the modern German for matte. Orpiment and realgar are the yellow and red arsenical sulphides. The _cadmia_ was no doubt the cobalt-arsenic minerals (see note on p. 112). The "solidified juices" were generally anything that could be expelled short of smelting, _i.e._, roasted off or leached out, as shown in note 4, p. 1; they embrace the sulphates, salts, sulphur, bitumen, and arsenical sulphides, etc. For further information on leaching out the sulphates, alum, etc., see note 10, p. 564.

## BOOK IX.[1]

Since I have written of the varied work of preparing the ores, I will now write of the various methods of smelting them. Although those who burn, roast and calcine[2] the ore, take from it something which is mixed or combined with the metals; and those who crush it with stamps take away much; and those who wash, screen and sort it, take away still more; yet they cannot remove all which conceals the metal from the eye and renders it crude and unformed. Wherefore smelting is necessary, for by this means earths, solidified juices, and stones are separated from the metals so that they obtain their proper colour and become pure, and may be of great use to mankind in many ways. When the ore is smelted, those things which were mixed with the metal before it was melted are driven forth, because the metal is perfected by fire in this manner. Since metalliferous ores differ greatly amongst themselves, first as to the metals which they contain, then as to the quantity of the metal which is in them, and then by the fact that some are rapidly melted by fire and others slowly, there are, therefore, many methods of smelting. Constant practice has taught the smelters by which of these methods they can obtain the most metal from any one ore. Moreover, while sometimes there are many methods of smelting the same ore, by which an equal weight of metal is melted out, yet one is done at a greater cost and labour than the others. Ore is either melted with a furnace or without one; if smelted with a furnace the tap-hole is either temporarily closed or always open, and if smelted without a furnace, it is done either in pots or in trenches. But in order to make this matter clearer, I will describe each in detail, beginning with the buildings and the furnaces.

A wall which will be called the "second wall" is constructed of brick or stone, two feet and as many palms thick, in order that it may be strong enough to bear the weight. It is built fifteen feet high, and its length depends on the number of furnaces which are put in the works; there are usually six furnaces, rarely more, and often less. There are three furnace walls, a back one which is against the "second" wall, and two side ones, of which I will speak later. These should be made of natural stone, as this is more serviceable than burnt bricks, because bricks soon become defective and crumble away, when the smelter or his deputy chips off the accretions which adhere to the walls when the ore is smelted. Natural stone resists injury by the fire and lasts a long time, especially that which is soft and devoid of cracks; but, on the contrary, that which is hard and has many cracks is burst asunder by the fire and destroyed. For this reason, furnaces which are made of the latter are easily weakened by the fire, and when the accretions are chipped off they crumble to pieces. The front furnace wall should be made of brick, and there should be in the lower part a mouth three palms wide and one and a half feet high, when the hearth is completed. A hole slanting upward, three palms long, is made through the back furnace wall, at the height of a cubit, before the hearth has been prepared; through this hole and a hole one foot long in the "second" wall--as the back of this wall has an arch--is inserted a pipe of iron or bronze, in which are fixed the nozzles of the bellows. The whole of the front furnace wall is not more than five feet high, so that the ore may be conveniently put into the furnace, together with those things which the master needs for his work of smelting. Both the side walls of the furnace are six feet high, and the back one seven feet, and they are three palms thick. The interior of the furnace is five palms wide, six palms and a digit long, the width being measured by the space which lies between the two side walls, and the length by the space between the front and the back walls; however, the upper part of the furnace widens out somewhat.

[Illustration 357 (Blast Furnaces): A--Furnaces. B--Forehearths.]

There are two doors in the second wall if there are six furnaces, one of the doors being between the second and third furnaces and the other between the fourth and fifth furnaces. They are a cubit wide and six feet high, in order that the smelters may not have mishaps in coming and going. It is necessary to have a door to the right of the first furnace, and similarly one to the left of the last, whether the wall is longer or not. The second wall is carried further when the rooms for the cupellation furnaces, or any other building, adjoin the rooms for the blast furnaces, these buildings being only divided by a partition. The smelter, and the ones who attend to the first and the last furnaces, if they wish to look at the bellows or to do anything else, go out through the doors at the end of the wall, and the other people go through the other doors, which are the common ones. The furnaces are placed at a distance of six feet from one another, in order that the smelters and their assistants may more easily sustain the fierceness of the heat. Inasmuch as the interior of each furnace is five palms wide and each is six feet distant from the other, and inasmuch as there is a space of four feet three palms at the right side of the first furnace and as much at the left side of the last furnace, and there are to be six furnaces in one building, then it is necessary to make the second wall fifty-two feet long; because the total of the widths of all of the furnaces is seven and a half feet, the total of the spaces between the furnaces is thirty feet, the space on the outer sides of the first and last furnaces is nine feet and two palms, and the thickness of the two transverse walls is five feet, which make a total measurement of fifty-two feet.[3]

Outside each furnace hearth there is a small pit full of powder which is compressed by ramming, and in this manner is made the forehearth which receives the metal flowing from the furnaces. Of this I will speak later.

[Illustration 358 (Blast Furnaces): A--Furnaces. B--Forehearth. C--Door. D--Water tank. E--Stone which covers it. F--Material of the vent walls. G--Stone which covers it. H--Pipe exhaling the vapour.]

Buried about a cubit under the forehearth and the hearth of the furnace is a transverse water-tank, three feet long, three palms wide and a cubit deep. It is made of stone or brick, with a stone cover, for if it were not covered, the heat would draw the moisture from below and the vapour might be blown into the hearth of the furnace as well as into the forehearth, and would dampen the blast. The moisture would vitiate the blast, and part of the metal would be absorbed and part would be mixed with the slags, and in this manner the melting would be greatly damaged. From each water-tank is built a walled vent, to the same depth as the tank, but six digits wide; this vent slopes upward, and sooner or later penetrates through to the other side of the wall, against which the furnace is built. At the end of this vent there is an opening where the steam, into which the water has been converted, is exhausted through a copper or iron tube or pipe. This method of making the tank and the vent is much the best. Another kind has a similar vent but a different tank, for it does not lie transversely under the forehearth, but lengthwise; it is two feet and a palm long, and a foot and three palms wide, and a foot and a palm deep. This method of making tanks is not condemned by us, as is the construction of those tanks without a vent; the latter, which have no opening into the air through which the vapour may discharge freely, are indeed to be condemned.

[Illustration 359 (Bellows for blast furnaces)]

Fifteen feet behind the second wall is constructed the first wall, thirteen feet high. In both of these are fixed roof beams[4], which are a foot wide and thick, and nineteen feet and a palm long; these are placed three feet distant from one another. As the second wall is two feet higher than the first wall, recesses are cut in the back of it two feet high, one foot wide, and a palm deep, and in these recesses, as it were in mortises, are placed one end of each of the beams. Into these ends are mortised the bottoms of just as many posts; these posts are twenty-four feet high, three palms wide and thick, and from the tops of the posts the same number of rafters stretch downward to the ends of the beams superimposed on the first wall; the upper ends of the rafters are mortised into the posts and the lower ends are mortised into the ends of the beams laid on the first wall; the rafters support the roof, which consists of burnt tiles. Each separate rafter is propped up by a separate timber, which is a cross-beam, and is joined to its post. Planks close together are affixed to the posts above the furnaces; these planks are about two digits thick and a palm wide, and they, together with the wicker work interposed between the timbers, are covered with lute so that there may be no risk of fire to the timbers and wicker-work. In this practical manner is constructed the back part of the works, which contains the bellows, their frames, the mechanism for compressing the bellows, and the instrument for distending them, of all of which I will speak hereafter.

[Illustration 361 (Plan of Smelter Building): The four long walls: A--First. B--Second. C--Third. D--Fourth. The seven transverse walls: E--First. F--Second. G--Third. H--Fourth. I--Fifth. K--Sixth. L--Seventh, or middle.]

In front of the furnaces is constructed the third long wall and likewise the fourth. Both are nine feet high, but of the same length and thickness as the other two, the fourth being nine feet distant from the third; the third is twenty-one and a half feet from the second. At a distance of twelve feet from the second wall, four posts seven and a half feet high, a cubit wide and thick, are set upon rock laid underneath. Into the tops of the posts the roof beam is mortised; this roof beam is two feet and as many palms longer than the distance between the second and the fifth transverse walls, in order that its ends may rest on the transverse walls. If there should not be so long a beam at hand, two are substituted for it. As the length of the long beam is as above, and as the posts are equidistant, it is necessary that the posts should be a distance of nine feet, one palm, two and two-fifths digits from each other, and the end ones this distance from the transverse walls. On this longitudinal beam and to the third and fourth walls are fixed twelve secondary beams twenty-four feet long, one foot wide, three palms thick, and distant from each other three feet, one palm, and two digits. In these secondary beams, where they rest on the longitudinal beams, are mortised the ends of the same number of rafters as there are posts which stand on the second wall. The ends of the rafters do not reach to the tops of the posts, but are two feet away from them, that through this opening, which is like the open part of a forge, the furnaces can emit their fumes. In order that the rafters should not fall down, they are supported partly by iron rods, which extend from each rafter to the opposite post, and partly supported by a few tie-beams, which in the same manner extend from some rafters to the posts opposite, and give them stability. To these tie-beams, as well as to the rafters which face the posts, a number of boards, about two digits thick and a palm wide, are fixed at a distance of a palm from each other, and are covered with lute so that they do not catch fire. In the secondary beams, where they are laid on the fourth wall, are mortised the lower ends of the same number of rafters as those in a set of rafters[5] opposite them. From the third long wall these rafters are joined and tied to the ends of the opposite rafters, so that they may not slip, and besides they are strengthened with substructures which are made of cross and oblique timbers. The rafters support the roof.

In this manner the front part of the building is made, and is divided into three parts; the first part is twelve feet wide and is under the hood, which consists of two walls, one vertical and one inclined. The second part is the same number of feet wide and is for the reception of the ore to be smelted, the fluxes, the charcoal, and other things which are needed by the smelter. The third part is nine feet wide and contains two separate rooms of equal size, in one of which is the assay furnace, while the other contains the metal to be melted in the cupellation furnaces. It is thus necessary that in the building there should be, besides the four long walls, seven transverse walls, of which the first is constructed from the upper end of the first long wall to the upper end of the second long wall; the second proceeds from the end of this to the end of the third long wall; the third likewise from this end of the last extends to the end of the fourth long wall; the fourth leads from the lower end of the first long wall to the lower end of the second long wall; the fifth extends from the end of this to the end of the third long wall; the sixth extends from this last end to the end of the fourth long wall; the seventh divides into two parts the space between the third and fourth long walls.

To return to the back part of the building, in which, as I said, are the bellows[6], their frames, the machinery for compressing them, and the instrument for distending them. Each bellows consists of a body and a head. The body is composed of two "boards," two bows, and two hides. The upper board is a palm thick, five feet and three palms long, and two and a half feet wide at the back part, where each of the sides is a little curved, and it is a cubit wide at the front part near the head. The whole of the body of the bellows tapers toward the head. That which we now call the "board" consists of two pieces of pine, joined and glued together, and of two strips of linden wood which bind the edges of the board, these being seven digits wide at the back, and in front near the head of the bellows one and a half digits wide. These strips are glued to the boards, so that there shall be less damage from the iron nails driven through the hide. There are some people who do not surround the boards with strips, but use boards only, which are very thick. The upper board has an aperture and a handle; the aperture is in the middle of the board and is one foot three palms distant from where the board joins the head of the bellows, and is six digits long and four wide. The lid for this aperture is two palms and a digit long and wide, and three digits thick; toward the back of the lid is a little notch cut into the surface so that it may be caught by the hand; a groove is cut out of the top of the front and sides, so that it may engage in mouldings a palm wide and three digits thick, which are also cut out in a similar manner under the edges. Now, when the lid is drawn forward the hole is closed, and when drawn back it is opened; the smelter opens the aperture a little so that the air may escape from the bellows through it, if he fears the hides might be burst when the bellows are too vigorously and quickly inflated; he, however, closes the aperture if the hides are ruptured and the air escapes. Others perforate the upper board with two or three round holes in the same place as the rectangular one, and they insert plugs in them which they draw out when it is necessary. The wooden handle is seven palms long, or even longer, in order that it may extend outside; one-half of this handle, two palms wide and one thick, is glued to the end of the board and fastened with pegs covered with glue; the other half projects beyond the board, and is rounded and seven digits thick. Besides this, to the handle and to the board is fixed a cleat two feet long, as many palms wide and one palm thick, and to the under side of the same board, at a distance of three palms from the end, is fixed another cleat two feet long, in order that the board may sustain the force of distension and compression; these two cleats are glued to the board, and are fastened to it with pegs covered with glue.

The lower bellows-board, like the upper, is made of two pieces of pine and of two strips of linden wood, all glued together; it is of the same width and thickness as the upper board, but is a cubit longer, this extension being part of the head of which I have more to say a little later. This lower bellows-board has an air-hole and an iron ring. The air-hole is about a cubit distant from the posterior end, and it is midway between the sides of the bellows-board, and is a foot long and three palms wide; it is divided into equal parts by a small rib which forms part of the board, and is not cut from it; this rib is a palm long and one-third of a digit wide. The flap of the air-hole is a foot and three digits long, three palms and as many digits wide; it is a thin board covered with goat skin, the hairy part of which is turned toward the ground. There is fixed to one end of the flap, with small iron nails, one-half of a doubled piece of leather a palm wide and as long as the flap is wide; the other half of the leather, which is behind the flap, is twice perforated, as is also the bellows-board, and these perforations are seven digits apart. Passing through these a string is tied on the under side of the board; and thus the flap when tied to the board does not fall away. In this manner are made the flap and the air-hole, so when the bellows are distended the flap opens, when compressed it closes. At a distance of about a foot beyond the air-hole a slightly elliptical iron ring, two palms long and one wide, is fastened by means of an iron staple to the under part of the bellows-board; it is at a distance of three palms from the back of the bellows. In order that the lower bellows-board may remain stationary, a wooden bolt is driven into the ring, after it penetrates through the hole in the transverse supporting plank which forms part of the frame for the bellows. There are some who dispense with the ring and fasten the bellows-board to the frame with two iron screws something like nails.

The bows are placed between the two boards and are of the same length as the upper board. They are both made of four pieces of linden wood three digits thick, of which the two long ones are seven digits wide at the back and two and a half at the front; the third piece, which is at the back, is two palms wide. The ends of the bows are a little more than a digit thick, and are mortised to the long pieces, and both having been bored through, wooden pegs covered with glue are fixed in the holes; they are thus joined and glued to the long pieces. Each of the ends is bowed (_arcuatur_) to meet the end of the long part of the bow, whence its name "bow" originated. The fourth piece keeps the ends of the bow distended, and is placed a cubit distant from the head of the bellows; the ends of this piece are mortised into the ends of the bow and are joined and glued to them; its length without the tenons is a foot, and its width a palm and two digits. There are, besides, two other very small pieces glued to the head of the bellows and to the lower board, and fastened to them by wooden pegs covered with glue, and they are three palms and two digits long, one palm high, and a digit thick, one half being slightly cut away. These pieces keep the ends of the bow away from the hole in the bellows-head, for if they were not there, the ends, forced inward by the great and frequent movement, would be broken.

The leather is of ox-hide or horse-hide, but that of the ox is far preferable to that of the horse. Each of these hides, for there are two, is three and a half feet wide where they are joined at the back part of the bellows. A long leathern thong is laid along each of the bellows-boards and each of the bows, and fastened by T-shaped iron nails five digits long; each of the horns of the nails is two and a half digits long and half a digit wide. The hide is attached to the bellows-boards by means of these nails, so that a horn of one nail almost touches the horn of the next; but it is different with the bows, for the hide is fastened to the back piece of the bow by only two nails, and to the two long pieces by four nails. In this practical manner they put ten nails in one bow and the same number in the other. Sometimes when the smelter is afraid that the vigorous motion of the bellows may pull or tear the hide from the bows, he also fastens it with little strips of pine by means of another kind of nail, but these strips cannot be fastened to the back pieces of the bow, because these are somewhat bent. Some people do not fix the hide to the bellows-boards and bows by iron nails, but by iron screws, screwed at the same time through strips laid over the hide. This method of fastening the hide is less used than the other, although there is no doubt that it surpasses it in excellence.

Lastly, the head of the bellows, like the rest of the body, consists of two boards, and of a nozzle besides. The upper board is one cubit long, one and a half palms thick. The lower board is part of the whole of the lower bellows-board; it is of the same length as the upper piece, but a palm and a digit thick. From these two glued together is made the head, into which, when it has been perforated, the nozzle is fixed. The back part of the head, where it is attached to the rest of the bellows-body, is a cubit wide, but three palms forward it becomes two digits narrower. Afterward it is somewhat cut away so that the front end may be rounded, until it is two palms and as many digits in diameter, at which point it is bound with an iron ring three digits wide.

The nozzle is a pipe made of a thin plate of iron; the diameter in front is three digits, while at the back, where it is encased in the head of the bellows, it is a palm high and two palms wide. It thus gradually widens out, especially at the back, in order that a copious wind can penetrate into it; the whole nozzle is three feet long.

[Illustration 365 (Bellows for blast furnaces): A--Upper bellows-board. B--Lower bellows-board. C--The two pieces of wood of which each consists. D--Posterior arched part of each. E--Tapered front part of each. F--Pieces of linden wood. G--Aperture in the upper board. H--Lid. I--Little mouldings of wood. K--Handle. L--Cleat on the outside. The cleat inside I am not able to depict. M--Interior of the lower bellows-board. N--Part of the head. O--Air-hole. P--Supporting bar. Q--Flap. R--Hide. S--Thong. T--Exterior of the lower board. V--Staple. X--Ring. Y--Bow. Z--Its long pieces. AA--Back piece of the bow. BB--The bowed ends. CC--Crossbar distending the bow. DD--The two little pieces. EE--Hide. FF--Nail. GG--Horn of the nail. HH--A screw. II--Long thong. KK--Head. LL--Its lower board. MM--Its upper board. NN--Nozzle. OO--The whole of the lower bellows-board. PP--The two exterior plates of the head hinges. QQ--Their curved piece. RR--Middle plate of the head. SS--The two outer plates of the upper bellows-board. TT--Its middle plate. VV--Little axle. XX--Whole bellows.]

The upper bellows-board is joined to the head of the bellows in the following way. An iron plate[7], a palm wide and one and a half palms long, is first fastened to the head at a distance of three digits from the end; from this plate there projects a piece three digits long and two wide, curved in a small circle. The other side has a similar plate. Then in the same part of the upper board are fixed two other iron plates, distant two digits from the edge, each of which are six digits wide and seven long; in each of these plates the middle part is cut away for a little more than three digits in length and for two in depth, so that the curved part of the plates on the head corresponding to them may fit into this cut out part. From both sides of each plate there project pieces, three digits long and two digits wide, similarly curved into small circles. A little iron pin is passed through these curved pieces of the plates, like a little axle, so that the upper board of the bellows may turn upon it. The little axle is six digits long and a little more than a digit thick, and a small groove is cut out of the upper board, where the plates are fastened to it, in such a manner that the little axle when fixed to the plates may not fall out. Both plates fastened to the bellows-board are affixed by four iron nails, of which the heads are on the inner part of the board, whereas the points, clinched at the top, are transformed into heads, so to speak. Each of the other plates is fastened to the head of the bellows by means of a nail with a wide head, and by two other nails of which the heads are on the edge of the bellows-head. Midway between the two plates on the bellows-board there remains a space two palms wide, which is covered by an iron plate fastened to the board by little nails; and another plate corresponding to this is fastened to the head between the other two plates; they are two palms and the same number of digits wide.

The hide is common to the head as to all the other parts of the body; the plates are covered with it, as well as the front part of the upper bellows-board, and both the bows and the back of the head of the bellows, so that the wind may not escape from that part of the bellows. It is three palms and as many digits wide, and long enough to extend from one of the sides of the lower board over the back of the upper; it is fastened by many T-headed nails on one side to the upper board, and on the other side to the head of the bellows, and both ends are fastened to the lower bellows-board.

In the above manner the bellows is made. As two are required for each furnace, it is necessary to have twelve bellows, if there are to be six furnaces in one works.

[Illustration 368 (Bellows for blast furnaces): A--Front sill. B--Back sill. C--Front posts. D--Their slots. E--Beam imposed upon them. F--Higher posts. G--Their slots. H--Beam imposed upon them. I--Timber joined in the mortises of the posts. K--Planks. L--Transverse supporting planks. M--The holes in them. N--Pipe. O--Its front end. P--Its rear end.]

Now it is time to describe their framework. First, two sills a little shorter than the furnace wall are placed on the ground. The front one of these is three palms wide and thick, and the back one three palms and two digits. The front one is two feet distant from the back wall of the furnace, and the back one is six feet three palms distant from the front one. They are set into the earth, that they may remain firm; there are some who accomplish this by means of pegs which, through several holes, penetrate deeply into the ground.

Then twelve short posts are erected, whose lower ends are mortised into the sill that is near the back of the furnace wall; these posts are two feet high, exclusive of the tenons, and are three palms and the same number of digits wide, and two palms thick. A slot one and a half palms wide is cut through them, beginning two palms from the bottom and extending for a height of three palms. All the posts are not placed at the same intervals, the first being at a distance of three feet five digits from the second, and likewise the third from the fourth, but the second is two feet one palm and three digits from the third; the intervals between the other posts are arranged in the same manner, equal and unequal, of which each four pertain to two furnaces. The upper ends of these posts are mortised into a transverse beam which is twelve feet, two palms, and three digits long, and projects five digits beyond the first post and to the same distance beyond the fourth; it is two palms and the same number of digits wide, and two palms thick. Since each separate transverse beam supports four bellows, it is necessary to have three of them.

Behind the twelve short posts the same number of higher posts are erected, of which each has the middle part of the lower end cut out, so that its two resulting lower ends are mortised into the back sill; these posts, exclusive of the tenons, are twelve feet and two palms high, and are five palms wide and two palms thick. They are cut out from the bottom upward, the slot being four feet and five digits high and six digits wide. The upper ends of these posts are mortised into a long beam imposed upon them; this long beam is placed close under the timbers which extend from the wall at the back of the furnace to the first long wall; the beam is three palms wide and two palms thick, and forty-three feet long. If such a long one is not at hand, two or three may be substituted for it, which when joined together make up that length. These higher posts are not placed at equal distances, but the first is at a distance of two feet three palms one digit from the second, and the third is at the same distance from the fourth; while the second is at a distance of one foot three palms and the same number of digits from the third, and in the same manner the rest of the posts are arranged at equal and unequal intervals. Moreover, there is in every post, where it faces the shorter post, a mortise at a foot and a digit above the slot; in these mortises of the four posts is tenoned a timber which itself has four mortises. Tenons are enclosed in mortises in order that they may be better joined, and they are transfixed with wooden pins. This timber is thirteen feet three palms one digit long, and it projects beyond the first post a distance of two palms and two digits, and to the same number of palms and digits beyond the fourth post. It is two palms and as many digits wide, and also two palms thick. As there are twelve posts it is necessary to have three timbers of this kind.

On each of these timbers, and on each of the cross-beams which are laid upon the shorter posts, are placed four planks, each nine feet long, two palms three digits wide, and two palms one digit thick. The first plank is five feet one palm one digit distant from the second, at the front as well as at the back, for each separate plank is placed outside of the posts. The third is at the same distance from the fourth, but the second is one foot and three digits distant from the third. In the same manner the rest of the eight planks are arranged at intervals, the fifth from the sixth and the seventh from the eighth are at the same distances as the first from the second and the third from the fourth; the sixth is at the same distance from the seventh as the second from the third.

Two planks support one transverse plank six feet long, one foot wide, one palm thick, placed at a distance of three feet and two palms from the back posts. When there are six of these supporting planks, on each separate one are placed two bellows; the lower bellows-boards project a palm beyond them. From each of the bellows-boards an iron ring descends through a hole in its supporting plank, and a wooden peg is driven into the ring, so that the bellows-board may remain stationary, as I stated above.

The two bellows communicate, each by its own plank, to the back of a copper pipe in which are set both of the nozzles, and their ends are tightly fastened in it. The pipe is made of a rolled copper or iron plate, a foot and two palms and the same number of digits long; the plate is half a digit thick, but a digit thick at the back. The interior of the pipe is three digits wide, and two and a half digits high in the front, for it is not absolutely round; and at the back it is a foot and two palms and three digits in diameter. The plate from which the pipe is made is not entirely joined up, but at the front there is left a crack half a digit wide, increasing at the back to three digits. This pipe is placed in the hole in the furnace, which, as I said, was in the middle of the wall and the arch. The nozzles of the bellows, placed in this pipe, are a distance of five digits from its front end.

[Illustration 370 (Bellows for blast furnaces): A--Lever which when depressed by means of a cam compresses the bellows. B--Slots through the posts. C--Bar. D--Iron implement with a rectangular link. E--Iron instrument with round ring. F--Handle of bellows. G--Upper post. H--Upper lever. I--Box with equal sides. K--Box narrow at the bottom. L--Pegs driven into the upper lever.]

The levers are of the same number as the bellows, and when depressed by the cams of the long axle they compress the bellows. These levers are eight feet three palms long, one palm wide and thick, and the ends are inserted in the slots of the posts; they project beyond the front posts to a distance of two palms, and the same distance beyond the back posts in order that each may have its end depressed by its two cams on the axle. The cams not only penetrate into the slots of the back posts, but project three digits beyond them. An iron pin is set in round holes made through both sides of the slot of each front post, at three palms and as many digits from the bottom; the pin penetrates the lever, which turns about it when depressed or raised. The back of the lever for the length of a cubit is a palm and a digit wider than the rest, and is perforated; in this hole is engaged a bar six feet and two palms long, three digits wide, and about one and one-half digits thick; it is somewhat hooked at the upper end, and approaches the handle of the bellows. Under the lever there is a nail, which penetrates through a hole in the bar, so that the lever and bar may move together. The bar is perforated in the upper end at a distance of six digits from the top; this hole is two palms long and a digit wide, and in it is engaged the hook of an iron implement which is a digit thick. At the upper part this implement has either a round or square opening, like a link, and at the lower end is hooked; the link is two digits high and wide and the hook is three digits long; the middle part between the link and the hook is three palms and two digits long. The link of this implement engages either the handle of the bellows, or else a large ring which does engage it. This iron ring is a digit thick, two palms wide on the inside of the upper part, and two digits in the lower part, and this iron ring, not unlike the first one, engages the handle of the bellows. The iron ring either has its narrower part turned upward, and in it is engaged the ring of another iron implement, similar to the first, whose hook, extending upward, grips the rope fastened to the iron ring holding the end of the second lever, of which I will speak presently; or else the iron ring grips this lever, and then in its hook is engaged the ring of the other implement whose ring engages the handle of the bellows, and in this case the rope is dispensed with.

Resting on beams fixed in the two walls is a longitudinal beam, at a distance of four and a half feet from the back posts; it is two palms wide, one and a half palms thick. There are mortised into this longitudinal beam the lower ends of upper posts three palms wide and two thick, which are six feet two palms high, exclusive of their tenons. The upper ends of these posts are mortised into an upper longitudinal beam, which lies close under the rafters of the building; this upper longitudinal beam is two palms wide and one thick. The upper posts have a slot cut out upward from a point two feet from the bottom, and the slot is two feet high and six digits wide. Through these upper posts a round hole is bored from one side to the other at a point three feet one palm from the bottom, and a small iron axle penetrates through the hole and is fastened there. Around this small iron axle turns the second lever when it is depressed and raised. This lever is eight feet long, and its other end is three digits wider than the rest of the lever; at this widest point is a hole two digits wide and three high, in which is fixed an iron ring, to which is tied the rope I have mentioned; it is five palms long, its upper loop is two palms and as many digits wide, and the lower one is one palm one digit wide. This half of the second lever, the end of which I have just mentioned, is three palms high and one wide; it projects three feet beyond the slot of the post on which it turns; the other end, which faces the back wall of the furnaces, is one foot and a palm high and a foot wide.

On this part of the lever stands and is fixed a box three and a half feet long, one foot and one palm wide, and half a foot deep; but these measurements vary; sometimes the bottom of this box is narrower, sometimes equal in width to the top. In either case, it is filled with stones and earth to make it heavy, but the smelters have to be on their guard and make provision against the stones falling out, owing to the constant motion; this is prevented by means of an iron band which is placed over the top, both ends being wedge-shaped and driven into the lever so that the stones can be held in. Some people, in place of the box, drive four or more pegs into the lever and put mud between them, the required amount being added to the weight or taken away from it.

There remains to be considered the method of using this machine. The lower lever, being depressed by the cams, compresses the bellows, and the compression drives the air through the nozzle. Then the weight of the box on the other end of the upper lever raises the upper bellows-board, and the air is drawn in, entering through the air-hole.

[Illustration 372 (Bellows for blast furnaces): A--Axle. B--Water-wheel. C--Drum composed of rundles. D--Other axle. E--Toothed wheel. F--Its spokes. G--Its segments. H--Its teeth. I--Cams of the axle.]

The machine whose cams depress the lower lever is made as follows. First there is an axle, on whose end outside the building is a water-wheel; at the other end, which is inside the building, is a drum made of rundles. This drum is composed of two double hubs, a foot apart, which are five digits thick, the radius all round being a foot and two digits; but they are double, because each hub is composed of two discs, equally thick, fastened together with wooden pegs glued in. These hubs are sometimes covered above and around by iron plates. The rundles are thirty in number, a foot and two palms and the same number of digits long, with each end fastened into a hub; they are rounded, three digits in diameter, and the same number of digits apart. In this practical manner is made the drum composed of rundles.

There is a toothed wheel, two palms and a digit thick, on the end of another axle; this wheel is composed of a double disc[8]. The inner disc is composed of four segments a palm thick, everywhere two palms and a digit wide. The outer disc, like the inner, is made of four segments, and is a palm and a digit thick; it is not equally wide, but where the head of the spokes are inserted it is a foot and a palm and digit wide, while on each side of the spokes it becomes a little narrower, until the narrowest part is only two palms and the same number of digits wide. The outer segments are joined to the inner ones in such a manner that, on the one hand, an outer segment ends in the middle of an inner one, and, on the other hand, the ends of the inner segments are joined in the middle of the outer ones; there is no doubt that by this kind of joining the wheel is made stronger. The outer segments are fastened to the inner by means of a large number of wooden pegs. Each segment, measured over its round back, is four feet and three palms long. There are four spokes, each two palms wide and a palm and a digit thick; their length, excluding the tenons, being two feet and three digits. One end of the spoke is mortised into the axle, where it is firmly fastened with pegs; the wide part of the other end, in the shape of a triangle, is mortised into the outer segment opposite it, keeping the shape of the same as far as the segment ascends. They also are joined together with wooden pegs glued in, and these pegs are driven into the spokes under the inner disc. The parts of the spokes in the shape of the triangle are on the inside; the outer part is simple. This triangle has two sides equal, the erect ones as is evident, which are a palm long; the lower side is not of the same length, but is five digits long, and a mortise of the same shape is cut out of the segments. The wheel has sixty teeth, since it is necessary that the rundle drum should revolve twice while the toothed wheel revolves once. The teeth are a foot long, and project one palm from the inner disc of the wheel, and three digits from the outer disc; they are a palm wide and two and a half digits thick, and it is necessary that they should be three digits apart, as were the rundles.

The axle should have a thickness in proportion to the spokes and the segments. As it has two cams to depress each of the levers, it is necessary that it should have twenty-four cams, which project beyond it a foot and a palm and a digit. The cams are of almost semicircular shape, of which the widest part is three palms and a digit wide, and they are a palm thick; they are distributed according to the four sides of the axle, on the upper, the lower and the two lateral sides. The axle has twelve holes, of which the first penetrates through from the upper side to the lower, the second from one lateral side to the other; the first hole is four feet two palms distant from the second; each alternate one of these holes is made in the same direction, and they are arranged at equal intervals. Each single cam must be opposite another; the first is inserted into the upper part of the first hole, the second into the lower part of the same hole, and so fixed by pegs that they do not fall out; the third cam is inserted into that part of the second hole which is on the right side, and the fourth into that part on the left. In like manner all the cams are inserted into the consecutive holes, for which reason it happens that the cams depress the levers of the bellows in rotation. Finally we must not omit to state that this is only one of many such axles having cams and a water-wheel.

I have arrived thus far with many words, and yet it is not unreasonable that I have in this place pursued the subject minutely, since the smelting of all the metals, to which I am about to proceed, could not be undertaken without it.

The ores of gold, silver, copper, and lead, are smelted in a furnace by four different methods. The first method is for the rich ores of gold or silver, the second for the mediocre ores, the third for the poor ores, and the fourth method is for those ores which contain copper or lead, whether they contain precious metals or are wanting in them. The smelting of the first ores is performed in the furnace of which the tap-hole is intermittently closed; the other three ores are melted in furnaces of which the tap-holes are always open.

[Illustration 373 (Stamp-mill): A--Charcoal. B--Mortar-box. C--Stamps.]

First, I will speak of the manner in which the furnaces are prepared for the smelting of the ores, and of the first method of smelting. The powder from which the hearth and forehearth should be made is composed of charcoal and earth (clay?). The charcoal is crushed by the stamps in a mortar-box, the front of which is closed by a board at the top, while the charcoal, crushed to powder, is removed through the open part below; the stamps are not shod with iron, but are made entirely of wood, although at the lower part they are bound round at the wide part by an iron band.

[Illustration 374 (Clay Washing): A--Tub. B--Sieve. C--Rods. D--Bench-frame.]

The powder into which the charcoal is crushed is thrown on to a sieve whose bottom consists of interwoven withes of wood. The sieve is drawn backward and forward over two wooden or iron rods placed in a triangular position on a tub, or over a bench-frame set on the floor of the building; the powder which falls into the tub or on to the floor is of suitable size, but the pieces of small charcoal which remain in the sieve are emptied out and thrown back under the stamps.

[Illustration 375 (Clay Washing): A--Screen. B--Poles. C--Shovel. D--Two-wheeled cart. E--Hand-sieve. F--Narrow boards. G--Box. H--Covered pit.]

When the earth is dug up it is first exposed to the sun that it may dry. Later on it is thrown with a shovel on to a screen--set up obliquely and supported by poles,--made of thick, loosely woven hazel withes, and in this way the fine earth and its small lumps pass through the holes of the screen, but the clods and stones do not pass through, but run down to the ground. The earth which passes through the screen is conveyed in a two-wheeled cart to the works and there sifted. This sieve, which is not dissimilar to the one described above, is drawn backward and forward upon narrow boards of equal length placed over a long box; the powder which falls through the sieve into the box is suitable for the mixture; the lumps that remain in the sieve are thrown away by some people, but by others they are placed under the stamps. This powdered earth is mixed with powdered charcoal, moistened, and thrown into a pit, and in order that it may remain good for a long time, the pit is covered up with boards so that the mixture may not become contaminated.

[Illustration 377 (Implements for Furnace Work): A--Furnace. B--Ladder. C--Board fixed to it. D--Hoe. E--Five-toothed rake. F--Wooden spatula. G--Broom. H--Rammer. I--Rammer, same diameter. K--Two wooden spatulas. L--Curved blade. M--Bronze rammer. N--Another bronze rammer. O--Wide spatula. P--Rod. Q--Wicker basket. R--Two buckets of leather in which water is carried for putting out a conflagration, should the _officina_ catch fire. S--Brass pump with which the water is squirted out. T--Two hooks. V--Rake. X--Workman beating the clay with an iron implement.]

They take two parts of pulverised charcoal and one part of powdered earth, and mix them well together with a rake; the mixture is moistened by pouring water over it so that it may easily be made into shapes resembling snowballs; if the powder be light it is moistened with more water, if heavy with less. The interior of the new furnace is lined with lute, so that the cracks in the walls, if there are any, may be filled up, but especially in order to preserve the rock from injury by fire. In old furnaces in which ore has been melted, as soon as the rocks have cooled the assistant chips away, with a spatula, the accretions which adhere to the walls, and then breaks them up with an iron hoe or a rake with five teeth. The cracks of the furnace are first filled in with fragments of rock or brick, which he does by passing his hand into the furnace through its mouth, or else, having placed a ladder against it, he mounts by the rungs to the upper open part of the furnace. To the upper part of the ladder a board is fastened that he may lean and recline against it. Then standing on the same ladder, with a wooden spatula, he smears the furnace walls over with lute; this spatula is four feet long, a digit thick, and for a foot upward from the bottom it is a palm wide, or even wider, generally two and a half digits. He spreads the lute equally over the inner walls of the furnace. The mouth of the copper pipe[9] should not protrude from the lute, lest sows[10] form round about it and thus impede the melting, for the furnace bellows could not force a blast through them. Then the same assistant throws a little powdered charcoal into the pit of the forehearth and sprinkles it with pulverised earth. Afterward, with a bucket he pours water into it and sweeps this all over the forehearth pit, and with the broom drives the turbid water into the furnace hearth and likewise sweeps it out. Next he throws the mixed and moistened powder into the furnace, and then a second time mounting the steps of the ladder, he introduces the rammer into the furnace and pounds the powder so that the hearth is made solid. The rammer is rounded and three palms long; at the bottom it is five digits in diameter, at the top three and a half, therefore it is made in the form of a truncated cone; the handle of the rammer is round and five feet long and two and a half digits thick; the upper part of the rammer, where the handle is inserted, is bound with an iron band two digits wide. There are some who, instead, use two rounded rammers three and a half digits in diameter, the same at the bottom as at the top. Some people prefer two wooden spatulas, or a rammer spatula.

In a similar manner, mixed and moistened powder is thrown and pounded with a rammer in the forehearth pit, which is outside the furnace. When this is nearly completed, powder is again put in, and pushed with the rammer up toward the protruding copper pipe, so that from a point a digit under the mouth of the copper pipe the hearth slopes down into the crucible of the forehearth,[11] and the metal can run down. The same is repeated until the forehearth pit is full, then afterward this is hollowed out with a curved blade; this blade is of iron, two palms and as many digits long, three digits wide, blunt at the top and sharp at the bottom. The crucible of the forehearth must be round, a foot in diameter and two palms deep if it has to contain a _centumpondium_ of lead, or if only seventy _librae_, then three palms in diameter and two palms deep like the other. When the forehearth has been hollowed out it is pounded with a round bronze rammer. This is five digits high and the same in diameter, having a curved round handle one and a half digits thick; or else another bronze rammer is used, which is fashioned in the shape of a cone, truncated at the top, on which is imposed another cut away at the bottom, so that the middle part of the rammer may be grasped by the hand; this is six digits high, and five digits in diameter at the lower end and four at the top. Some use in its place a wooden spatula two and a half palms wide at the lower end and one palm thick.

The assistant, having prepared the forehearth, returns to the furnace and besmears both sides as well as the top of the mouth with simple lute. In the lower part of the mouth he places lute that has been dipped in charcoal dust, to guard against the risk of the lute attracting to itself the powder of the hearth and vitiating it. Next he lays in the mouth of the furnace a straight round rod three quarters of a foot long and three digits in diameter. Afterward he places a piece of charcoal on the lute, of the same length and width as the mouth, so that it is entirely closed up; if there be not at hand one piece of charcoal so large, he takes two instead. When the mouth is thus closed up, he throws into the furnace a wicker basket full of charcoal, and in order that the piece of charcoal with which the mouth of the furnace is closed should not then fall out, the master holds it in with his hand. The pieces of charcoal which are thrown into the furnace should be of medium size, for if they are large they impede the blast of the bellows and prevent it from blowing through the tap-hole of the furnace into the forehearth to heat it. Then the master covers over the charcoal, placed at the mouth of the furnace, with lute and extracts the wooden rod, and thus the furnace is prepared. Afterward the assistant throws four or five larger baskets full of charcoal into the furnace, filling it right up; he also throws a little charcoal into the forehearth, and places glowing coals upon it in order that it may be kindled, but in order that the flames of this fire should not enter through the tap-hole of the furnace and fire the charcoal inside, he covers the tap-hole with lute or closes it with fragments of pottery. Some do not warm the forehearth the same evening, but place large charcoals round the edge of it, one leaning on the other; those who follow the first method sweep out the forehearth in the morning, and clean out the little pieces of charcoal and cinders, while those who follow the latter method take, early in the morning, burning firebrands, which have been prepared by the watchman of the works, and place them on the charcoal.

At the fourth hour the master begins his work. He first inserts a small piece of glowing coal into the furnace, through the bronze nozzle-pipe of the bellows, and blows up the fire with the bellows; thus within the space of half an hour the forehearth, as well as the hearth, becomes warmed, and of course more quickly if on the preceding day ores have been smelted in the same furnace, but if not then it warms more slowly. If the hearth and forehearth are not warmed before the ore to be smelted is thrown in, the furnace is injured and the metals lost; or if the powder from which both are made is damp in summer or frozen in winter, they will be cracked, and, giving out a sound like thunder, they will blow out the metals and other substances with great peril to the workmen. After the furnace has been warmed, the master throws in slags, and these, when melted, flow out through the tap-hole into the forehearth. Then he closes up the tap-hole at once with mixed lute and charcoal dust; this plug he fastens with his hand to a round wooden rammer that is five digits thick, two palms high, with a handle three feet long. The smelter extracts the slags from the forehearth with a hooked bar; if the ore to be smelted is rich in gold or silver he puts into the forehearth a _centumpondium_ of lead, or half as much if the ore is poor, because the former requires much lead, the latter little; he immediately throws burning firebrands on to the lead so that it melts. Afterward he performs everything according to the usual manner and order, whereby he first throws into the furnace as many cakes melted from pyrites[12], as he requires to smelt the ore; then he puts in two wicker baskets full of ore with litharge and hearth-lead[13], and stones which fuse easily by fire of the second order, all mixed together; then one wicker basket full of charcoal, and lastly the slags. The furnace now being filled with all the things I have mentioned, the ore is slowly smelted; he does not put too much of it against the back wall of the furnace, lest sows should form around the nozzles of the bellows and the blast be impeded and the fire burn less fiercely.

This, indeed, is the custom of many most excellent smelters, who know how to govern the four elements[14]. They combine in right proportion the ores, which are part earth, placing no more than is suitable in the furnaces; they pour in the needful quantity of water; they moderate with skill the air from the bellows; they throw the ore into that part of the fire which burns fiercely. The master sprinkles water into each part of the furnace to dampen the charcoal slightly, so that the minute parts of ore may adhere to it, which otherwise the blast of the bellows and the force of the fire would agitate and blow away with the fumes. But as the nature of the ores to be smelted varies, the smelters have to arrange the hearth now high, now low, and to place the pipe in which the nozzles of the bellows are inserted sometimes on a great and sometimes at a slight angle, so that the blast of the bellows may blow into the furnace in either a mild or a vigorous manner. For those ores which heat and fuse easily, a low hearth is necessary for the work of the smelters, and the pipe must be placed at a gentle angle to produce a mild blast from the bellows. On the contrary, those ores that heat and fuse slowly must have a high hearth, and the pipe must be placed at a steep incline in order to blow a strong blast of the bellows, and it is necessary, for this kind of ore, to have a very hot furnace in which slags, or cakes melted from pyrites, or stones which melt easily in the fire[15], are first melted, so that the ore should not settle in the hearth of the furnace and obstruct and choke up the tap-hole, as the minute metallic

## particles that have been washed from the ores are wont to do. Large

bellows have wide nozzles, for if they were narrow the copious and strong blast would be too much compressed and too acutely blown into the furnace, and then the melted material would be chilled, and would form sows around the nozzle, and thus obstruct the opening into the furnace, which would cause great damage to the proprietors' property. If the ores agglomerate and do not fuse, the smelter, mounting on the ladder placed against the side of the furnace, divides the charge with a pointed or hooked bar, which he also pushes down into the pipe in which the nozzle of the bellows is placed, and by a downward movement dislodges the ore and the sows from around it.

After a quarter of an hour, when the lead which the assistant has placed in the forehearth is melted, the master opens the tap-hole of the furnace with a tapping-bar. This bar is made of iron, is three and a half feet long, the forward end pointed and a little curved, and the back end hollow so that into it may be inserted a wooden handle, which is three feet long and thick enough to be well grasped by the hand. The slag first flows from the furnace into the forehearth, and in it are stones mixed with metal or with the metal adhering to them partly altered, the slag also containing earth and solidified juices. After this the material from the melted pyrites flows out, and then the molten lead contained in the forehearth absorbs the gold and silver. When that which has run out has stood for some time in the forehearth, in order to be able to separate one from the other, the master first either skims off the slags with the hooked bar or else lifts them off with an iron fork; the slags, as they are very light, float on the top. He next draws off the cakes of melted pyrites, which as they are of medium weight hold the middle place; he leaves in the forehearth the alloy of gold or silver with the lead, for these being the heaviest, sink to the bottom. As, however, there is a difference in slags, the uppermost containing little metal, the middle more, and the lowest much, he puts these away separately, each in its own place, in order that to each heap, when it is re-smelted, he may add the proper fluxes, and can put in as much lead as is demanded for the metal in the slag; when the slag is re-melted, if it emits much odour, there is some metal in it; if it emits no odour, then it contains none. He puts the cakes of melted pyrites away separately, as they were nearest in the forehearth to the metal, and contain a little more of it than the slags; from all these cakes a conical mound is built up, by always placing the widest of them at the bottom. The hooked bar has a hook on the end, hence its name; otherwise it is similar to other bars.

[Illustration 383 (Blast Furnaces): A, B, C--Three furnaces. At the first stands the smelter, who with a ladle pours the alloy out of the forehearth into the moulds. D--Forehearth. E--Ladle. F--Moulds. G--Round wooden rammer. H--Tapping-bar. At the second furnace stands the smelter, who opens the tap-hole with his tapping-bar. The assistant, standing on steps placed against the third furnace which has been broken open, chips off the accretions. I--Steps. K--Spatula. L--The other hooked bar. M--Mine captain carrying a cake, in which he has stuck the pick, to the scales to be weighed. N--Another mine captain opens a chest in which his things are kept.]

Afterward the master closes up the tap-hole and fills the furnace with the same materials I described above, and again, the ores having been melted, he opens the tap-hole, and with a hooked bar extracts the slags and the cakes melted from pyrites, which have run down into the forehearth. He repeats the same operation until a certain and definite part of the ore has been smelted, and the day's work is at an end; if the ore was rich the work is finished in eight hours; if poor, it takes a longer time. But if the ore was so rich as to be smelted in less than eight hours, another operation is in the meanwhile combined with the first, and both are performed in the space of ten hours. When all the ore has been smelted, he throws into the furnace a basket full of litharge or hearth-lead, so that the metal which has remained in the accretions may run out with these when melted. When he has finally drawn out of the forehearth the slags and the cakes melted from pyrites, he takes out, with a ladle, the lead alloyed with gold or silver and pours it into little iron or copper pans, three palms wide and as many digits deep, but first lined on the inside with lute and dried by warming, lest the glowing molten substances should break through. The iron ladle is two palms wide, and in other respects it is similar to the others, all of which have a sufficiently long iron shaft, so that the fire should not burn the wooden part of the handle. When the alloy has been poured out of the forehearth, the smelter foreman and the mine captain weigh the cakes.

Then the master breaks out the whole of the mouth of the furnace with a crowbar, and with that other hooked bar, the rabble and the five-toothed rake, he extracts the accretions and the charcoal. This crowbar is not unlike the other hooked one, but larger and wider; the handle of the rabble is six feet long and is half of iron and half of wood. The furnace having cooled, the master chips off the accretions clinging to the walls with a rectangular spatula six digits long, a palm broad, and sharp on the front edge; it has a round handle four feet long, half of it being of iron and half of wood. This is the first method of smelting ores.

Because they generally consist of unequal constituents, some of which melt rapidly and others slowly, the ores rich in gold and silver cannot be smelted as rapidly or as easily by the other methods as they can by the first method, for three important reasons. The first reason is that, as often as the closed tap-hole of the furnace is opened with a tapping-bar, so often can the smelter observe whether the ore is melting too quickly or too slowly, or whether it is flaming in scattered bits, and not uniting in one mass; in the first case the ore is smelting too slowly and not without great expense; in the second case the metal mixes with the slag which flows out of the furnace into the forehearth, wherefore there is the expense of melting it again; in the third case, the metal is consumed by the violence of the fire. Each of these evils has its remedy; if the ore melts slowly or does not come together, it is necessary to add some amount of fluxes which melt the ore; or if they melt too readily, to decrease the amount.

The second reason is that each time that the furnace is opened with a tapping-bar, it flows out into the forehearth, and the smelter is able to test the alloy of gold and lead or of silver with lead, which is called _stannum_.[16] When the tap-hole is opened the second or third time, this test shows us whether the alloy of gold or silver has become richer, or whether the lead is too debilitated and wanting in strength to absorb any more gold or silver. If it has become richer, some portion of lead added to it should renew its strength; if it has not become richer, it is poured out of the forehearth that it may be replaced with fresh lead.

The third reason is that if the tap-hole of the furnace is always open when the ore and other things are being smelted, the fluxes, which are easily melted, run out of the furnace before the rich gold and silver ores, for these are sometimes of a kind that oppose and resist melting by the fire for a longer period. It follows in this case, that some part of the ore is either consumed or is mixed with the accretions, and as a result little lumps of ore not yet melted are now and then found in the accretions. Therefore when these ores are being smelted, the tap-hole of the furnace should be closed for a time, as it is necessary to heat and mix the ore and the fluxes at the same time; since the fluxes fuse more rapidly than the ore, when the molten fluxes are held in the furnace, they thus melt the ore which does not readily fuse or mix with the lead. The lead absorbs the gold or silver, just as tin or lead when melted in the forehearth absorbs the other unmelted metal which has been thrown into it. But if the molten matter is poured upon that which is not molten, it runs off on all sides and consequently does not melt it. It follows from all this that ores rich in gold or silver, when put into a furnace with its tap-hole always open, cannot for that reason be smelted so successfully as in one where the tap-hole is closed for a time, so that during this time the ore may be melted by the molten fluxes. Afterward, when the tap-hole has been opened, they flow into the forehearth and mix there with the molten lead. This method of smelting the ores is used by us and by the Bohemians.

[Illustration 385 (Blast Furnaces): A, B--Two furnaces. C--Forehearths. D--Dipping-pot. The smelter standing by the first furnace draws off the slags with a hooked bar. E--Hooked bar. F--Slags. G--The assistant drawing a bucket of water which he pours over the glowing slags to quench them. H--Basket made of twigs of wood intertwined. I--Rabble. K--Ore to be smelted. L--The master stands at the other furnace and prepares the forehearth by ramming it with two rammers. M--Crowbar.]

The three remaining methods of smelting ores are similar to each other in that the tap-holes of the furnaces always remain open, so that the molten metals may continually run out. They differ greatly from each other, however, for the tap-hole of the first of this kind is deeper in the furnace and narrower than that of the third, and besides it is invisible and concealed. It easily discharges into the forehearth, which is one and a half feet higher than the floor of the building, in order that below it to the left a dipping-pot can be made. When the forehearth is nearly full of the slags, which well up from the invisible tap-hole of the furnace, they are skimmed off from the top with a hooked bar; then the alloy of gold or silver with lead and the melted pyrites, being uncovered, flow into the dipping-pot, and the latter are made into cakes; these cakes are broken and thrown back into the furnace so that all their metal may be smelted out. The alloy is poured into little iron moulds.

The smelter, besides lead and cognate things, uses fluxes which combine with the ore, of which I gave a sufficient account in Book VII. The metals which are melted from ores that fuse readily in the fire, are profitable because they are smelted in a short time, while those which are difficult to fuse are not as profitable, because they take a long time. When fluxes remain in the furnace and do not melt, they are not suitable; for this reason, accretions and slags are the most convenient for smelting, because they melt quickly. It is necessary to have an industrious and experienced smelter, who in the first place takes care not to put into the furnace more ores mixed with fluxes than it can accommodate.

The powder out of which this furnace hearth and the adjoining forehearth and the dipping-pot are usually made, consists mostly of equal proportions of charcoal dust and of earth, or of equal parts of the same and of ashes. When the hearth of the furnace is prepared, a rod that will reach to the forehearth is put into it, higher up if the ore to be smelted readily fuses, and lower down if it fuses with difficulty. When the dipping-pot and forehearth are finished, the rod is drawn out of the furnace so that the tap-hole is open, and through it the molten material flows continuously into the forehearth, which should be very near the furnace in order that it may keep very hot and the alloy thus be made purer. If the ore to be smelted does not melt easily, the hearth of the furnace must not be made too sloping, lest the molten fluxes should run down into the forehearth before the ore is smelted, and the metal thus remain in the accretions on the sides of the furnace. The smelter must not ram the hearth so much that it becomes too hard, nor make the mistake of ramming the lower part of the mouth to make it hard, for it could not breathe[17], nor could the molten matter flow freely out of the furnace. The ore which does not readily melt is thrown as much as possible to the back of the furnace, and toward that part where the fire burns very fiercely, so that it may be smelted longer. In this way the smelter may direct it whither he wills. Only when it glows at the part near the bellows' nozzle does it signify that all the ore is smelted which has been thrown to the side of the furnace in which the nozzles are placed. If the ore is easily melted, one or two wicker baskets full are thrown into the front part of the furnace so that the fire, being driven back by it, may also smelt the ore and the sows that form round about the nozzles of the bellows. This process of smelting is very ancient among the Tyrolese[18], but not so old among the Bohemians.

[Illustration 387 (Blast Furnaces): A, B--Two furnaces. C--Forehearth. D--Dipping-pots. The master stands at the one furnace and draws away the slags with an iron fork. E--Iron fork. F--Wooden hoe with which the cakes of melted pyrites are drawn out. G--The forehearth crucible: one-half inside is to be seen open in the other furnace. H--The half outside the furnace. I--The assistant prepares the forehearth, which is separated from the furnace that it may be seen. K--Bar. L--Wooden rammer. M--Ladder. N--Ladle.]

The second method of smelting ores stands in a measure midway between that one performed in a furnace of which the tap-hole is closed intermittently, and the first of the methods performed in a furnace where the tap-hole is always open. In this manner are smelted the ores of gold and silver that are neither very rich nor very poor, but mediocre, which fuse easily and are readily absorbed by the lead. It was found that in this way a large quantity of ore could be smelted at one operation without much labour or great expense, and could thus be alloyed with lead. This furnace has two crucibles, one of which is half inside the furnace and half outside, so that the lead being put into this crucible, the part of the lead which is in the furnace absorbs the metals of the ores which easily fuse; the other crucible is lower, and the alloy and the molten pyrites run into it. Those who make use of this method of smelting, tap the alloy of gold or silver with lead from the upper crucible once or twice if need be, and throw in other lead or litharge, and each absorbs that flux which is nearest. This method of smelting is in use in Styria[19].

[Illustration 389 (Furnaces): A, B--Two furnaces. C--Tap-holes of furnaces. D--Forehearths. E--Their tap-holes. F--Dipping-pots. G--At the one furnace stands the smelter carrying a wicker basket full of charcoal. At the other furnace stands a smelter who with the third hooked bar breaks away the material which has frozen the tap-hole of the furnace. H--Hooked bar. I--Heap of charcoal. K--Barrow on which is a box made of wicker work in which the coals are measured. L--Iron spade.]

The furnace in the third method of smelting ores has the tap-hole likewise open, but the furnace is higher and wider than the others, and its bellows are larger; for these reasons a larger charge of the ore can be thrown into it. When the mines yield a great abundance of ore for the smelter, they smelt in the same furnace continuously for three days and three nights, providing there be no defect either in the hearth or in the forehearth. In this kind of a furnace almost every kind of accretion will be found. The forehearth of the furnace is not unlike the forehearth of the first furnace of all, except that it has a tap-hole. However, because large charges of ore are smelted uninterruptedly, and the melted material runs out and the slags are skimmed off, there is need for a second forehearth crucible, into which the molten material runs through an opened tap-hole when the first is full. When a smelter has spent twelve hours' labour on this work, another always takes his place. The ores of copper and lead and the poorest ores of gold and silver are smelted by this method, because they cannot be smelted by the other three methods on account of the greater expense occasioned. Yet by this method a _centumpondium_ of ore containing only one or two _drachmae_ of gold, or only a half to one _uncia_, of silver,[20] can be smelted; because there is a large amount of ore in each charge, smelting is continuous, and without expensive fluxes such as lead, litharge, and hearth-lead. In this method of smelting we must use only cupriferous pyrites which easily melt in the fire, in truth the cakes melted out from this, if they no longer absorb much gold or silver, are replenished again from crude pyrites alone. If from this poor ore, with melted pyrites alone, material for cakes cannot be made, there are added other fluxes which have not previously been melted. These fluxes are, namely, lead ore, stones easily fused by fire of the second order and sand made from them, limestone, _tophus_, white schist, and iron stone[21].

Although this method of smelting ores is rough and might not seem to be of great use, yet it is clever and useful; for a great weight of ores, in which the gold, silver, or copper are in small quantities, may be reduced into a few cakes containing all the metal. If on being first melted they are too crude to be suitable for the second melting, in which the lead absorbs the precious metals that are in the cakes, or in which the copper is melted out of them, yet they can be made suitable if they are repeatedly roasted, sometimes as often as seven or eight times, as I have explained in the last book. Smelters of this kind are so clever and expert, that in smelting they take out all the gold and silver which the assayer in assaying the ores has stated to be contained in them, because if during the first operation, when he makes the cakes, there is a _drachma_ of gold or half an _uncia_ of silver lost from the ores, the smelter obtains it from the slags by the second smelting. This method of smelting ores is old and very common to most of those who use other methods.

[Illustration 393 (Lead smelting Furnaces): A--Furnace of the Carni. B--Low wall. C--Wood. D--Ore dripping lead. E--Large crucible. F--Moulds. G--Ladle. H--Slabs of lead. I--Rectangular hole at the back of the furnace. K--Saxon furnace. L--Opening in the back of the furnace. M--Wood. N--Upper crucible. O--Dipping-pot. P--Westphalian method of melting. Q--Heaps of charcoal. R--Straw. S--Wide slabs. T--Crucibles. V--Polish hearth.]

Although lead ores are usually smelted in the third furnace--whose tap-hole is always open,--yet not a few people melt them in special furnaces by a method which I will briefly explain. The _Carni_[22] first burn such lead ores, and afterward break and crush them with large round mallets. Between the two low walls of a hearth, which is inside a furnace made of and vaulted with a rock that resists injury by the fire and does not burn into chalk, they place green wood with a layer of dry wood on the top of it; then they throw the ore on to this, and when the wood is kindled the lead drips down and runs on to the underlying sloping hearth[23]. This hearth is made of pulverised charcoal and earth, as is also a large crucible, one-half of which lies under the furnace and the other half outside it, into which runs the lead. The smelter, having first skimmed off the slags and other things with a hoe, pours the lead with a ladle into moulds, taking out the cakes after they have cooled. At the back of the furnace is a rectangular hole, so that the fire may be allowed more draught, and so that the smelter can crawl through it into the furnace if necessity demands.

The Saxons who inhabit Gittelde, when smelting lead ore in a furnace not unlike a baking oven, put the wood in through a hole at the back of the furnace, and when it begins to burn vigorously the lead trickles out of the ore into a forehearth. When this is full, the smelting being accomplished, the tap-hole is opened with a bar, and in this way the lead, together with the slags, runs into the dipping-pots below. Afterward the cakes of lead, when they are cold, are taken from the moulds.

In Westphalia they heap up ten wagon-loads of charcoal on some hillside which adjoins a level place, and the top of the heap being made flat, straw is thrown upon it to the thickness of three or four digits. On the top of this is laid as much pure lead ore as the heap can bear; then the charcoal is kindled, and when the wind blows, it fans the fire so that the ore is smelted. In this wise the lead, trickling down from the heap, flows on to the level and forms broad thin slabs. A few hundred pounds of lead ore are kept at hand, which, if things go well, are scattered over the heap. These broad slabs are impure and are laid upon dry wood which in turn is placed on green wood laid over a large crucible, and the former having been kindled, the lead is re-melted.

The Poles use a hearth of bricks four feet high, sloping on both sides and plastered with lute. On the upper level part of the hearth large pieces of wood are piled, and on these is placed small wood with lute put in between; over the top are laid wood shavings, and upon these again pure lead ore covered with large pieces of wood. When these are kindled, the ore melts and runs down on to the lower layer of wood; and when this is consumed by the fire, the metal is collected. If necessity demand, it is melted over and over again in the same manner, but it is finally melted by means of wood laid over the large crucible, the slabs of lead being placed upon it.

The concentrates from washing are smelted together with slags (fluxes?) in a third furnace, of which the tap-hole is always open.

[Illustration 395 (Blast Furnaces): A--Furnaces. B--Vaulted roof. C--Columns. D--Dust-chamber. E--Opening. F--Chimney. G--Window. H--Door. I--Chute.]

It is worth while to build vaulted dust-chambers over the furnaces, especially over those in which the precious ores are to be smelted, in order that the thicker part of the fumes, in which metals are not wanting, may be caught and saved. In this way two or more furnaces are combined under the same vaulted ceiling, which is supported by the wall, against which the furnaces are built, and by four columns. Under this the smelters of the ore perform their work. There are two openings through which the fumes rise from the furnaces into the wide vaulted chamber, and the wider this is the more fumes it collects; in the middle of this chamber over the arch is an opening three palms high and two wide. This catches the fumes of both furnaces, which have risen up from both sides of the vaulted chamber to its arch, and have fallen again because they could not force their way out; and they thus pass out through the opening mentioned, into the chimney which the Greeks call [Greek: kapnodoche], the name being taken from the object. The chimney has thin iron plates fastened into the walls, to which the thinner metallic substances adhere when ascending with the fumes. The thicker metallic substances, or _cadmia_,[25] adhere to the vaulted chamber, and often harden into stalactites. On one side of the chamber is a window in which are set panes of glass, so that the light may be transmitted, but the fumes kept in; on the other side is a door, which is kept entirely closed while the ores are being smelted in the furnaces, so that none of the fumes may escape. It is opened in order that the workman, passing through it, may be enabled to enter the chamber and remove the soot and _pompholyx_[26] and chip off the _cadmia_; this sweeping is done twice a year. The soot mixed with _pompholyx_ and the _cadmia_, being chipped off, is thrown down through a long chute made of four boards joined in the shape of a rectangle, that they should not fly away. They fall on to the floor, and are sprinkled with salt water, and are again smelted with ore and litharge, and become an emolument to the proprietors. Such chambers, which catch the metallic substances that rise with the fumes, are profitable for all metalliferous ores; but especially for the minute metallic particles collected by washing crushed ores and rock, because these usually fly out with the fire of the furnaces.

I have explained the four general methods of smelting ores; now I will state how the ores of each metal are smelted, or how the metal is obtained from the ore. I will begin with gold. Its sand, the concentrates from washing, or the gold dust collected in any other manner, should very often not be smelted, but should be mixed with quicksilver and washed with tepid water, so that all the impurities may be eliminated. This method I explained in Book VII. Or they are placed in the _aqua_ which separates gold from silver, for this also separates its impurities. In this method we see the gold sink in the glass ampulla, and after all the _aqua_ has been drained from the particles, it frequently remains as a gold-coloured residue at the bottom; this powder, when it has been moistened with oil made from argol[27], is then dried and placed in a crucible, where it is melted with borax or with saltpetre and salt; or the same very fine dust is thrown into molten silver, which absorbs it, and from this it is again parted by _aqua valens_[28].

It is necessary to smelt gold ore either outside the blast furnace in a crucible, or inside the blast furnace; in the former case a small charge of ore is used, in the latter a large charge of it. _Rudis_ gold, of whatever colour it is, is crushed with a _libra_ each of sulphur and salt, a third of a _libra_ of copper, and a quarter of a _libra_ of argol; they should be melted in a crucible on a slow fire for three hours, then the alloy is put into molten silver that it may melt more rapidly. Or a _libra_ of the same crude gold, crushed up, is mixed together with half a _libra_ of _stibium_ likewise crushed, and put into a crucible with half an _uncia_ of copper filings, and heated until they melt, then a sixth part of granulated lead is thrown into the same crucible. As soon as the mixture emits an odour, iron-filings are added to it, or if these are not at hand, iron hammer-scales, for both of these break the strength of the _stibium_. When the fire consumes it, not alone with it is some strength of the _stibium_ consumed, but some

## particles of gold and also of silver, if it be mixed with the gold[29].

When the button has been taken out of the crucible and cooled, it is melted in a cupel, first until the antimony is exhaled, and thereafter until the lead is separated from it.

Crushed pyrites which contains gold is smelted in the same way; it and the _stibium_ should be of equal weight and in truth the gold may be made from them in a number of different ways[30]. One part of crushed material is mixed with six parts of copper, one part of sulphur, half a part of salt, and they are all placed in a pot and over them is poured wine distilled by heating liquid argol in an ampulla. The pot is covered and smeared over with lute and is put in a hot place, so that the mixture moistened with wine may dry for the space of six days, then it is heated for three hours over a gentle fire that it may combine more rapidly with the lead. Finally it is put into a cupel and the gold is separated from the lead[31].

Or else one _libra_ of the concentrates from washing pyrites, or other stones to which gold adheres, is mixed with half a _libra_ of salt, half a _libra_ of argol, a third of a _libra_ of glass-galls, a sixth of a _libra_ of gold or silver slags, and a _sicilicus_ of copper. The crucible into which these are put, after it has been covered with a lid, is sealed with lute and placed in a small furnace that is provided with small holes through which the air is drawn in, and then it is heated until it turns red and the substances put in have alloyed; this should take place within four or five hours. The alloy having cooled, it is again crushed to powder and a pound of litharge is added to it; then it is heated again in another crucible until it melts. The button is taken out, purged of slag, and placed in a cupel, where the gold is separated from the lead.

Or to a _libra_ of the powder prepared from such metalliferous concentrates, is added a _libra_ each of salt, of saltpetre, of argol, and of glass-galls, and it is heated until it melts. When cooled and crushed, it is washed, then to it is added a _libra_ of silver, a third of copper filings, a sixth of litharge, and it is likewise heated again until it melts. After the button has been purged of slag, it is put into the cupel, and the gold and silver are separated from the lead; the gold is parted from the silver with _aqua valens_. Or else a _libra_ of the powder prepared from such metalliferous concentrates, a quarter of a _libra_ of copper filings, and two _librae_ of that second powder[32] which fuses ores, are heated until they melt. The mixture when cooled is again reduced to powder, roasted and washed, and in this manner a blue powder is obtained. Of this, and silver, and that second powder which fuses ores, a _libra_ each are taken, together with three _librae_ of lead, and a quarter of a _libra_ of copper, and they are heated together until they melt; then the button is treated as before. Or else a _libra_ of the powder prepared from such metalliferous concentrates, half a _libra_ of saltpetre, and a quarter of a _libra_ of salt are heated until they melt. The alloy when cooled is again crushed to powder, one _libra_ of which is absorbed by four pounds of molten silver. Or else a _libra_ of the powder made from that kind of concentrates, together with a _libra_ of sulphur, a _libra_ and a half of salt, a third of a _libra_ of salt made from argol, and a third of a _libra_ of copper resolved into powder with sulphur, are heated until they melt. Afterward the lead is re-melted, and the gold is separated from the other metals. Or else a _libra_ of the powder of this kind of concentrates, together with two _librae_ of salt, half a _libra_ of sulphur, and one _libra_ of litharge, are heated, and from these the gold is melted out. By these and similar methods concentrates containing gold, if there be a small quantity of them or if they are very rich, can be smelted outside the blast furnace.

If there be much of them and they are poor, then they are smelted in the blast furnace, especially the ore which is not crushed to powder, and

## particularly when the gold mines yield an abundance of it[33]. The gold

concentrates mixed with litharge and hearth-lead, to which are added iron-scales, are smelted in the blast furnace whose tap-hole is intermittently closed, or else in the first or the second furnaces in which the tap-hole is always open. In this manner an alloy of gold and lead is obtained which is put into the cupellation furnace. Two parts of roasted pyrites or _cadmia_ which contain gold, are put with one part of unroasted, and are smelted together in the third furnace whose tap-hole is always open, and are made into cakes. When these cakes have been repeatedly roasted, they are re-smelted in the furnace whose tap-hole is temporarily closed, or in one of the two others whose tap-holes are always open. In this manner the lead absorbs the gold, whether pure or argentiferous or cupriferous, and the alloy is taken to the cupellation furnace. Pyrites, or other gold ore which is mixed with much material that is consumed by fire and flies out of the furnace, is melted with stone from which iron is melted, if this is at hand. Six parts of such pyrites, or of gold ore reduced to powder and sifted, four of stone from which iron is made, likewise crushed, and three of slaked lime, are mixed together and moistened with water; to these are added two and a half parts of the cakes which contain some copper, together with one and a half parts of slag. A basketful of fragments of the cakes is thrown into the furnace, then the mixture of other things, and then the slag. Now when the middle part of the forehearth is filled with the molten material which runs down from the furnace, the slags are first skimmed off, and then the cakes made of pyrites; afterward the alloy of copper, gold and silver, which settles at the bottom, is taken out. The cakes are gently roasted and re-smelted with lead, and made into cakes, which are carried to other works. The alloy of copper, gold, and silver is not roasted, but is re-melted again in a crucible with an equal portion of lead. Cakes are also made much richer in copper and gold than those I spoke of. In order that the alloy of gold and silver may be made richer, to eighteen _librae_ of it are added forty-eight _librae_ of crude ore, three _librae_ of the stone from which iron is made, and three-quarters of a _libra_ of the cakes made from pyrites, and mixed with lead, all are heated together in the crucible until they melt. When the slag and the cakes melted from pyrites have been skimmed off, the alloy is carried to other furnaces.

There now follows silver, of which the native silver or the lumps of _rudis_ silver[34] obtained from the mines are not smelted in the blast furnaces, but in small iron pans, of which I will speak at the proper place; these lumps are heated and thrown into molten silver-lead alloy in the cupellation furnace when the silver is being separated from the lead, and refined. The tiny flakes or tiny lumps of silver adhering to stones or marble or rocks, or again the same little lumps mixed with earth, or silver not pure enough, should be smelted in the furnace of which the tap-hole is only closed for a short time, together with cakes melted from pyrites, with silver slags, and with stones which easily fuse in fire of the second order.

In order that particles of silver should not fly away[35] from the lumps of ore consisting of minute threads of pure silver and twigs of native silver, they are enclosed in a pot, and are placed in the same furnace where the rest of the silver ores are being smelted. Some people smelt lumps of native silver not sufficiently pure, in pots or triangular crucibles, whose lids are sealed with lute. They do not place these pots in the blast furnace, but arrange them in the assay furnace into which the draught of the air blows through small holes. To one part of the native silver they add three parts of powdered litharge, as many parts of hearth-lead, half a part of galena[36], and a small quantity of salt and iron-scales. The alloy which settles at the bottom of the other substances in the pot is carried to the cupellation furnace, and the slags are re-melted with the other silver slags. They crush under the stamps and wash the pots or crucibles to which silver-lead alloy or slags adhere, and having collected the concentrates they smelt them together with the slags. This method of smelting _rudis_ silver, if there is a small quantity of it, is the best, because the smallest portion of silver does not fly out of the pot or the crucible, and get lost.

If bismuth ore or antimony ore or lead ore[37] contains silver, it is smelted with the other ores of silver; likewise galena or pyrites, if there is a small amount of it. If there be much galena, whether it contain a large or a small amount of silver, it is smelted separately from the others; which process I will explain a little further on.

Because lead and copper ores and their metals have much in common with silver ores, it is fitting that I should say a great deal concerning them, both now and later on. Also in the same manner, pyrites are smelted separately if there be much of them. To three parts of roasted lead or copper ore and one part of crude ore, are added concentrates if they were made by washing the same ore, together with slags, and all are put in the third furnace whose tap-hole is always open. Cakes are made from this charge, which, when they have been quenched with water, are roasted. Of these roasted cakes generally four parts are again mixed with one part of crude pyrites and re-melted in the same furnace. Cakes are again made from this charge, and if there is a large amount of copper in these cakes, copper is made immediately after they have been roasted and re-melted; if there is little copper in the cakes they are also roasted, but they are re-smelted with a little soft slag. In this method the molten lead in the forehearth absorbs the silver. From the pyritic material which floats on the top of the forehearth are made cakes for the third time, and from them when they have been roasted and re-smelted is made copper. Similarly, three parts of roasted _cadmia_[38] in which there is silver, are mixed with one part of crude pyrites, together with slag, and this charge is smelted and cakes are made from it; these cakes having been roasted are re-smelted in the same furnace. By this method the lead contained in the forehearth absorbs the silver, and the silver-lead is taken to the cupellation furnace. Crude quartz and stones which easily fuse in fire of the third order, together with other ores in which there is a small amount of silver, ought to be mixed with crude roasted pyrites or _cadmia_, because the roasted cakes of pyrites or _cadmia_ cannot be profitably smelted separately. In a similar manner earths which contain little silver are mixed with the same; but if pyrites and _cadmia_ are not available to the smelter, he smelts such silver ores and earths with litharge, hearth-lead, slags, and stones which easily melt in the fire. The concentrates[39] originating from the washing of _rudis_ silver, after first being roasted[40] until they melt, are smelted with mixed litharge and hearth-lead, or else, after being moistened with water, they are smelted with cakes made from pyrites and _cadmia_. By neither of these methods do (the concentrates) fall back in the furnace, or fly out of it, driven by the blast of the bellows and the agitation of the fire. If the concentrates originated from galena they are smelted with it after having been roasted; and if from pyrites, then with pyrites.

Pure copper ore, whether it is its own colour or is tinged with chrysocolla or azure, and copper glance, or grey or black _rudis_ copper, is smelted in a furnace of which the tap-hole is closed for a very short time, or else is always open[41]. If there is a large amount of silver in the ore it is run into the forehearth, and the greater part of the silver is absorbed by the molten lead, and the remainder is sold with the copper to the proprietor of the works in which silver is parted from copper[42]. If there is a small amount of silver in the ore, no lead is put into the forehearth to absorb the silver, and the above-mentioned proprietors buy it in with the copper; if there be no silver, copper is made direct. If such copper ore contains some minerals which do not easily melt, as pyrites or _cadmia metallica fossilis_[43], or stone from which iron is melted, then crude pyrites which easily fuse are added to it, together with slag. From this charge, when smelted, they make cakes; and from these, when they have been roasted as much as is necessary and re-smelted, the copper is made. But if there be some silver in the cakes, for which an outlay of lead has to be made, then it is first run into the forehearth, and the molten lead absorbs the silver.

Indeed, _rudis_ copper ore of inferior quality, whether ash-coloured or purple, blackish and occasionally in parts blue, is smelted in the first furnace whose tap-hole is always open. This is the method of the Tyrolese. To as much _rudis_ copper ore as will fill eighteen vessels, each of which holds almost as much as seven Roman _moduli_[44], the first smelter--for there are three--adds three cartloads of lead slags, one cartload of schist, one fifth of a _centumpondium_ of stones which easily fuse in the fire, besides a small quantity of concentrates collected from copper slag and accretions, all of which he smelts for the space of twelve hours, and from which he makes six _centumpondia_ of primary cakes and one-half of a _centumpondium_ of alloy. One half of the latter consists of copper and silver, and it settles to the bottom of the forehearth. In every _centumpondium_ of the cakes there is half a _libra_ of silver and sometimes half an _uncia_ besides; in the half of a _centumpondium_ of the alloy there is a _bes_ or three-quarters of silver. In this way every week, if the work is for six days, thirty-six _centumpondia_ of cakes are made and three _centumpondia_ of alloy, in all of which there is often almost twenty-four _librae_ of silver. The second smelter separates from the primary cakes the greater part of the silver by absorbing it in lead. To eighteen _centumpondia_ of cakes made from crude copper ore, he adds twelve _centumpondia_ of hearth-lead and litharge, three _centumpondia_ of stones from which lead is smelted, five _centumpondia_ of hard cakes rich in silver, and two _centumpondia_ of exhausted liquation cakes[45]; he adds besides, some of the slags resulting from smelting crude copper, together with a small quantity of concentrates made from accretions, all of which he melts for the space of twelve hours, and makes eighteen _centumpondia_ of secondary cakes, and twelve _centumpondia_ of copper-lead-silver alloy; in each _centumpondium_ of the latter there is half a _libra_ of silver. After he has taken off the cakes with a hooked bar, he pours the alloy out into copper or iron moulds; by this method they make four cakes of alloy, which are carried to the works in which silver is parted from copper. On the following day, the same smelter, taking eighteen _centumpondia_ of the secondary cakes, again adds twelve _centumpondia_ of hearth-lead and litharge, three _centumpondia_ of stones from which lead is smelted, five _centumpondia_ of hard cakes rich in silver, together with slags from the smelting of the primary cakes, and with concentrates washed from the accretions which are usually made at that time. This charge is likewise smelted for the space of twelve hours, and he makes as many as thirteen _centumpondia_ of tertiary cakes and eleven _centumpondia_ of copper-lead-silver alloy, each _centumpondium_ of which contains one-third of a _libra_ and half an _uncia_ of silver. When he has skimmed off the tertiary cakes with a hooked bar, the alloy is poured into copper moulds, and by this method four cakes of alloy are made, which, like the preceding four cakes of alloy, are carried to the works in which silver is parted from copper. By this method the second smelter makes primary cakes on alternate days and secondary cakes on the intermediate days. The third smelter takes eleven cartloads of the tertiary cakes and adds to them three cartloads of hard cakes poor in silver, together with the slag from smelting the secondary cakes, and the concentrates from the accretions which are usually made at that time. From this charge when smelted, he makes twenty _centumpondia_ of quaternary cakes, which are called "hard cakes," and also fifteen _centumpondia_ of those "hard cakes rich in silver," each _centumpondium_ of which contains a third of a _libra_ of silver. These latter cakes the second smelter, as I said before, adds to the primary and secondary cakes when he re-melts them. In the same way, from eleven cartloads of quaternary cakes thrice roasted, he makes the "final" cakes, of which one _centumpondium_ contains only half an _uncia_ of silver. In this operation he also makes fifteen _centumpondia_ of "hard cakes poor in silver," in each _centumpondium_ of which is a sixth of a _libra_ of silver. These hard cakes the third smelter, as I have said, adds to the tertiary cakes when he re-smelts them, while from the "final" cakes, thrice roasted and re-smelted, is made black copper[46].

The _rudis_ copper from which pure copper is made, if it contains little silver or if it does not easily melt, is first smelted in the third furnace of which the tap-hole is always open; and from this are made cakes, which after being seven times roasted are re-smelted, and from these copper is melted out; the cakes of copper are carried to a furnace of another kind, in which they are melted for the third time, in order that in the copper "bottoms" there may be more silver, while in the "tops" there may be less, which process is explained in Book XI.

Pyrites, when they contain not only copper, but also silver, are smelted in the manner I described when I treated of ores of silver. But if they are poor in silver, and if the copper which is melted out of them cannot easily be treated, they are smelted according to the method which I last explained.

Finally, the copper schists containing bitumen or sulphur are roasted, and then smelted with stones which easily fuse in a fire of the second order, and are made into cakes, on the top of which the slags float. From these cakes, usually roasted seven times and re-melted, are melted out slags and two kinds of cakes; one kind is of copper and occupies the bottom of the crucible, and these are sold to the proprietors of the works in which silver is parted from copper; the other kind of cakes are usually re-melted with primary cakes. If the schist contains but a small amount of copper, it is burned, crushed under the stamps, washed and sieved, and the concentrates obtained from it are melted down; from this are made cakes from which, when roasted, copper is made. If either chrysocolla or azure, or yellow or black earth containing copper and silver, adheres to the schist, it is not washed, but is crushed and smelted with stones which easily fuse in fire of the second order.

Lead ore, whether it be _molybdaena_[47], pyrites, (galena?) or stone from which it is melted, is often smelted in a special furnace, of which I have spoken above, but no less often in the third furnace of which the tap-hole is always open. The hearth and forehearth are made from powder containing a small portion of iron hammer-scales; iron slag forms the principal flux for such ores; both of these the expert smelters consider useful and to the owner's advantage, because it is the nature of iron to attract lead. If it is _molybdaena_ or the stone from which lead is smelted, then the lead runs down from the furnace into the forehearth, and when the slags have been skimmed off, the lead is poured out with a ladle. If pyrites are smelted, the first to flow from the furnace into the forehearth, as may be seen at Goslar, is a white molten substance, injurious and noxious to silver, for it consumes it. For this reason the slags which float on the top having been skimmed off, this substance is poured out; or if it hardens, then it is taken out with a hooked bar; and the walls of the furnace exude the same substance[48]. Then the _stannum_ runs out of the furnace into the forehearth; this is an alloy of lead and silver. From the silver-lead alloy they first skim off the slags, not rarely white, as some pyrites[49] are, and afterward they skim off the cakes of pyrites, if there are any. In these cakes there is usually some copper; but since there is usually but a very small quantity, and as the forest charcoal is not abundant, no copper is made from them. From the silver-lead poured into iron moulds they likewise make cakes; when these cakes have been melted in the cupellation furnace, the silver is parted from the lead, because part of the lead is transformed into litharge and part into hearth-lead, from which in the blast furnace on re-melting they make de-silverized lead, for in this lead each _centumpondium_ contains only a _drachma_ of silver, when before the silver was parted from it each _centumpondium_ contained more or less than three _unciae_ of silver[50].

The little black stones[51] and others from which tin is made, are smelted in their own kind of furnace, which should be narrower than the other furnaces, that there may be only the small fire which is necessary for this ore. These furnaces are higher, that the height may compensate for the narrowness and make them of almost the same capacity as the other furnaces. At the top, in front, they are closed and on the other side they are open, where there are steps, because they cannot have the steps in front on account of the forehearth; the smelters ascend by these steps to put the tin-stone into the furnace. The hearth of the furnace is not made of powdered earth and charcoal, but on the floor of the works are placed sandstones which are not too hard; these are set on a slight slope, and are two and three-quarters feet long, the same number of feet wide, and two feet thick, for the thicker they are the longer they last in the fire. Around them is constructed a rectangular furnace eight or nine feet high, of broad sandstones, or of those common substances which by nature are composed of diverse materials[52]. On the inside the furnace is everywhere evenly covered with lute. The upper part of the interior is two feet long and one foot wide, but below it is not so long and wide. Above it are two hood-walls, between which the fumes ascend from the furnace into the dust chamber, and through this they escape by a narrow opening in the roof. The sandstones are sloped at the bed of the furnace, so that the tin melted from the tin-stone may flow through the tap-hole of the furnace into the forehearth.[53]

As there is no need for the smelters to have a fierce fire, it is not necessary to place the nozzles of the bellows in bronze or iron pipes, but only through a hole in the furnace wall. They place the bellows higher at the back so that the blast from the nozzles may blow straight toward the tap-hole of the furnace. That it may not be too fierce, the nozzles are wide, for if the fire were fiercer, tin could not be melted out from the tin-stone, as it would be consumed and turned into ashes. Near the steps is a hollowed stone, in which is placed the tin-stone to be smelted; as often as the smelter throws into the furnace an iron shovel-ful of this tin-stone, he puts on charcoal that was first put into a vat and washed with water to be cleansed from the grit and small stones which adhere to it, lest they melt at the same time as the tin-stone and obstruct the tap-hole and impede the flow of tin from the furnace. The tap-hole of the furnace is always open; in front of it is a forehearth a little more than half a foot deep, three-quarters of two feet long and one foot wide; this is lined with lute, and the tin from the tap-hole flows into it. On one side of the forehearth is a low wall, three-quarters of a foot wider and one foot longer than the forehearth, on which lies charcoal powder. On the other side the floor of the building slopes, so that the slags may conveniently run down and be carried away. As soon as the tin begins to run from the tap-hole of the furnace into the forehearth, the smelter scrapes down some of the powdered charcoal into it from the wall, so that the slags may be separated from the hot metal, and so that it may be covered, lest any part of it, being very hot, should fly away with the fumes. If after the slag has been skimmed off, the powder does not cover up the whole of the tin, the smelter draws a little more charcoal off the wall with a scraper. After he has opened the tap-hole of the forehearth with a tapping-bar, in order that the tin can flow into the tapping-pot, likewise smeared with lute, he again closes the tap-hole with pure lute or lute mixed with powdered charcoal. The smelter, if he be diligent and experienced, has brooms at hand with which he sweeps down the walls above the furnace; to these walls and to the dust chamber minute tin-stones sometimes adhere with part of the fumes. If he be not sufficiently experienced in these matters and has melted at the same time all of the tin-stone,--which is commonly of three sizes, large, medium, and very small,--not a little waste of the proprietor's tin results; because, before the large or the medium sizes have melted, the small have either been burnt up in the furnace, or else, flying up from it, they not only adhere to the walls but also fall in the dust chamber. The owner of the works has the sweepings by right from the owner of the ore. For the above reasons the most experienced smelter melts them down separately; indeed, he melts the very small size in a wider furnace, the medium in a medium-sized furnace, and the largest size in the narrowest furnace. When he melts down the small size he uses a gentle blast from the bellows, with the medium-sized a moderate one, with the large size a violent blast; and when he smelts the first size he needs a slow fire, for the second a medium one, and for the third a fierce one; yet he uses a much less fierce fire than when he smelts the ores of gold, silver, or copper. When the workmen have spent three consecutive days and nights in this work, as is usual, they have finished their labours; in this time they are able to melt out a large weight of small sized tin-stone which melts quickly, but less of the large ones which melt slowly, and a moderate quantity of the medium-sized which holds the middle course. Those who do not smelt the tin-stone in furnaces made sometimes wide, sometimes medium, or sometimes narrow, in order that great loss should not be occasioned, throw in first the smallest size, then the medium, then the large size, and finally those which are not quite pure; and the blast of the bellows is altered as required. In order that the tin-stone thrown into the furnace should not roll off from the large charcoal into the forehearth before the tin is melted out of it, the smelter uses small charcoal; first some of this moistened with water is placed in the furnace, and then he frequently repeats this succession of charcoal and tin-stone.

The tin-stone, collected from material which during the summer was washed in a ditch through which a stream was diverted, and during the winter was screened on a perforated iron plate, is smelted in a furnace a palm wider than that in which the fine tin-stone dug out of the earth is smelted. For the smelting of these, a more vigorous blast of the bellows and a fiercer fire is needed than for the smelting of the large tin-stone. Whichever kind of tin-stone is being smelted, if the tin first flows from the furnace, much of it is made, and if slags first flow from the furnace, then only a little. It happens that the tin-stone is mixed with the slags when it is either less pure or ferruginous--that is, not enough roasted--and is imperfect when put into the furnace, or when it has been put in in a larger quantity than was necessary; then, although it may be pure and melt easily, the ore either runs out of the furnace at the same time, mixed with the slags, or else it settles so firmly at the bottom of the furnace that the operation of smelting being necessarily interrupted, the furnace freezes up.

[Illustration 415 (Tin smelting Furnaces): A--Furnace. B--Its tap-hole. C--Forehearth. D--Its tap-hole. E--Slags. F--Scraper. G--Dipping-pot. H--Walls of the chimney. I--Broom. K--Copper plate. L--Latticework bars. M--Iron seal or die. N--Hammer.]

The tap-hole of the forehearth is opened and the tin is diverted into the dipping-pot, and as often as the slags flow down the sloping floor of the building they are skimmed off with a rabble; as soon as the tin has run out of the forehearth, the tap-hole is again closed up with lute mixed with powdered charcoal. Glowing coals are put in the dipping-pot so that the tin, after it has run out, should not get chilled. If the metal is so impure that nothing can be made from it, the material which has run out is made into cakes to be re-smelted in the hearth, of which I shall have something to say later; if the metal is pure, it is poured immediately upon thick copper plates, at first in straight lines and then transversely over these to make a lattice. Each of these lattice bars is impressed with an iron die; if the tin was melted out of ore excavated from mines, then one stamp only, namely, that of the Magistrate, is usually imprinted, but if it is made from tin-stone collected on the ground after washing, then it is impressed with two seals, one the Magistrate's and the other a fork which the washers use. Generally, three of this kind of lattice bars are beaten and amalgamated into one mass with a wooden mallet.

The slags that are skimmed off are afterward thrown with an iron shovel into a small trough hollowed from a tree, and are cleansed from charcoal by agitation; when taken out they are broken up with a square iron mallet, and then they are re-melted with the fine tin-stone next smelted. There are some who crush the slags three times under wet stamps and re-melt them three times; if a large quantity of this be smelted while still wet, little tin is melted from it, because the slag, soon melted again, flows from the furnace into the forehearth. Under the wet stamps are also crushed the lute and broken rock with which such furnaces are lined, and also the accretions, which often contain fine tin-stone, either not melted or half-melted, and also prills of tin. The tin-stone not yet melted runs out through the screen into a trough, and is washed in the same way as tin-stone, while the partly melted and the prills of tin are taken from the mortar-box and washed in the sieve on which not very minute particles remain, and thence to the canvas strake. The soot which adheres to that part of the chimney which emits the smoke, also often contains very fine tin-stone which flies from the furnace with the fumes, and this is washed in the strake which I have just mentioned, and in other sluices. The prills of tin and the partly melted tin-stone that are contained in the lute and broken rock with which the furnace is lined, and in the remnants of the tin from the forehearth and the dipping-pot, are smelted together with the tin-stone.

When tin-stone has been smelted for three days and as many nights in a furnace prepared as I have said above, some little particles of the rock from which the furnace is constructed become loosened by the fire and fall down; and then the bellows being taken away, the furnace is broken through at the back, and the accretions are first chipped off with hammers, and afterward the whole of the interior of the furnace is re-fitted with the prepared sandstone, and again evenly lined with lute. The sandstone placed on the bed of the furnace, if it has become faulty, is taken out, and another is laid down in its place; those rocks which are too large the smelter chips off and fits with a sharp pick.

[Illustration 417 (Tin smelting Furnaces): A--Furnaces. B--Forehearths. C--Their tap-holes. D--Dipping-pots. E--Pillars. F--Dust-chamber. G--Window. H--Chimneys. I--Tub in which the coals are washed.]

Some build two furnaces against the wall just like those I have described, and above them build a vaulted ceiling supported by the wall and by four pillars. Through holes in the vaulted ceiling the fumes from the furnaces ascend into a dust chamber, similar to the one described before, except that there is a window on each side and there is no door. The smelters, when they have to clear away the flue-dust, mount by the steps at the side of the furnaces, and climb by ladders into the dust chamber through the apertures in the vaulted ceilings over the furnaces. They then remove the flue-dust from everywhere and collect it in baskets, which are passed from one to the other and emptied. This dust chamber differs from the other described, in the fact that the chimneys, of which it has two, are not dissimilar to those of a house; they receive the fumes which, being unable to escape through the upper part of the chamber, are turned back and re-ascend and release the tin; thus the tin set free by the fire and turned to ash, and the little tin-stones which fly up with the fumes, remain in the dust chamber or else adhere to copper plates in the chimney.

[Illustration 418 (Refining Tin): A--Hearths. B--Dipping-pots. C--Wood. D--Cakes. E--Ladle. F--Copper plate. G--Lattice-shaped bars. H--Iron dies. I--Wooden mallet. K--Mass of tin bars. L--Shovel.]

If the tin is so impure that it cracks when struck with the hammer, it is not immediately made into lattice-like bars, but into the cakes which I have spoken of before, and these are refined by melting again on a hearth. This hearth consists of sandstones, which slope toward the centre and a little toward a dipping-pot; at their joints they are covered with lute. Dry logs are arranged on each side, alternately upright and lengthwise, and more closely in the middle; on this wood are placed five or six cakes of tin which all together weigh about six _centumpondia_; the wood having been kindled, the tin drips down and flows continuously into the dipping-pot which is on the floor. The impure tin sinks to the bottom of this dipping-pot and the pure tin floats on the top; then both are ladled out by the master, who first takes out the pure tin, and by pouring it over thick plates of copper makes lattice-like bars. Afterward he takes out the impure tin from which he makes cakes; he discriminates between them, when he ladles and pours, by the ease or difficulty of the flow. One _centumpondium_ of the lattice-like bars sells for more than a _centumpondium_ of cakes, for the price of the former exceeds the price of the latter by a gold coin[54]. These lattice-like bars are lighter than the others, and when five of them are pounded and amalgamated with a wooden mallet, a mass is made which is stamped with an iron die. There are some who do not make a dipping-pot on the floor for the tin to run into, but in the hearth itself; out of this the master, having removed the charcoal, ladles the tin and pours it over the copper-plate. The dross which adheres to the wood and the charcoal, having been collected, is re-smelted in the furnace.

[Illustration 419 (Blast Furnaces): A--Furnace. B--Bellows. C--Iron Disc. D--Nozzle. E--Wooden Disc. F--Blow-hole. G--Handle. H--Haft. I--Hoops. K--Masses of tin.]

Some of the Lusitanians melt tin from tin-stone in small furnaces. They use round bellows made of leather, of which the fore end is a round iron disc and the rear end a disc of wood; in a hole in the former is fixed the nozzle, in the middle of the latter the blow-hole. Above this is the handle or haft, which draws open the round bellows and lets in the air, or compresses it and drives the air out. Between the discs are several iron hoops to which the leather is fastened, making such folds as are to be seen in paper lanterns that are folded together. Since this kind of bellows does not give a vigorous blast, because they are drawn apart and compressed slowly, the smelter is not able during a whole day to smelt much more than half a _centumpondium_ of tin.

[Illustration 422 (Iron smelting Furnaces): A--Hearth. B--Heap. C--Slag-vent. D--Iron mass. E--Wooden mallets. F--Hammer. G--Anvil.]

Very good iron ore is smelted[55] in a furnace almost like the cupellation furnace. The hearth is three and a half feet high, and five feet long and wide; in the centre of it is a crucible a foot deep and one and a half feet wide, but it may be deeper or shallower, wider or narrower, according to whether more or less ore is to be made into iron. A certain quantity of iron ore is given to the master, out of which he may smelt either much or little iron. He being about to expend his skill and labour on this matter, first throws charcoal into the crucible, and sprinkles over it an iron shovel-ful of crushed iron ore mixed with unslaked lime. Then he repeatedly throws on charcoal and sprinkles it with ore, and continues this until he has slowly built up a heap; it melts when the charcoal has been kindled and the fire violently stimulated by the blast of the bellows, which are skilfully fixed in a pipe. He is able to complete this work sometimes in eight hours, sometimes in ten; and again sometimes in twelve. In order that the heat of the fire should not burn his face, he covers it entirely with a cap, in which, however, there are holes through which he may see and breathe. At the side of the hearth is a bar which he raises as often as is necessary, when the bellows blow too violent a blast, or when he adds more ore and charcoal. He also uses the bar to draw off the slags, or to open or close the gates of the sluice, through which the waters flow down on to the wheel which turns the axle that compresses the bellows. In this sensible way, iron is melted out and a mass weighing two or three _centumpondia_ may be made, providing the iron ore was rich. When this is done the master opens the slag-vent with the tapping-bar, and when all has run out he allows the iron mass to cool. Afterward he and his assistant stir the iron with the bar, and then in order to chip off the slags which had until then adhered to it, and to condense and flatten it, they take it down from the furnace to the floor, and beat it with large wooden mallets having slender handles five feet long. Thereupon it is immediately placed on the anvil, and repeatedly beaten by the large iron hammer that is raised by the cams of an axle turned by a water-wheel. Not long afterward it is taken up with tongs and placed under the same hammer, and cut up with a sharp iron into four, five, or six pieces, according to whether it is large or small. These pieces, after they have been re-heated in the blacksmith's forge and again placed on the anvil, are shaped by the smith into square bars or into ploughshares or tyres, but mainly into bars. Four, six, or eight of these bars weigh one-fifth of a _centumpondium_, and from these they make various implements. During the blows from the hammer by which it is shaped by the smith, a youth pours water with a ladle on to the glowing iron, and this is why the blows make such a loud sound that they may be heard a long distance from the works. The masses, if they remain and settle in the crucible of the furnace in which the iron is smelted, become hard iron which can only be hammered with difficulty, and from these they make the iron-shod heads for the stamps, and such-like very hard articles.

[Illustration 424 (Iron smelting Furnaces): A--Furnace. B--Stairs. C--Ore. D--Charcoal.]

But to iron ore which is cupriferous, or which when heated[56] melts with difficulty, it is necessary for us to give a fiercer fire and more labour; because not only must we separate the parts of it in which there is metal from those in which there is no metal, and break it up by dry stamps, but we must also roast it, so that the other metals and noxious juices may be exhaled; and we must wash it, so that the lighter parts may be separated from it. Such ores are smelted in a furnace similar to the blast furnace, but much wider and higher, so that it may hold a great quantity of ore and much charcoal; mounting the stairs at the side of the furnace, the smelters fill it partly with fragments of ore not larger than nuts, and partly with charcoal; and from this kind of ore once or twice smelted they make iron which is suitable for re-heating in the blacksmith's forge, after it is flattened out with the large iron hammer and cut into pieces with the sharp iron.

[Illustration 425 (Steel making Furnaces): A--Forge. B--Bellows. C--Tongs. D--Hammer. E--Cold stream.]

By skill with fire and fluxes is made that kind of iron from which steel is made, which the Greeks call [Greek: stomoma]. Iron should be selected which is easy to melt, is hard and malleable. Now although iron may be smelted from ore which contains other metals, yet it is then either soft or brittle; such (iron) must be broken up into small pieces when it is hot, and then mixed with crushed stone which melts. Then a crucible is made in the hearth of the smith's furnace, from the same moistened powder from which are made the forehearths in front of the furnaces in which ores of gold or silver are smelted; the width of this crucible is about one and a half feet and the depth one foot. The bellows are so placed that the blast may be blown through the nozzle into the middle of the crucible. Then the whole of the crucible is filled with the best charcoal, and it is surrounded by fragments of rock to hold in place the pieces of iron and the superimposed charcoal. As soon as all the charcoal is kindled and the crucible is glowing, a blast is blown from the bellows and the master pours in gradually as much of the mixture of iron and flux as he wishes. Into the middle of this, when it is melted, he puts four iron masses each weighing thirty pounds, and heats them for five or six hours in a fierce fire; he frequently stirs the melted iron with a bar, so that the small pores in each mass absorb the minute

## particles, and these particles by their own strength consume and expand

the thick particles of the masses, which they render soft and similar to dough. Afterward the master, aided by his assistant, takes out a mass with the tongs and places it on the anvil, where it is pounded by the hammer which is alternately raised and dropped by means of the water-wheel; then, without delay, while it is still hot, he throws it into water and tempers it; when it is tempered, he places it again on the anvil, and breaks it with a blow from the same hammer. Then at once examining the fragments, he decides whether the iron in some part or other, or as a whole, appears to be dense and changed into steel; if so, he seizes one mass after another with the tongs, and taking them out he breaks them into pieces. Afterward he heats the mixture up again, and adds a portion afresh to take the place of that which has been absorbed by the masses. This restores the energy of that which is left, and the pieces of the masses are again put back into the crucible and made purer. Each of these, after having been heated, is seized with the tongs, put under the hammer and shaped into a bar. While they are still glowing, he at once throws them into the very coldest nearby running water, and in this manner, being suddenly condensed, they are changed into pure steel, which is much harder and whiter than iron.

The ores of the other metals are not smelted in furnaces. Quicksilver ores and also antimony are melted in pots, and bismuth in troughs.

[Illustration 427 (Quicksilver distillation Furnaces): A--Hearth. B--Poles. C--Hearth without fire in which the pots are placed. D--Rocks. E--Rows of pots. F--Upper pots. G--Lower pots.]

I will first speak of quicksilver. This is collected when found in pools formed from the outpourings of the veins and stringers; it is cleansed with vinegar and salt, and then it is poured into canvas or soft leather, through which, when squeezed and compressed, the quicksilver runs out into a pot or pan. The ore of quicksilver is reduced in double or single pots. If in double pots, then the upper one is of a shape not very dissimilar to the glass ampullas used by doctors, but they taper downward toward the bottom, and the lower ones are little pots similar to those in which men and women make cheese, but both are larger than these; it is necessary to sink the lower pots up to the rims in earth, sand, or ashes. The ore, broken up into small pieces is put into the upper pots; these having been entirely closed up with moss, are placed upside down in the openings of the lower pots, where they are joined with lute, lest the quicksilver which takes refuge in them should be exhaled. There are some who, after the pots have been buried, do not fear to leave them uncemented, and who boast that they are able to produce no less weight of quicksilver than those who do cement them, but nevertheless cementing with lute is the greatest protection against exhalation. In this manner seven hundred pairs of pots are set together in the ground or on a hearth. They must be surrounded on all sides with a mixture consisting of crushed earth and charcoal, in such a way that the upper pots protrude to a height of a palm above it. On both sides of the hearth rocks are first laid, and upon them poles, across which the workmen place other poles transversely; these poles do not touch the pots, nevertheless the fire heats the quicksilver, which fleeing from the heat is forced to run down through the moss into the lower pots. If the ore is being reduced in the upper pots, it flees from them, wherever there is an exit, into the lower pots, but if the ore on the contrary is put in the lower pots the quicksilver rises into the upper pot or into the operculum, which, together with the gourd-shaped vessels, are cemented to the upper pots.

The pots, lest they should become defective, are moulded from the best potters' clay, for if there are defects the quicksilver flies out in the fumes. If the fumes give out a very sweet odour it indicates that the quicksilver is being lost, and since this loosens the teeth, the smelters and others standing by, warned of the evil, turn their backs to the wind, which drives the fumes in the opposite direction; for this reason, the building should be open around the front and the sides, and exposed to the wind. If these pots are made of cast copper they last a long time in the fire. This process for reducing the ores of quicksilver is used by most people.

In a similar manner the antimony ore,[57] if free from other metals, is reduced in upper pots which are twice as large as the lower ones. Their size, however, depends on the cakes, which have not the same weight everywhere; for in some places they are made to weigh six _librae_, in other places ten, and elsewhere twenty. When the smelter has concluded his operation, he extinguishes the fire with water, removes the lids from the pots, throws earth mixed with ash around and over them, and when they have cooled, takes out the cakes from the pots.

[Illustration 429 (Quicksilver distillation Furnaces): A--Pots. B--Opercula. C--Nozzles. D--Gourd-shaped earthenware vessels.]

Other methods for reducing quicksilver are given below. Big-bellied pots, having been placed in the upper rectangular open part of a furnace, are filled with the crushed ore. Each of these pots is covered with a lid with a long nozzle--commonly called a _campana_--in the shape of a bell, and they are cemented. Each of the small earthenware vessels shaped like a gourd receives two of these nozzles, and these are likewise cemented. Dried wood having been placed in the lower part of the furnace and kindled, the ore is heated until all the quicksilver has risen into the operculum which is over the pot; it then flows from the nozzle and is caught in the earthenware gourd-shaped vessel.

[Illustration 430 (Quicksilver distillation Furnaces): A--Enclosed chamber. B--Door. C--Little windows. D--Mouths through the walls. E--Furnace in the enclosed chamber. F--Pots.]

Others build a hollow vaulted chamber, of which the paved floor is made concave toward the centre. Inside the thick walls of the chamber are the furnaces. The doors through which the wood is put are in the outer part of the same wall. They place the pots in the furnaces and fill them with crushed ore, then they cement the pots and the furnaces on all sides with lute, so that none of the vapour may escape from them, and there is no entrance to the furnaces except through their mouths. Between the dome and the paved floor they arrange green trees, then they close the door and the little windows, and cover them on all sides with moss and lute, so that none of the quicksilver can exhale from the chamber. After the wood has been kindled the ore is heated, and exudes the quicksilver; whereupon, impatient with the heat, and liking the cold, it escapes to the leaves of the trees, which have a cooling power. When the operation is completed the smelter extinguishes the fire, and when all gets cool he opens the door and the windows, and collects the quicksilver, most of which, being heavy, falls of its own accord from the trees, and flows into the concave part of the floor; if all should not have fallen from the trees, they are shaken to make it fall.

[Illustration 431 (Quicksilver distillation Furnaces): A--Larger pot. B--Smaller. C--Tripod. D--Tub in which the sand is washed.]

The following is the fourth method of reducing ores of quicksilver. A larger pot standing on a tripod is filled with crushed ore, and over the ore is put sand or ashes to a thickness of two digits, and tamped; then in the mouth of this pot is inserted the mouth of another smaller pot and cemented with lute, lest the vapours are emitted. The ore heated by the fire exhales the quicksilver, which, penetrating through the sand or the ashes, takes refuge in the upper pot, where condensing into drops it falls back into the sand or the ashes, from which the quicksilver is washed and collected.

[Illustration 432 (Quicksilver distillation Furnaces): A--Pots. B--Lids. C--Stones. D--Furnace.]

The fifth method is not very unlike the fourth. In the place of these pots are set other pots, likewise of earthenware, having a narrow bottom and a wide mouth. These are nearly filled with crushed ore, which is likewise covered with ashes to a depth of two digits and tamped in. The pots are covered with lids a digit thick, and they are smeared over on the inside with liquid litharge, and on the lid are placed heavy stones. The pots are set on the furnace, and the ore is heated and similarly exhales quicksilver, which fleeing from the heat takes refuge in the lid; on congealing there, it falls back into the ashes, from which, when washed, the quicksilver is collected.

By these five methods quicksilver may be made, and of these not one is to be despised or repudiated; nevertheless, if the mine supplies a great abundance of ore, the first is the most expeditious and practical, because a large quantity of ore can be reduced at the same time without great expense.[58]

[Illustration 434 (Bismuth Smelting): A--Pit across which wood is placed. B--Forehearth. C--Ladle. D--Iron mould. E--Cakes. F--Empty pot lined with stones in layers. G--Troughs. H--Pits dug at the foot of the troughs. I--Small wood laid over the troughs. K--Wind.]

Bismuth[59] ore, free from every kind of silver, is smelted by various methods. First a small pit is dug in the dry ground; into this pulverised charcoal is thrown and tamped in, and then it is dried with burning charcoal. Afterward, thick dry pieces of beech wood are placed over the pit, and the bismuth ore is thrown on it. As soon as the kindled wood burns, the heated ore drips with bismuth, which runs down into the pit, from which when cooled the cakes are removed. Because pieces of burnt wood, or often charcoal and occasionally slag, drop into the bismuth which collects in the pit, and make it impure, it is put back into another kind of crucible to be melted, so that pure cakes may be made. There are some who, bearing these things in mind, dig a pit on a sloping place and below it put a forehearth, into which the bismuth continually flows, and thus remains clean; then they take it out with ladles and pour it into iron pans lined inside with lute, and make cakes of it. They cover such pits with flat stones, whose joints are besmeared with a lute of mixed dust and crushed charcoal, lest the joints should absorb the molten bismuth. Another method is to put the ore in troughs made of fir-wood and placed on sloping ground; they place small firewood over it, kindling it when a gentle wind blows, and thus the ore is heated. In this manner the bismuth melts and runs down from the troughs into a pit below, while there remains slag, or stones, which are of a yellow colour, as is also the wood laid across the pit. These are also sold.

[Illustration 435 (Bismuth Smelting): A--Wood. B--Bricks. C--Pans. D--Furnace. E--Crucible. F--Pipe. G--Dipping-pot.]

Others reduce the ore in iron pans as next described. They lay small pieces of dry wood alternately straight and transversely upon bricks, one and a half feet apart, and set fire to it. Near it they put small iron pans lined on the inside with lute, and full of broken ore; then when the wind blows the flame of the fierce fire over the pans, the bismuth drips out of the ore; wherefore, in order that it may run, the ore is stirred with the tongs; but when they decide that all the bismuth is exuded, they seize the pans with the tongs and remove them, and pour out the bismuth into empty pans, and by turning many into one they make cakes. Others reduce the ore, when it is not mixed with _cadmia_,[60] in a furnace similar to the iron furnace. In this case they make a pit and a crucible of crushed earth mixed with pulverised charcoal, and into it they put the broken ore, or the concentrates from washing, from which they make more bismuth. If they put in ore, they reduce it with charcoal and small dried wood mixed, and if concentrates, they use charcoal only; they blow both materials with a gentle blast from a bellows. From the crucible is a small pipe through which the molten bismuth runs down into a dipping-pot, and from this cakes are made.

[Illustration 436 (Bismuth Smelting): A--Hearth in which ore is melted. B--Hearth on which lie drops of bismuth. C--Tongs. D--Basket. E--Wind.]

On a dump thrown up from the mines, other people construct a hearth exposed to the wind, a foot high, three feet wide, and four and a half feet long. It is held together by four boards, and the whole is thickly coated at the top with lute. On this hearth they first put small dried sticks of fir wood, then over them they throw broken ore; then they lay more wood over it, and when the wind blows they kindle it. In this manner the bismuth drips out of the ore, and afterward the ashes of the wood consumed by the fire and the charcoals are swept away. The drops of bismuth which fall down into the hearth are congealed by the cold, and they are taken away with the tongs and thrown into a basket. From the melted bismuth they make cakes in iron pans.

[Illustration 437 (Bismuth Smelting): A--Box. B--Pivot. C--Transverse wood beams. D--Grate. E--Its feet. F--Burning wood. G--Stick. H--Pans in which the bismuth is melted. I--Pans for moulds. K--Cakes. L--Fork. M--Brush.]

Others again make a box eight feet long, four feet wide, and two feet high, which they fill almost full of sand and cover with bricks, thus making the hearth. The box has in the centre a wooden pivot, which turns in a hole in two beams laid transversely one upon the other; these beams are hard and thick, are sunk into the ground, both ends are perforated, and through these holes wedge-shaped pegs are driven, in order that the beams may remain fixed, and that the box may turn round, and may be turned toward the wind from whichever quarter of the sky in may blow. In such a hearth they put an iron grate, as long and wide as the box and three-quarters of a foot high; it has six feet, and there are so many transverse bars that they almost touch one another. On the grate they lay pine-wood and over it broken ore, and over this they again lay pine-wood. When it has been kindled the ore melts, out of which the bismuth drips down; since very little wood is burned, this is the most profitable method of smelting the bismuth. The bismuth drips through the grate on to the hearth, while the other things remain upon the grate with the charcoal. When the work is finished, the workman takes a stick from the hearth and overturns the grate, and the things which have been accumulated on it; with the brush he sweeps up the bismuth and collects it in a basket, and then he melts it in an iron pan and makes cakes. As soon as possible after it is cool, he turns the pans over, so that the cakes may fall out, using for this purpose a two-pronged fork of which one prong is again forked. And immediately afterward he returns to his labours.

END OF BOOK IX.

FOOTNOTES:

[1] The history of the fusion of ores and of metals is the history of individual processes, and such information as we have been able to discover upon the individual methods previous to Agricola we give on the pages where such processes are discussed. In general the records of the beginnings of metallurgy are so nebular that, if one wishes to shirk the task, he can adopt the explanation of William Pryce one hundred and fifty years ago: "It is very probable that the nature and use of Metals were not revealed to Adam in his state of innocence: the toil and labour necessary to procure and use those implements of the iron age could not be known, till they made part of the curse incurred by his fall: 'In the sweat of thy face shalt thou eat bread, till thou return unto the ground; in sorrow shalt thou eat of it all the days of thy life' (Genesis). That they were very early discovered, however, is manifest from the Mosaick account of Tubal Cain, who was the first instructor of every artificer in Brass [_sic_] and Iron" (_Mineralogia Cornubiensis_, p. 2).

It is conceivable that gold could be found in large enough pieces to have had general use in pre-historic times, without fusion; but copper, which was also in use, must have been smelted, and therefore we must assume a considerable development of human knowledge on the subject prior to any human record. Such incidental mention as exists after record begins does not, of course, extend to the beginning of any

## particular branch of the art--in fact, special arts obviously existed

long before such mention, and down to the complete survey of the state of the art by Agricola our dates are necessarily "prior to" some first mention in literature, or "prior to" the known period of existing remains of metallurgical operations. The scant Egyptian records, the Scriptures, and the Shoo King give a little insight prior to 1000 B.C. The more extensive Greek literature of about the 5th to the 3rd centuries B.C., together with the remains of Greek mines, furnish another datum point of view, and the Roman and Greek writers at the beginning of the Christian era give a still larger view. After them our next step is to the Monk Theophilus and the Alchemists, from the 12th to the 14th centuries. Finally, the awakening of learning at the end of the 15th and the beginning of the 16th centuries, enables us for the first time to see practically all that was known. The wealth of literature which exists subsequent to this latter time makes history thereafter a matter of some precision, but it is not included in this undertaking. Considering the great part that the metals have played in civilization, it is astonishing what a minute amount of information is available on metallurgy. Either the ancient metallurgists were secretive as to their art, or the ancient authors despised such common things, or, as is equally probable, the very partial preservation of ancient literature, by painful transcription over a score of centuries, served only for those works of more general interest. In any event, if all the direct or indirect material on metallurgy prior to the 15th century were compiled, it would not fill 40 pages such as these.

It may be of service to give a tabular summary indicating approximately the time when evidence of particular operations appear on the historical horizon:

Gold washed from alluvial Prior to recorded civilization

Copper reduced from ores by smelting Prior to recorded civilization

Bitumen mined and used Prior to recorded civilization

Tin reduced from ores by smelting Prior to 3500 B.C.

Bronze made Prior to 3500 B.C.

Iron reduced from ores by smelting Prior to 3500 B.C.

Soda mined and used Prior to 3500 B.C.

Gold reduced from ores by concentration Prior to 2500 B.C.

Silver reduced from ores by smelting Prior to 2000 B.C.

Lead reduced from ores by smelting Prior to 2000 B.C. (perhaps prior to 3500 B.C.)

Silver parted from lead by cupellation Prior to 2000 B.C.

Bellows used in furnaces Prior to 1500 B.C.

Steel produced Prior to 1000 B.C.

Base metals separated from ores by water Prior to 500 B.C. concentration

Gold refined by cupellation Prior to 500 B.C.

Sulphide ores smelted for lead Prior to 500 B.C.

Mercury reduced from ores by (?) Prior to 400 B.C.

White-lead made with vinegar Prior to 300 B.C.

Touchstone known for determining gold and silver Prior to 300 B.C. fineness

Quicksilver reduced from ore by distillation Prior to Christian Era

Silver parted from gold by cementation with salt Prior to " "

Brass made by cementation of copper and calamine Prior to " "

Zinc oxides obtained from furnace fumes by Prior to " " construction of dust chambers

Antimony reduced from ores by smelting (accidental) Prior to " "

Gold recovered by amalgamation Prior to " "

Refining of copper by repeated fusion Prior to " "

Sulphide ores smelted for copper Prior to " "

Vitriol (blue and green) made Prior to " "

Alum made Prior to " "

Copper refined by oxidation and poling Prior to 1200 A.D.

Gold parted from copper by cupelling with lead Prior to 1200 A.D.

Gold parted from silver by fusion with sulphur Prior to 1200 A.D.

Manufacture of nitric acid and _aqua regia_ Prior to 1400 A.D.

Gold parted from silver by nitric acid Prior to 1400 A.D.

Gold parted from silver with antimony sulphide Prior to 1500 A.D.

Gold parted from copper with sulphur Prior to 1500 A.D.

Silver parted from iron with antimony sulphide Prior to 1500 A.D.

First text book on assaying Prior to 1500 A.D.

Silver recovered from ores by amalgamation Prior to 1500 A.D.

Separation of silver from copper by liquation Prior to 1540 A.D.

Cobalt and manganese used for pigments Prior to 1540 A.D.

Roasting copper ores prior to smelting Prior to 1550 A.D.

Stamp-mill used Prior to 1550 A.D.

Bismuth reduced from ore Prior to 1550 A.D.

Zinc reduced from ore (accidental) Prior to 1550 A.D.

Further, we believe it desirable to sketch at the outset the development of metallurgical appliances as a whole, leaving the details to special footnotes; otherwise a comprehensive view of the development of such devices is difficult to grasp.

We can outline the character of metallurgical appliances at various periods in a few words. It is possible to set up a description of the imaginary beginning of the "bronze age" prior to recorded civilization, starting with the savage who accidentally built a fire on top of some easily reducible ore, and discovered metal in the ashes, etc.; but as this method has been pursued times out of number to no particular purpose, we will confine ourselves to a summary of such facts as we can assemble. "Founders' hoards" of the bronze age are scattered over Western Europe, and indicate that smelting was done in shallow pits with charcoal. With the Egyptians we find occasional inscriptions showing small furnaces with forced draught, in early cases with a blow-pipe, but later--about 1500 B.C.--with bellows also. The crucible was apparently used by the Egyptians in secondary melting, such remains at Mt. Sinai probably dating before 2000 B.C. With the advent of the Prophets, and the first Greek literature--9th to 7th century B.C.--we find frequent references to bellows. The remains of smelting appliances at Mt. Laurion (500-300 B.C.) do not indicate much advance over the primitive hearth; however, at this locality we do find evidence of the ability to separate minerals by specific gravity, by washing crushed ore over inclined surfaces with a sort of buddle attachment. Stone grinding-mills were used to crush ore from the earliest times of Mt. Laurion down to the Middle Ages. About the beginning of the Christian era the writings of Diodorus, Strabo, Dioscorides, and Pliny indicate considerable advance in appliances. Strabo describes high stacks to carry off lead fumes; Dioscorides explains a furnace with a dust-chamber to catch _pompholyx_ (zinc oxide); Pliny refers to the upper and lower crucibles (a forehearth) and to the pillars and arches of the furnaces. From all of their descriptions we may conclude that the furnaces had then reached some size, and were, of course, equipped with bellows. At this time sulphide copper and lead ores were smelted; but as to fluxes, except lead for silver, and lead and soda for gold, we have practically no mention. Charcoal was the universal fuel for smelting down to the 18th century. Both Dioscorides and Pliny describe a distillation apparatus used to recover quicksilver. A formidable list of mineral products and metal alloys in use, indicate in themselves considerable apparatus, of the details of which we have no indication; in the main these products were lead sulphide, sulphate, and oxide (red-lead and litharge); zinc oxide; iron sulphide, oxide and sulphate; arsenic and antimony sulphides; mercury sulphide, sulphur, bitumen, soda, alum and potash; and of the alloys, bronze, brass, pewter, electrum and steel.

From this period to the period of the awakening of learning our only light is an occasional gleam from Theophilus and the Alchemists. The former gave a more detailed description of metallurgical appliances than had been done before, but there is little vital change apparent from the apparatus of Roman times. The Alchemists gave a great stimulus to industrial chemistry in the discovery of the mineral acids, and described distillation apparatus of approximately modern form.

The next period--the Renaissance--is one in which our descriptions are for the first time satisfactory, and a discussion would be but a review of _De Re Metallica_.

[2] See footnote 2, p. 267, on verbs used for roasting.

[3] Agricola has here either forgotten to take into account his three-palm-thick furnace walls, which will make the length of this long wall sixty-one feet, or else he has included this foot and a half in each case in the six-foot distance between the furnaces, so that the actual clear space is only four and a half feet between the furnace with four feet on the ends.

[4] The paucity of terms in Latin for describing structural members, and the consequent repetition of "beam" (_trabs_), "timber" (_tignum_), "billet" (_tigillum_), "pole" (_asser_), with such modifications as small, large, and transverse, and with long explanatory clauses showing their location, renders the original very difficult to follow. We have, therefore, introduced such terms as "posts," "tie-beams," "sweeps," "levers," "rafters," "sills," "moulding," "braces," "cleats," "supports," etc., as the context demands.

[5] This set of rafters appears to start from the longitudinal beam.

[6] Devices for creating an air current must be of very old invention, for it is impossible to conceive of anything but the crudest melting of a few simple ores without some forced draft. Wilkinson (The Ancient Egyptians, II, p. 316) gives a copy of an illustration of a foot-bellows from a tomb of the time of Thotmes III. (1500 B.C.). The rest of the world therefore, probably obtained them from the Egyptians. They are mentioned frequently in the Bible, the most pointed reference to metallurgical purposes being Jeremiah (VI, 29): "The bellows are burned, the lead is consumed in the fire; the founder melteth in vain; for the wicked are not plucked away." Strabo (VII, 3) states that Ephorus ascribed the invention of bellows to Anacharsis--a Thracian prince of about 600 B.C.

[7] This whole arrangement could be summarized by the word "hinge."

[8] The rim of this wheel is obviously made of segments fixed in two layers; the "disc" meaning the aggregate of segments on either side of the wheel.

[9] It has not been considered necessary to introduce the modern term _twyer_ in these descriptions, as the literal rendering is sufficiently clear.

[10] _Ferruminata_. These accretions are practically always near the hearth, and would correspond to English "sows," and therefore that term has been adopted. It will be noted that, like most modern metallurgists, Agricola offers no method for treating them. Pliny (XXXIV, 37) describes a "sow," and uses the verb _ferruminare_ (to weld or solder): "Some say that in the furnace there are certain masses of stone which become soldered together, and that the copper fuses around it, the mass not becoming liquid unless it is transferred to another furnace; it thus forms a sort of knot, as it were, of the metal."

[11] What are known in English as "crucible," "furnace well," "forehearth," "dipping-pot," "tapping-pot," "receiving-pot," etc., are in the text all _catinus_, _i.e._, crucible. For easier reading, however, we have assigned the names indicated in the context.

[12] _Panes ex pyrite conflati_. While the term _matte_ would cover most cases where this expression appears, and in many cases would be more expressive to the modern reader, yet there are instances where the expression as it stands indicates its particular origin, and it has been, therefore, considered advisable to adhere to the literal rendering.

[13] _Molybdaena_. See note 37, p. 476. It was the saturated furnace bottoms from cupellation.

[14] The four elements were earth, air, fire, and water.

[15] "Stones which easily melt in the fire." Nowhere in _De Re Metallica_ does the author explain these substances. However in the _Interpretatio_ (p. 465) he gives three genera or orders with their German equivalents, as follows:--"_Lapides qui igni liquescunt primi generis,--Schoene fluesse; secundi,--fluesse zum schmeltzen flock quertze; tertii,--quertze oder kiselstein."_ We confess our inability to make certain of most of the substances comprised in the first and second orders. We consider they were in part fluor-spar, and in any event the third order embraced varieties of quartz, flint, and silicious material generally. As the matter is of importance from a metallurgical point of view, we reproduce at some length Agricola's own statements on the subject from _Bermannus_ and _De Natura Fossilium_. In the latter (p. 268) he states: "Finally there now remain those stones which I call 'stones which easily melt in the fire,' because when thrown into hot furnaces they flow (_fluunt_). There are three orders (_genera_) of these. The first resembles the transparent gems; the second is not similar, and is generally not translucent; it is translucent in some part, and in rare instances altogether translucent. The first is sparingly found in silver and other mines; the second abounds in veins of its own. The third genus is the material from which glass is made, although it can also be made out of the other two. The stones of the first order are not only transparent, but are also resplendent, and have the colours of gems, for some resemble crystal, others emerald, heliotrope, lapis lazuli, amethyst, sapphire, ruby, _chrysolithus_, _morion_ (cairngorm?), and other gems, but they differ from them in hardness.... To the first genus belongs the _lapis alabandicus_ (modern albandite?), if indeed it was different from the alabandic carbuncle. It can be melted, according to Pliny, in the fire, and fused for the preparation of glass. It is black, but verging upon purple. It comes from Caria, near Alabanda, and from Miletus in the same province. The second order of stones does not show a great variety of colours, and seldom beautiful ones, for it is generally white, whitish, greyish, or yellowish. Because these (stones) very readily melt in the fire, they are added to the ores from which the metals are smelted. The small stones found in veins, veinlets, and the spaces between the veins, of the highest peaks of the Sudetic range (_Suditorum montium_), belong

## partly to this genus and partly to the first. They differ in size, being

large and small; and in shape, some being round or angular or pointed; in colour they are black or ash-grey, or yellow, or purple, or violet, or iron colour. All of these are lacking in metals. Neither do the little stones contain any metals which are usually found in the streams where gold dust is collected by washing.... In the rivers where are collected the small stones from which tin is smelted, there are three genera of small stones to be found, all somewhat rounded and of very light weight, and devoid of all metals. The largest are black, both on the outside and inside, smooth and brilliant like a mirror; the medium-sized are either bluish black or ash-grey; the smallest are of a yellowish colour, somewhat like a silkworm. But because both the former and the latter stones are devoid of metals, and fly to pieces under the blows of the hammer, we classify them as sand or gravel. Glass is made from the stones of the third order, and particularly from sand. For when this is thrown into the heated furnace it is melted by the fire.... This kind of stone is either found in its own veins, which are occasionally very wide, or else scattered through the mines. It is less hard than flint, on account of which no fire can be struck from it. It is not transparent, but it is of many colours--that is to say, white, yellowish, ash-grey, brown, black, green, blue, reddish or red. This genus of stones occurs here and there in mountainous regions, on banks of rivers, and in the fields. Those which are black right through to the interior, and not merely on the surface, are more rare; and very frequently one coloured vein is intersected by another of a different colour--for instance, a white one by a red one; the green is often spotted with white, the ash-grey with black, the white with crimson. Fragments of these stones are frequently found on the surface of the earth, and in the running water they become polished by rubbing against stones of their own or of another genus. In this way, likewise, fragments of rocks are not infrequently shaped into spherical forms.... This stone is put to many uses; the streets are paved with it, whatever its colour; the blue variety is added to the ash of pines for making those other ashes which are used by wool-dyers. The white variety is burned, ground, and sifted, and from this they make the sand out of which glass is made. The whiter the sand is, the more useful it is."

Perusal of the following from _Bermannus_ (p. 458) can leave little doubt as to the first or second order being in part fluor-spar. Agricola derived the name _fluores_ from _fluo_ "to flow," and we in turn obtain "fluorite," or "fluorspar," from Agricola. "_Bermannus_.--These stones are similar to gems, but less hard. Allow me to explain word for word. Our miners call them _fluores_, not inappropriately to my mind, for by the heat of fire, like ice in the sun, they liquefy and flow away. They are of varied and bright colours. _Naevius_.--Theophrastus says of them that they are made by a conflux in the earth. These red _fluores_, to employ the words just used by you, are the ruby silver which you showed us before. _Bermannus_.--At the first glance it appears so, although it is not infrequently translucent. _Naevius_.--Then they are rubies? _Bermannus_.--Not that either. _Naevius_.--In what way, then, can they be distinguished from rubies? _Bermannus_.--Chiefly by this sign, that they glitter more feebly when translucent. Those which are not translucent may be distinguished from rubies. Moreover, _fluores_ of all kinds melt when they are subject to the first fire; rubies do not melt in fire. _Naevius_.--You distinguish well. _Bermannus_.--You see the other kind, of a paler purple colour? _Naevius_.--They appear to be an inferior kind of amethyst, such as are found in many places in Bohemia. _Bermannus_.--Indeed, they are not very dissimilar, therefore the common people who do not know amethysts well, set them in rings for gems, and they are easily sold. The third kind, as you see here, is white. _Naevius_.--I should have thought it a crystal. _Bermannus_.--A fourth is a yellow colour, a fifth ash colour, a sixth blackish. Some are violet, some green, others gold-coloured. _Anton_.--What is the use of _fluores_? _Bermannus_.--They are wont to be made use of when metals are smelted, as they cause the material in the fire to be much more fluid, exactly like a kind of stone which we said is made from pyrites (matte); it is, indeed, made not far from here, at Breitenbrunn, which is near Schwarzenberg. Moreover, from _fluores_ they can make colours which artists use."

[16] _Stannum_. (_Interpretatio_,--_werck_, modern _werk_). This term has been rendered throughout as "silver-lead" or "silver-lead alloy." It was the argentiferous lead suitable for cupellation. Agricola, in using it in this sense, was no doubt following his interpretation of its use by Pliny. Further remarks upon this subject will be found in note 33, p. 473.

[17] _Expirare_,--to exhale or blow out.

[18] _Rhetos_. The ancient Rhaetia comprised not only the greater part of Tyrol, but also parts of Switzerland and Lombardy. The mining section was, however, in Tyrol.

[19] _Noricum_ was a region south of the Danube, embracing not only modern Styria, but also parts of Austria, Salzberg, and Carinthia.

[20] One _drachma_ of gold to a _centumpondium_ would be (if we assume these were Roman weights) 3 ozs. 1 dwt. Troy per short ton. One-half _uncia_ of silver would be 12 ozs. 3 dwts. per short ton.

[21] For discussion of these fluxes see note page 232.

[22] _Carni_. Probably the people of modern Austrian Carniola, which lies south of Styria and west of Croatia.

[23] HISTORICAL NOTE ON SMELTING LEAD AND SILVER.--The history of lead and silver smelting is by no means a sequent array of exact facts. With one possible exception, lead does not appear upon the historical horizon until long after silver, and yet their metallurgy is so inextricably mixed that neither can be considered wholly by itself. As silver does not occur native in any such quantities as would have supplied the amounts possessed by the Ancients, we must, therefore, assume its reduction by either (1) intricate chemical processes, (2) amalgamation, (3) reduction with copper, (4) reduction with lead. It is impossible to conceive of the first with the ancient knowledge of chemistry; the second (see note 12, p. 297) does not appear to have been known until after Roman times; in any event, quicksilver appears only at about 400 B.C. The third was impossible, as the parting of silver from copper without lead involves metallurgy only possible during the last century. Therefore, one is driven to the conclusion that the fourth case obtained, and that the lead must have been known practically contemporaneously with silver. There is a leaden figure exhibited in the British Museum among the articles recovered from the Temple of Osiris at Abydos, and considered to be of the Archaic period--prior to 3800 B.C. The earliest known Egyptian silver appears to be a necklace of beads, supposed to be of the XII. Dynasty (2400 B.C.), which is described in the 17th Memoir, Egyptian Exploration Fund (London, 1898, p. 22). With this exception of the above-mentioned lead specimen, silver articles antedate positive evidence of lead by nearly a millennium, and if we assume lead as a necessary factor in silver production, we must conclude it was known long prior to any direct (except the above solitary possibility) evidence of lead itself. Further, if we are to conclude its necessary association with silver, we must assume a knowledge of cupellation for the parting of the two metals. Lead is mentioned in 1500 B.C. among the spoil captured by Thotmes III. Leaden objects have frequently been found in Egyptian tombs as early as Rameses III. (1200 B.C.). The statement is made by Pulsifer (Notes for a History of Lead, New York 1888, p. 146) that Egyptian pottery was glazed with lead. We have been unable to find any confirmation of this. It may be noted, incidentally, that lead is not included in the metals of the "Tribute of Yue" in the Shoo King (The Chinese Classics, 2500 B.C.?), although silver is so included.

After 1200 or 1300 B.C. evidences of the use of lead become frequent. Moses (Numbers XXXI, 22-23) directs the Israelites with regard to their plunder from the Midianites (1300 B.C.): "Only the gold and the silver, the brass [_sic_], the iron, the tin, and the lead. Everything that may abide the fire, ye shall make it go through the fire, and it shall be clean; nevertheless, it shall be purified with the water of separation, and all that abideth not the fire ye shall make go through the water." Numerous other references occur in the Scriptures (Psalms XII, 6; Proverbs XVII, 3; XXV, 4; etc.), one of the most pointed from a metallurgical point of view being that of Jeremiah (600 B.C.), who says (VI, 29-30): "The bellows are burned, the lead is consumed of the fire; the founder melteth in vain; for the wicked are not plucked away. Reprobate silver shall men call them because the Lord hath rejected them." From the number of his metaphors in metallurgical terms we may well conclude that Jeremiah was of considerable metallurgical experience, which may account for his critical tenor of mind. These Biblical references all point to a knowledge of separating silver and lead. Homer mentions lead (Iliad XXIV, 109), and it has been found in the remains of ancient Troy and Mycenae (H. Schliemann, "Troy and its Remains," London, 1875, and "Mycenae," New York, 1877). Both Herodotus (I, 186) and Diodorus (II, 1) speak of the lead used to fix iron clamps in the stone bridge of Nitocris (600 B.C.) at Babylon.

Our best evidence of ancient lead-silver metallurgy is the result of the studies at Mt. Laurion by Edouard Ardaillon (_Mines du Laurion dans l'Antiquite_, Paris, 1897). Here the very extensive old workings and the slag heaps testify to the greatest activity. The re-opening of the mines in recent years by a French Company has well demonstrated their technical character, and the frequent mention in Greek History easily determines their date. These deposits of argentiferous galena were extensively worked before 500 B.C. and while the evidence of concentration methods is ample, there is but little remaining of the ancient smelters. Enough, however, remains to demonstrate that the galena was smelted in small furnaces at low heat, with forced draught, and that it was subsequently cupelled. In order to reduce the sulphides the ancient smelters apparently depended upon partial roasting in the furnace at a preliminary period in reduction, or else upon the ferruginous character of the ore, or upon both. See notes p. 27 and p. 265. Theognis (6th century B.C.) and Hippocrates (5th century B.C.) are frequently referred to as mentioning the refining of gold with lead; an inspection of the passages fails to corroborate the importance which has been laid upon them. Among literary evidences upon lead metallurgy of later date, Theophrastus (300 B.C.) describes the making of white-lead with lead plates and vinegar. Diodorus Siculus (1st century B.C.), in his well-known quotation from Agatharchides (2nd century B.C.) with regard to gold mining and treatment in Egypt, describes the refining of gold with lead. (See note 8, p. 279.) Strabo (63 B.C.-24 A.D.) says (III, 2, 8): "The furnaces for silver are constructed lofty in order that the vapour, which is dense and pestilent, may be raised and carried off." And again (III, 2, 10), in quoting from Polybius (204-125 B.C.): "Polybius, speaking of the silver mines of New Carthage, tells us that they are extremely large, distant from the city about 20 stadia, and occupy a circuit of 400 stadia; that there are 40,000 men regularly engaged in them, and that they yield daily to the Roman people (a revenue of) 25,000 drachmae. The rest of the process I pass over, as it is too long; but as for the silver ore collected, he tells us that it is broken up and sifted through sieves over water; that what remains is to be again broken, and the water having been strained off it is to be sifted and broken a third time. The dregs which remain after the fifth time are to be melted, and the lead being poured off, the silver is obtained pure. These silver mines still exist; however, they are no longer the property of the State, neither these nor those elsewhere, but are possessed by private individuals. The gold mines, on the contrary, nearly all belong to the State. Both at Castlon and other places there are singular lead mines worked. They contain a small proportion of silver, but not sufficient to pay for the expense of refining" (Hamilton's Trans.). Dioscorides (1st century A.D.), among his medicines, describes several varieties of litharge, their origin, and the manner of making white-lead (see on pp. 465, 440), but he gives no very tangible information on lead smelting. Pliny, at the same period in speaking of silver, (XXXIII, 31), says: "After this we speak of silver, the next folly. Silver is only found in shafts, there being no indications like shining particles as in the case of gold. This earth is sometimes red, sometimes of an ashy colour. It is impossible to melt it except with lead ore (_vena plumbi_), called _galena_, which is generally found next to silver veins. And this the same agency of fire separates part into lead, which floats on the silver like oil on water." (We have transferred lead and silver in this last sentence, otherwise it means nothing.) Also (XXXIV, 47) he says: "There are two different sources of lead, it being smelted from its own ore, whence it comes without the admixture of any other substance, or else from an ore which contains it in common with silver. The metal, which flows liquid at the first melting in the furnace, is called _stannum_ that at the second melting is silver; that which remains in the furnace is _galena_, which is added to a third part of the ore. This being again melted, produces lead with a deduction of two-ninths." We have, despite some grammatical objections, rendered this passage quite differently from other translators, none of whom have apparently had any knowledge of metallurgy; and we will not, therefore, take the several pages of space necessary to refute their extraordinary and unnecessary hypotheses. From a metallurgical point of view, two facts must be kept in mind,--first, that _galena_ in this instance was the same substance as _molybdaena_, and they were both either a variety of litharge or of lead carbonates; second, that the _stannum_ of the Ancients was silver-lead alloy. Therefore, the metallurgy of this paragraph becomes a simple melting of an argentiferous lead ore, its subsequent cupellation, with a return of the litharge to the furnace. Pliny goes into considerable detail as to varieties of litharge, for further notes upon which see p. 466. The Romans were most active lead-silver miners, not only in Spain, but also in Britain. There are scores of lead pigs of the Roman era in various English museums, many marked "_ex argent_." Bruce (The Roman Wall, London, 1852, p. 432) describes some Roman lead furnaces in Cumberland where the draught was secured by driving a tapering tunnel into the hills. The Roman lead slag ran high in metal, and formed a basis for quite an industry in England in the early 18th century (Hunt, British Mining, London, 1887, p. 26, etc.). There is nothing in mediaeval literature which carries us further with lead metallurgy than the knowledge displayed by Pliny, until we arrive at Agricola's period. The history of cupellation is specially dealt with in note on p. 465.

[25] _Cadmia_. In the German Translation this is given as _kobelt_. It would be of uncertain character, but no doubt partially furnace calamine. (See note on p. 112.)

[26] _Pompholyx_. (_Interpretatio_ gives the German as _Weisser huetten rauch als ober dem garherde und ober dem kupfer ofen_). This was the impure protoxide of zinc deposited in the furnace outlets, and is modern "tutty." The ancient products, no doubt, contained arsenical oxides as well. It was well known to the Ancients, and used extensively for medicinal purposes, they dividing it into two species--_pompholyx_ and _spodos_. The first adequate description is by Dioscorides (V, 46): "_Pompholyx_ differs from _spodos_ in species, not in genus. For _spodos_ is blacker, and is often heavier, full of straws and hairs, like the refuse that is swept from the floors of copper smelters. But _pompholyx_ is fatty, unctuous, white and light enough to fly in the air. Of this there are two kinds--the one inclines to sky blue and is unctuous; the other is exceedingly white, and is extremely light. White _pompholyx_ is made every time that the artificer, in the preparation and perfecting of copper (brass?) sprinkles powdered _cadmia_ upon it to make it more perfect, for the soot which rises being very fine becomes _pompholyx_. Other _pompholyx_ is made, not only in working copper (brass?), but is also made from _cadmia_ by continually blowing with bellows. The manner of doing it is as follows:--The furnace is constructed in a two-storied building, and there is a medium-sized aperture opening to the upper chamber; the building wall nearest the furnace is pierced with a small opening to admit the nozzle of the bellows. The building must have a fair-sized door for the artificer to pass in and out. Another small building must adjoin this, in which are the bellows and the man who works them. Then the charcoal in the furnace is lighted, and the artificer continually throws broken bits of _cadmia_ from the place above the furnace, whilst his assistant, who is below, throws in charcoals, until all of the _cadmia_ inside is consumed. By this means the finest and lightest part of the stuff flies up with the smoke to the upper chamber, and adheres to the walls of the roof. The substance which is thus formed has at first the appearance of bubbles on water, afterward increasing in size, it looks like skeins of wool. The heaviest parts settle in the bottom, while some fall over and around the furnaces, and some lie on the floor of the building. This latter part is considered inferior, as it contains a lot of earth and becomes full of dirt."

Pliny (XXXIV, 33) appears somewhat confused as to the difference between the two species: "That which is called _pompholyx_ and _spodos_ is found in the copper-smelting furnaces, the difference between them being that _pompholyx_ is separated by washing, while _spodos_ is not washed. Some have called that which is white and very light _pompholyx_, and it is the soot of copper and _cadmia_; whereas _spodos_ is darker and heavier. It is scraped from the walls of the furnace, and is mixed with particles of metal, and sometimes with charcoal." (XXXIV, 34.) "The Cyprian _spodos_ is the best. It is formed by fusing _cadmia_ with copper ore. This being the lightest part of the metal, it flies up in the fumes from the furnace, and adheres to the roof, being distinguished from the soot by its whiteness. That which is less white is immature from the furnace, and it is this which some call '_pompholyx_.'" Agricola (_De Natura Fossilium_, p. 350) traverses much the same ground as the authors previously quoted, and especially recommends the _pompholyx_ produced when making brass by melting alternate layers of copper and calamine (_cadmia fossilis_).

[27] _Oleo, ex fece vini sicca confecto_. This oil, made from argol, is probably the same substance mentioned a few lines further on as "wine," distilled by heating argol in a retort. Still further on, salt made from argol is mentioned. It must be borne in mind that this argol was crude tartrates from wine vats, and probably contained a good deal of organic matter. Heating argol sufficiently would form potash, but that the distillation product could be anything effective it is difficult to see.

[28] _Aqua valens_. No doubt mainly nitric acid, the preparation of which is explained at length in Book X, p. 439.

[29] _Quod cum ignis consumit non modo una cum eo, quae ipsius stibii vis est, aliqua auri particula, sed etiam argenti, si cum auro fuerit permistum, consumitur._ The meaning is by no means clear. On p. 451 is set out the old method of parting silver from gold with antimony sulphide, of which this may be a variation. The silver combines with sulphur, and the reduced antimony forms an alloy with the gold. The added iron and copper would also combine with the sulphur from the antimony sulphide, and no doubt assist by increasing the amount of free collecting agent and by increasing the volume of the matte. (See note 17, p. 451.)

[30] There follow eight different methods of treating crude bullion or rich concentrates. In a general way three methods are involved,--1st, reduction with lead or antimony, and cupellation; 2nd, reduction with silver, and separation with nitric acid; 3rd, reduction with lead and silver, followed by cupellation and parting with nitric acid. The use of sulphur or antimony sulphide would tend to part out a certain amount of silver, and thus obtain fairly pure bullion upon cupellation. But the introduction of copper could only result deleteriously, except that it is usually accompanied by sulphur in some form, and would thus probably pass off harmlessly as a matte carrying silver. (See note 33 below.)

[31] It is not very clear where this lead comes from. Should it be antimony? The German translation gives this as "silver."

[32] These powders are described in Book VII., p. 236. It is difficult to say which the second really is. There are numbers of such recipes in the _Probierbuechlein_ (see Appendix B), with which a portion of these are identical.

[33] A variety of methods are involved in this paragraph: 1st, crude gold ore is smelted direct; 2nd, gold concentrates are smelted in a lead bath with some addition of iron--which would simply matte off--the lead bullion being cupelled; 3rd, roasted and unroasted pyrites and _cadmia_ (probably blende, cobalt, arsenic, etc.) are melted into a matte; this matte is repeatedly roasted, and then re-melted in a lead bath; 4th, if the material "flies out of the furnace" it is briquetted with iron ore and lime, and the briquettes smelted with copper matte. Three products result: (_a_) slag; (_b_) matte; (_c_) copper-gold-silver alloy. The matte is roasted, re-smelted with lead, and no doubt a button obtained, and further matte. The process from this point is not clear. It appears that the copper bullion is melted with lead, and normally this product would be taken to the liquation furnace, but from the text it would appear that the lead-copper bullion was melted again with iron ore and pyrites, in which case some of the copper would be turned into the matte, and the lead alloy would be richer in gold and silver.

HISTORICAL NOTE ON GOLD.--There is ample evidence of gold being used for ornamental purposes prior to any human record. The occurrence of large quantities of gold in native form, and the possibility of working it cold, did not necessitate any particular metallurgical ingenuity. The earliest indications of metallurgical work are, of course, among the Egyptians, the method of washing being figured as early as the monuments of the IV Dynasty (prior to 3800 B.C.). There are in the British Museum two stelae of the XII Dynasty (2400 B.C.) (144 Bay 1 and 145 Bay 6) relating to officers who had to do with gold mining in Nubia, and upon one there are references to working what appears to be ore. If this be true, it is the earliest reference to this subject. The Papyrus map (1500 B.C.) of a gold mine, in the Turin Museum (see note 16, p. 129), probably refers to a quartz mine. Of literary evidences there is frequent mention of refining gold and passing it through the fire in the Books of Moses, arts no doubt learned from the Egyptians. As to working gold, ore as distinguished from alluvial, we have nothing very tangible, unless it be the stelae above, until the description of Egyptian gold mining by Agatharchides (see note 8, p. 279). This geographer, of about the 2nd century B.C., describes very clearly indeed the mining, crushing, and concentration of ore and the refining of the concentrates in crucibles with lead, salt, and barley bran. We may mention in passing that Theognis (6th Century B.C.) is often quoted as mentioning the refining of gold with lead, but we do not believe that the passage in question (1101): "But having been put to the test and being rubbed beside (or against) lead as being refined gold, you will be fair," etc.; or much the same statement again (418) will stand much metallurgical interpretation. In any event, the myriads of metaphorical references to fining and purity of gold in the earliest shreds of literature do not carry us much further than do those of Shakespeare or Milton. Vitruvius and Pliny mention the recovery or refining of gold with mercury (see note 12, p. 297 on Amalgamation); and it appears to us that gold was parted from silver by cementation with salt prior to the Christian era. We first find mention of parting with sulphur in the 12th century, with nitric acid prior to the 14th century, by antimony sulphide prior to the 15th century, and by cementation with nitre by Agricola. (See historical note on parting gold and silver, p. 458.) The first mention of parting gold from copper occurs in the early 16th century (see note 24, p. 462). The first comprehensive description of gold metallurgy in all its branches is in _De Re Metallica_.

[34] _Rudis_ silver comprised all fairly pure silver ores, such as silver sulphides, chlorides, arsenides, etc. This is more fully discussed in note 6, p. 108.

[35] _Evolent_,--volatilize?

[36] _Lapidis plumbarii facile liquescentis_. The German Translation gives _glantz_, _i.e._, Galena, and the _Interpretatio_ also gives _glantz_ for _lapis plumbarius_. We are, however, uncertain whether this "easily melting" material is galena or some other lead ore.

[37] _Molybdaena_ is usually hearth-lead in _De Re Metallica_, but the German translation in this instance uses _pleyertz_, lead ore. From the context it would not appear to mean hearth-lead--saturated bottoms of cupellation furnaces--for such material would not contain appreciable silver. Agricola does confuse what are obviously lead carbonates with his other _molybdaena_ (see note 37, p. 476).

[38] The term _cadmia_ is used in this paragraph without the usual definition. Whether it was _cadmia fornacis_ (furnace accretions) or _cadmia metallica_ (cobalt-arsenic-blende mixture) is uncertain. We believe it to be the former.

[39] _Ramentum si lotura ex argento rudi_. This expression is generally used by the author to indicate concentrates, but it is possible that in this sentence it means the tailings after washing rich silver minerals, because the treatment of the _rudis_ silver has been already discussed above.

[40] _Ustum_. This might be rendered "burnt." In any event, it seems that the material is sintered.

[41] _Aes purum sive proprius ei color insederit, sive chrysocolla vel caeruleo fuerit tinctum, et rude plumbei coloris, aut fusci, aut nigri._ There are six copper minerals mentioned in this sentence, and from our study of Agricola's _De Natura Fossilium_ we hazard the following:--_Proprius ei color insederit_,--"its own colour,"--probably cuprite or "ruby copper." _Tinctum chrysocolla_--partly the modern mineral of that name and partly malachite. _Tinctum caeruleo_, partly azurite and partly other blue copper minerals. _Rude plumbei coloris_,--"lead coloured,"--was certainly chalcocite (copper glance). We are uncertain of _fusci aut nigri_, but they were probably alteration products. For further discussion see note on p. 109.

[42] HISTORICAL NOTE ON COPPER SMELTING.--The discoverer of the reduction of copper by fusion, and his method, like the discoverer of tin and iron, will never be known, because he lived long before humanity began to make records of its discoveries and doings. Moreover, as different races passed independently and at different times through the so-called "Bronze Age," there may have been several independent discoverers. Upon the metallurgy of pre-historic man we have some evidence in the many "founders' hoards" or "smelters' hoards" of the Bronze Age which have been found, and they indicate a simple shallow pit in the ground into which the ore was placed, underlaid with charcoal. Rude round copper cakes eight to ten inches in diameter resulted from the cooling of the metal in the bottom of the pit. Analyses of such Bronze Age copper by Professor Gowland and others show a small percentage of sulphur, and this is possible only by smelting oxidized ores. Copper objects appear in the pre-historic remains in Egypt, are common throughout the first three dynasties, and bronze articles have been found as early as the IV Dynasty (from 3800 to 4700 B.C., according to the authority adopted). The question of the origin of this bronze, whether from ores containing copper and tin or by alloying the two metals, is one of wide difference of opinion, and we further discuss the question in note 53, p. 411, under Tin. It is also interesting to note that the crucible is the emblem of copper in the hieroglyphics. The earliest source of Egyptian copper was probably the Sinai Peninsula, where there are reliefs as early as Seneferu (about 3700 B.C.), indicating that he worked the copper mines. Various other evidences exist of active copper mining prior to 2500 B.C. (Petrie, Researches in Sinai, London, 1906, p. 51, etc.). The finding of crucibles here would indicate some form of refining. Our knowledge of Egyptian copper metallurgy is limited to deductions from their products, to a few pictures of crude furnaces and bellows, and to the minor remains on the Sinai Peninsula; none of the pictures were, so far as we are aware, prior to 2300 B.C., but they indicate a considerable advance over the crude hearth, for they depict small furnaces with forced draught--first a blow-pipe, and in the XVIII Dynasty (about 1500 B.C.) the bellows appear. Many copper articles have been found scattered over the Eastern Mediterranean and Asia Minor of pre-Mycenaean Age, some probably as early as 3000 B.C. This metal is mentioned in the "Tribute of Yue" in the Shoo King (2500 B.C.?); but even less is known of early Chinese metallurgy than of the Egyptian. The remains of Mycenaean, Phoenician, Babylonian, and Assyrian civilizations, stretching over the period from 1800 to 500 B.C., have yielded endless copper and bronze objects, the former of considerable purity, and the latter a fairly constant proportion of from 10% to 14% tin. The copper supply of the pre-Roman world seems to have come largely, first from Sinai, and later from Cyprus, and from the latter comes our word copper, by way of the Romans shortening _aes cyprium_ (Cyprian copper) to _cuprum_. Research in this island shows that it produced copper from 3000 B.C., and largely because of its copper it passed successively under the domination of the Egyptians, Assyrians, Phoenicians, Greeks, Persians, and Romans. The bronze objects found in Cyprus show 2% to 10% of tin, although tin does not, so far as modern research goes, occur on that island. There can be no doubt that the Greeks obtained their metallurgy from the Egyptians, either direct or second-hand--possibly through Mycenae or Phoenicia. Their metallurgical gods and the tradition of Cadmus indicate this much.

By way of literary evidences, the following lines from Homer (Iliad, XVIII.) have interest as being the first preserved description in any language of a metallurgical work. Hephaestus was much interrupted by Thetis, who came to secure a shield for Achilles, and whose general conversation we therefore largely omit. We adopt Pope's translation:--

There the lame architect the goddess found Obscure in smoke, his forges flaming round, While bathed in sweat from fire to fire he flew; And puffing loud the roaring bellows blew. * * * In moulds prepared, the glowing ore (metal?) he pours. * * * "Vouchsafe, oh Thetis! at our board to share The genial rites and hospitable fare; While I the labours of the forge forego, And bid the roaring bellows cease to blow." Then from his anvil the lame artist rose; Wide with distorted legs oblique he goes, And stills the bellows, and (in order laid) Locks in their chests his instruments of trade; Then with a sponge, the sooty workman dress'd His brawny arms embrown'd and hairy breast. * * * Thus having said, the father of the fires To the black labours of his forge retires. Soon as he bade them blow the bellows turn'd Their iron mouths; and where the furnace burn'd Resounding breathed: at once the blast expires, And twenty forges catch at once the fires; Just as the God directs, now loud, now low, They raise a tempest, or they gently blow; In hissing flames huge silver bars are roll'd, And stubborn brass (copper?) and tin, and solid gold; Before, deep fixed, the eternal anvils stand. The ponderous hammer loads his better hand; His left with tongs turns the vex'd metal round. And thick, strong strokes, the doubling vaults rebound Then first he formed the immense and solid shield;

Even if we place the siege of Troy at any of the various dates from 1350 to 1100 B.C., it does not follow that the epic received its final form for many centuries later, probably 900-800 B.C.; and the experience of the race in metallurgy at a much later period than Troy may have been drawn upon to fill in details. It is possible to fill a volume with indirect allusion to metallurgical facts and to the origins of the art, from Greek mythology, from Greek poetry, from the works of the grammarians, and from the Bible. But they are of no more technical value than the metaphors from our own tongue. Greek literature in general is singularly lacking in metallurgical description of technical value, and it is not until Dioscorides (1st Century A.D.) that anything of much importance can be adduced. Aristotle, however, does make an interesting reference to what may be brass (see note on p. 410), and there can be no doubt that if we had the lost work of Aristotle's successor, Theophrastus (372-288 B.C.), on metals we should be in possession of the first adequate work on metallurgy. As it is, we find the green and blue copper minerals from Cyprus mentioned in his "Stones." And this is the first mention of any particular copper ore. He also mentions (XIX.) pyrites "which melt," but whether it was a copper variety cannot be determined. Theophrastus further describes the making of verdigris (see note 4, p. 440). From Dioscorides we get a good deal of light on copper treatment, but as his objective was to describe medicinal preparations, the information is very indirect. He states (V, 100) that "pyrites is a stone from which copper is made." He mentions _chalcitis_ (copper sulphide, see note on, p. 573); while his _misy_, _sory_, _melanteria_, _caeruleum_, and _chrysocolla_ were all oxidation copper or iron minerals. (See notes on p. 573.) In giving a method of securing _pompholyx_ (zinc oxide), "the soot flies up when the copper refiners sprinkle powdered _cadmia_ over the molten metal" (see note 26, p. 394); he indirectly gives us the first definite indication of making brass, and further gives some details as to the furnaces there employed, which embraced bellows and dust chambers. In describing the making of flowers of copper (see note 26, p. 538) he states that in refining copper, when the "molten metal flows through its tube into a receptacle, the workmen pour cold water on it, the copper spits and throws off the flowers." He gives the first description of vitriol (see note 11, p. 572), and describes the pieces as "shaped like dice which stick together in bunches like grapes." Altogether, from Dioscorides we learn for the first time of copper made from sulphide ores, and of the recovery of zinc oxides from furnace fumes; and he gives us the first certain description of making brass, and finally the first notice of blue vitriol.

The next author we have who gives any technical detail of copper work is Pliny (23-79 A.D.), and while his statements carry us a little further than Dioscorides, they are not as complete as the same number of words could have afforded had he ever had practical contact with the subject, and one is driven to the conclusion that he was not himself much of a metallurgist. Pliny indicates that copper ores were obtained from veins by underground mining. He gives the same minerals as Dioscorides, but is a good deal confused over _chrysocolla_ and _chalcitis_. He gives no description of the shapes of furnaces, but frequently mentions the bellows, and speaks of the _cadmia_ and _pompholyx_ which adhered to the walls and arches of the furnaces. He has nothing to say as to whether fluxes are used or not. As to fuel, he says (XXXIII, 30) that "for smelting copper and iron pine wood is the best." The following (XXXIV, 20) is of the greatest interest on the subject:--"Cyprian copper is known as _coronarium_ and _regulare_; both are ductile.... In other mines are made that known as _regulare_ and _caldarium_. These differ, because the _caldarium_ is only melted, and is brittle to the hammer; whereas the _regulare_ is malleable or ductile. All Cyprian copper is this latter kind. But in other mines with care the difference can be eliminated from _caldarium_, the impurities being carefully purged away by smelting with fire, it is made into _regulare_. Among the remaining kinds of copper the best is that of Campania, which is most esteemed for vessels and utensils. This kind is made in several ways. At Capua it is melted with wood, not with charcoal, after which it is sprinkled with water and washed through an oak sieve. After it is melted a number of times Spanish _plumbum argentum_ (probably pewter) is added to it in proportion of ten pounds of the lead to one hundred pounds of copper, and thereby it is made pliable and assumes that pleasing colour which in other kinds of copper is effected by oil and the sun. In many parts of the Italian provinces they make a similar kind of metal; but there they add eight pounds of lead, and it is re-melted over charcoal because of the scarcity of wood. Very different is the method carried on in Gaul,

## particularly where the ore is smelted between red hot stones, for this

burns the metal and renders it black and brittle. Moreover, it is re-melted only a single time, whereas the oftener this operation is repeated the better the quality becomes. It is well to remark that all copper fuses best when the weather is intensely cold." The red hot stones in Gaul were probably as much figments of imagination as was the assumption of one commentator that they were a reverberatory furnace. Apart from the above, Pliny says nothing very direct on refining copper. It is obvious that more than one melting was practised, but that anything was known of the nature of oxidation by a blast and reduction by poling is uncertain. We produce the three following statements in connection with some bye-products used for medicinal purposes, which at least indicate operations subsequent to the original melting. As to whether they represent this species of refining or not, we leave it to the metallurgical profession (XXXIV, 24):--"The flowers of copper are used in medicine; they are made by fusing copper and moving it to another furnace, where the rapid blast separates it into a thousand

## particles, which are called flowers. These scales are also made when the

copper cakes are cooled in water (XXXIV, 35). _Smega_ is prepared in the copper works; when the metal is melted and thoroughly smelted charcoal is added to it and gradually kindled; after this, being blown upon by a powerful bellows, it spits out, as it were, copper chaff (XXXIV, 37). There is another product of these works easily distinguished from _smega_, which the Greeks call _diphrygum_. This substance has three different origins.... A third way of making it is from the residues which fall to the bottom in copper furnaces. The difference between the different substances (in the furnace) is that the copper itself flows into a receiver; the slag makes its escape from the furnace; the flowers float on the top (of the copper?), and the _diphrygum_ remains behind. Some say that in the furnace there are certain masses of stone which, being smelted, become soldered together, and that the copper fuses around it, the mass not becoming liquid unless it is transferred to another furnace. It thus forms a sort of knot, as it were, in the metal."

Pliny is a good deal confused over the copper alloys, failing to recognise _aurichalcum_ as the same product as that made by mixing _cadmia_ and molten copper. Further, there is always the difficulty in translation arising from the fact that the Latin _aes_ was indiscriminately copper, brass, and bronze. He does not, except in one instance (XXXIV., 2), directly describe the mixture of _cadmia_ and copper. "Next to Livian (copper) this kind (_corduban_, from Spain) most readily absorbs _cadmia_, and becomes almost as excellent as _aurichalcum_ for making _sesterces_." As to bronze, there is no very definite statement; but the _argentatium_ given in the quotation above from XXXIV, 20, is stated in XXXIV, 48, to be a mixture of tin and lead. The Romans carried on most extensive copper mining in various parts of their empire; these activities extended from Egypt through Cyprus, Central Europe, the Spanish Peninsula, and Britain. The activity of such works is abundantly evidenced in the mines, but very little remains upon the surface to indicate the equipment; thus, while mining methods are clear enough, the metallurgy receives little help from these sources. At Rio Tinto there still remain enormous slag heaps from the Romans, and the Phoenician miners before them. Professor W. A. Carlyle informs us that the ore worked must have been almost exclusively sulphides, as only negligible quantities of carbonates exist in the deposits; they probably mixed basic and siliceous ores. There is some evidence of roasting, and the slags run from .2 to .6%. They must have run down mattes, but as to how they ultimately arrived at metallic copper there is no evidence to show.

The special processes for separating other metals from copper by liquation and matting, or of refining by poling, etc., are none of them clearly indicated in records or remains until we reach the 12th century. Here we find very adequate descriptions of copper smelting and refining by the Monk Theophilus (see Appendix B). We reproduce two paragraphs of interest from Hendrie's excellent translation (p. 305 and 313): "Copper is engendered in the earth. When a vein of which is found, it is acquired with the greatest labour by digging and breaking. It is a stone of a green colour and most hard, and naturally mixed with lead. This stone, dug up in abundance, is placed upon a pile and burned after the manner of chalk, nor does it change colour, but yet loses its hardness, so that it can be broken up. Then, being bruised small, it is placed in the furnace; coals and the bellows being applied, it is incessantly forged by day and night. This should be done carefully and with caution; that is, at first coals are placed in, then small pieces of stone are distributed over them, and again coals, and then stone anew, and it is thus arranged until it is sufficient for the size of the furnace. And when the stone has commenced to liquefy, the lead flows out through some small cavities, and the copper remains within. (313) Of the purification of copper. Take an iron dish of the size you wish, and line it inside and out with clay strongly beaten and mixed, and it is carefully dried. Then place it before a forge upon the coals, so that when the bellows act upon it the wind may issue partly within and partly above it, and not below it. And very small coals being placed round it, place copper in it equally, and add over it a heap of coals. When, by blowing a long time, this has become melted, uncover it and cast immediately fine ashes of coals over it, and stir it with a thin and dry piece of wood as if mixing it, and you will directly see the burnt lead adhere to these ashes like a glue. Which being cast out again superpose coals, and blowing for a long time, as at first, again uncover it, and then do as you did before. You do this until at length, by cooking it, you can withdraw the lead entirely. Then pour it over the mould which you have prepared for this, and you will thus prove if it be pure. Hold it with pincers, glowing as it is, before it has become cold, and strike it with a large hammer strongly over the anvil, and if it be broken or split you must liquefy it anew as before."

The next writer of importance was Biringuccio, who was contemporaneous with Agricola, but whose book precedes _De Re Metallica_ by 15 years. That author (III, 2) is the first to describe particularly the furnace used in Saxony and the roasting prior to smelting, and the first to mention fluxes in detail. He, however, describes nothing of matte smelting; in copper refining he gives the whole process of poling, but omits the pole. It is not until we reach _De Re Metallica_ that we find adequate descriptions of the copper minerals, roasting, matte smelting, liquation, and refining, with a wealth of detail which eliminates the necessity for a large amount of conjecture regarding technical methods of the time.

[43] _Cadmia metallica fossilis_ (see note on p. 112). This was undoubtedly the complex cobalt-arsenic-zinc minerals found in Saxony. In the German translation, however, this is given as _Kalmey_, calamine, which is unlikely from the association with pyrites.

[44] The Roman _modius_ (_modulus_?) held about 550 cubic inches, the English peck holding 535 cubic inches. Then, perhaps, his seven _moduli_ would be roughly, 1 bushel 3 pecks, and 18 vessels full would be about 31 bushels--say, roughly, 5,400 lbs. of ore.

[45] Exhausted liquation cakes (_panes aerei fathiscentes_). This is the copper sponge resulting from the first liquation of lead, and still contains a considerable amount of lead. The liquation process is discussed in great detail in Book XI.

[46] The method of this paragraph involves two main objectives--first, the gradual enrichment of matte to blister copper; and, second, the creation of large cakes of copper-lead-silver alloy of suitable size and ratio of metals for liquation. This latter process is described in detail in Book XI. The following groupings show the circuit of the various products, the "lbs." being Roman _librae_:--

CHARGE. PRODUCTS.

{ Crude ore 5,400 lbs. } Primary matte (1) 600 lbs. { Lead slags 3 cartloads } 1st { Schist 1 cartload } Silver-copper alloy (A) 50 " { Flux 20 lbs. } { Concentrates from } Slags (B) { slags & accretions Small quantity }

{ Primary matte (1) 1,800 lbs. } Secondary matte (2) 1,800 lbs. { Hearth-lead & litharge 1,200 " } { Lead ore 300 " } Silver-copper-lead 2nd { Rich hard cakes (A_{4}) 500 " } alloy (liquation { Liquated cakes 200 " } cakes) (A_{2}) 1,200 " { Slags (B) } { Concentrates from } Slags (B_{2}) { accretions }

{ Secondary matte (2) 1,800 lbs. } Tertiary matte (3) 1,300 lbs. { Hearth-lead & litharge 1,200 " } Silver-copper-lead { Lead ore 300 " } alloy (liquation 3rd { Rich hard cakes (A_{4}) 500 " } cakes) (A_{3}) 1,100 " { Slags (B_{2}) } Slags (B_{3}) { Concentrates from } { accretions }

{ Tertiary matte (3) 11 cartloads } Quaternary hard cakes { Poor hard cakes (A_{5}) 3 " } matte (4) 2,000 lbs. 4th { Slags (B_{3}) } Rich hard cakes of { Concentrates from } matte (A_{4}) 1,500 " { accretions }

{ Roasted quartz } Poor hard cakes of 5th { Matte (4) (three } matte (A_{5}) 1,500 lbs. { times roasted) 11 cartloads } Final cakes of matte (5)

6th Final matte three times roasted is smelted to blister copper.

The following would be a rough approximation of the value of the various products:--

(1.) Primary matte = 158 ounces troy per short ton. (2.) Secondary matte = 85 " " " (3.) Tertiary matte = 60 " " " (4.) Quaternary matte = Indeterminate. A. Copper-silver alloy = 388 ounces Troy per short ton. A_{2} Copper-silver-lead alloy = 145 " " " A_{3} " " " = 109 " " " A_{4} Rich hard cakes = 97 " " " A_{5} Poor hard cakes = Indeterminate. Final blister copper = 12 ozs. Troy per short ton.

[47] This expression is usually used for hearth-lead, but in this case the author is apparently confining himself to lead ore, and apparently refers to lead carbonates. The German Translation gives _pleyschweiss_. The pyrites mentioned in this paragraph may mean galena, as pyrites was to Agricola a sort of genera.

[48] (_Excoquitur_) ... "_si vero pyrites, primo e fornace, ut Goselariae videre licet, in catinum defluit liquor quidam candidus, argento inimicus et nocivus; id enim comburit: quo circa recrementis, quae supernatant, detractis effunditur: vel induratus conto uncinato extrahitur: eundem liquorem parietes fornacis exudant._" In the Glossary the following statement appears: "_Liquor candidus primo e fornace defluens cum Goselariae excoquitur pyrites,--kobelt; quem parietes fornacis exudant,--conterfei._" In this latter statement Agricola apparently recognised that there were two different substances, _i.e._, that the substance found in the furnace walls--_conterfei_--was not the same substance as that which first flowed from the furnace--_kobelt_. We are at no difficulty in recognizing _conterfei_ as metallic zinc; it was long known by that term, and this accidental occurrence is repeatedly mentioned by other authors after Agricola. The substance which first flowed into the forehearth presents greater difficulties; it certainly was not zinc. In _De Natura Fossilium_ (p. 347), Agricola says that at Goslar the lead has a certain white slag floating upon it, the "colour derived from the pyrites (_pyriten argenteum_) from which it was produced." _Pyriten argenteum_ was either marcasite or mispickel, neither of which offers much suggestion; nor are we able to hazard an explanation of value.

HISTORICAL NOTE ON ZINC. The history of zinc metallurgy falls into two distinct lines--first, that of the metal, and second, that of zinc ore, for the latter was known and used to make brass by cementation with copper and to yield oxides by sublimation for medicinal purposes, nearly 2,000 years before the metal became generally known and used in Europe.

There is some reason to believe that metallic zinc was known to the Ancients, for bracelets made of it, found in the ruins of Cameros (prior to 500 B.C.), may have been of that age (Raoul Jagnaux, _Traite de Chimie Generale_, 1887, II, 385); and further, a passage in Strabo (63 B.C.-24 A.D.) is of much interest. He states: (XIII, 1, 56) "There is found at Andeira a stone which when burnt becomes iron. It is then put into a furnace, together with some kind of earth, when it distils a mock silver (_pseudargyrum_), or with the addition of copper it becomes the compound called _orichalcum_. There is found a mock silver near Tismolu also." (Hamilton's Trans., II, p. 381). About the Christian era the terms _orichalcum_ or _aurichalcum_ undoubtedly refer to brass, but whether these terms as used by earlier Greek writers do not refer to bronze only, is a matter of considerable doubt. Beyond these slight references we are without information until the 16th Century. If the metal was known to the Ancients it must have been locally, for by its greater adaptability to brass-making it would probably have supplanted the crude melting of copper with zinc minerals.

It appears that the metal may have been known in the Far East prior to such knowledge in Europe; metallic zinc was imported in considerable quantities from the East as early as the 16th and 17th centuries under such terms as _tuteneque_, _tuttanego_, _calaem_, and _spiauter_--the latter, of course, being the progenitor of our term spelter. The localities of Eastern production have never been adequately investigated. W. Hommel (Engineering and Mining Journal, June 15, 1912) gives a very satisfactory review of the Eastern literature upon the subject, and considers that the origin of manufacture was in India, although the most of the 16th and 17th Century product came from China. The earliest certain description seems to be some recipes for manufacture quoted by Praphulla Chandra Ray (A History of Hindu Chemistry, London, 1902, p. 39) dating from the 11th to the 14th Centuries. There does not appear to be any satisfactory description of the Chinese method until that of Sir George Staunton (Journal Asiatique Paris, 1835, p. 141.) We may add that spelter was produced in India by crude distillation of calamine in clay pots in the early part of the 19th Century (Brooke, Jour. Asiatic Soc. of Bengal, vol. XIX, 1850, p. 212), and the remains of such smelting in Rajputana are supposed to be very ancient.

The discovery of zinc in Europe seems to have been quite independent of the East, but precisely where and when is clouded with much uncertainty. The _marchasita aurea_ of Albertus Magnus has been called upon to serve as metallic zinc, but such belief requires a hypothesis based upon a great deal of assumption. Further, the statement is frequently made that zinc is mentioned in Basil Valentine's Triumphant Chariot of Antimony (the only one of the works attributed to this author which may date prior to the 17th Century), but we have been unable to find any such reference. The first certain mention of metallic zinc is generally accredited to Paracelsus (1493-1541), who states (_Liber Mineralium_ II.): "Moreover there is another metal generally unknown called _zinken_. It is of peculiar nature and origin; many other metals adulterate it. It can be melted, for it is generated from three fluid principles; it is not malleable. Its colour is different from other metals and does not resemble others in its growth. Its ultimate matter (_ultima materia_) is not to me yet fully known. It admits of no mixture and does not permit of the _fabricationes_ of other metals. It stands alone entirely to itself." We do not believe that this book was published until after Agricola's works. Agricola introduced the following statements into his revised edition of _Bermannus_ (p. 431), published in 1558: "It (a variety of pyrites) is almost the colour of galena, but of entirely different components. From it there is made gold and silver, and a great quantity is dug in Reichenstein, which is in Silesia, as was recently reported to me. Much more is found at Raurici, which they call _zincum_, which species differs from pyrites, for the latter contains more silver than gold, the former only gold or hardly any silver." In _De Natura Fossilium_ (p. 368): "For this _cadmia_ is put, in the same way as quicksilver, in a suitable vessel so that the heat of the fire will cause it to sublime, and from it is made a black or brown or grey body which the Alchemists call _cadmia sublimata_. This possesses corrosive properties to the highest degree. Cognate with this _cadmia_ and pyrites is a compound which the Noricans and Rhetians call _zincum_." We leave it to readers to decide how near this comes to metallic zinc; in any event, he apparently did not recognise his _conterfei_ from the furnaces as the same substance as the _zincum_ from Silesia. The first correlation of these substances was apparently by Lohneys, in 1617, who says (_Vom Bergwerk_, p. 83-4): "When the people in the smelting works are smelting, there is made under the furnace and in the cracks in the walls among the badly plastered stones, a metal which is called _zinc_ or _counterfeht_, and when the wall is scraped it falls into a vessel placed to receive it. This metal greatly resembles tin, but it is harder and less malleable.... The Alchemists have a great desire for this _zinc_ or bismuth." That this metal originated from blende or calamine was not recognised until long after, and Libavis (_Alchymia_, Frankfort, 1606), in describing specimens which came from the East, did not so identify it, this office being performed by Glauber, who says (_De Prosperitate Germanias_, Amsterdam, 1656): "Zink is a volatile mineral or half-ripe metal when it is extracted from its ore. It is more brilliant than tin and not so fusible or malleable ... it turns (copper) into brass, as does _lapis calaminaris_, for indeed this stone is nothing but infusible zinc, and this zinc might be called a fusible _lapis calaminaris_, inasmuch as both of them partake of the same nature.... It sublimates itself up into the cracks of the furnace, whereupon the smelters frequently break it out." The systematic distillation of zinc from calamine was not discovered in Europe until the 18th Century. Henkel is generally accredited with the first statement to that effect. In a contribution published as an Appendix to his other works, of which we have had access only to a French translation (_Pyritologie_, Paris, 1760, p. 494), he concludes that zinc is a half-metal of which the best ore is calamine, but believes it is always associated with lead, and mentions that an Englishman lately arrived from Bristol had seen it being obtained from calamine in his own country. He further mentions that it can be obtained by heating calamine and lead ore mixed with coal in a thick earthen vessel. The Bristol works were apparently those of John Champion, established about 1740. The art of distillation was probably learned in the East.

Definite information as to the zinc minerals goes back to but a little before the Christian Era, unless we accept nebular references to _aurichalcum_ by the poets, or what is possibly zinc ore in the "earth" mentioned by Aristotle (_De Mirabilibus_, 62): "Men say that the copper of the Mossynoeci is very brilliant and white, no tin being mixed with it; but there is a kind of earth there which is melted with it." This might quite well be an arsenical mineral. But whether we can accept the poets or Aristotle or the remark of Strabo given above, as sufficient evidence or not, there is no difficulty with the description of _cadmia_ and _pompholyx_ and _spodos_ of Dioscorides (1st Century), parts of which we reproduce in note 26, p. 394. His _cadmia_ is described as rising from the copper furnaces and clinging to the iron bars, but he continues: "_Cadmia_ is also prepared by burning the stone called pyrites, which is found near Mt. Soloi in Cyprus.... Some say that _cadmia_ may also be found in stone quarries, but they are deceived by stones having a resemblance to _cadmia_." _Pompholyx_ and _spodos_ are evidently furnace calamine. From reading the quotation given on p. 394, there can be no doubt that these materials, natural or artificial, were used to make brass, for he states (V, 46): "White _pompholyx_ is made every time that the artificer in the working and perfecting of the copper sprinkles powdered _cadmia_ upon it to make it more perfect, the soot arising from this ... is _pompholyx_." Pliny is confused between the mineral _cadmia_ and furnace _calamine_, and none of his statements are very direct on the subject of brass making. His most pointed statement is (XXXIV, 2): "... Next to Livian (copper) this kind best absorbs _cadmia_, and is almost as good as _aurichalcum_ for making sesterces and double asses." As stated above, there can be little doubt that the _aurichalcum_ of the Christian Era was brass, and further, we do know of brass sesterces of this period. Other Roman writers of this and later periods refer to earth used with copper for making brass. Apart from these evidences, however, there is the evidence of analyses of coins and objects, the earliest of which appears to be a large brass of the Cassia family of 20 B.C., analyzed by Phillips, who found 17.3% zinc (Records of Mining and Metallurgy, London, 1857, p. 13). Numerous analyses of coins and other objects dating during the following century corroborate the general use of brass. Professor Gowland (Presidential Address, Inst. of Metals, 1912) rightly considers the Romans were the first to make brass, and at about the above period, for there appears to be no certainty of any earlier production. The first adequate technical description of brass making is in about 1200 A.D. being that of Theophilus, who describes (Hendrie's Trans., p. 307) calcining _calamina_ and mixing it with finely divided copper in glowing crucibles. The process was repeated by adding more calamine and copper until the pots were full of molten metal. This method is repeatedly described with minor variations by Biringuccio, Agricola (_De Nat. Fos._), and others, down to the 18th Century. For discussion of the zinc minerals see note on p. 112.

[49] "_... non raro, ut nonnulli pyritae sunt, candida...._" This is apparently the unknown substance mentioned above.

[50] One _drachma_ is about 3 ounces Troy per short ton. Three _unciae_ are about 72 ounces 6 dwts. Troy per short ton.

[51] In this section, which treats of the metallurgy of _plumbum candidum_, "tin," the word _candidum_ is very often omitted in the Latin, leaving only _plumbum_, which is confusing at times with lead. The black tin-stone, _lapilli nigri_ has been treated in a similar manner, _lapilli_ (small stones) constantly occurring alone in the Latin. This has been rendered as "tin-stone" throughout, and the material prior to extraction of the _lapilli nigri_ has been rendered "tin-stuff," after the Cornish.

[52] "_... ex saxis vilibus, quae natura de diversa materia composuit._" The Glossary gives _grindstein_. Granite (?).

[53] HISTORICAL NOTES ON TIN METALLURGY. The first appearance of tin lies in the ancient bronzes. And while much is written upon the "Bronze Age" by archaeologists, we seriously doubt whether or not a large part of so-called bronze is not copper. In any event, this period varied with each race, and for instance, in Britain may have been much later than Egyptian historic times. The bronze articles of the IV Dynasty (from 3800 to 4700 B.C. depending on the authority) place us on certain ground of antiquity. Professor Gowland (Presidential Address, Inst. of Metals, London, 1912) maintains that the early bronzes were the result of direct smelting of stanniferous copper ores, and while this may be partially true for Western Europe, the distribution and nature of the copper deposits do not warrant this assumption for the earlier scenes of human

## activity--Asia Minor, Egypt, and India. Further, the lumps of rough tin

and also of copper found by Borlase (Tin Mining in Spain, Past and Present, London, 1897, p. 25) in Cornwall, mixed with bronze celts under conditions certainly indicating the Bronze Age, is in itself of considerable evidence of independent melting. To our mind the vast majority of ancient bronzes must have been made from copper and tin mined and smelted independently. As to the source of supply of ancient tin, we are on clear ground only with the advent of the Phoenicians, 1500-1000 B.C., who, as is well known, distributed to the ancient world a supply from Spain and Britain. What the source may have been prior to this time has been subject to much discussion, and while some slender threads indicate the East, we believe that a more local supply to Egypt, etc., is not impossible. The discovery of large tin fields in Central Africa and the native-made tin ornaments in circulation among the negroes, made possible the entrance of the metal into Egypt along the trade routes. Further, we see no reason why alluvial tin may not have existed within easy reach and have become exhausted. How quickly such a source of metal supply can be forgotten and no evidence remain, is indicated by the seldom remembered alluvial gold supply from Ireland. However, be these conjectures as they may, the East has long been the scene of tin production and of transportation activity. Among the slender evidences that point in this direction is that the Sanskrit term for tin is _kastira_, a term also employed by the Chaldeans, and represented in Arabic by _kasdir_, and it may have been the progenitor of the Greek _cassiteros_. There can be no doubt that the Phoenicians also traded with Malacca, etc., but beyond these threads there is little to prove the pre-western source. The strained argument of Beckmann (Hist. of Inventions, vol. II., p. 207) that the _cassiteros_ of Homer and the _bedil_ of the Hebrews was possibly not tin, and that tin was unknown at this time, falls to the ground in the face of the vast amount of tin which must have been in circulation to account for the bronze used over a period 2,000 years prior to those peoples. Tin is early mentioned in the Scriptures (Numbers XXXI, 22), being enumerated among the spoil of the Midianites (1200 B.C.?), also Ezekiel (600 B.C., XXVII, 12) speaks of tin from Tarshish (the Phoenician settlement on the coast of Spain). According to Homer tin played considerable part in Vulcan's metallurgical stores. Even approximately at what period the Phoenicians began their distribution from Spain and Britain cannot be determined. They apparently established their settlements at Gades (Cadiz) in Tarshish, beyond Gibraltar, about 1100 B.C. The remains of tin mining in the Spanish peninsula prior to the Christian Era indicate most extensive production by the Phoenicians, but there is little evidence as to either mining or smelting methods. Generally as to the technical methods of mining and smelting tin, we are practically without any satisfactory statement down to Agricola. However, such scraps of information as are available are those in Homer (see note on p. 402), Diodorus, and Pliny.

Diodorus says (V, 2) regarding tin in Spain: "They dig it up, and melt it down in the same way as they do gold and silver;" and again, speaking of the tin in Britain, he says: "These people make tin, which they dig up with a great deal of care and labour; being rocky, the metal is mixed with earth, out of which they melt the metal, and then refine it." Pliny (XXXIV, 47), in the well-known and much-disputed passage: "Next to be considered are the characteristics of lead, which is of two kinds, black and white. The most valuable is the white; the Greeks called it _cassiteros_, and there is a fabulous story of its being searched for and carried from the islands of Atlantis in barks covered with hides. Certainly it is obtained in Lusitania and Gallaecia on the surface of the earth from black-coloured sand. It is discovered by its great weight, and it is mixed with small pebbles in the dried beds of torrents. The miners wash these sands, and that which settles they heat in the furnace. It is also found in gold mines, which are called _alutiae_. A stream of water passing through detaches small black pebbles variegated with white spots, the weight of which is the same as gold. Hence it is that they remain in the baskets of the gold collectors with the gold; afterward, they are separated in a _camillum_ and when melted become white lead."

There is practically no reference to the methods of Cornish tin-working over the whole period of 2,000 years that mining operations were carried on there prior to the Norman occupation. From then until Agricola's time, a period of some four centuries, there are occasional references in Stannary Court proceedings, Charters, and such-like official documents which give little metallurgical insight. From a letter of William de Wrotham, Lord Warden of the Stannaries, in 1198, setting out the regulations for the impost on tin, it is evident that the black tin was smelted once at the mines and that a second smelting or refining was carried out in specified towns under the observation of the Crown Officials. In many other official documents there are repeated references to the right to dig turfs and cut wood for smelting the tin. Under note 8, p. 282, we give some further information on tin concentration, and the relation of Cornish and German tin miners. Biringuccio (1540) gives very little information on tin metallurgy, and we are brought to _De Re Metallica_ for the first clear exposition.

As to the description on these pages it must be remembered that the tin-stone has been already roasted, thus removing some volatile impurities and oxidizing others, as described on page 348. The furnaces and the methods of working the tin, here described, are almost identical with those in use in Saxony to-day. In general, since Agricola's time tin has not seen the mechanical and metallurgical development of the other metals. The comparatively small quantities to be dealt with; the necessity of maintaining a strong reducing atmosphere, and consequently a mild cold blast; and the comparatively low temperature demanded, gave little impetus to other than crude appliances until very modern times.

[54] _Aureo nummo_. German Translation gives _reinschen guelden_, which was the equivalent of about $1.66, or 6.9 shillings. The purchasing power of money was, however, several times as great as at present.

[55] In the following descriptions of iron-smelting, we have three processes described; the first being the direct reduction of malleable iron from ore, the second the transition stage then in progress from the direct to indirect method by way of cast-iron; and the third a method of making steel by cementation. The first method is that of primitive iron-workers of all times and all races, and requires little comment. A pasty mass was produced, which was subsequently hammered to make it exude the slag, the hammered mass being the ancient "bloom." The second process is of considerable interest, for it marks one of the earliest descriptions of working iron in "a furnace similar to a blast furnace, but much wider and higher." This original German _Stueckofen_ or high bloomery furnace was used for making "masses" of wrought-iron under essentially the same conditions as its progenitor the forge--only upon a larger scale. With high temperatures, however, such a furnace would, if desired, yield molten metal, and thus the step to cast-iron as a preliminary to wrought-iron became very easy and natural, in fact Agricola mentions above that if the iron is left to settle in the furnace it becomes hard. The making of malleable iron by subsequent treatment of the cast-iron--the indirect method--originated in about Agricola's time, and marks the beginning of one of those subtle economic currents destined to have the widest bearing upon civilization. It is to us uncertain whether he really understood the double treatment or not. In the above paragraph he says from ore "once or twice smelted they make iron," etc., and in _De Natura Fossilium_ (p. 339) some reference is made to pouring melted iron, all of which would appear to be cast-iron. He does not, however, describe the 16th Century method of converting cast into wrought iron by way of in effect roasting the pig iron to eliminate carbon by oxidation, with subsequent melting into a "ball" or "mass." It must be borne in mind that puddling for this purpose did not come into use until the end of the 18th Century. A great deal of discussion has arisen as to where and at what time cast-iron was made systematically, but without satisfactory answer; in any event, it seems to have been in about the end of the 14th Century, as cast cannon began to appear about that time. It is our impression that the whole of this discussion on iron in _De Re Metallica_ is an abstract from Biringuccio, who wrote 15 years earlier, as it is in so nearly identical terms. Those interested will find a translation of Biringuccio's statement with regard to steel in Percy's Metallurgy of Iron and Steel, London, 1864, p. 807.

HISTORICAL NOTE ON IRON SMELTING. The archaeologists' division of the history of racial development into the Stone, Bronze, and Iron Ages, based upon objects found in tumuli, burial places, etc., would on the face of it indicate the prior discovery of copper metallurgy over iron, and it is generally so maintained by those scientists. The metallurgists have not hesitated to protest that while this distinction of "Ages" may serve the archaeologists, and no doubt represents the sequence in which the metal objects are found, yet it by no means follows that this was the order of their discovery or use, but that iron by its rapidity of oxidation has simply not been preserved. The arguments which may be advanced from our side are in the main these. Iron ore is of more frequent occurrence than copper ores, and the necessary reduction of copper oxides (as most surface ores must have been) to fluid metal requires a temperature very much higher than does the reduction of iron oxides to wrought-iron blooms, which do not necessitate fusion. The comparatively greater simplicity of iron metallurgy under primitive conditions is well exemplified by the hill tribes of Northern Nigeria, where in village forges the negroes reduce iron sufficient for their needs, from hematite. Copper alone would not be a very serviceable metal to primitive man, and he early made the advance to bronze; this latter metal requires three metallurgical operations, and presents immeasurably greater difficulties than iron. It is, as Professor Gowland has demonstrated (Presidential Address, Inst. of Metals, London, 1912) quite possible to make bronze from melting stanniferous copper ores, yet such combined occurrence at the surface is rare, and, so far as known, the copper sources from which Asia Minor and Egypt obtained their supply do not contain tin. It seems to us, therefore, that in most cases the separate fusions of different ores and their subsequent re-melting were required to make bronze. The arguments advanced by the archaeologists bear mostly upon the fact that, had iron been known, its superiority would have caused the primitive races to adopt it, and we should not find such an abundance of bronze tools. As to this, it may be said that bronze weapons and tools are plentiful enough in Egyptian, Mycenaean, and early Greek remains, long after iron was demonstrably well known. There has been a good deal pronounced by etymologists on the history of iron and copper, for instance, by Max Mueller, (Lectures on the Science of Language, Vol. II, p. 255, London, 1864), and many others, but the amazing lack of metallurgical knowledge nullifies practically all their conclusions. The oldest Egyptian texts extant, dating 3500 B.C., refer to iron, and there is in the British Museum a piece of iron found in the Pyramid of Kephron (3700 B.C.) under conditions indicating its co-incident origin. There is exhibited also a fragment of oxidized iron lately found by Professor Petrie and placed as of the VI Dynasty (B.C. 3200). Despite this evidence of an early knowledge of iron, there is almost a total absence of Egyptian iron objects for a long period subsequent to that time, which in a measure confirms the view of its disappearance rather than that of ignorance of it. Many writers have assumed that the Ancients must have had some superior art of hardening copper or bronze, because the cutting of the gigantic stonework of the time could not have been done with that alloy as we know it; no such hardening appears among the bronze tools found, and it seems to us that the argument is stronger that the oldest Egyptian stoneworkers employed mostly iron tools, and that these have oxidized out of existence. The reasons for preferring copper alloys to iron for decorative objects were equally strong in ancient times as in the present day, and accounts sufficiently for these articles, and, therefore, iron would be devoted to more humble objects less likely to be preserved. Further, the Egyptians at a later date had some prejudices against iron for sacred purposes, and the media of preservation of most metal objects were not open to iron. We know practically nothing of very early Egyptian metallurgy, but in the time of Thotmes III. (1500 B.C.) bellows were used upon the forge.

Of literary evidences the earliest is in the Shoo King among the Tribute of Yue (2500 B.C.?). Iron is frequently mentioned in the Bible, but it is doubtful if any of the early references apply to steel. There is scarcely a Greek or Latin author who does not mention iron in some connection, and of the earliest, none are so suggestive from a metallurgical point of view as Homer, by whom "laboured" mass (wrought-iron?) is often referred to. As, for instance, in the Odyssey (I., 234) Pallas in the guise of Mentes, says according to Pope:

"Freighted with iron from my native land I steer my voyage to the Brutian strand, To gain by commerce for the laboured mass A just proportion of refulgent brass."

(Brass is modern poetic licence for copper or bronze). Also, in the Odyssey (IX, 465) when Homer describes how Ulysses plunged the stake into Cyclop's eye, we have the first positive evidence of steel, although hard iron mentioned in the Tribute of Yue, above referred to, is sometimes given as steel:

"And as when armourers temper in the ford The keen-edg'd pole-axe, or the shining sword, The red-hot metal hisses in the lake."

No doubt early wrought-iron was made in the same manner as Agricola describes. We are, however, not so clear as to the methods of making steel. Under primitive methods of making wrought-iron it is quite possible to carburize the iron sufficiently to make steel direct from ore. The primitive method of India and Japan was to enclose lumps of wrought-iron in sealed crucibles with charcoal and sawdust, and heat them over a long period. Neither Pliny nor any of the other authors of the period previous to the Christian Era give us much help on steel metallurgy, although certain obscure expressions of Aristotle have been called upon (for instance, St. John V. Day, Prehistoric Use of Iron and Steel, London, 1877, p. 134) to prove its manufacture by immersing wrought-iron in molten cast-iron.

[56] _Quae vel aerosa est, vel cocta_. It is by no means certain that _cocta_, "cooked" is rightly translated, for the author has not hitherto used this expression for heated. This may be residues from roasting and leaching pyrites for vitriol, etc.

[57] Agricola draws no sharp line of distinction between antimony the metal, and its sulphide. He uses the Roman term _stibi_ or _stibium_ (_Interpretatio_,--_Spiesglas_) throughout this book, and evidently in most cases means the sulphide, but in others, particularly in parting gold and silver, metallic antimony would be reduced out. We have been in much doubt as to the term to introduce into the text, as the English "stibnite" carries too much precision of meaning. Originally the "antimony" of trade was the sulphide. Later, with the application of that term to the metal, the sulphide was termed "grey antimony," and we have either used _stibium_ for lack of better alternative, or adopted "grey antimony." The method described by Agricola for treating antimony sulphide is still used in the Harz, in Bohemia, and elsewhere. The stibnite is liquated out at a low heat and drips from the upper to the lower pot. The resulting purified antimony sulphide is the modern commercial "crude antimony" or "grey antimony."

HISTORICAL NOTE ON THE METALLURGY OF ANTIMONY. The Egyptologists have adopted the term "antimony" for certain cosmetics found in Egyptian tombs from a very early period. We have, however, failed to find any reliable analyses which warrant this assumption, and we believe that it is based on the knowledge that antimony was used as a base for eye ointments in Greek and Roman times, and not upon proper chemical investigation. It may be that the ideograph which is interpreted as antimony may really mean that substance, but we only protest that the chemist should have been called in long since. In St. Jerome's translation of the Bible, the cosmetic used by Jezebel (II. Kings IX, 30) and by the lady mentioned by Ezekiel (XXIII, 40), "who didst wash thyself and paintedst thine eyes" is specifically given as _stibio_. Our modern translation carries no hint of the composition of the cosmetic, and whether some of the Greek or Hebrew MSS. do furnish a basis for such translation we cannot say. The Hebrew term for this mineral was _kohl_, which subsequently passed into "alcool" and "alkohol" in other languages, and appears in the Spanish Bible in the above passage in Ezekiel as _alcoholaste_. The term _antimonium_ seems to have been first used in Latin editions of Geber published in the latter part of the 15th Century. In any event, the metal is clearly mentioned by Dioscorides (1st Century), who calls it _stimmi_, and Pliny, who termed it _stibium_, and they leave no doubt that it was used as a cosmetic for painting the eyebrows and dilating the eyes. Dioscorides (V, 59) says: "The best _stimmi_ is very brilliant and radiant. When broken it divides into layers with no part earthy or dirty; it is brittle. Some call it _stimmi_, others _platyophthalmon_ (wide eyed); others _larbason_, others _gynaekeion_ (feminine).... It is roasted in a ball of dough with charcoal until it becomes a cinder.... It is also roasted by putting it on live charcoal and blowing it. If it is roasted too much it becomes lead." Pliny states (XXXIII, 33 and 34): "In the same mines in which silver is found, properly speaking there is a stone froth. It is white and shining, not transparent; is called _stimmi_, or _stibi_, or _alabastrum_, and _larbasis_. There are two kinds of it, the male and the female. The most approved is the female, the male being more uneven, rougher, less heavy, not so radiant, and more gritty. The female kind is bright and friable, laminar and not globular. It is astringent and refrigerative, and its principal use is for the eyes.... It is burned in manure in a furnace, is quenched with milk, ground with rain water in a mortar, and while thus turbid it is poured into a copper vessel and purified with nitrum ... above all in roasting it care should be taken that it does not turn to lead." There can be little doubt from Dioscorides' statement of its turning to lead that he had seen the metal antimony, although he thought it a species of lead. Of further interest in connection with the ancient knowledge of the metal is the Chaldean vase made of antimony described by Berthelot (_Comptes Rendus_, 1887, CIV, 265). It is possible that Agricola knew the metal, although he gives no details as to de-sulphurizing it or for recovering the metal itself. In _De Natura Fossilium_ (p. 181) he makes a statement which would indicate the metal, "_Stibium_ when melted in the crucible and refined has as much right to be regarded as a metal as is accorded to lead by most writers. If when smelted a certain portion be added to tin, a printer's alloy is made from which type is cast that is used by those who print books." Basil Valentine, in his "Triumphal Chariot of Antimony," gives a great deal that is new with regard to this metal, even if we can accredit the work with no earlier origin than its publication--about 1600; it seems possible however, that it was written late in the 15th Century (see Appendix B). He describes the preparation of the metal from the crude ore, both by roasting and reduction from the oxide with argol and saltpetre, and also by fusing with metallic iron. While the first description of these methods is usually attributed to Valentine, it may be pointed out that in the _Probierbuechlein_ (1500) as well as in Agricola the separation of silver from iron by antimony sulphide implies the same reaction, and the separation of silver and gold with antimony sulphide, often attributed to Valentine, is repeatedly set out in the _Probierbuechlein_ and in _De Re Metallica_. Biringuccio (1540) has nothing of importance to say as to the treatment of antimonial ores, but mentions it as an alloy for bell-metal, which would imply the metal.

[58] HISTORICAL NOTE ON THE METALLURGY OF QUICKSILVER. The earliest mention of quicksilver appears to have been by Aristotle (_Meteorologica_ IV, 8, 11), who speaks of it as fluid silver (_argyros chytos_). Theophrastus (105) states: "Such is the production of quicksilver, which has its uses. This is obtained from cinnabar rubbed with vinegar in a brass mortar with a brass pestle." (Hill's Trans., p. 139). Theophrastus also (103) mentions cinnabar from Spain and elsewhere. Dioscorides (V, 70) appears to be the first to describe the recovery of quicksilver by distillation: "Quicksilver (_hydrargyros_, _i.e._, liquid silver) is made from _ammion_, which is called _cinnabari_. An iron bowl containing _cinnabari_ is put into an earthen vessel and covered over with a cup-shaped lid smeared with clay. Then it is set on a fire of coals and the soot which sticks to the cover when wiped off and cooled is quicksilver. Quicksilver is also found in drops falling from the walls of the silver mines. Some say there are quicksilver mines. It can be kept only in vessels of glass, lead, tin (?), or silver, for if put in vessels of any other substances it consumes them and flows through." Pliny (XXXIII, 41): "There has been discovered a way of extracting _hydrargyros_ from the inferior _minium_ as a substitute for quicksilver, as mentioned. There are two methods: either by pounding _minium_ and vinegar in a brass mortar with a brass pestle, or else by putting _minium_ into a flat earthen dish covered with a lid, well luted with potter's clay. This is set in an iron pan and a fire is then lighted under the pan, and continually blown by a bellows. The perspiration collects on the lid and is wiped off and is like silver in colour and as liquid as water." Pliny is somewhat confused over the _minium_--or the text is corrupt, for this should be the genuine _minium_ of Roman times. The methods of condensation on the leaves of branches placed in a chamber, of condensing in ashes placed over the mouth of the lower pot, and of distilling in a retort, are referred to by Biringuccio (A.D. 1540), but with no detail.

[59] Most of these methods depend upon simple liquation of native bismuth. The sulphides, oxides, etc., could not be obtained without fusing in a furnace with appropriate de-sulphurizing or reducing agents, to which Agricola dimly refers. In _Bermannus_ (p. 439), he says: "_Bermannus_.--I will show you another kind of mineral which is numbered amongst metals, but appears to me to have been unknown to the Ancients; we call it _bisemutum_. _Naevius_.--Then in your opinion there are more kinds of metals than the seven commonly believed? _Bermannus_.--More, I consider; for this which just now I said we called _bisemutum_, cannot correctly be called _plumbum candidum_ (tin) nor _nigrum_ (lead), but is different from both, and is a third one. _Plumbum candidum_ is whiter and _plumbum nigrum_ is darker, as you see. _Naevius_.--We see that this is of the colour of _galena_. _Ancon_.--How then can _bisemutum_, as you call it, be distinguished from _galena_? _Bermannus_.--Easily; when you take it in your hands it stains them with black unless it is quite hard. The hard kind is not friable like _galena_, but can be cut. It is blacker than the kind of crude silver which we say is almost the colour of lead, and thus is different from both. Indeed, it not rarely contains some silver. It generally shows that there is silver beneath the place where it is found, and because of this our miners are accustomed to call it the 'roof of silver.' They are wont to roast this mineral, and from the better part they make metal; from the poorer part they make a pigment of a kind not to be despised." This pigment was cobalt blue (see note on p. 112), indicating a considerable confusion of these minerals. This quotation is the first description of bismuth, and the above text the first description of bismuth treatment. There is, however, bare mention of the mineral earlier, in the following single line from the _Probierbuechlein_ (p. 1): "Jupiter (controls) the ores of tin and _wismundt_." And it is noted in the _Nuetzliche Bergbuechlein_ in association with silver (see Appendix B).

[60] This _cadmia_ is given in the German translation as _kobelt_. It is probably the cobalt-arsenic-bismuth minerals common in Saxony. A large portion of the world's supply of bismuth to-day comes from the cobalt treatment works near Schneeberg. For further discussion of _cadmia_ see note on p. 112.

## BOOK X.

Questions as to the methods of smelting ores and of obtaining metals I discussed in Book IX. Following this, I should explain in what manner the precious metals are parted from the base metals, or on the other hand the base metals from the precious[1]. Frequently two metals, occasionally more than two, are melted out of one ore, because in nature generally there is some amount of gold in silver and in copper, and some silver in gold, copper, lead, and iron; likewise some copper in gold, silver, lead, and iron, and some lead in silver; and lastly, some iron in copper[2]. But I will begin with gold.

Gold is parted from silver, or likewise the latter from the former, whether it be mixed by nature or by art, by means of _aqua valens_[3], and by powders which consist of almost the same things as this _aqua_. In order to preserve the sequence, I will first speak of the ingredients of which this _aqua_ is made, then of the method of making it, then of the manner in which gold is parted from silver or silver from gold. Almost all these ingredients contain vitriol or alum, which, by themselves, but much more when joined with saltpetre, are powerful to part silver from gold. As to the other things that are added to them, they cannot individually by their own strength and nature separate those metals, but joined they are very powerful. Since there are many combinations, I will set out a few. In the first, the use of which is common and general, there is one _libra_ of vitriol and as much salt, added to a third of a _libra_ of spring water. The second contains two _librae_ of vitriol, one of saltpetre, and as much spring or river water by weight as will pass away whilst the vitriol is being reduced to powder by the fire. The third consists of four _librae_ of vitriol, two and a half _librae_ of saltpetre, half a _libra_ of alum, and one and a half _librae_ of spring water. The fourth consists of two _librae_ of vitriol, as many _librae_ of saltpetre, one quarter of a _libra_ of alum, and three-quarters of a _libra_ of spring water. The fifth is composed of one _libra_ of saltpetre, three _librae_ of alum, half a _libra_ of brick dust, and three-quarters of a _libra_ of spring water. The sixth consists of four _librae_ of vitriol, three _librae_ of saltpetre, one of alum, one _libra_ likewise of stones which when thrown into a fierce furnace are easily liquefied by fire of the third order, and one and a half _librae_ of spring water. The seventh is made of two _librae_ of vitriol, one and a half _librae_ of saltpetre, half a _libra_ of alum, and one _libra_ of stones which when thrown into a glowing furnace are easily liquefied by fire of the third order, and five-sixths of a _libra_ of spring water. The eighth is made of two _librae_ of vitriol, the same number of _librae_ of saltpetre, one and a half _librae_ of alum, one _libra_ of the lees of the _aqua_ which parts gold from silver; and to each separate _libra_ a sixth of urine is poured over it. The ninth contains two _librae_ of powder of baked bricks, one _libra_ of vitriol, likewise one _libra_ of saltpetre, a handful of salt, and three-quarters of a _libra_ of spring water. Only the tenth lacks vitriol and alum, but it contains three _librae_ of saltpetre, two _librae_ of stones which when thrown into a hot furnace are easily liquefied by fire of the third order, half a _libra_ each of verdigris[4], of _stibium_, of iron scales and filings, and of asbestos[5], and one and one-sixth _librae_ of spring water.

All the vitriol from which the _aqua_ is usually made is first reduced to powder in the following way. It is thrown into an earthen crucible lined on the inside with litharge, and heated until it melts; then it is stirred with a copper wire, and after it has cooled it is pounded to powder. In the same manner saltpetre melted by the fire is pounded to powder when it has cooled. Some indeed place alum upon an iron plate, roast it, and make it into powder.

Although all these _aquae_ cleanse gold concentrates or dust from impurities, yet there are certain compositions which possess singular power. The first of these consists of one _libra_ of verdigris and three-quarters of a _libra_ of vitriol. For each _libra_ there is poured over it one-sixth of a _libra_ of spring or river water, as to which, since this pertains to all these compounds, it is sufficient to have mentioned once for all. The second composition is made from one _libra_ of each of the following, artificial orpiment, vitriol, lime, alum, ash which the dyers of wool use, one quarter of a _libra_ of verdigris, and one and a half _unciae_ of _stibium_. The third consists of three _librae_ of vitriol, one of saltpetre, half a _libra_ of asbestos, and half a _libra_ of baked bricks. The fourth consists of one _libra_ of saltpetre, one _libra_ of alum, and half a _libra_ of sal-ammoniac.[6]

[Illustration 442 (Nitric Acid Making): A--Furnace. B--Its round hole. C--Air-holes. D--Mouth of the furnace. E--Draught opening under it. F--Earthenware crucible. G--Ampulla. H--Operculum. I--Its spout. K--Other ampulla. L--Basket in which this is usually placed lest it be broken.]

The furnace in which _aqua valens_ is made[7] is built of bricks, rectangular, two feet long and wide, and as many feet high and a half besides. It is covered with iron plates supported with iron rods; these plates are smeared on the top with lute, and they have in the centre a round hole, large enough to hold the earthen vessel in which the glass ampulla is placed, and on each side of the centre hole are two small round air-holes. The lower part of the furnace, in order to hold the burning charcoal, has iron plates at the height of a palm, likewise supported by iron rods. In the middle of the front there is the mouth, made for the purpose of putting the fire into the furnace; this mouth is half a foot high and wide, and rounded at the top, and under it is the draught opening. Into the earthen vessel set over the hole is placed clean sand a digit deep, and in it the glass ampulla is set as deeply as it is smeared with lute. The lower quarter is smeared eight or ten times with nearly liquid lute, each time to the thickness of a blade, and each time it is dried again, until it has become as thick as the thumb; this kind of lute is well beaten with an iron rod, and is thoroughly mixed with hair or cotton thread, or with wool and salt, that it should not crackle. The many things of which the compounds are made must not fill the ampulla completely, lest when boiling they rise into the operculum. The operculum is likewise made of glass, and is closely joined to the ampulla with linen, cemented with wheat flour and white of egg moistened with water, and then lute free from salt is spread over that part of it. In a similar way the spout of the operculum is joined by linen covered with lute to another glass ampulla which receives the distilled _aqua_. A kind of thin iron nail or small wooden peg, a little thicker than a needle, is fixed in this joint, in order that when air seems necessary to the artificer distilling by this process he can pull it out; this is necessary when too much of the vapour has been driven into the upper part. The four air-holes which, as I have said, are on the top of the furnace beside the large hole on which the ampulla is placed, are likewise covered with lute.

All this preparation having been accomplished in order, and the ingredients placed in the ampulla, they are gradually heated over burning charcoal until they begin to exhale vapour and the ampulla is seen to trickle with moisture. But when this, on account of the rising of the vapour, turns red, and the _aqua_ distils through the spout of the operculum, then one must work with the utmost care, lest the drops should fall at a quicker rate than one for every five movements of the clock or the striking of its bell, and not slower than one for every ten; for if it falls faster the glasses will be broken, and if it drops more slowly the work begun cannot be completed within the definite time, that is within the space of twenty-four hours. To prevent the first accident, part of the coals are extracted by means of an iron implement similar to pincers; and in order to prevent the second happening, small dry pieces of oak are placed upon the coals, and the substances in the ampulla are heated with a sharper fire, and the air-holes on the furnace are re-opened if need arise. As soon as the drops are being distilled, the glass ampulla which receives them is covered with a piece of linen moistened with water, in order that the powerful vapour which arises may be repelled. When the ingredients have been heated and the ampulla in which they were placed is whitened with moisture, it is heated by a fiercer fire until all the drops have been distilled[8]. After the furnace has cooled, the _aqua_ is filtered and poured into a small glass ampulla, and into the same is put half a _drachma_ of silver[9], which when dissolved makes the turbid _aqua_ clear. This is poured into the ampulla containing all the rest of the _aqua_, and as soon as the lees have sunk to the bottom the _aqua_ is poured off, removed, and reserved for use.

Gold is parted from silver by the following method[10]. The alloy, with lead added to it, is first heated in a cupel until all the lead is exhaled, and eight ounces of the alloy contain only five _drachmae_ of copper or at most six, for if there is more copper in it, the silver separated from the gold soon unites with it again. Such molten silver containing gold is formed into granules, being stirred by means of a rod split at the lower end, or else is poured into an iron mould, and when cooled is made into thin leaves. As the process of making granules from argentiferous gold demands greater care and diligence than making them from any other metals, I will now explain the method briefly. The alloy is first placed in a crucible, which is then covered with a lid and placed in another earthen crucible containing a few ashes. Then they are placed in the furnace, and after they are surrounded by charcoal, the fire is blown by the blast of a bellows, and lest the charcoal fall away it is surrounded by stones or bricks. Soon afterward charcoal is thrown over the upper crucible and covered with live coals; these again are covered with charcoal, so that the crucible is surrounded and covered on all sides with it. It is necessary to heat the crucibles with charcoal for the space of half an hour or a little longer, and to provide that there is no deficiency of charcoal, lest the alloy become chilled; after this the air is blown in through the nozzle of the bellows, that the gold may begin to melt. Soon afterward it is turned round, and a test is quickly taken to see whether it be melted, and if it is melted, fluxes are thrown into it; it is advisable to cover up the crucible again closely that the contents may not be exhaled. The contents are heated together for as long as it would take to walk fifteen paces, and then the crucible is seized with tongs and the gold is emptied into an oblong vessel containing very cold water, by pouring it slowly from a height so that the granules will not be too big; in proportion as they are lighter, more fine and more irregular, the better they are, therefore the water is frequently stirred with a rod split into four parts from the lower end to the middle.

The leaves are cut into small pieces, and they or the silver granules are put into a glass ampulla, and the _aqua_ is poured over them to a height of a digit above the silver. The ampulla is covered with a bladder or with waxed linen, lest the contents exhale. Then it is heated until the silver is dissolved, the indication of which is the bubbling of the _aqua_. The gold remains in the bottom, of a blackish colour, and the silver mixed with the _aqua_ floats above. Some pour the latter into a copper bowl and pour into it cold water, which immediately congeals the silver; this they take out and dry, having poured off the _aqua_[11]. They heat the dried silver in an earthenware crucible until it melts, and when it is melted they pour it into an iron mould.

The gold which remains in the ampulla they wash with warm water, filter, dry, and heat in a crucible with a little _chrysocolla_ which is called borax, and when it is melted they likewise pour it into an iron mould.

Some workers, into an ampulla which contains gold and silver and the _aqua_ which separates them, pour two or three times as much of this _aqua valens_ warmed, and into the same ampulla or into a dish into which all is poured, throw fine leaves of black lead and copper; by this means the gold adheres to the lead and the silver to the copper, and separately the lead from the gold, and separately the copper from the silver, are parted in a cupel. But no method is approved by us which loses the _aqua_ used to part gold from silver, for it might be used again[12].

[Illustration 446 (Parting precious metals with nitric acid): A--Ampullae arranged in the vessels. B--An ampulla standing upright between iron rods. C--Ampullae placed in the sand which is contained in a box, the spouts of which reach from the opercula into ampullae placed under them. D--Ampullae likewise placed in sand which is contained in a box, of which the spouts from the opercula extend crosswise into ampullae placed under them. E--Other ampullae receiving the distilled _aqua_ and likewise arranged in sand contained in the lower boxes. F--Iron tripod, in which the ampulla is usually placed when there are not many particles of gold to be parted from the silver. G--Vessel.]

A glass ampulla, which bulges up inside at the bottom like a cone, is covered on the lower part of the outside with lute in the way explained above, and into it is put silver bullion weighing three and a half Roman _librae_. The _aqua_ which parts the one from the other is poured into it, and the ampulla is placed in sand contained in an earthen vessel, or in a box, that it may be warmed with a gentle fire. Lest the _aqua_ should be exhaled, the top of the ampulla is plastered on all sides with lute, and it is covered with a glass operculum, under whose spout is placed another ampulla which receives the distilled drops; this receiver is likewise arranged in a box containing sand. When the contents are heated it reddens, but when the redness no longer appears to increase, it is taken out of the vessel or box and shaken; by this motion the _aqua_ becomes heated again and grows red; if this is done two or three times before other _aqua_ is added to it, the operation is sooner concluded, and much less _aqua_ is consumed. When the first charge has all been distilled, as much silver as at first is again put into the ampulla, for if too much were put in at once, the gold would be parted from it with difficulty. Then the second _aqua_ is poured in, but it is warmed in order that it and the ampulla may be of equal temperature, so that the latter may not be cracked by the cold; also if a cold wind blows on it, it is apt to crack. Then the third _aqua_ is poured in, and also if circumstances require it, the fourth, that is to say more _aqua_ and again more is poured in until the gold assumes the colour of burned brick. The artificer keeps in hand two _aquae_, one of which is stronger than the other; the stronger is used at first, then the less strong, then at the last again the stronger. When the gold becomes of a reddish yellow colour, spring water is poured in and heated until it boils. The gold is washed four times and then heated in the crucible until it melts. The water with which it was washed is put back, for there is a little silver in it; for this reason it is poured into an ampulla and heated, and the drops first distilled are received by one ampulla, while those which come later, that is to say when the operculum begins to get red, fall into another. This latter _aqua_ is useful for testing the gold, the former for washing it; the former may also be poured over the ingredients from which the _aqua valens_ is made.

The _aqua_ that was first distilled, which contains the silver, is poured into an ampulla wide at the base, the top of which is also smeared with lute and covered by an operculum, and is then boiled as before in order that it may be separated from the silver. If there be so much _aqua_ that (when boiled) it rises into the operculum, there is put into the ampulla one lozenge or two; these are made of soap, cut into small pieces and mixed together with powdered argol, and then heated in a pot over a gentle fire; or else the contents are stirred with a hazel twig split at the bottom, and in both cases the _aqua_ effervesces, and soon after again settles. When the powerful vapour appears, the _aqua_ gives off a kind of oil, and the operculum becomes red. But, lest the vapours should escape from the ampulla and the operculum in that part where their mouths communicate, they are entirely sealed all round. The _aqua_ is boiled continually over a fiercer fire, and enough charcoal must be put into the furnace so that the live coals touch the vessel. The ampulla is taken out as soon as all the _aqua_ has been distilled, and the silver, which is dried by the heat of the fire, alone remains in it; the silver is shaken out and put in an earthenware crucible, and heated until it melts. The molten glass is extracted with an iron rod curved at the lower end, and the silver is made into cakes. The glass extracted from the crucible is ground to powder, and to this are added litharge, argol, glass-galls, and saltpetre, and they are melted in an earthen crucible. The button that settles is transferred to the cupel and re-melted.

If the silver was not sufficiently dried by the heat of the fire, that which is contained in the upper part of the ampulla will appear black; this when melted will be consumed. When the lute, which was smeared round the lower part of the ampulla, has been removed, it is placed in the crucible and is re-melted, until at last there is no more appearance of black[13].

If to the first _aqua_ the other which contains silver is to be added, it must be poured in before the powerful vapours appear, and the _aqua_ gives off the oily substance, and the operculum becomes red; for he who pours in the _aqua_ after the vapour appears causes a loss, because the _aqua_ generally spurts out and the glass breaks. If the ampulla breaks when the gold is being parted from the silver or the silver from the _aqua_, the _aqua_ will be absorbed by the sand or the lute or the bricks, whereupon, without any delay, the red hot coals should be taken out of the furnace and the fire extinguished. The sand and bricks after being crushed should be thrown into a copper vessel, warm water should be poured over them, and they should be put aside for the space of twelve hours; afterward the water should be strained through a canvas, and the canvas, since it contains silver, should be dried by the heat of the sun or the fire, and then placed in an earthen crucible and heated until the silver melts, this being poured out into an iron mould. The strained water should be poured into an ampulla and separated from the silver, of which it contains a minute portion; the sand should be mixed with litharge, glass-galls, argol, saltpetre, and salt, and heated in an earthen crucible. The button which settles at the bottom should be transferred to a cupel, and should be re-melted, in order that the lead may be separated from the silver. The lute, with lead added, should be heated in an earthen crucible, then re-melted in a cupel.

We also separate silver from gold by the same method when we assay them. For this purpose the alloy is first rubbed against a touchstone, in order to learn what proportion of silver there is in it; then as much silver as is necessary is added to the argentiferous gold, in a _bes_ of which there must be less than a _semi-uncia_ or a _semi-uncia_ and a _sicilicus_[14] of copper. After lead has been added, it is melted in a cupel until the lead and the copper have exhaled, then the alloy of gold with silver is flattened out, and little tubes are made of the leaves; these are put into a glass ampulla, and strong _aqua_ is poured over them two or three times. The tubes after this are absolutely pure, with the exception of only a quarter of a _siliqua_, which is silver; for only this much silver remains in eight _unciae_ of gold[15].

As great expense is incurred in parting the metals by the methods that I have explained, as night vigils are necessary when _aqua valens_ is made, and as generally much labour and great pains have to be expended on this matter, other methods for parting have been invented by clever men, which are less costly, less laborious, and in which there is less loss if through carelessness an error is made. There are three methods, the first performed with sulphur, the second with antimony, the third by means of some compound which consists of these or other ingredients.

[Illustration 449 (Parting precious metals with sulphur): A--Pot. B--Circular fire. C--Crucibles. D--Their lids. E--Lid of the pot. F--Furnace. G--Iron rod.]

In the first method,[16] the silver containing some gold is melted in a crucible and made into granules. For every _libra_ of granules, there is taken a sixth of a _libra_ and a _sicilicus_ of sulphur (not exposed to the fire); this, when crushed, is sprinkled over the moistened granules, and then they are put into a new earthen pot of the capacity of four _sextarii_, or into several of them if there is an abundance of granules. The pot, having been filled, is covered with an earthen lid and smeared over, and placed within a circle of fire set one and a half feet distant from the pot on all sides, in order that the sulphur added to the silver should not be distilled when melted. The pot is opened, the black-coloured granules are taken out, and afterward thirty-three _librae_ of these granules are placed in an earthen crucible, if it has such capacity. For every _libra_ of silver granules, weighed before they were sprinkled with sulphur, there is weighed out also a sixth of a _libra_ and a _sicilicus_ of copper, if each _libra_ consists either of three-quarters of a _libra_ of silver and a quarter of a _libra_ of copper, or of three-quarters of a _libra_ and a _semi-uncia_ of silver and a sixth of a _libra_ and a _semi-uncia_ of copper. If, however, the silver contains five-sixths of a _libra_ of silver and a sixth of a _libra_ of copper, or five-sixths of a _libra_ and a _semi-uncia_ of silver and an _uncia_ and a half of copper, then there are weighed out a quarter of a _libra_ of copper granules. If a _libra_ contains eleven-twelfths of a _libra_ of silver and one _uncia_ of copper, or eleven-twelfths and a _semi-uncia_ of silver and a _semi-uncia_ of copper, then are weighed out a quarter of a _libra_ and a _semi-uncia_ and a _sicilicus_ of copper granules. Lastly, if there is only pure silver, then as much as a third of a _libra_ and a _semi-uncia_ of copper granules are added. Half of these copper granules are added soon afterward to the black-coloured silver granules. The crucible should be tightly covered and smeared over with lute, and placed in a furnace, into which the air is drawn through the draught-holes. As soon as the silver is melted, the crucible is opened, and there is placed in it a heaped ladleful more of granulated copper, and also a heaped ladleful of a powder which consists of equal parts of litharge, of granulated lead, of salt, and of glass-galls; then the crucible is again covered with the lid. When the copper granules are melted, more are put in, together with the powder, until all have been put in.

A little of the regulus is taken from the crucible, but not from the gold lump which has settled at the bottom, and a _drachma_ of it is put into each of the cupels, which contain an _uncia_ of molten lead; there should be many of these cupels. In this way half a _drachma_ of silver is made. As soon as the lead and copper have been separated from the silver, a third of it is thrown into a glass ampulla, and _aqua valens_ is poured over it. By this method is shown whether the sulphur has parted all the gold from the silver, or not. If one wishes to know the size of the gold lump which has settled at the bottom of the crucible, an iron rod moistened with water is covered with chalk, and when the rod is dry it is pushed down straight into the crucible, and the rod remains bright to the height of the gold lump; the remaining part of the rod is coloured black by the regulus, which adheres to the rod if it is not quickly removed.

If when the rod has been extracted the gold is observed to be satisfactorily parted from the silver, the regulus is poured out, the gold button is taken out of the crucible, and in some clean place the regulus is chipped off from it, although it usually flies apart. The lump itself is reduced to granules, and for every _libra_ of this gold they weigh out a quarter of a _libra_ each of crushed sulphur and of granular copper, and all are placed together in an earthen crucible, not into a pot. When they are melted, in order that the gold may more quickly settle at the bottom, the powder which I have mentioned is added.

Although minute particles of gold appear to scintillate in the regulus of copper and silver, yet if all that are in a _libra_ do not weigh as much as a single sesterce, then the sulphur has satisfactorily parted the gold from the silver; but if it should weigh a sesterce or more, then the regulus is thrown back again into the earthen crucible, and it is not advantageous to add sulphur, but only a little copper and powder, by which method a gold lump is again made to settle at the bottom; and this one is added to the other button which is not rich in gold.

When gold is parted from sixty-six _librae_ of silver, the silver, copper, and sulphur regulus weighs one hundred and thirty-two _librae_. To separate the copper from the silver we require five hundred _librae_ of lead, more or less, with which the regulus is melted in the second furnace. In this manner litharge and hearth-lead are made, which are re-smelted in the first furnace. The cakes that are made from these are placed in the third furnace, so that the lead may be separated from the copper and used again, for it contains very little silver. The crucibles and their covers are crushed, washed, and the sediment is melted together with litharge and hearth-lead.

Those who wish to separate all the silver from the gold by this method leave one part of gold to three of silver, and then reduce the alloy to granules. Then they place it in an ampulla, and by pouring _aqua valens_ over it, part the gold from the silver, which process I explained in

## Book VII.

If sulphur from the lye with which _sal artificiosus_ is made, is strong enough to float an egg thrown into it, and is boiled until it no longer emits fumes, and melts when placed upon glowing coals, then, if such sulphur is thrown into the melted silver, it parts the gold from it.

[Illustration 453 (Parting precious metals with antimony): A--Furnace in which the air is drawn in through holes. B--Goldsmith's forge. C--Earthen crucibles. D--Iron pots. E--Block.]

Silver is also parted from gold by means of _stibium_[17]. If in a _bes of_ gold there are seven, or six, or five double _sextulae_ of silver, then three parts of _stibium_ are added to one part of gold; but in order that the _stibium_ should not consume the gold, it is melted with copper in a red hot earthen crucible. If the gold contains some portion of copper, then to eight _unciae_ of _stibium_ a _sicilicus_ of copper is added; and if it contains no copper, then half an _uncia_, because copper must be added to _stibium_ in order to part gold from silver. The gold is first placed in a red hot earthen crucible, and when melted it swells, and a little _stibium_ is added to it lest it run over; in a short space of time, when this has melted, it likewise again swells, and when this occurs it is advisable to put in all the remainder of the _stibium_, and to cover the crucible with a lid, and then to heat the mixture for the time required to walk thirty-five paces. Then it is at once poured out into an iron pot, wide at the top and narrow at the bottom, which was first heated and smeared over with tallow or wax, and set on an iron or wooden block. It is shaken violently, and by this agitation the gold lump settles to the bottom, and when the pot has cooled it is tapped loose, and is again melted four times in the same way. But each time a less weight of _stibium_ is added to the gold, until finally only twice as much _stibium_ is added as there is gold, or a little more; then the gold lump is melted in a cupel. The _stibium_ is melted again three or four times in an earthen crucible, and each time a gold lump settles, so that there are three or four gold lumps, and these are all melted together in a cupel.

To two _librae_ and a half of such _stibium_ are added two _librae_ of argol and one _libra_ of glass-galls, and they are melted in an earthen crucible, where a lump likewise settles at the bottom; this lump is melted in the cupel. Finally, the _stibium_ with a little lead added, is melted in the cupel, in which, after all the rest has been consumed by the fire, the silver alone remains. If the _stibium_ is not first melted in an earthen crucible with argol and glass-galls, before it is melted in the cupel, part of the silver is consumed, and is absorbed by the ash and powder of which the cupel is made.

The crucible in which the gold and silver alloy are melted with _stibium_, and also the cupel, are placed in a furnace, which is usually of the kind in which the air is drawn in through holes; or else they are placed in a goldsmith's forge.

Just as _aqua valens_ poured over silver, from which the sulphur has parted the gold, shows us whether all has been separated or whether

## particles of gold remain in the silver; so do certain ingredients, if

placed in the pot or crucible "alternately" with the gold, from which the silver has been parted by _stibium_, and heated, show us whether all have been separated or not.

We use cements[18] when, without _stibium_, we part silver or copper or both so ingeniously and admirably from gold. There are various cements. Some consist of half a _libra_ of brick dust, a quarter of a _libra_ of salt, an _uncia_ of saltpetre, half an _uncia_ of sal-ammoniac, and half an _uncia_ of rock salt. The bricks or tiles from which the dust is made must be composed of fatty clays, free from sand, grit, and small stones, and must be moderately burnt and very old.

Another cement is made of a _bes_ of brick dust, a third of rock salt, an _uncia_ of saltpetre, and half an _uncia_ of refined salt. Another cement is made of a _bes_ of brick dust, a quarter of refined salt, one and a half _unciae_ of saltpetre, an _uncia_ of sal-ammoniac, and half an _uncia_ of rock salt. Another has one _libra_ of brick dust, and half a _libra_ of rock salt, to which some add a sixth of a _libra_ and a _sicilicus_ of vitriol. Another is made of half a _libra_ of brick dust, a third of a _libra_ of rock salt, an _uncia_ and a half of vitriol, and one _uncia_ of saltpetre. Another consists of a _bes_ of brick dust, a third of refined salt, a sixth of white vitriol[19], half an _uncia_ of verdigris, and likewise half an _uncia_ of saltpetre. Another is made of one and a third _librae_ of brick dust, a _bes_ of rock salt, a sixth of a _libra_ and half an _uncia_ of sal-ammoniac, a sixth and half an _uncia_ of vitriol, and a sixth of saltpetre. Another contains a _libra_ of brick dust, a third of refined salt, and one and a half _unciae_ of vitriol.

Those ingredients above are peculiar to each cement, but what follows is common to all. Each of the ingredients is first separately crushed to powder; the bricks are placed on a hard rock or marble, and crushed with an iron implement; the other things are crushed in a mortar with a pestle; each is separately passed through a sieve. Then they are all mixed together, and are moistened with vinegar in which a little sal-ammoniac has been dissolved, if the cement does not contain any. But some workers, however, prefer to moisten the gold granules or gold-leaf instead.

The cement should be placed, alternately with the gold, in new and clean pots in which no water has ever been poured. In the bottom the cement is levelled with an iron implement, and afterward the gold granules or leaves are placed one against the other, so that they may touch it on all sides; then, again, a handful of the cement, or more if the pots are large, is thrown in and levelled with an iron implement; the granules and leaves are laid over this in the same manner, and this is repeated until the pot is filled. Then it is covered with a lid, and the place where they join is smeared over with artificial lute, and when this is dry the pots are placed in the furnace.

[Illustration 455 (Parting precious metals by cementation): A--Furnace. B--Pot. C--Lid. D--Air-holes.]

The furnace has three chambers, the lowest of which is a foot high; into this lowest chamber the air penetrates through an opening, and into it the ashes fall from the burnt wood, which is supported by iron rods, arranged to form a grating. The middle chamber is two feet high, and the wood is pushed in through its mouth. The wood ought to be oak, holmoak, or turkey-oak, for from these the slow and lasting fire is made which is necessary for this operation. The upper chamber is open at the top so that the pots, for which it has the depth, may be put into it; the floor of this chamber consists of iron rods, so strong that they may bear the weight of the pots and the heat of the fire; they are sufficiently far apart that the fire may penetrate well and may heat the pots. The pots are narrow at the bottom, so that the fire entering into the space between them may heat them; at the top the pots are wide, so that they may touch and hold back the heat of the fire. The upper part of the furnace is closed in with bricks not very thick, or with tiles and lute, and two or three air-holes are left, through which the fumes and flames may escape.

The gold granules or leaves and the cement, alternately placed in the pots, are heated by a gentle fire, gradually increasing for twenty-four hours, if the furnace was heated for two hours before the full pots were stood in it, and if this was not done, then for twenty-six hours. The fire should be increased in such a manner that the pieces of gold and the cement, in which is the potency to separate the silver and copper from the gold, may not melt, for in this case the labour and cost will be spent in vain; therefore, it is ample to have the fire hot enough that the pots always remain red. After so many hours all the burning wood should be drawn out of the furnace. Then the refractory bricks or tiles are removed from the top of the furnace, and the glowing pots are taken out with the tongs. The lids are removed, and if there is time it is well to allow the gold to cool by itself, for then there is less loss; but if time cannot be spared for that operation, the pieces of gold are immediately placed separately into a wooden or bronze vessel of water and gradually quenched, lest the cement which absorbs the silver should exhale it. The pieces of gold, and the cement adhering to them, when cooled or quenched, are rolled with a little mallet so as to crush the lumps and free the gold from the cement. Then they are sifted by a fine sieve, which is placed over a bronze vessel; in this manner the cement containing the silver or the copper or both, falls from the sieve into the bronze vessel, and the gold granules or leaves remain on it. The gold is placed in a vessel and again rolled with the little mallet, so that it may be cleansed from the cement which absorbs silver and copper.

The particles of cement, which have dropped through the holes of the sieve into the bronze vessel, are washed in a bowl, over a wooden tub, being shaken about with the hands, so that the minute particles of gold which have fallen through the sieve may be separated. These are again washed in a little vessel, with warm water, and scrubbed with a piece of wood or a twig broom, that the moistened cement may be detached. Afterward all the gold is again washed with warm water, and collected with a bristle brush, and should be washed in a copper full of holes, under which is placed a little vessel. Then it is necessary to put the gold on an iron plate, under which is a vessel, and to wash it with warm water. Finally, it is placed in a bowl, and, when dry, the granules or leaves are rubbed against a touchstone at the same time as a touch-needle, and considered carefully as to whether they be pure or alloyed. If they are not pure enough, the granules or the leaves, together with the cement which attracts silver and copper, are arranged alternately in layers in the same manner, and again heated; this is done as often as is necessary, but the last time it is heated as many hours as are required to cleanse the gold.

Some people add another cement to the granules or leaves. This cement lacks the ingredients of metalliferous origin, such as verdigris and vitriol, for if these are in the cement, the gold usually takes up a little of the base metal; or if it does not do this, it is stained by them. For this reason some very rightly never make use of cements containing these things, because brick dust and salt alone, especially rock salt, are able to extract all the silver and copper from the gold and to attract it to themselves.

It is not necessary for coiners to make absolutely pure gold, but to heat it only until such a fineness is obtained as is needed for the gold money which they are coining.

The gold is heated, and when it shows the necessary golden yellow colour and is wholly pure, it is melted and made into bars, in which case they are either prepared by the coiners with _chrysocolla_, which is called by the Moors borax, or are prepared with salt of lye made from the ashes of ivy or of other salty herbs.

The cement which has absorbed silver or copper, after water has been poured over it, is dried and crushed, and when mixed with hearth-lead and de-silverized lead, is smelted in the blast furnace. The alloy of silver and lead, or of silver and copper and lead, which flows out, is again melted in the cupellation furnace, in order that the lead and copper may be separated from the silver. The silver is finally thoroughly purified in the refining furnace, and in this practical manner there is no silver lost, or only a minute quantity.

There are besides this, certain other cements[20] which part gold from silver, composed of sulphur, _stibium_ and other ingredients. One of these compounds consists of half an _uncia_ of vitriol dried by the heat of the fire and reduced to powder, a sixth of refined salt, a third of _stibium_, half a _libra_ of prepared sulphur (not exposed to the fire), one _sicilicus_ of glass, likewise one _sicilicus_ of saltpetre, and a _drachma_ of sal-ammoniac.[21] The sulphur is prepared as follows: it is first crushed to powder, then it is heated for six hours in sharp vinegar, and finally poured into a vessel and washed with warm water; then that which settles at the bottom of the vessel is dried. To refine the salt it is placed in river water and boiled, and again evaporated. The second compound contains one _libra_ of sulphur (not exposed to fire) and two _librae_ of refined salt. The third compound is made from one _libra_ of sulphur (not exposed to the fire), half a _libra_ of refined salt, a quarter of a _libra_ of sal-ammoniac, and one _uncia_ of red-lead. The fourth compound consists of one _libra_ each of refined salt, sulphur (not exposed to the fire) and argol, and half a _libra_ of _chrysocolla_ which the Moors call borax. The fifth compound has equal proportions of sulphur (not exposed to the fire), sal-ammoniac, saltpetre, and verdigris.

The silver which contains some portion of gold is first melted with lead in an earthen crucible, and they are heated together until the silver exhales the lead. If there was a _libra_ of silver, there must be six _drachmae_ of lead. Then the silver is sprinkled with two _unciae_ of that powdered compound and is stirred; afterward it is poured into another crucible, first warmed and lined with tallow, and then violently shaken. The rest is performed according to the process I have already explained.

Gold may be parted without injury from silver goblets and from other gilt vessels and articles[22], by means of a powder, which consists of one part of sal-ammoniac and half a part of sulphur. The gilt goblet or other article is smeared with oil, and the powder is dusted on; the article is seized in the hand, or with tongs, and is carried to the fire and sharply tapped, and by this means the gold falls into water in vessels placed underneath, while the goblet remains uninjured.

Gold is also parted from silver on gilt articles by means of quicksilver. This is poured into an earthen crucible, and so warmed by the fire that the finger can bear the heat when dipped into it; the silver-gilt objects are placed in it, and when the quicksilver adheres to them they are taken out and placed on a dish, into which, when cooled, the gold falls, together with the quicksilver. Again and frequently the same silver-gilt object is placed in heated quicksilver, and the same process is continued until at last no more gold is visible on the object; then the object is placed in the fire, and the quicksilver which adheres to it is exhaled. Then the artificer takes a hare's foot, and brushes up into a dish the quicksilver and the gold which have fallen together from the silver article, and puts them into a cloth made of woven cotton or into a soft leather; the quicksilver is squeezed through one or the other into another dish.[23] The gold remains in the cloth or the leather, and when collected is placed in a piece of charcoal hollowed out, and is heated until it melts, and a little button is made from it. This button is heated with a little _stibium_ in an earthen crucible and poured out into another little vessel, by which method the gold settles at the bottom, and the _stibium_ is seen to be on the top; then the work is completed. Finally, the gold button is put in a hollowed-out brick and placed in the fire, and by this method the gold is made pure. By means of the above methods gold is parted from silver and also silver from gold.

Now I will explain the methods used to separate copper from gold[24]. The salt which we call _sal-artificiosus_,[25] is made from a _libra_ each of vitriol, alum, saltpetre, and sulphur not exposed to the fire, and half a _libra_ of sal-ammoniac; these ingredients when crushed are heated with one part of lye made from the ashes used by wool dyers, one part of unslaked lime, and four parts of beech ashes. The ingredients are boiled in the lye until the whole has been dissolved. Then it is immediately dried and kept in a hot place, lest it turn into oil; and afterward when crushed, a _libra_ of lead-ash is mixed with it. With each _libra_ of this powdered compound one and a half _unciae_ of the copper is gradually sprinkled into a hot crucible, and it is stirred rapidly and frequently with an iron rod. When the crucible has cooled and been broken up, the button of gold is found.

The second method for parting is the following. Two _librae_ of sulphur not exposed to the fire, and four _librae_ of refined salt are crushed and mixed; a sixth of a _libra_ and half an _uncia_ of this powder is added to a _bes_ of granules made of lead, and twice as much copper containing gold; they are heated together in an earthen crucible until they melt. When cooled, the button is taken out and purged of slag. From this button they again make granules, to a third of a _libra_ of which is added half a _libra_ of that powder of which I have spoken, and they are placed in alternate layers in the crucible; it is well to cover the crucible and to seal it up, and afterward it is heated over a gentle fire until the granules melt. Soon afterward, the crucible is taken off the fire, and when it is cool the button is extracted. From this, when purified and again melted down, the third granules are made, to which, if they weigh a sixth of a _libra_, is added one half an _uncia_ and a _sicilicus_ of the powder, and they are heated in the same manner, and the button of gold settles at the bottom of the crucible.

The third method is as follows. From time to time small pieces of sulphur, enveloped in or mixed with wax, are dropped into six _librae_ of the molten copper, and consumed; the sulphur weighs half an _uncia_ and a _sicilicus_. Then one and a half _sicilici_ of powdered saltpetre are dropped into the same copper and likewise consumed; then again half an _uncia_ and a _sicilicus_ of sulphur enveloped in wax; afterward one and a half _sicilici_ of lead-ash enveloped in wax, or of minium made from red-lead. Then immediately the copper is taken out, and to the gold button, which is now mixed with only a little copper, they add _stibium_ to double the amount of the button; these are heated together until the _stibium_ is driven off; then the button, together with lead of half the weight of the button, are heated in a cupel. Finally, the gold is taken out of this and quenched, and if there is a blackish colour settled in it, it is melted with a little of the _chrysocolla_ which the Moors call borax; if too pale, it is melted with _stibium_, and acquires its own golden-yellow colour. There are some who take out the molten copper with an iron ladle and pour it into another crucible, whose aperture is sealed up with lute, and they place it over glowing charcoal, and when they have thrown in the powders of which I have spoken, they stir the whole mass rapidly with an iron rod, and thus separate the gold from the copper; the former settles at the bottom of the crucible, the latter floats on the top. Then the aperture of the crucible is opened with the red-hot tongs, and the copper runs out. The gold which remains is re-heated with _stibium_, and when this is exhaled the gold is heated for the third time in a cupel with a fourth part of lead, and then quenched.

The fourth method is to melt one and a third _librae_ of the copper with a sixth of a _libra_ of lead, and to pour it into another crucible smeared on the inside with tallow or gypsum; and to this is added a powder consisting of half an _uncia_ each of prepared sulphur, verdigris, and saltpetre, and an _uncia_ and a half of _sal coctus_. The fifth method consists of placing in a crucible one _libra_ of the copper and two _librae_ of granulated lead, with one and a half _unciae_ of _sal-artificiosus_; they are at first heated over a gentle fire and then over a fiercer one. The sixth method consists in heating together a _bes_ of the copper and one-sixth of a _libra_ each of sulphur, salt, and _stibium_. The seventh method consists of heating together a _bes_ of the copper and one-sixth each of iron scales and filings, salt, _stibium_, and glass-galls. The eighth method consists of heating together one _libra_ of the copper, one and a half _librae_ of sulphur, half a _libra_ of verdigris, and a _libra_ of refined salt. The ninth method consists of placing in one _libra_ of the molten copper as much pounded sulphur, not exposed to the fire, and of stirring it rapidly with an iron rod; the lump is ground to powder, into which quicksilver is poured, and this attracts to itself the gold.

Gilded copper articles are moistened with water and placed on the fire, and when they are glowing they are quenched with cold water, and the gold is scraped off with a brass rod. By these practical methods gold is separated from copper.

Either copper or lead is separated from silver by the methods which I will now explain.[26] This is carried on in a building near by the works, or in the works in which the gold or silver ores or alloys are smelted. The middle wall of such a building is twenty-one feet long and fifteen feet high, and from this a front wall is distant fifteen feet toward the river; the rear wall is nineteen feet distant, and both these walls are thirty-six feet long and fourteen feet high; a transverse wall extends from the end of the front wall to the end of the rear wall; then fifteen feet back a second transverse wall is built out from the front wall to the end of the middle wall. In that space which is between those two transverse walls are set up the stamps, by means of which the ores and the necessary ingredients for smelting are broken up. From the further end of the front wall, a third transverse wall leads to the other end of the middle wall, and from the same to the end of the rear wall. The space between the second and third transverse walls, and between the rear and middle long walls, contains the cupellation furnace, in which lead is separated from gold or silver. The vertical wall of its chimney is erected upon the middle wall, and the sloping chimney-wall rests on the beams which extend from the second transverse wall to the third; these are so located that they are at a distance of thirteen feet from the middle long wall and four from the rear wall, and they are two feet wide and thick. From the ground up to the roof-beams is twelve feet, and lest the sloping chimney-wall should fall down, it is partly supported by means of many iron rods, and partly by means of a few tie-beams covered with lute, which extend from the small beams of the sloping chimney-wall to the beams of the vertical chimney-wall. The rear roof is arranged in the same way as the roof of the works in which ore is smelted. In the space between the middle and the front long walls and between the second[27] and the third transverse walls are the bellows, the machinery for depressing and the instrument for raising them. A drum on the axle of a water-wheel has rundles which turn the toothed drum of an axle, whose long cams depress the levers of the bellows, and also another toothed drum on an axle, whose cams raise the tappets of the stamps, but in the opposite direction. So that if the cams which depress the levers of the bellows turn from north to south, the cams of the stamps turn from south to north.

[Illustration 468 (Cupellation Furnace): A--Rectangular stones. B--Sole-stone. C--Air-holes. D--Internal walls. E--Dome. F--Crucible. G--Bands. H--Bars. I--Apertures in the dome. K--Lid of the dome. L--Rings. M--Pipes. N--Valves. O--Chains.]

Lead is separated from gold or silver in a cupellation furnace, of which the structure consists of rectangular stones, of two interior walls of which the one intersects the other transversely, of a round sole, and of a dome. Its crucible is made from powder of earth and ash; but I will first speak of the structure and also of the rectangular stones. A circular wall is built four feet and three palms high, and one foot thick; from the height of two feet and three palms from the bottom, the upper part of the interior is cut away to the width of one palm, so that the stone sole may rest upon it. There are usually as many as fourteen stones; on the outside they are a foot and a palm wide, and on the inside narrower, because the inner circle is much smaller than the outer; if the stones are wider, fewer are required, if narrower more; they are sunk into the earth to a depth of a foot and a palm. At the top each one is joined to the next by an iron staple, the points of which are embedded in holes, and into each hole is poured molten lead. This stone structure has six air-holes near the ground, at a height of a foot above the ground; they are two feet and a palm from the bottom of the stones; each of these air-holes is in two stones, and is two palms high, and a palm and three digits wide. One of them is on the right side, between the wall which protects the main wall from the fire, and the channel through which the litharge flows out of the furnace crucible; the other five air-holes are distributed all round at equal distances apart; through these escapes the moisture which the earth exhales when heated, and if it were not for these openings the crucible would absorb the moisture and be damaged. In such a case a lump would be raised, like that which a mole throws up from the earth, and the ash would float on the top, and the crucible would absorb the silver-lead alloy; there are some who, because of this, make the rear part of the structure entirely open. The two inner walls, of which one intersects the other, are built of bricks, and are a brick in thickness. There are four air-holes in these, one in each part, which are about one digit's breadth higher and wider than the others. Into the four compartments is thrown a wheelbarrowful of slag, and over this is placed a large wicker basket full of charcoal dust. These walls extend a cubit above the ground, and on these, and on the ledge cut in the rectangular stones, is placed the stone sole; this sole is a palm and three digits thick, and on all sides touches the rectangular stones; if there are any cracks in it they are filled up with fragments of stone or brick. The front part of the sole is sloped so that a channel can be made, through which the litharge flows out. Copper plates are placed on this part of the sole-stone so that the silver-lead or other alloy may be more rapidly heated.

A dome which has the shape of half a sphere covers the crucible. It consists of iron bands and of bars and of a lid. There are three bands, each about a palm wide and a digit thick; the lowest is at a distance of one foot from the middle one, and the middle one a distance of two feet from the upper one. Under them are eighteen iron bars fixed by iron rivets; these bars are of the same width and thickness as the bands, and they are of such a length, that curving, they reach from the lower band to the upper, that is two feet and three palms long, while the dome is only one foot and three palms high. All the bars and bands of the dome have iron plates fastened on the underside with iron wire. In addition, the dome has four apertures; the rear one, which is situated opposite the channel through which the litharge flows out, is two feet wide at the bottom; toward the top, since it slopes gently, it is narrower, being a foot, three palms, and a digit wide; there is no bar at this place, for the aperture extends from the upper band to the middle one, but not to the lower one. The second aperture is situated above the channel, is two and a half feet wide at the bottom, and two feet and a palm at the top; and there is likewise no bar at this point; indeed, not only does the bar not extend to the lower band, but the lower band itself does not extend over this part, in order that the master can draw the litharge out of the crucible. There are besides, in the wall which protects the principal wall against the heat, near where the nozzles of the bellows are situated, two apertures, three palms wide and about a foot high, in the middle of which two rods descend, fastened on the inside with plates. Near these apertures are placed the nozzles of the bellows, and through the apertures extend the pipes in which the nozzles of the bellows are set. These pipes are made of iron plates rolled up; they are two palms three digits long, and their inside diameter is three and a half digits; into these two pipes the nozzles of the bellows penetrate a distance of three digits from their valves. The lid of the dome consists of an iron band at the bottom, two digits wide, and of three curved iron bars, which extend from one point on the band to the point opposite; they cross each other at the top, where they are fixed by means of iron rivets. On the under side of the bars there are likewise plates fastened by rivets; each of the plates has small holes the size of a finger, so that the lute will adhere when the interior is lined. The dome has three iron rings engaged in wide holes in the heads of iron claves, which fasten the bars to the middle band at these points. Into these rings are fastened the hooks of the chains with which the dome is raised, when the master is preparing the crucible.

On the sole and the copper plates and the rock of the furnace, lute mixed with straw is placed to a depth of three digits, and it is pounded with a wooden rammer until it is compressed to a depth of one digit only. The rammer-head is round and three palms high, two palms wide at the bottom, and tapering upward; its handle is three feet long, and where it is set into the rammer-head it is bound around with an iron band. The top of the stonework in which the dome rests is also covered with lute, likewise mixed with straw, to the thickness of a palm. All this, as soon as it becomes loosened, must be repaired.

[Illustration 470 (Cupellation Furnace): A--An artificer tamping the crucible with a rammer. B--Large rammer. C--Broom. D--Two smaller rammers. E--Curved iron plates. F--Part of a wooden strip. G--Sieve. H--Ashes. I--Iron shovel. K--Iron plate. L--block of wood. M--Rock. N--Basket made of woven twigs. O--Hooked bar. P--Second hooked bar. Q--Old linen rag. R--bucket. S--Doeskin. T--Bundles of straw. V--Wood. X--Cakes of lead alloy. Y--Fork. Z--Another workman covers the outside of the furnace with lute where the dome fits on it. AA--Basket full of ashes. BB--Lid of the dome. CC--The assistant standing on the steps pours charcoal into the crucible through the hole at the top of the dome. DD--Iron implement with which the lute is beaten. EE--Lute. FF--Ladle with which the workman or master takes a sample. GG--Rabble with which the scum of impure lead is drawn off. HH--Iron wedge with which the silver mass is raised.]

The artificer who undertakes the work of parting the metals, distributes the operation into two shifts of two days. On the one morning he sprinkles a little ash into the lute, and when he has poured some water over it he brushes it over with a broom. Then he throws in sifted ashes and dampens them with water, so that they could be moulded into balls like snow. The ashes are those from which lye has been made by letting water percolate through them, for other ashes which are fatty would have to be burnt again in order to make them less fat. When he has made the ashes smooth by pressing them with his hands, he makes the crucible slope down toward the middle; then he tamps it, as I have described, with a rammer. He afterward, with two small wooden rammers, one held in each hand, forms the channel through which the litharge flows out. The heads of these small rammers are each a palm wide, two digits thick, and one foot high; the handle of each is somewhat rounded, is a digit and a half less in diameter than the rammer-head, and is three feet in length; the rammer-head as well as the handle is made of one piece of wood. Then with shoes on, he descends into the crucible and stamps it in every direction with his feet, in which manner it is packed and made sloping. Then he again tamps it with a large rammer, and removing his shoe from his right foot he draws a circle around the crucible with it, and cuts out the circle thus drawn with an iron plate. This plate is curved at both ends, is three palms long, as many digits wide, and has wooden handles a palm and two digits long, and two digits thick; the iron plate is curved back at the top and ends, which penetrate into handles. There are some who use in the place of the plate a strip of wood, like the rim of a sieve; this is three digits wide, and is cut out at both ends that it may be held in the hands. Afterward he tamps the channel through which the litharge discharges. Lest the ashes should fall out, he blocks up the aperture with a stone shaped to fit it, against which he places a board, and lest this fall, he props it with a stick. Then he pours in a basketful of ashes and tamps them with the large rammer; then again and again he pours in ashes and tamps them with the rammer. When the channel has been made, he throws dry ashes all over the crucible with a sieve, and smooths and rubs it with his hands. Then he throws three basketsful of damp ashes on the margin all round the edge of the crucible, and lets down the dome. Soon after, climbing upon the crucible, he builds up ashes all around it, lest the molten alloy should flow out. Then, having raised the lid of the dome, he throws a basketful of charcoal into the crucible, together with an iron shovelful of glowing coals, and he also throws some of the latter through the apertures in the sides of the dome, and he spreads them with the same shovel. This work and labour is finished in the space of two hours.

An iron plate is set in the ground under the channel, and upon this is placed a wooden block, three feet and a palm long, a foot and two palms and as many digits wide at the back, and two palms and as many digits wide in front; on the block of wood is placed a stone, and over it an iron plate similar to the bottom one, and upon this he puts a basketful of charcoal, and also an iron shovelful of burning charcoals. The crucible is heated in an hour, and then, with the hooked bar with which the litharge is drawn off, he stirs the remainder of the charcoal about. This hook is a palm long and three digits wide, has the form of a double triangle, and has an iron handle four feet long, into which is set a wooden one six feet long. There are some who use instead a simple hooked bar. After about an hour's time, he stirs the charcoal again with the bar, and with the shovel throws into the crucible the burning charcoals lying in the channel; then again, after the space of an hour, he stirs the burning charcoals with the same bar. If he did not thus stir them about, some blackness would remain in the crucible and that part would be damaged, because it would not be sufficiently dried. Therefore the assistant stirs and turns the burning charcoal that it may be entirely burnt up, and so that the crucible may be well heated, which takes three hours; then the crucible is left quiet for the remaining two hours.

When the hour of eleven has struck, he sweeps up the charcoal ashes with a broom and throws them out of the crucible. Then he climbs on to the dome, and passing his hand in through its opening, and dipping an old linen rag in a bucket of water mixed with ashes, he moistens the whole of the crucible and sweeps it. In this way he uses two bucketsful of the mixture, each holding five Roman _sextarii_,[28] and he does this lest the crucible, when the metals are being parted, should break open; after this he rubs the crucible with a doe skin, and fills in the cracks. Then he places at the left side of the channel, two fragments of hearth-lead, laid one on the top of the other, so that when partly melted they remain fixed and form an obstacle, that the litharge will not be blown about by the wind from the bellows, but remain in its place. It is expedient, however, to use a brick in the place of the hearth-lead, for as this gets much hotter, therefore it causes the litharge to form more rapidly. The crucible in its middle part is made two palms and as many digits deeper.[29]

There are some who having thus prepared the crucible, smear it over with incense[30], ground to powder and dissolved in white of egg, soaking it up in a sponge and then squeezing it out again; there are others who smear over it a liquid consisting of white of egg and double the amount of bullock's blood or marrow. Some throw lime into the crucible through a sieve.

Afterward the master of the works weighs the lead with which the gold or silver or both are mixed, and he sometimes puts a hundred _centumpondia_[31] into the crucible, but frequently only sixty, or fifty, or much less. After it has been weighed, he strews about in the crucible three small bundles of straw, lest the lead by its weight should break the surface. Then he places in the channel several cakes of lead alloy, and through the aperture at the rear of the dome he places some along the sides; then, ascending to the opening at the top of the dome, he arranges in the crucible round about the dome the cakes which his assistant hands to him, and after ascending again and passing his hands through the same aperture, he likewise places other cakes inside the crucible. On the second day those which remain he, with an iron fork, places on the wood through the rear aperture of the dome.

When the cakes have been thus arranged through the hole at the top of the dome, he throws in charcoal with a basket woven of wooden twigs. Then he places the lid over the dome, and the assistant covers over the joints with lute. The master himself throws half a basketful of charcoal into the crucible through the aperture next to the nozzle pipe, and prepares the bellows, in order to be able to begin the second operation on the morning of the following day. It takes the space of one hour to carry out such a piece of work, and at twelve all is prepared. These hours all reckoned up make a sum of eight hours.

Now it is time that we should come to the second operation. In the morning the workman takes up two shovelsful of live charcoals and throws them into the crucible through the aperture next to the pipes of the nozzles; then through the same hole he lays upon them small pieces of fir-wood or of pitch pine, such as are generally used to cook fish. After this the water-gates are opened, in order that the machine may be turned which depresses the levers of the bellows. In the space of one hour the lead alloy is melted; and when this has been done, he places four sticks of wood, twelve feet long, through the hole in the back of the dome, and as many through the channel; these sticks, lest they should damage the crucible, are both weighted on the ends and supported by trestles; these trestles are made of a beam, three feet long, two palms and as many digits wide, two palms thick, and have two spreading legs at each end. Against the trestle, in front of the channel, there is placed an iron plate, lest the litharge, when it is extracted from the furnace, should splash the smelter's shoes and injure his feet and legs. With an iron shovel or a fork he places the remainder of the cakes through the aperture at the back of the dome on to the sticks of wood already mentioned.

The native silver, or silver glance, or grey silver, or ruby silver, or any other sort, when it has been flattened out[32], and cut up, and heated in an iron crucible, is poured into the molten lead mixed with silver, in order that impurities may be separated. As I have often said, this molten lead mixed with silver is called _stannum_[33].

[Illustration 474 (Cupellation Furnace): A--Furnace. B--Sticks of wood. C--Litharge. D--Plate. E--The foreman when hungry eats butter, that the poison which the crucible exhales may not harm him, for this is a special remedy against that poison.]

When the long sticks of wood are burned up at the fore end, the master, with a hammer, drives into them pointed iron bars, four feet long and two digits wide at the front end, and beyond that one and a half digits wide and thick; with these he pushes the sticks of wood forward and the bars then rest on the trestles. There are others who, when they separate metals, put two such sticks of wood into the crucible through the aperture which is between the bellows, as many through the holes at the back, and one through the channel; but in this case a larger number of long sticks of wood is necessary, that is, sixty; in the former case, forty long sticks of wood suffice to carry out the operation. When the lead has been heated for two hours, it is stirred with a hooked bar, that the heat may be increased.

If it be difficult to separate the lead from the silver, he throws copper and charcoal dust into the molten silver-lead alloy. If the alloy of argentiferous gold and lead, or the silver-lead alloy, contains impurities from the ore, then he throws in either equal portions of argol and Venetian glass or of sal-ammoniac, or of Venetian glass and of Venetian soap; or else unequal portions, that is, two of argol and one of iron rust; there are some who mix a little saltpetre with each compound. To one _centumpondium_ of the alloy is added a _bes_ or a _libra_ and a third of the powder, according to whether it is more or less impure. The powder certainly separates the impurities from the alloy. Then, with a kind of rabble he draws out through the channel, mixed with charcoal, the scum, as one might say, of the lead; the lead makes this scum when it becomes hot, but that less of it may be made it must be stirred frequently with the bar.

Within the space of a quarter of an hour the crucible absorbs the lead; at the time when it penetrates into the crucible it leaps and bubbles. Then the master takes out a little lead with an iron ladle, which he assays, in order to find what proportion of silver there is in the whole of the alloy; the ladle is five digits wide, the iron part of its handle is three feet long and the wooden part the same. Afterward, when they are heated, he extracts with a bar the litharge which comes from the lead and the copper, if there be any of it in the alloy. Wherefore, it might more rightly be called _spuma_ of lead than of silver[34]. There is no injury to the silver, when the lead and copper are separated from it. In truth the lead becomes much purer in the crucible of the other furnace, in which silver is refined. In ancient times, as the author Pliny[35] relates, there was under the channel of the crucible another crucible, and the litharge flowed down from the upper one into the lower one, out of which it was lifted up and rolled round with a stick in order that it might be of moderate weight. For which reason, they formerly made it into small tubes or pipes, but now, since it is not rolled round a stick, they make it into bars.

If there be any danger that the alloy might flow out with the litharge, the foreman keeps on hand a piece of lute, shaped like a cylinder and pointed at both ends; fastening this to a hooked bar he opposes it to the alloy so that it will not flow out.

[Illustration 476 (Cleansing of Silver Cakes): A--Cake. B--Stone. C--Hammer. D--Brass wire. E--Bucket containing water. F--Furnace from which the cake has been taken, which is still smoking. G--Labourer carrying a cake out of the works.]

Now when the colour begins to show in the silver, bright spots appear, some of them being almost white, and a moment afterward it becomes absolutely white. Then the assistant lets down the water-gates, so that, the race being closed, the water-wheel ceases to turn and the bellows are still. Then the master pours several buckets of water on to the silver to cool it; others pour beer over it to make it whiter, but this is of no importance since the silver has yet to be refined. Afterward, the cake of silver is raised with the pointed iron bar, which is three feet long and two digits wide, and has a wooden handle four feet long fixed in its socket. When the cake of silver has been taken from the crucible, it is laid upon a stone, and from part of it the hearth-lead, and from the other part the litharge, is chipped away with a hammer; then it is cleansed with a bundle of brass wire dipped in water. When the lead is separated from the silver, more silver is frequently found than when it was assayed; for instance, if before there were three _unciae_ and as many _drachmae_ in a _centumpondium_, they now sometimes find three _unciae_ and a half[36]. Often the hearth-lead remaining in the crucible is a palm deep; it is taken out with the rest of the ashes and is sifted, and that which remains in the sieve, since it is hearth-lead, is added to the hearth-lead[37].

The ashes which pass through the sieve are of the same use as they were at first, for, indeed, from these and pulverised bones they make the cupels. Finally, when much of it has accumulated, the yellow _pompholyx_ adhering to the walls of the furnace, and likewise to those rings of the dome near the apertures, is cleared away.

[Illustration 479 (Crane for cupellation furnace): A--Crane-post. B--Socket. C--Oak cross-sills. D--Band. E--Roof-beam. F--Frame. G--Lower small cross-beam. H--Upright timber. I--Bars which come from the sides of the crane-post. K--Bars which come from the sides of the upright timber. L--Rundle drums. M--Toothed wheels. N--Chain. O--Pulley. P--Beams of the crane-arm. Q--Oblique beams supporting the beams of the crane-arm. R--Rectangular iron plates. S--Trolley. T--Dome of the furnace. V--Ring. X--Three chains. Y--Crank. Z--The crane-post of the other contrivance. AA--Crane-arm. BB--Oblique beam. CC--Ring of the crane-arm. DD--The second ring. EE--Lever-bar. FF--Third ring. GG--Hook. HH--Chain of the dome. II--Chain of the lever-bar.]

I must also describe the crane with which the dome is raised. When it is made, there is first set up a rectangular upright post twelve feet long, each side of which measures a foot in width. Its lower pinion turns in a bronze socket set in an oak sill; there are two sills placed crosswise so that the one fits in a mortise in the middle of the other, and the other likewise fits in the mortise of the first, thus making a kind of a cross; these sills are three feet long and one foot wide and thick. The crane-post is round at its upper end and is cut down to a depth of three palms, and turns in a band fastened at each end to a roof-beam, from which springs the inclined chimney wall. To the crane-post is affixed a frame, which is made in this way: first, at a height of a cubit from the bottom, is mortised into the crane-post a small cross-beam, a cubit and three digits long, except its tenons, and two palms in width and thickness. Then again, at a height of five feet above it, is another small cross-beam of equal length, width, and thickness, mortised into the crane-post. The other ends of these two small cross-beams are mortised into an upright timber, six feet three palms long, and three-quarters wide and thick; the mortise is transfixed by wooden pegs. Above, at a height of three palms from the lower small cross-beam, are two bars, one foot one palm long, not including the tenons, a palm three digits wide, and a palm thick, which are mortised in the other sides of the crane-post. In the same manner, under the upper small cross-beam are two bars of the same size. Also in the upright timber there are mortised the same number of bars, of the same length as the preceding, but three digits thick, a palm two digits wide, the two lower ones being above the lower small cross-beam. From the upright timber near the upper small cross-beam, which at its other end is mortised into the crane-post, are two mortised bars. On the outside of this frame, boards are fixed to the small cross-beams, but the front and back parts of the frame have doors, whose hinges are fastened to the boards which are fixed to the bars that are mortised to the sides of the crane-post.

Then boards are laid upon the lower small cross-beam, and at a height of two palms above these there is a small square iron axle, the sides of which are two digits wide; both ends of it are round and turn in bronze or iron bearings, one of these bearings being fastened in the crane-post, the other in the upright timber. About each end of the small axle is a wooden disc, of three palms and a digit radius and one palm thick, covered on the rim with an iron band; these two discs are distant two palms and as many digits from each other, and are joined with five rundles; these rundles are two and a half digits thick and are placed three digits apart. Thus a drum is made, which is a palm and a digit distant from the upright timber, but further from the crane-post, namely, a palm and three digits. At a height of a foot and a palm above this little axle is a second small square iron axle, the thickness of which is three digits; this one, like the first one, turns in bronze or iron bearings. Around it is a toothed wheel, composed of two discs a foot three palms in diameter, a palm and two digits thick; on the rim of this there are twenty-three teeth, a palm wide and two digits thick; they protrude a palm from the wheel and are three digits apart. And around this same axle, at a distance of two palms and as many digits toward the upright timber, is another disc of the same diameter as the wheel and a palm thick; this turns in a hollowed-out place in the upright timber. Between this disc and the disc of the toothed wheel another drum is made, having likewise five rundles. There is, in addition to this second axle, at a height of a cubit above it, a small wooden axle, the journals of which are of iron; the ends are bound round with iron rings so that the journals may remain firmly fixed, and the journals, like the little iron axles, turn in bronze or iron bearings. This third axle is at a distance of about a cubit from the upper small cross-beam; it has, near the upright timber, a toothed wheel two and a half feet in diameter, on the rim of which are twenty-seven teeth; the other part of this axle, near the crane-post, is covered with iron plates, lest it should be worn away by the chain which winds around it. The end link of the chain is fixed in an iron pin driven into the little axle; this chain passes out of the frame and turns over a little pulley set between the beams of the crane-arm.

Above the frame, at a height of a foot and a palm, is the crane-arm. This consists of two beams fifteen feet long, three palms wide, and two thick, mortised into the crane-post, and they protrude a cubit from the back of the crane-post and are fastened together. Moreover, they are fastened by means of a wooden pin which penetrates through them and the crane-post; this pin has at the one end a broad head, and at the other a hole, through which is driven an iron bolt, so that the beams may be tightly bound into the crane-post. The beams of the crane-arm are supported and stayed by means of two oblique beams, six feet and two palms long, and likewise two palms wide and thick; these are mortised into the crane-post at their lower ends, and their upper ends are mortised into the beams of the crane-arm at a point about four feet from the crane-post, and they are fastened with iron nails. At the back of the upper end of these oblique beams, toward the crane-post, is an iron staple, fastened into the lower sides of the beams of the crane-arm, in order that it may hold them fast and bind them. The outer end of each beam of the crane-arm is set in a rectangular iron plate, and between these are three rectangular iron plates, fixed in such a manner that the beams of the crane-arm can neither move away from, nor toward, each other. The upper sides of these crane-arm beams are covered with iron plates for a length of six feet, so that a trolley can move on it.

The body of the trolley is made of wood from the Ostrya or any other hard tree, and is a cubit long, a foot wide, and three palms thick; on both edges of it the lower side is cut out to a height and width of a palm, so that the remainder may move backward and forward between the two beams of the crane-arm; at the front, in the middle part, it is cut out to a width of two palms and as many digits, that a bronze pulley, around a small iron axle, may turn in it. Near the corners of the trolley are four holes, in which as many small wheels travel on the beams of the crane-arm. Since this trolley, when it travels backward and forward, gives out a sound somewhat similar to the barking of a dog, we have given it this name[38]. It is propelled forward by means of a crank, and is drawn back by means of a chain. There is an iron hook whose ring turns round an iron pin fastened to the right side of the trolley, which hook is held by a sort of clavis, which is fixed in the right beam of the crane-arm.

At the end of the crane-post is a bronze pulley, the iron axle of which is fastened in the beams of the crane-arm, and over which the chain passes as it comes from the frame, and then, penetrating through the hollow in the top of the trolley, it reaches to the little bronze pulley of the trolley, and passing over this it hangs down. A hook on its end engages a ring, in which are fixed the top links of three chains, each six feet long, which pass through the three iron rings fastened in the holes of the claves which are fixed into the middle iron band of the dome, of which I have spoken.

Therefore when the master wishes to lift the dome by means of the crane, the assistant fits over the lower small iron axle an iron crank, which projects from the upright beam a palm and two digits; the end of the little axle is rectangular, and one and a half digits wide and one digit thick; it is set into a similar rectangular hole in the crank, which is two digits long and a little more than a digit wide. The crank is semi-circular, and one foot three palms and two digits long, as many digits wide, and one digit thick. Its handle is straight and round, and three palms long, and one and a half digits thick. There is a hole in the end of the little axle, through which an iron pin is driven so that the crank may not come off. The crane having four drums, two of which are rundle-drums and two toothed-wheels, is more easily moved than another having two drums, one of which has rundles and the other teeth.

Many, however, use only a simple contrivance, the pivots of whose crane-post turn in the same manner, the one in an iron socket, the other in a ring. There is a crane-arm on the crane-post, which is supported by an oblique beam; to the head of the crane-arm a strong iron ring is fixed, which engages a second iron ring. In this iron ring a strong wooden lever-bar is fastened firmly, the head of which is bound by a third iron ring, from which hangs an iron hook, which engages the rings at the ends of the chains from the dome. At the other end of the lever-bar is another chain, which, when it is pulled down, raises the opposite end of the bar and thus the dome; and when it is relaxed the dome is lowered.

[Illustration 481 (Cupellation Furnace at Freiberg): A--Chamber of the furnace. B--Its bed. C--Passages. D--Rammer. E--Mallet. F--Artificer making tubes from litharge according to the Roman method. G--Channel. H--Litharge. I--Lower crucible or hearth. K--Stick. L--Tubes.]

In certain places, as at Freiberg in Meissen, the upper part of the cupellation furnace is vaulted almost like an oven. This chamber is four feet high and has either two or three apertures, of which the first, in front, is one and a half feet high and a foot wide, and out of this flows the litharge; the second aperture and likewise the third, if there be three, are at the sides, and are a foot and a half high and two and a half feet wide, in order that he who prepares the crucible may be able to creep into the furnace. Its circular bed is made of cement, it has two passages two feet high and one foot wide, for letting out the vapour, and these lead directly through from one side to the other, so that the one passage crosses the other at right angles, and thus four openings are to be seen; these are covered at the top by rocks, wide, but only a palm thick. On these and on the other parts of the interior of the bed made of cement, is placed lute mixed with straw, to a depth of three digits, as it was placed over the sole and the plates of copper and the rocks of that other furnace. This, together with the ashes which are thrown in, the master or the assistant, who, upon his knees, prepares the crucible, tamps down with short wooden rammers and with mallets likewise made of wood.

[Illustration 482 (Cupellation Furnace in Poland): A--Furnace similar to an oven. B--Passage. C--Iron bars. D--Hole through which the litharge is drawn out. E--Crucible which lacks a dome. F--Thick sticks. G--Bellows.]

The cupellation furnace in Poland and Hungary is likewise vaulted at the top, and is almost similar to an oven, but in the lower part the bed is solid, and there is no opening for the vapours, while on one side of the crucible is a wall, between which and the bed of the crucible is a passage in place of the opening for vapours; this passage is covered by iron bars or rods extending from the wall to the crucible, and placed a distance of two digits from each other. In the crucible, when it is prepared, they first scatter straw, and then they lay in it cakes of silver-lead alloy, and on the iron bars they lay wood, which when kindled heats the crucible. They melt cakes to the weight of sometimes eighty _centumpondia_ and sometimes a hundred _centumpondia_[39]. They stimulate a mild fire by means of a blast from the bellows, and throw on to the bars as much wood as is required to make a flame which will reach into the crucible, and separate the lead from the silver. The litharge is drawn out on the other side through an aperture that is just wide enough for the master to creep through into the crucible. The Moravians and Carni, who very rarely make more than a _bes_ or five-sixths of a _libra_ of silver, separate the lead from it, neither in a furnace resembling an oven, nor in the crucible covered by a dome, but on a crucible which is without a cover and exposed to the wind; on this crucible they lay cakes of silver-lead alloy, and over them they place dry wood, and over these again thick green wood. The wood having been kindled, they stimulate the fire by means of a bellows.

[Illustration 484 (Refining Silver): A--Pestle with teeth. B--Pestle without teeth. C--Dish or tray full of ashes. D--Prepared tests placed on boards or shelves. E--Empty tests. F--Wood. G--Saw.]

[Illustration 485 (Refining Silver): A--Straight knife having wooden handles. B--Curved knife likewise having wooden handles. C--Curved knife without wooden handles. D--Sieve. E--Balls. F--Iron door which the master lets down when he refines silver, lest the heat of the fire should injure his eyes. G--Iron implement on which the wood is placed when the liquid silver is to be refined. H--Its other part passing through the ring of another iron implement enclosed in the wall of the furnace. I--Tests in which burning charcoal has been thrown.]

I have explained the method of separating lead from gold or silver. Now I will speak of the method of refining silver, for I have already explained the process for refining gold. Silver is refined in a refining furnace, over whose hearth is an arched chamber built of bricks; this chamber in the front part is three feet high. The hearth itself is five feet long and four wide. The walls are unbroken along the sides and back, but in front one chamber is placed over the other, and above these and the wall is the upright chimney. The hearth has a round pit, a cubit wide and two palms deep, into which are thrown sifted ashes, and in this is placed a prepared earthenware "test," in such a manner that it is surrounded on all sides by ashes to a height equal to its own. The earthenware test is filled with a powder consisting of equal portions of bones ground to powder, and of ashes taken from the crucible in which lead is separated from gold or silver; others mix crushed brick with the ashes, for by this method the powder attracts no silver to itself. When the powder has been made up and moistened with water, a little is thrown into the earthenware test and tamped with a wooden pestle. This pestle is round, a foot long, and a palm and a digit wide, out of which extend six teeth, each a digit thick, and a digit and a third long and wide, and almost a digit apart; these six teeth form a circle, and in the centre of them is the seventh tooth, which is round and of the same length as the others, but a digit and a half thick; this pestle tapers a little from the bottom up, that the upper part of the handle may be round and three digits thick. Some use a round pestle without teeth. Then a little powder is again moistened, and thrown into the test, and tamped; this work is repeated until the test is entirely full of the powder, which the master then cuts out with a knife, sharp on both sides, and turned upward at both ends so that the central part is a palm and a digit long; therefore it is partly straight and partly curved. The blade is one and a half digits wide, and at each end it turns upward two palms, which ends to the depth of a palm are either not sharpened or they are enclosed in wooden handles. The master holds the knife with one hand and cuts out the powder from the test, so that it is left three digits thick all round; then he sifts the powder of dried bones over it through a sieve, the bottom of which is made of closely-woven bristles. Afterward a ball made of very hard wood, six digits in diameter, is placed in the test and rolled about with both hands, in order to make the inside even and smooth; for that matter he may move the ball about with only one hand. The tests[40] are of various capacities, for some of them when prepared hold much less than fifteen _librae_ of silver, others twenty, some thirty, others forty, and others fifty. All these tests thus prepared are dried in the sun, or set in a warm and covered place; the more dry and old they are the better. All of them, when used for refining silver, are heated by means of burning charcoal placed in them. Others use instead of these tests an iron ring; but the test is more useful, for if the powder deteriorates the silver remains in it, while there being no bottom to the ring, it falls out; besides, it is easier to place in the hearth the test than the iron ring, and furthermore it requires much less powder. In order that the test should not break and damage the silver, some bind it round with an iron band.

[Illustration 486 (Refining Silver): A--Grate. B--Brass block. C--Block of wood. D--Cakes of silver. E--Hammer. F--Block of wood channelled in the middle. G--Bowl full of holes. H--Block of wood fastened to an iron implement. I--Fir-wood. K--Iron bar. L--Implement with a hollow end. The implement which has a circular end is shown in the next picture. M--Implement, the extremity of which is bent upwards. N--Implement in the shape of tongs.]

In order that they may be more easily broken, the silver cakes are placed upon an iron grate by the refiner, and are heated by burning charcoal placed under them. He has a brass block two palms and two digits long and wide, with a channel in the middle, which he places upon a block of hard wood. Then with a double-headed hammer, he beats the hot cakes of silver placed on the brass block, and breaks them in pieces. The head of this hammer is a foot and two digits long, and a palm wide. Others use for this purpose merely a block of wood channelled in the top. While the fragments of the cake are still hot, he seizes them with the tongs and throws them into a bowl with holes in the bottom, and pours water over them. When the fragments are cooled, he puts them nicely into the test by placing them so that they stand upright and project from the test to a height of two palms, and lest one should fall against the other, he places little pieces of charcoal between them; then he places live charcoal in the test, and soon two twig basketsful of charcoal. Then he blows in air with the bellows. This bellows is double, and four feet two palms long, and two feet and as many palms wide at the back; the other parts are similar to those described in Book VII. The nozzle of the bellows is placed in a bronze pipe a foot long, the aperture in this pipe being a digit in diameter in front and quite round, and at the back two palms wide. The master, because he needs for the operation of refining silver a fierce fire, and requires on that account a vigorous blast, places the bellows very much inclined, in order that, when the silver has melted, it may blow into the centre of the test. When the silver bubbles, he presses the nozzle down by means of a small block of wood moistened with water and fastened to an iron rod, the outer end of which bends upward. The silver melts when it has been heated in the test for about an hour; when it is melted, he removes the live coals from the test and places over it two billets of fir-wood, a foot and three palms long, a palm two digits wide, one palm thick at the upper part, and three digits at the lower. He joins them together at the lower edges, and into the billets he again throws the coals, for a fierce fire is always necessary in refining silver. It is refined in two or three hours, according to whether it was pure or impure, and if it is impure it is made purer by dropping granulated copper or lead into the test at the same time. In order that the refiner may sustain the great heat from the fire while the silver is being refined, he lets down an iron door, which is three feet long and a foot and three palms high; this door is held on both ends in iron plates, and when the operation is concluded, he raises it again with an iron shovel, so that its edge holds against the iron hook in the arch, and thus the door is held open. When the silver is nearly refined, which may be judged by the space of time, he dips into it an iron bar, three and a half feet long and a digit thick, having a round steel point. The small drops of silver that adhere to the bar he places on the brass block and flattens with a hammer, and from their colour he decides whether the silver is sufficiently refined or not. If it is thoroughly purified it is very white, and in a _bes_ there is only a _drachma_ of impurities. Some ladle up the silver with a hollow iron implement. Of each _bes_ of silver one _sicilicus_ is consumed, or occasionally when very impure, three _drachmae_ or half an _uncia_[41].

[Illustration 488 (Cleansing of Silver Cakes): A--Implement with a ring. B--Ladle. C--Its hole. D--Pointed bar. E--Forks. F--Cake of silver laid upon the implement shaped like tongs. G--Tub of water. H--Block of wood, with a cake laid upon it. I--Hammer. K--Silver again placed upon the implement resembling tongs. L--Another tub full of water. M--Brass wires. N--Tripod. O--Another block. P--Chisel. Q--Crucible of the furnace. R--Test still smoking.]

The refiner governs the fire and stirs the molten silver with an iron implement, nine feet long, a digit thick, and at the end first curved toward the right, then curved back in order to form a circle, the interior of which is a palm in diameter; others use an iron implement, the end of which is bent directly upward. Another iron implement has the shape of tongs, with which, by compressing it with his hands, he seizes the coals and puts them on or takes them off; this is two feet long, one and a half digits wide, and the third of a digit thick.

When the silver is seen to be thoroughly refined, the artificer removes the coals from the test with a shovel. Soon afterward he draws water in a copper ladle, which has a wooden handle four feet long; it has a small hole at a point half-way between the middle of the bowl and the edge, through which a hemp seed just passes. He fills this ladle three times with water, and three times it all flows out through the hole on to the silver, and slowly quenches it; if he suddenly poured much water on it, it would burst asunder and injure those standing near. The artificer has a pointed iron bar, three feet long, which has a wooden handle as many feet long, and he puts the end of this bar into the test in order to stir it. He also stirs it with a hooked iron bar, of which the hook is two digits wide and a palm deep, and the iron part of its handle is three feet long and the wooden part the same. Then he removes the test from the hearth with a shovel or a fork, and turns it over, and by this means the silver falls to the ground in the shape of half a sphere; then lifting the cake with a shovel he throws it into a tub of water, where it gives out a great sound. Or else, having lifted the cake of silver with a fork, he lays it upon the iron implement similar to tongs, which are placed across a tub full of water; afterward, when cooled, he takes it from the tub again and lays it on the block made of hard wood and beats it with a hammer, in order to break off any of the powder from the test which adheres to it. The cake is then placed on the implement similar to tongs, laid over the tub full of water, and cleaned with a bundle of brass wire dipped into the water; this operation of beating and cleansing is repeated until it is all clean. Afterward he places it on an iron grate or tripod; the tripod is a palm and two digits high, one and a half digits wide, and its span is two palms wide; then he puts burning charcoal under the tripod or grate, in order again to dry the silver that was moistened by the water. Finally, the Royal Inspector[42] in the employment of the King or Prince, or the owner, lays the silver on a block of wood, and with an engraver's chisel he cuts out two small pieces, one from the under and the other from the upper side. These are tested by fire, in order to ascertain whether the silver is thoroughly refined or not, and at what price it should be sold to the merchants. Finally he impresses upon it the seal of the King or the Prince or the owner, and, near the same, the amount of the weight.

[Illustration 489 (Refining Silver): A--Muffle. B--Its little windows. C--Its little bridge. D--Bricks. E--Iron door. F--Its little window. G--Bellows. H--Hammer-chisel. I--Iron ring which some use instead of the test. K--Pestle with which the ashes placed in the ring are pounded.]

There are some who refine silver in tests placed under iron or earthenware muffles. They use a furnace, on the hearth of which they place the test containing the fragments of silver, and they place the muffle over it; the muffle has small windows at the sides, and in front a little bridge. In order to melt the silver, at the sides of the muffle are laid bricks, upon which the charcoal is placed, and burning firebrands are put on the bridge. The furnace has an iron door, which is covered on the side next to the fire with lute in order that it may not be injured. When the door is closed it retains the heat of the fire, but it has a small window, so that the artificers may look into the test and may at times stimulate the fire with the bellows. Although by this method silver is refined more slowly than by the other, nevertheless it is more useful, because less loss is caused, for a gentle fire consumes fewer particles than a fierce fire continually excited by the blast of the bellows. If, on account of its great size, the cake of silver can be carried only with difficulty when it is taken out of the muffle, they cut it up into two or three pieces while it is still hot, with a wedge or a hammer-chisel; for if they cut it up after it has cooled, little pieces of it frequently fly off and are lost.

END OF BOOK X.

FOOTNOTES:

[1] _Vile a precioso_.

[2] The reagents mentioned in this Book are much the same as those of

## Book VII, where (p. 220) a table is given showing the Latin and Old

German terms. Footnotes in explanation of our views as to these substances may be most easily consulted through the index.

[3] _Aqua valens_, literally strong, potent, or powerful water. It will appear later, from the method of manufacture, that hydrochloric, nitric, and sulphuric acids and _aqua regia_ were more or less all produced and all included in this term. We have, therefore, used either the term _aqua valens_ or simply _aqua_ as it occurs in the text. The terms _aqua fortis_ and _aqua regia_ had come into use prior to Agricola, but he does not use them; the Alchemists used various terms, often _aqua dissolvia_. It is apparent from the uses to which this reagent was put in separating gold and silver, from the method of clarifying it with silver and from the red fumes, that Agricola could have had practical contact only with nitric acid. It is probable that he has copied part of the recipes for the compounds to be distilled from the Alchemists and from such works as the _Probierbuechlein_. In any event he could not have had experience with them all, for in some cases the necessary ingredients for making nitric acid are not all present, and therefore could be of no use for gold and silver separation. The essential ingredients for the production of this acid by distillation, were saltpetre, water, and either vitriol or alum. The other substances mentioned were unnecessary, and any speculation as to the combinations which would result, forms a useful exercise in chemistry, but of little purpose here. The first recipe would no doubt produce hydrochloric acid.

[4] Agricola, in the _Interpretatio_, gives the German equivalent for the Latin _aerugo_ as _Spanschgruen_--"because it was first brought to Germany from Spain; foreigners call it _viride aeris_ (copper green)." The English "verdigris" is a corruption of _vert de grice_. Both verdigris and white lead were very ancient products, and they naturally find mention together among the ancient authors. The earliest description of the method of making is from the 3rd Century B.C., by Theophrastus, who says (101-2): "But these are works of art, as is also Ceruse (_psimythion_) to make which, lead is placed in earthen vessels over sharp vinegar, and after it has acquired some thickness of a kind of rust, which it commonly does in about ten days, they open the vessels and scrape off, as it were, a kind of foulness; they then place the lead over the vinegar again, repeating over and over again the same method of scraping it till it is wholly dissolved; what has been scraped off they then beat to powder and boil for a long time; and what at last subsides to the bottom of the vessel is the white lead.... Also in a manner somewhat resembling this, verdigris (_ios_) is made, for copper is placed over lees of wine (grape refuse?), and the rust which it acquires by this means is taken off for use. And it is by this means that the rust which appears is produced." (Based on Hill's translation.) Vitruvius (VII, 12), Dioscorides (V, 51), and Pliny (XXXIV, 26 and 54), all describe the method of making somewhat more elaborately.

[5] _Amiantus_ (_Interpretatio_ gives _federwis_, _pliant_, _salamanderhar_). From Agricola's elaborate description in _De Natura Fossilium_ (p. 252) there can be no doubt that he means asbestos. This mineral was well-known to the Ancients, and is probably earliest referred to (3rd Century B.C.) by Theophrastus in the following passage (29): "There is also found in the mines of Scaptesylae a stone, in its external appearance somewhat resembling wood, on which, if oil be poured, it burns; but when the oil is burnt away, the burning of the stone ceases, as if it were in itself not liable to such accidents." There can be no doubt that Strabo (X, 1) describes the mineral: "At Carystus there is found in the earth a stone, which is combed like wool, and woven, so that napkins are made of this substance, which, when soiled, are thrown into the fire and cleaned, as in the washing of linen." It is also described by Dioscorides (V, 113) and Pliny (XIX, 4). Asbestos cloth has been found in Pre-Augustinian Roman tombs.

[6] This list of four recipes is even more obscure than the previous list. If they were distilled, the first and second mixtures would not produce nitric acid, although possibly some sulphuric would result. The third might yield nitric, and the fourth _aqua regia_. In view of the water, they were certainly not used as cements, and the first and second are deficient in the vital ingredients.

[7] _Distillation_, at least in crude form, is very old. Aristotle (_Meteorologica_, IV.) states that sweet water can be made by evaporating salt-water and condensing the steam. Dioscorides and Pliny both describe the production of mercury by distillation (note 58, p. 432). The Alchemists of the Alexandrian School, from the 1st to the 6th Centuries, mention forms of imperfect apparatus--an ample discussion of which may be found in Kopp, _Beitraege zur Geschichte der Chemie_, Braunschweig, 1869, p. 217.

[8] It is desirable to note the contents of the residues in the retort, for it is our belief that these are the materials to which the author refers as "lees of the water which separates gold from silver," in many places in Book VII. They would be strange mixtures of sodium, potassium, aluminium sulphates, with silica, brickdust, asbestos, and various proportions of undigested vitriol, salt, saltpetre, alum, iron oxides, etc. Their effect must have been uncertain. Many old German metallurgies also refer to the _Todenkopf der Scheidwasser_, among them the _Probierbuechlein_ before Agricola, and after him Lazarus Ercker (_Beschreibung Allerfuernemsten_, etc., Prague, 1574). See also note 16, p. 234.

[9] This use of silver could apply to one purpose only, that is, the elimination of minor amounts of hydrochloric from the nitric acid, the former originating no doubt from the use of salt among the ingredients. The silver was thus converted into a chloride and precipitated. This use of a small amount of silver to purify the nitric acid was made by metallurgists down to fairly recent times. Biringuccio (IV, 2) and Lazarus Ercker (p. 71) both recommend that the silver be dissolved first in a small amount of acid, and the solution poured into the newly-manufactured supply. They both recommend preserving this precipitate and its cupellation after melting with lead--which Agricola apparently overlooked.

[10] In this description of parting by nitric acid, the author digresses from his main theme on pages 444 and 445, to explain a method apparently for small quantities where the silver was precipitated by copper, and to describe another cryptic method of precipitation. These subjects are referred to in notes 11 and 12 below. The method of parting set out here falls into six stages: _a_--cupellation, _b_--granulation, _c_--solution in acid, _d_--treatment of the gold residues, _e_--evaporation of the solution, _f_--reduction of the silver nitrate. For nitric acid parting, bullion must be free from impurities, which cupellation would ensure; if copper were left in, it would have the effect he mentions if we understand "the silver separated from the gold soon unites with it again," to mean that the silver unites with the copper, for the copper would go into solution and come down with the silver on evaporation. Agricola does not specifically mention the necessity of an excess of silver in this description, although he does so elsewhere, and states that the ratio must be at least three parts silver to one part gold. The first description of the solution of the silver is clear enough, but that on p. 445 is somewhat difficult to follow, for the author states that the bullion is placed in a retort with the acid, and that distillation is carried on between each additional charge of acid. So far as the arrangement of a receiver might relate to the saving of any acid that came over accidentally in the boiling, it can be understood, but to distill off much acid would soon result in the crystallization of the silver nitrate, which would greatly impede the action of subsequent acid additions, and finally the gold could not be separated from such nitrate in the way described. The explanation may be (apart from incidental evaporation when heating) that the acids used were very weak, and that by the evaporation of a certain amount of water, not only was the acid concentrated, but room was provided for the further charges. The acid in the gold wash-water, mentioned in the following paragraph, was apparently thus concentrated. The "glass" mentioned as being melted with litharge, argols, nitre, etc., was no doubt the silver nitrate. The precipitation of the silver from the solution as a chloride, by the use of salt, so generally used during the 18th and 19th Centuries, was known in Agricola's time, although he does not mention it. It is mentioned in Geber and the _Probierbuechlein_. The clarity of the latter on the subject is of some interest (p. 34a): "How to pulverise silver and again make it into silver. Take the silver and dissolve it in water with the _starckenwasser_, _aqua fort_, and when that is done, take the silver water and pour it into warm salty water, and immediately the silver settles to the bottom and becomes powder. Let it stand awhile until it has well settled, then pour away the water from it and dry the settlings, which will become a powder like ashes. Afterward one can again make it into silver. Take the powder and put it on a _test_, and add thereto the powder from the settlings from which the _aqua forte_ has been made, and add lead. Then if there is a great deal, blow on it until the lead has incorporated itself ... blow it until it _plickt_ (_blickens_). Then you will have as much silver as before."

[11] The silver is apparently precipitated by the copper of the bowl. It would seem that this method was in considerable use for small amounts of silver nitrate in the 16th Century. Lazarus Ercker gives elaborate directions for this method (_Beschreibung Allerfuernemsten_, etc., Prague, 1574, p. 77).

[12] We confess to a lack of understanding of this operation with leaves of lead and copper.

[13] We do not understand this "appearance of black." If the nitrate came into contact with organic matter it would, of course, turn black by reduction of the silver, and sunlight would have the same effect.

[14] This would be equal to from 62 to 94 parts of copper in 1,000.

[15] As 144 _siliquae_ are 1 _uncia_, then 1/4 _siliqua_ in 8 _unciae_ would equal one part silver in 4,608 parts gold, or about 999.8 fine.

[16] The object of this treatment with sulphur and copper is to separate a considerable portion of silver from low-grade bullion (_i.e._, silver containing some gold), in preparation for final treatment of the richer gold-silver alloy with nitric acid. Silver sulphide is created by adding sulphur, and is drawn off in a silver-copper regulus. After the first sentence, the author uses silver alone where he obviously means silver "containing some gold," and further he speaks of the "gold lump" (_massula_) where he likewise means a button containing a great deal of silver. For clarity we introduced the term "regulus" for the Latin _mistura_. The operation falls into six stages: _a_, granulation; _b_, sulphurization of the granulated bullion; _c_, melting to form a combination of the silver sulphide with copper into a regulus, an alloy of gold and silver settling out; _d_, repetition of the treatment to abstract further silver from the "lump;" _e_, refining the "lump" with nitric acid; _f_, recovery of the silver from the regulus by addition of lead, liquation and cupellation.

The use of a "circle of fire" secures a low temperature that would neither volatilize the sulphur nor melt the bullion. The amount of sulphur given is equal to a ratio of 48 parts bullion and 9 parts sulphur. We are not certain about the translation of the paragraph in relation to the proportion of copper added to the granulated bullion; because in giving definite quantities of copper to be added in the contingencies of various original copper contents in the bullion, it would be expected that they were intended to produce some positive ratio of copper and silver. However, the ratio as we understand the text in various cases works out to irregular amounts, _i.e._, 48 parts of silver to 16, 12.6, 24, 20.5, 20.8, 17.8, or 18 parts of copper. In order to obtain complete separation there should be sufficient sulphur to have formed a sulphide of the copper as well as of the silver, or else some of the copper and silver would come down metallic with the "lump". The above ratio of copper added to the sulphurized silver, in the first instance would give about 18 parts of copper and 9 parts of sulphur to 48 parts of silver. The copper would require 4.5 parts of sulphur to convert it into sulphide, and the silver about 7 parts, or a total of 11.5 parts required against 9 parts furnished. It is plain, therefore, that insufficient sulphur is given. Further, the litharge would probably take up some sulphur and throw down metallic lead into the "lump". However, it is necessary that there should be some free metallics to collect the gold, and, therefore, the separation could not be complete in one operation. In any event, on the above ratios the "gold lump" from the first operation was pretty coppery, and contained some lead and probably a good deal of silver, because the copper would tend to desulphurize the latter. The "powder" of glass-galls, salt, and litharge would render the mass more liquid and assist the "gold lump" to separate out.

The Roman silver _sesterce_, worth about 2-1/8 pence or 4.2 American cents, was no doubt used by Agricola merely to indicate an infinitesimal quantity. The test to be applied to the regulus by way of cupellation and parting of a sample with nitric acid, requires no explanation. The truth of the description as to determining whether the gold had settled out, by using a chalked iron rod, can only be tested by actual experiment. It is probable, however, that the sulphur in the regulus would attack the iron and make it black. The re-melting of the regulus, if some gold remains in it, with copper and "powder" without more sulphur, would provide again free metallics to gather the remaining gold, and by desulphurizing some silver this button would probably not be very pure.

From the necessity for some free metallics besides the gold in the first treatment, it will be seen that a repetition of the sulphur addition and re-melting is essential gradually to enrich the "lump". Why more copper is added is not clear. In the second melting, the ratio is 48 parts of the "gold lump", 12 parts of sulphur and 12 parts copper. In this case the added copper would require about 3 parts sulphur, and if we consider the deficiency of sulphur in the first operations pertained entirely to the copper, then about 2.5 parts would be required to make good the shortage, or in other words the second addition of sulphur is sufficient. In the final parting of the "lump" it will be noticed that the author states that the silver ratio must be arranged as three of silver to one of gold. As to the recovery of the silver from the regulus, he states that 66 _librae_ of silver give 132 _librae_ of _regulus_. To this, 500 _librae_ of lead are added, and it is melted in the "second" furnace, and the litharge and hearth-lead made are re-melted in the "first" furnace, the cakes made being again treated in the "third" furnace to separate the copper and lead. The "first" is usually the blast furnace, the "second" furnace is the cupellation furnace, and the "third" the liquation furnace. It is difficult to understand this procedure. The charge sent to the cupellation furnace would contain between 3% and 5% copper, and between 3% and 5% sulphur. However, possibly the sulphur and copper could be largely abstracted in the skimmings from the cupellation furnace, these being subsequently liquated in the "third" furnace. It may be noted that two whole lines from this paragraph are omitted in the editions of _De Re Metallica_ after 1600. For historical note on sulphur separation see page 461.

[17] There can be no doubt that in most instances Agricola's _stibium_ is antimony sulphide, but it does not follow that it was the mineral _stibnite_, nor have we considered it desirable to introduce the precision of either of these modern terms, and have therefore retained the Latin term where the sulphide is apparently intended. The use of antimony sulphide to part silver from gold is based upon the greater affinity of silver than antimony for sulphur. Thus the silver, as in the last process, is converted into a sulphide, and is absorbed in the regulus, while the metallic antimony alloys with the gold and settles to the bottom of the pot. This process has several advantages over the sulphurization with crude sulphur; antimony is a more convenient vehicle of sulphur, for it saves the preliminary sulphurization with its attendant difficulties of volatilization of the sulphur; it also saves the granulation necessary in the former method; and the treatment of the subsequent products is simpler. However, it is possible that the sulphur-copper process was better adapted to bullion where the proportion of gold was low, because the fineness of the bullion mentioned in connection with the antimonial process was apparently much higher than the previous process. For instance, a _bes_ of gold, containing 5, 6, or 7 double _sextulae_ of silver would be .792, .750 or .708 fine. The antimonial method would have an advantage over nitric acid separation, in that high-grade bullion could be treated direct without artificial decrease of fineness required by inquartation to about .250 fine, with the consequent incidental losses of silver involved.

The process in this description falls into six operations: _a_, sulphurization of the silver by melting with antimony sulphide; _b_, separation of the gold "lump" (_massula_) by jogging; _c_, re-melting the regulus (_mistura_) three or four times for recovery of further "lumps"; _d_, re-melting of the "lump" four times, with further additions of antimony sulphide; _e_, cupellation of the regulus to recover the silver; _f_, cupellation of the antimony from the "lump" to recover the gold. Percy seems to think it difficult to understand the insistence upon the addition of copper. Biringuccio (IV, 6) states, among other things, that copper makes the ingredients more liquid. The later metallurgists, however, such as Ercker, Lohneys, and Schlueter, do not mention this addition; they do mention the "swelling and frothing," and recommend that the crucible should be only partly filled. As to the copper, we suggest that it would desulphurize part of the antimony and thus free some of that metal to collect the gold. If we assume bullion of the medium fineness mentioned and containing no copper, then the proportions in the first charge would be about 36 parts gold, 12 parts silver, 41 parts sulphur, 103 parts antimony, and 9 parts copper. The silver and copper would take up 4.25 parts of sulphur, and thus free about 10.6 parts of antimony as metallics. It would thus appear that the amount of metallics provided to assist the collection of the gold was little enough, and that the copper in freeing 5.6 parts of the antimony was useful. It appears to have been necessary to have a large excess of antimony sulphide; for even with the great surplus in the first charge, the reaction was only partial, as is indicated by the necessity for repeated melting with further antimony.

The later metallurgists all describe the separation of the metallic antimony from the gold as being carried out by oxidation of the antimony, induced by a jet of air into the crucible, this being continued until the mass appears limpid and no cloud forms in the surface in cooling. Agricola describes the separation of the silver from the regulus by preliminary melting with argols, glass-gall, and some lead, and subsequent cupellation of the lead-silver alloy. The statement that unless this preliminary melting is done, the cupel will absorb silver, might be consonant with an attempt at cupellation of sulphides, and it is difficult to see that much desulphurizing could take place with the above fluxes. In fact, in the later descriptions of the process, iron is used in this melting, and we are under the impression that Agricola had omitted this item for a desulphurizing reagent. At the Dresden Mint, in the methods described by Percy (Metallurgy Silver and Gold, p. 373) the gold lumps were tested for fineness, and from this the amount of gold retained in the regulus was computed. It is not clear from Agricola's account whether the test with nitric acid was applied to the regulus or to the "lumps". For historical notes see p. 461.

[18] As will be shown in the historical note, this process of separating gold and silver is of great antiquity--in all probability the only process known prior to the Middle Ages, and in any event, the first one used. In general the process was performed by "cementing" the disintegrated bullion with a paste and subjecting the mass to long-continued heat at a temperature under the melting point of the bullion. The cement (_compositio_) is of two different species; in the first species saltpetre and vitriol and some aluminous or silicious medium are the essential ingredients, and through them the silver is converted into nitrate and absorbed by the mass; in the second species, common salt and the same sort of medium are the essentials, and in this case the silver is converted into a chloride. Agricola does not distinguish between these two species, for, as shown by the text, his ingredients are badly mixed.

The process as here described falls into five operations: _a_, granulation of the bullion or preparation of leaves; _b_, heating alternate layers of cement and bullion in pots; _c_, washing the gold to free it of cement; _d_, melting the gold with borax or soda; _e_, treatment of the cement by way of melting with lead and cupellation to recover the silver. Investigation by Boussingault (_Ann. De Chimie_, 1833, p. 253-6), D'Elhuyar (_Bergbaukunde_, Leipzig, 1790, Vol. II, p. 200), and Percy (Metallurgy of Silver and Gold, p. 395), of the action of common salt upon silver under cementation conditions, fairly well demonstrated the reactions involved in the use of this species of cement. Certain factors are essential besides salt: _a_, the admission of air, which is possible through the porous pots used; _b_, the presence of some moisture to furnish hydrogen; _c_, the addition of alumina or silica. The first would be provided by Agricola in the use of new pots, the second possibly by use of wood fuel in a closed furnace, the third by the inclusion of brickdust. The alumina or silica at high temperatures decomposes the salt, setting free hydrochloric acid and probably also free chlorine. The result of the addition of vitriol in Agricola's ingredients is not discussed by those investigators, but inasmuch as vitriol decomposes into sulphuric acid under high temperatures, this acid would react upon the salt to free hydrochloric acid, and thus assist to overcome deficiencies in the other factors. It is possible also that sulphuric acid under such conditions would react directly upon the silver to form silver sulphates, which would be absorbed into the cement. As nitric acid is formed by vitriol and saltpetre at high temperatures, the use of these two substances as a cementing compound would produce nitric acid, which would at once attack the silver to form silver nitrate, which would be absorbed into the melted cement. In this case the brickdust probably acted merely as a vehicle for the absorption, and to lower the melting point of the mass and prevent fusion of the metal. While nitric acid will only part gold and silver when the latter is in great excess, yet when applied as fumes under cementation conditions it appears to react upon a minor ratio of silver. While the reactions of the two above species of compounds can be accounted for in a general way, the problem furnished by Agricola's statements is by no means simple, for only two of his compounds are simply salt cements, the others being salt and nitre mixtures. An inspection of these compounds produces at once a sense of confusion. Salt is present in every compound, saltpetre in all but two, vitriol in all but three. Lewis (_Traite Singulier de Metallique_, Paris, 1743, II, pp. 48-60), in discussing these processes, states that salt and saltpetre must never be used together, as he asserts that in this case _aqua regia_ would be formed and the gold dissolved. Agricola, however, apparently found no such difficulty. As to the other ingredients, apart from nitre, salt, vitriol, and brickdust, they can have been of no use. Agricola himself points out that ingredients of "metallic origin" corrupt the gold and that brickdust and common salt are sufficient. In a description of this process in the _Probierbuechlein_ (p. 58), no nitre is mentioned. This booklet does mention the recovery of the silver from the cement by amalgamation with mercury--the earliest mention of silver amalgamation.

[19] While a substance which we now know to be natural zinc sulphate was known to Agricola (see note 11, p. 572), it is hardly possible that it is referred to here. If green vitriol be dehydrated and powdered, it is white.

[20] The processes involved by these "other" compounds are difficult to understand, because of the lack of information given as to the method of operation. It might be thought that these were five additional recipes for cementing pastes, but an inspection of their internal composition soon dissipates any such assumption, because, apart from the lack of brickdust or some other similar necessary ingredient, they all contain more or less sulphur. After describing a preliminary treatment of the bullion by cupellation, the author says: "Then the silver is sprinkled with two _unciae_ of that powdered compound and is stirred. Afterward it is poured into another crucible ... and violently shaken. The rest is performed according to the process I have already explained." As he has already explained four or five parting processes, it is not very clear to which one this refers. In fact, the whole of this discussion reads as if he were reporting hearsay, for it lacks in every respect the infinite detail of his usual descriptions. In any event, if the powder was introduced into the molten bullion, the effect would be to form some silver sulphides in a regulus of different composition depending upon the varied ingredients of different compounds. The enriched bullion was settled out in a "lump" and treated "as I have explained," which is not clear.

[21] HISTORICAL NOTE ON PARTING GOLD AND SILVER. Although the earlier Classics contain innumerable references to refining gold and silver, there is little that is tangible in them, upon which to hinge the metallurgy of parting the precious metals. It appears to us, however, that some ability to part the metals is implied in the use of the touchstone, for we fail to see what use a knowledge of the ratio of gold and silver in bullion could have been without the power to separate them. The touchstone was known to the Greeks at least as early as the 5th Century B.C. (see note 37, p. 252), and a part of Theophrastus' statement (LXXVIII.) on this subject bears repetition in this connection: "The nature of the stone which tries gold is also very wonderful, as it seems to have the same power as fire; which is also a test of that metal.... The trial by fire is by the colour and the quantity lost by it, but that of the stone is made only by rubbing," etc. This trial by fire certainly implies a parting of the metals. It has been argued from the common use of _electrum_--a gold-silver alloy--by the Ancients, that they did not know how to part the two metals or they would not have wasted gold in such a manner, but it seems to us that the very fact that _electrum_ was a positive alloy (20% gold, 80% silver), and that it was deliberately made (Pliny XXXIII, 23) and held of value for its supposed superior brilliancy to silver and the belief that goblets made of it detected poison, is sufficient answer to this.

To arrive by a process of elimination, we may say that in the Middle Ages, between 1100 and 1500 A.D., there were known four methods of

## parting these metals: _a_, parting by solution in nitric acid; _b_,

sulphurization of the silver in finely-divided bullion by heating it with sulphur, and the subsequent removal of the silver sulphide in a regulus by melting with copper, iron, or lead; _c_, melting with an excess of antimony sulphide, and the direct conversion of the silver to sulphide and its removal in a regulus; _d_, cementation of the finely-divided bullion with salt, and certain necessary collateral re-agents, and the separation of the silver by absorption into the cement as silver chloride. Inasmuch as it can be clearly established that mineral acids were unknown to the Ancients, we can eliminate that method. Further, we may say at once that there is not, so far as has yet been found, even a remote statement that could be applied to the sulphide processes. As to cementation with salt, however, we have some data at about the beginning of the Christian Era.

Before entering into a more detailed discussion of the history of various processes, it may be useful, in a word, to fix in the mind of the reader our view of the first authority on various processes, and his period.

(1) Separation by cementation with salt, Strabo (?) 63 B.C.-24 A.D.; Pliny 23-79 A.D.

(2) Separation by sulphur, Theophilus, 1150-1200 A.D.

(3) Separation by nitric acid, Geber, prior to 14th Century.

(4) Separation by antimony sulphide, Basil Valentine, end 14th Century, or _Probierbuechlein_, beginning 15th Century.

(5) Separation by antimony sulphide and copper, or sulphur and copper, _Probierbuechlein_, beginning 15th Century.

(6) Separation by cementation with saltpetre, Agricola, 1556.

(7) Separation by sulphur and iron, Schlueter, 1738.

(8) Separation by sulphuric acid, D'Arcet, 1802.

(9) Separation by chloride gas, Thompson, 1833.

(10) Separation electrolytically, latter part 19th Century.

## PARTING BY CEMENTATION. The following passage from Strabo is of prime

interest as the first definite statement on parting of any kind (III, 2, 8): "That when they have melted the gold and purified it by means of a kind of aluminous earth, the residue left is _electrum_. This, which contains a mixture of silver and gold, being again subjected to the fire, the silver is separated and the gold left (pure); for this metal is easily dissipated and fat, and on this account gold is most easily molten by straw, the flame of which is soft, and bearing a similarity (to the gold) causes it easily to dissolve, whereas coal, besides wasting a great deal, melts it too much, by reason of its vehemence, and carries it off (in vapour)." This statement has provoked the liveliest discussion, not only on account of the metallurgical interest and obscurity, but also because of differences of view as to its translation; we have given that of Mr. H. C. Hamilton (London, 1903). A review of this discussion will be found in Percy's Metallurgy of Gold and Silver, p. 399. That it refers to cementation at all hangs by a slender thread, but it seems more nearly this than anything else.

Pliny (XXXIII, 25) is a little more ample: "(The gold) is heated with double its weight of salt and thrice its weight of _misy_, and again with two portions of salt and one of a stone which they call _schistos_. The _virus_ is drawn out when these things are burnt together in an earthen crucible, itself remaining pure and incorrupt, the remaining ash being preserved in an earthen pot and mixed with water as a lotion for _lichen_ (ring-worm) on the face." Percy (Metallurgy Silver and Gold, p. 398) rightly considers that this undoubtedly refers to the parting of silver and gold by cementation with common salt. Especially as Pliny further on states that with regard to _misy_, "In purifying gold they mix it with this substance." There can be no doubt from the explanations of Pliny and Dioscorides that _misy_ was an oxidized pyrite, mostly iron sulphate. Assuming the latter case, then all of the necessary elements of cementation, _i.e._, vitriol, salt, and an aluminous or silicious element, are present.

The first entirely satisfactory evidence on parting is to be found in Theophilus (12th Century), and we quote the following from Hendrie's translation (p. 245): "Of Heating the Gold. Take gold, of whatsoever sort it may be, and beat it until thin leaves are made in breadth three fingers, and as long as you can. Then cut out pieces that are equally long and wide and join them together equally, and perforate through all with a fine cutting iron. Afterwards take two earthen pots proved in the fire, of such size that the gold can lie flat in them, and break a tile very small, or clay of the furnace burned and red, weigh it, powdered, into two equal parts, and add to it a third part salt for the same weight; which things being slightly sprinkled with urine, are mixed together so that they may not adhere together, but are scarcely wetted, and put a little of it upon a pot about the breadth of the gold, then a piece of the gold itself, and again the composition, and again the gold, which in the digestion is thus always covered, that gold may not be in contact with gold; and thus fill the pot to the top and cover it above with another pot, which you carefully lute round with clay, mixed and beaten, and you place it over the fire, that it may be dried. In the meantime compose a furnace from stones and clay, two feet in height, and a foot and a half in breadth, wide at the bottom, but narrow at the top, where there is an opening in the middle, in which project three long and hard stones, which may be able to sustain the flame for a long time, upon which you place the pots with the gold, and cover them with other tiles in abundance. Then supply fire and wood, and take care that a copious fire is not wanting for the space of a day and night. In the morning taking out the gold, again melt, beat and place it in the furnace as before. Again also, after a day and night, take it away and mixing a little copper with it, melt it as before, and replace it upon the furnace. And when you have taken it away a third time, wash and dry it carefully, and so weighing it, see how much is wanting, then fold it up and keep it."

The next mention is by Geber, of whose date and authenticity there is great doubt, but, in any event, the work bearing his name is generally considered to be prior to the 14th, although he has been placed as early as the 8th Century. We quote from Russell's translation, pp. 17 and 224, which we have checked with the Latin edition of 1542: "Sol, or gold, is beaten into thin plates and with them and common salt very well prepared lay upon lay in a vessel of calcination which set into the furnace and calcine well for three days until the whole is subtily calcined. Then take it out, grind well and wash it with vinegar, and dry it in the sun. Afterwards grind it well with half its weight of cleansed _sal-armoniac_; then set it to be dissolved until the whole be dissolved into most clear water." Further on: "Now we will declare the way of cementing. Seeing it is known to us that cement is very necessary in the examen of perfection, we say it is compounded of inflammable things. Of this kind are, all blackening, flying, penetrating, and burned things; as is vitriol, _sal-armoniac_, _flos aeris_ (copper oxide scales) and the ancient _fictile_ stone (earthen pots), and a very small quantity, or nothing, of sulphur, and urine with like acute and penetrating things. All these are impasted with urine and spread upon thin plates of that body which you intend shall be examined by this way of probation. Then the said plates must be laid upon a grate of iron included in an earthen vessel, yet so as one touch not the other that the virtue of the fire may have free and equal access to them. Thus the whole must be kept in fire in a strong earthen vessel for the space of three days. But here great caution is required that the plates may be kept but not melt."

Albertus Magnus (1205-1280) _De Mineralibus et Rebus Metallicis_, Lib. IV, describes the process as follows:--"But when gold is to be purified an earthen vessel is made like a cucurbit or dish, and upon it is placed a similar vessel; and they are luted together with the tenacious lute called by alchemists the lute of wisdom. In the upper vessel there are numerous holes by which vapour and smoke may escape; afterwards the gold in the form of short thin leaves is arranged in the vessel, the leaves being covered consecutively with a mixture obtained by mixing together soot, salt, and brick dust; and the whole is strongly heated until the gold becomes perfectly pure and the base substances with which it was mixed are consumed." It will be noted that salt is the basis of all these cement compounds. We may also add that those of Biringuccio and all other writers prior to Agricola were of the same kind, our author being the first to mention those with nitre.

## PARTING WITH NITRIC ACID. The first mention of nitric acid is in

connection with this purpose, and, therefore, the early history of this reagent becomes the history of the process. Mineral acids of any kind were unknown to the Greeks or Romans. The works of the Alchemists and others from the 12th to the 15th Centuries, have been well searched by chemical historians for indications of knowledge of the mineral acids, and many of such suspected indications are of very doubtful order. In any event, study of the Alchemists for the roots of chemistry is fraught with the greatest difficulty, for not only is there the large ratio of fraud which characterised their operations, but there is even the much larger field of fraud which characterised the authorship and dates of writing attributed to various members of the cult. The mention of saltpetre by Roger Bacon (1214-94), and Albertus Magnus (1205-80), have caused some strain to read a knowledge of mineral acids into their works, but with doubtful result. Further, the Monk Theophilus (1150-1200) is supposed to have mentioned products which would be mineral acids, but by the most careful scrutiny of that work we have found nothing to justify such an assertion, and it is of importance to note that as Theophilus was a most accomplished gold and silver worker, his failure to mention it is at least evidence that the process was not generally known. The transcribed manuscripts and later editions of such authors are often altered to bring them "up-to-date." The first mention is in the work attributed to Geber, as stated above, of date prior to the 14th Century. The following passage from his _De Inventione Veritatis_ (Nuremberg edition, 1545, p. 182) is of interest:--"First take one _libra_ of vitriol of Cyprus and one-half _libra_ of saltpetre and one-quarter of alum of Jameni, extract the _aqua_ with the redness of the alembic--for it is very solvative--and use as in the foregoing chapters. This can be made acute if in it you dissolve a quarter of sal-ammoniac, which dissolves gold, sulphur, and silver." Distilling vitriol, saltpetre and alum would produce nitric acid. The addition of sal-ammoniac would make _aqua regia_; Geber used this solvent water--probably without being made "more acute"--to dissolve silver, and he crystallized out silver nitrate. It would not be surprising to find all the Alchemists subsequent to Geber mentioning acids. It will thus be seen that even the approximate time at which the mineral-acids were first made cannot be determined, but it was sometime previous to the 15th Century, probably not earlier than the 12th Century. Beckmann (Hist. of Inventions II, p. 508) states that it appears to have been an old tradition that acid for separating the precious metals was first used at Venice by some Germans; that they chiefly separated the gold from Spanish silver and by this means acquired great riches. Beckmann considers that the first specific description of the process seems to be in the work of William Budaeus (_De Asse_, 1516, III, p. 101), who speaks of it as new at this time. He describes the operation of one, Le Conte, at Paris, who also acquired a fortune through the method. Beckmann and others have, however, entirely overlooked the early _Probierbuechlein_. If our conclusions are correct that the first of these began to appear at about 1510, then they give the first description of inquartation. This book (see appendix) is made up of recipes, like a cook-book, and four or five different recipes are given for this purpose; of these we give one, which sufficiently indicates a knowledge of the art (p. 39): "If you would part them do it this way: Beat the silver which you suppose to contain gold, as thin as possible; cut it in small pieces and place it in 'strong' water (_starkwasser_). Put it on a mild fire till it becomes warm and throws up blisters or bubbles. Then take it and pour off the water into a copper-bowl; let it stand and cool. Then the silver settles itself round the copper bowl; let the silver dry in the copper bowl, then pour the water off and melt the silver in a crucible. Then take the gold also out of the glass _kolken_ and melt it together." Biringuccio (1540, Book VI.) describes the method, but with much less detail than Agricola. He made his acid from alum and saltpetre and calls it _lacque forti_.

## PARTING WITH SULPHUR. This process first appears in Theophilus

(1150-1200), and in form is somewhat different from that mentioned by Agricola. We quote from Hendrie's Translation, p. 317, "How gold is separated from silver. When you have scraped the gold from silver, place this scraping in a small cup in which gold or silver is accustomed to be melted, and press a small linen cloth upon it, that nothing may by chance be abstracted from it by the wind of the bellows, and placing it before the furnace, melt it; and directly lay fragments of sulphur in it, according to the quantity of the scraping, and carefully stir it with a thin piece of charcoal until its fumes cease; and immediately pour it into an iron mould. Then gently beat it upon the anvil lest by chance some of that black may fly from it which the sulphur has burnt, because it is itself silver. For the sulphur consumes nothing of the gold, but the silver only, which it thus separates from the gold, and which you will carefully keep. Again melt this gold in the same small cup as before, and add sulphur. This being stirred and poured out, break what has become black and keep it, and do thus until the gold appear pure. Then gather together all that black, which you have carefully kept, upon the cup made from the bone and ash, and add lead, and so burn it that you may recover the silver. But if you wish to keep it for the service of niello, before you burn it add to it copper and lead, according to the measure mentioned above, and mix with sulphur." This process appears in the _Probierbuechlein_ in many forms, different recipes containing other ingredients besides sulphur, such as salt, saltpetre, sal-ammoniac, and other things more or less effective. In fact, a series of hybrid methods between absolute melting with sulphur and cementation with salt, were in use, much like those mentioned by Agricola on p. 458.

## PARTING WITH ANTIMONY SULPHIDE. The first mention of this process lies

either in Basil Valentine's "Triumphant Chariot of Antimony" or in the first _Probierbuechlein_. The date to be assigned to the former is a matter of great doubt. It was probably written about the end of the 15th Century, but apparently published considerably later. The date of the _Probierbuechlein_ we have referred to above. The statement in the "Triumphal Chariot" is as follows (Waite's Translation, p. 117-118): "The elixir prepared in this way has the same power of penetrating and pervading the body with its purifying properties that antimony has of penetrating and purifying gold.... This much, however, I have proved beyond a possibility of doubt, that antimony not only purifies gold and frees it from foreign matter, but it also ameliorates all other metals, but it does the same for animal bodies." There are most specific descriptions of this process in the other works attributed to Valentine, but their authenticity is so very doubtful that we do not quote. The _Probierbuechlein_ gives several recipes for this process, all to the same metallurgical effect, of which we quote two: "How to separate silver from gold. Take 1 part of golden silver, 1 part of _spiesglass_, 1 part copper, 1 part lead; melt them together in a crucible. When melted pour into the crucible pounded sulphur and directly you have poured it in cover it up with soft lime so that the fumes cannot escape, and let it get cold and you will find your gold in a button. Put that same in a pot and blow on it." "How to part gold and silver by melting or fire. Take as much gold-silver as you please and granulate it; take 1 _mark_ of these grains, 1 _mark_ of powder; put them together in a crucible. Cover it with a small cover, put it in the fire, and let it slowly heat; blow on it gently until it melts; stir it all well together with a stick, pour it out into a mould, strike the mould gently with a knife so that the button may settle better, let it cool, then turn the mould over, strike off the button and twice as much _spiesglas_ as the button weighs, put them in a crucible, blow on it till it melts, then pour it again into a mould and break away the button as at first. If you want the gold to be good always add to the button twice as much _spiesglass_. It is usually good gold in three meltings. Afterward take the button, place it on a cupel, blow on it till it melts. And if it should happen that the gold is covered with a membrane, then add a very little lead, then it shines (_plickt_) and becomes clearer." Biringuccio (1540) also gives a fairly clear exposition of this method. All the old refiners varied the process by using mixtures of salt, antimony sulphide, and sulphur, in different proportions, with and without lead or copper; the net effect was the same. Later than Agricola these methods of parting bullion by converting the silver into a sulphide and carrying it off in a regulus took other forms. For instance, Schlueter (_Huette-Werken_, Braunschweig, 1738) describes a method by which, after the granulated bullion had been sulphurized by cementation with sulphur in pots, it was melted with metallic iron. Lampadius (_Grundriss Einer Allgemeinen Huettenkunde_, Goettingen, 1827) describes a treatment of the bullion, sulphurized as above, with litharge, thus creating a lead-silver regulus and a lead-silver-gold bullion which had to be repeatedly put through the same cycle. The principal object of these processes was to reduce silver bullion running low in gold to a ratio acceptable for nitric acid treatment.

Before closing the note on the separation of gold and silver, we may add that with regard to the three processes largely used to-day, the separation by solution of the silver from the bullion by concentrated sulphuric acid where silver sulphate is formed, was first described by D'Arcet, Paris, in 1802; the separation by introducing chlorine gas into the molten bullion and thus forming silver chlorides was first described by Lewis Thompson in a communication to the Society of Arts, 1833, and was first applied on a large scale by F. B. Miller at the Sydney Mint in 1867-70; we do not propose to enter into the discussion as to who is the inventor of electrolytic separation.

[22] There were three methods of gilding practised in the Middle Ages--the first by hammering on gold leaf; the second by laying a thin plate of gold on a thicker plate of silver, expanding both together, and fabricating the articles out of the sheets thus prepared; and the third by coating over the article with gold amalgam, and subsequently driving off the mercury by heat. Copper and iron objects were silver-plated by immersing them in molten silver after coating with sal-ammoniac or borax. Tinning was done in the same way.

[23] See note 12, p. 297, for complete discussion of amalgamation.

[24] These nine methods of separating gold from copper are based fundamentally upon the sulphur introduced in each case, whereby the copper is converted into sulphides and separated off as a matte. The various methods are much befogged by the introduction of extraneous ingredients, some of which serve as fluxes, while others would provide metallics in the shape of lead or antimony for collection of the gold, but others would be of no effect, except to increase the matte or slag. Inspection will show that the amount of sulphur introduced in many instances is in so large ratio that unless a good deal of volatilization took place there would be insufficient metallics to collect the gold, if it happened to be in small quantities. In a general way the auriferous button is gradually impoverished in copper until it is fit for cupellation with lead, except in one case where the final stage is accomplished by amalgamation. The lore of the old refiners was much after the order of that of modern cooks--they treasured and handed down various efficacious recipes, and of those given here most can be found in identical terms in the _Probierbuechlein_, some editions of which, as mentioned before, were possibly fifty years before _De Re Metallica_. This knowledge, no doubt, accumulated over long experience; but, so far as we are aware, there is no description of sulphurizing copper for this purpose prior to the publication mentioned.

[25] _Sal artificiosus_. The compound given under this name is of quite different ingredients from the stock fluxes given in Book VII under the same term. The method of preparation, no doubt, dehydrated this one; it would, however, be quite effective for its purpose of sulphurizing the copper. There is a compound given in the _Probierbuechlein_ identical with this, and it was probably Agricola's source of information.

[26] Throughout the book the cupellation furnace is styled the _secunda fornax_ (Glossary, _Treibeherd_). Except in one or two cases, where there is some doubt as to whether the author may not refer to the second variety of blast furnace, we have used "cupellation furnace." Agricola's description of the actual operation of the old German cupellation is less detailed than that of such authors as Schlueter (_Huette-Werken_, Braunschweig, 1738) or Winkler (_Beschreibung der Freyberger Schmelz Huttenprozesse_, Freyberg, 1837). The operation falls into four periods. In the first period, or a short time after melting, the first scum--the _abzug_--arises. This material contains most of the copper, iron, zinc, or sulphur impurities in the lead. In the second period, at a higher temperature, and with the blast turned on, a second scum arises--the _abstrich_. This material contains most of the antimony and arsenical impurities. In the third stage the litharge comes over. At the end of this stage the silver brightens--"_blicken_"--due to insufficient litharge to cover the entire surface. Winkler gives the following average proportion of the various products from a charge of 100 _centners_:--

_Abzug_ 2 _centners_, containing 64% lead _Abstrich_ 5-1/2 " " 73% " _Herdtplei_ 21-1/2 " " 60% " Impure litharge 18 " " 85% " Litharge 66 " " 89% " --- Total 113 _centners_

He estimates the lead loss at from 8% to 15%, and gives the average silver contents of _blicksilber_ as about 90%. Many analyses of the various products may be found in Percy (Metallurgy of Lead, pp. 198-201), Schnabel and Lewis (Metallurgy, Vol. I, p. 581); but as they must vary with every charge, a repetition of them here is of little purpose.

HISTORICAL NOTE ON CUPELLATION. The cupellation process is of great antiquity, and the separation of silver from lead in this manner very probably antedates the separation of gold and silver. We can be certain that the process has been used continuously for at least 2,300 years, and was only supplanted in part by Pattinson's crystallization process in 1833, and further invaded by Parks' zinc method in 1850, and during the last fifteen years further supplanted in some works by electrolytic methods. However, it yet survives as an important process. It seems to us that there is no explanation possible of the recovery of the large amounts of silver possessed from the earliest times, without assuming reduction of that metal with lead, and this necessitates cupellation. If this be the case, then cupellation was practised in 2500 B.C. The subject has been further discussed on p. 389. The first direct evidence of the process, however, is from the remains at Mt. Laurion (note 6, p. 27), where the period of greatest activity was at 500 B.C., and it was probably in use long before that time. Of literary evidences, there are the many metaphorical references to "fining silver" and "separating dross" in the Bible, such as Job (XXVIII, 1), Psalms (XII, 6, LXVI, 10), Proverbs (XVII, 3). The most certain, however, is Jeremiah (VI, 28-30): "They are all brass [_sic_] and iron; they are corrupters. The bellows are burned, the lead is consumed in the fire, the founder melteth in vain; for the wicked are not plucked away. Reprobate silver shall men call them." Jeremiah lived about 600 B.C. His contemporary Ezekiel (XXII, 18) also makes remark: "All they are brass and tin and iron and lead in the midst of the furnace; they are even the dross of the silver." Among Greek authors Theognis (6th century B.C.) and Hippocrates (5th century B.C.) are often cited as mentioning the refining of gold with lead, but we do not believe their statements will stand this construction without strain. Aristotle (Problems XXIV, 9) makes the following remark, which has been construed not only as cupellation, but also as the refining of silver in "tests." "What is the reason that boiling water does not leap out of the vessel ... silver also does this when it is purified. Hence those whose office it is in the silversmiths' shops to purify silver, derive gain by appropriation to themselves of the sweepings of silver which leap out of the melting-pot."

The quotation of Diodorus Siculus from Agatharchides (2nd century B.C.) on gold refining with lead and salt in Egypt we give in note 8, p. 279. The methods quoted by Strabo (63 B.C.-24 A.D.) from Polybius (204-125 B.C.) for treating silver, which appear to involve cupellation, are given in note 8, p. 281. It is not, however, until the beginning of the Christian era that we get definite literary information, especially with regard to litharge, in Dioscorides and Pliny. The former describes many substances under the terms _scoria_, _molybdaena_, _scoria argyros_ and _lithargyros_, which are all varieties of litharge. Under the latter term he says (V, 62): "One kind is produced from a lead sand (concentrates?), which has been heated in the furnaces until completely fused; another (is made) out of silver; another from lead. The best is from Attica, the second (best) from Spain; after that the kinds made in Puteoli, in Campania, and at Baia in Sicily, for in these places it is mostly produced by burning lead plates. The best of all is that which is a bright golden colour, called _chrysitis_, that from Sicily (is called) _argyritis_, that made from silver is called _lauritis_." Pliny refers in several passages to litharge (_spuma argenti_) and to what is evidently cupellation, (XXXIII, 31): "And this the same agency of fire separates part into lead, which floats on the silver like oil on water" (XXXIV, 47). "The metal which flows liquid at the first melting is called _stannum_, the second melting is silver; that which remains in the furnace is _galena_, which is added to a third part of the ore. This being again melted, produced lead with a deduction of two-ninths." Assuming _stannum_ to be silver-lead alloy, and _galena_ to be _molybdaena_, and therefore litharge, this becomes a fairly clear statement of cupellation (see note 23, p. 392). He further states (XXXIII, 35): "There is made in the same mines what is called _spuma argenti_ (litharge). There are three varieties of it; the best, known as _chrysitis_; the second best, which is called _argyritis_; and a third kind, which is called _molybditis_. And generally all these colours are to be found in the same tubes (see p. 480). The most approved kind is that of Attica; the next, that which comes from Spain. _Chrysitis_ is the product from the ore itself; _argyritis_ is made from the silver, and _molybditis_ is the result of smelting of lead, which is done at Puteoli, and from this has its name. All three are made as the material when smelted flows from an upper crucible into a lower one. From this last it is raised with an iron bar, and is then twirled round in the flames in order to make it less heavy (made in tubes). Thus, as may be easily perceived from the name, it is in reality the _spuma_ of a boiling substance--of the future metal, in fact. It differs from slag in the same way that the scum of a liquid differs from the lees, the one being purged from the material while purifying itself, the other an excretion of the metal when purified."

The works of either Theophilus (1150-1200 A.D.) or Geber (prior to the 14th century) are the first where adequate description of the cupel itself can be found. The uncertainty of dates renders it difficult to say which is earliest. Theophilus (Hendrie's Trans., p. 317) says: "How gold is separated from copper: But if at any time you have broken copper or silver-gilt vessels, or any other work, you can in this manner separate the gold. Take the bones of whatever animal you please, which (bones) you may have found in the street, and burn them, being cold, grind them finely, and mix with them a third part of beechwood ashes, and make cups as we have mentioned above in the purification of silver; you will dry these at the fire or in the sun. Then you carefully scrape the gold from the copper, and you will fold this scraping in lead beaten thin, and one of these cups being placed in the embers before the furnace, and now become warm, you place in this fold of lead with the scraping, and coals being heaped upon it you will blow it. And when it has become melted, in the same manner as silver is accustomed to be purified, sometimes by removing the embers and by adding lead, sometimes by re-cooking and warily blowing, you burn it until, the copper being entirely absorbed, the gold may appear pure."

We quote Geber from the Nuremberg edition of 1545, p. 152: "Now we describe the method of this. Take sifted ashes or _calx_, or the powder of the burned bones of animals, or all of them mixed, or some of them; moisten with water, and press it with your hand to make the mixture firm and solid, and in the middle of this bed make a round solid crucible and sprinkle a quantity of crushed glass. Then permit it to dry. When it is dry, place into the crucible that which we have mentioned which you intend to test. On it kindle a strong fire, and blow upon the surface of the body that is being tested until it melts, which, when melted, piece after piece of lead is thrown upon it, and blow over it a strong flame. When you see it agitated and moved with strong shaking motion it is not pure. Then wait until all of the lead is exhaled. If it vanishes and does not cease its motion it is not purified. Then again throw lead and blow again until the lead separates. If it does not become quiet again, throw in lead and blow on it until it is quiet and you see it bright and clear on the surface."

Cupellation is mentioned by most of the alchemists, but as a metallurgical operation on a large scale the first description is by Biringuccio in 1540.

[27] In Agricola's text this is "first,"--obviously an error.

[28] The Roman _sextarius_ was about a pint.

[29] This sentence continues, _Ipsa vero media pars praeterea digito_, to which we are unable to attribute any meaning.

[30] _Thus_, or _tus_--"incense."

[31] One _centumpondium_, Roman, equals about 70.6 lbs. avoirdupois; one _centner_, old German, equals about 114.2 lbs. avoirdupois. Therefore, if German weights are meant, the maximum charge would be about 5.7 short tons; if Roman weights, about 3.5 short tons.

[32] See description, p. 269.

[33] _Stannum_, as a term for lead-silver alloys, is a term which Agricola (_De Natura Fossilium_, pp. 341-3) adopted from his views of Pliny. In the _Interpretatio_ and the Glossary he gives the German equivalent as _werk_, which would sufficiently identify his meaning were it not obvious from the context. There can be little doubt that Pliny uses the term for lead alloys, but it had come into general use for tin before Agricola's time. The Roman term was _plumbum candidum_, and as a result of Agricola's insistence on using it and _stannum_ in what he conceived was their original sense, he managed to give considerable confusion to mineralogic literature for a century or two. The passages from Pliny, upon which he bases his use, are (XXXIV, 47): "The metal which flows liquid at the first melting in the furnace is called _stannum_, the second melting is silver," etc. (XXXIV, 48): "When copper vessels are coated with _stannum_ they produce a less disagreeable flavour, and it prevents verdigris. It is also remarkable that the weight is not increased.... At the present day a counterfeit _stannum_ is made by adding one-third of white copper to tin. It is also made in another way, by mixing together equal parts of tin and lead; this last is called by some _argentarium_.... There is also a composition called _tertiarium_, a mixture of two parts of lead and one of tin. Its price is twenty _denarii_ per pound, and it is used for soldering pipes. Persons still more dishonest mix together equal parts of _tertiarium_ and tin, and calling the compound _argentarium_, when it is melted coat articles with it." Although this last passage probably indicates that _stannum_ was a tin compound, yet it is not inconsistent with the view that the genuine _stannum_ was silver-lead, and that the counterfeits were made as stated by Pliny. At what period the term _stannum_ was adopted for tin is uncertain. As shown by Beckmann (Hist. of Inventions II, p. 225), it is used as early as the 6th century in occasions where tin was undoubtedly meant. We may point out that this term appears continuously in the official documents relating to Cornish tin mining, beginning with the report of William de Wrotham in 1198.

[34] The Latin term for litharge is _spuma argenti_, spume of silver.

[35] Pliny, XXXIII, 35. This quotation is given in full in the footnote p. 466. Agricola illustrates these "tubes" of litharge on p. 481.

[36] Assuming Roman weights, three _unciae_ and three _drachmae_ per _centumpondium_ would be about 82 ozs., and the second case would equal about 85 ozs. per short ton.

[37] Agricola uses throughout _De Re Metallica_ the term _molybdaena_ for this substance. It is obvious from the context that he means saturated furnace bottoms--the _herdpley_ of the old German metallurgists--and, in fact, he himself gives this equivalent in the _Interpretatio_, and describes it in great detail in _De Natura Fossilium_ (p. 353). The derivatives coined one time and another from the Greek _molybdos_ for lead, and their applications, have resulted in a stream of wasted ink, to which we also must contribute. Agricola chose the word _molybdaena_ in the sense here used from his interpretation of Pliny. The statements in Pliny are a hopeless confusion of _molybdaena_ and _galena_. He says (XXXIII, 35): "There are three varieties of it (litharge)--the best-known is _chrysitis_; the second best is called _argyritis_; and a third kind is called _molybditis_.... _Molybditis_ is the result of the smelting of lead.... Some people make two kinds of litharge, which they call _scirerytis_ and _peumene_; and a third variety being _molybdaena_, will be mentioned with lead." (XXXIV, 53): "_Molybdaena_, which in another place I have called _galena_, is an ore of mixed silver and lead. It is considered better in quality the nearer it approaches to a golden colour and the less lead there is in it; it is also friable and moderately heavy. When it is boiled with oil it becomes liver-coloured, adheres to the gold and silver furnaces, and in this state it is called _metallica_." From these two passages it would seem that _molybdaena_, a variety of litharge, might quite well be hearth-lead. Further (in XXXIV, 47), he says: "The metal which flows liquid at the first melting in the furnace is called _stannum_, at the second melting is silver, that which remains in the furnace is _galena_." If we still maintain that _molybdaena_ is hearth-lead, and _galena_ is its equivalent, then this passage becomes clear enough, the second melting being cupellation. The difficulty with Pliny, however, arises from the passage (XXXIII, 31), where, speaking of silver ore, he says: "It is impossible to melt it except with lead ore, called _galena_, which is generally found next to silver veins." Agricola (_Bermannus_, p. 427, &c.), devotes a great deal of inconclusive discussion to an attempt to reconcile this conflict of Pliny, and also that of Dioscorides. The probable explanation of this conflict arises in the resemblance of cupellation furnace bottoms to lead carbonates, and the native _molybdaena_ of Dioscorides; and some of those referred to by Pliny may be this sort of lead ores. In fact, in one or two places in

## Book IX, Agricola appears to use the term in this sense himself. After

Agricola's time the term _molybdaenum_ was applied to substances resembling lead, such as graphite, and what we now know as _molybdenite_ (_MoS_{2}_). Some time in the latter part of the 18th century, an element being separated from the latter, it was dubbed _molybdenum_, and confusion was five times confounded.

[38] Agricola here refers to the German word used in this connection, _i.e._, _hundt_, a dog.

[39] If Agricola means the German _centner_, this charge would be from about 4.6 to 5.7 short tons. If he is using Roman weights, it would be from about 3 to 3.7 short tons.

[40] The refining of silver in "tests" (Latin _testa_) is merely a second cupellation, with greater care and under stronger blast. Stirring the mass with an iron rod serves to raise the impurities which either volatilize as litharge or, floating to the edges, are absorbed into the "test." The capacity of the tests, from 15 _librae_ to 50 _librae_, would be from about 155 to 515 ozs. Troy.

[41] A _drachma_ of impurities in a _bes_, would be one part in 64, or 984.4 fine. A loss of a _sicilicus_ of silver to the _bes_, would be one

## part in 32, or about 3.1%; three _drachmae_ would equal 4.7%, and half

an _uncia_ 6.2%, or would indicate that the original bullion had a fineness in the various cases of about 950, 933, and 912.

[42] _Praefectus Regis_.

## BOOK XI.

Different methods of parting gold from silver, and, on the other hand, silver from gold, were discussed in the last book; also the separation of copper from the latter, and further, of lead from gold as well as from silver; and, lastly, the methods for refining the two precious metals. Now I will speak of the methods by which silver must be separated from copper, and likewise from iron.[1]

[Illustration 493 (Building Plan for Refinery): Six long walls: A--The first. B--The first part of the second. C--The further part of the second. D--The third. E--The fourth. F--The fifth. G--The sixth. Fourteen transverse walls: H--The first. I--The second. K--The third. L--The fourth. M--The fifth. N--The sixth. O--The seventh. P--The eighth. Q--The ninth. R--The tenth. S--The eleventh. T--The twelfth. V--The thirteenth. X--The fourteenth.]

The _officina_, or the building necessary for the purposes and use of those who separate silver from copper, is constructed in this manner. First, four long walls are built, of which the first, which is parallel with the bank of a stream, and the second, are both two hundred and sixty-four feet long. The second, however, stops at one hundred and fifty-one feet, and after, as it were, a break for a length of twenty-four feet, it continues again until it is of a length equal to the first wall. The third wall is one hundred and twenty feet long, starting at a point opposite the sixty-seventh foot of the other walls, and reaching to their one hundred and eighty-sixth foot. The fourth wall is one hundred and fifty-one feet long. The height of each of these walls, and likewise of the other two and of the transverse walls, of which I will speak later on, is ten feet, and the thickness two feet and as many palms. The second long wall only is built fifteen feet high, because of the furnaces which must be built against it. The first long wall is distant fifteen feet from the second, and the third is distant the same number of feet from the fourth, but the second is distant thirty-nine feet from the third. Then transverse walls are built, the first of which leads from the beginning of the first long wall to the beginning of the second long wall; and the second transverse wall from the beginning of the second long wall to the beginning of the fourth long wall, for the third long wall does not reach so far. Then from the beginning of the third long wall are built two walls--the one to the sixty-seventh foot of the second long wall, the other to the same point in the fourth long wall. The fifth transverse wall is built at a distance of ten feet from the fourth transverse wall toward the second transverse wall; it is twenty feet long, and starts from the fourth long wall. The sixth transverse wall is built also from the fourth long wall, at a point distant thirty feet from the fourth transverse wall, and it extends as far as the back of the third long wall. The seventh transverse wall is constructed from the second long wall, where this first leaves off, to the third long wall; and from the back of the third long wall the eighth transverse wall is built, extending to the end of the fourth long wall. Then the fifth long wall is built from the seventh transverse wall, starting at a point nineteen feet from the second long wall; it is one hundred and nine feet in length; and at a point twenty-four feet along it, the ninth transverse wall is carried to the third end of the second long wall, where that begins again. The tenth transverse wall is built from the end of the fifth long wall, and leads to the further end of the second long wall; and from there the eleventh transverse wall leads to the further end of the first long wall. Behind the fifth long wall, and five feet toward the third long wall, the sixth long wall is built, leading from the seventh transverse wall; its length is thirty-five feet, and from its further end the twelfth transverse wall is built to the third long wall, and from it the thirteenth transverse wall is built to the fifth long wall. The fourteenth transverse wall divides into equal parts the space which lies between the seventh transverse wall and the twelfth.

The length, height, breadth, and position of the walls are as above. Their archways, doors, and openings are made at the same time that the walls are built. The size of these and the way they are made will be much better understood hereafter. I will now speak of the furnace hoods and of the roofs. The first side[2] of the hood stands on the second long wall, and is similar in every respect to those whose structure I explained in Book IX, when I described the works in whose furnaces are smelted the ores of gold, silver, and copper. From this side of the hood a roof, which consists of burnt tiles, extends to the first long wall; and this part of the building contains the bellows, the machinery for compressing them, and the instruments for inflating them. In the middle space, which is situated between the second and third transverse walls, an upright post eight feet high and two feet thick and wide, is erected on a rock foundation, and is distant thirteen feet from the second long wall. On that upright post, and in the second transverse wall, which has at that point a square hole two feet high and wide, is placed a beam thirty-four feet and a palm long. Another beam, of the same length, width, and thickness, is fixed on the same upright post and in the third transverse wall. The heads of those two beams, where they meet, are joined together with iron staples. In a similar manner another post is erected, at a distance of ten feet from the first upright post in the direction of the fourth wall, and two beams are laid upon it and into the same walls in a similar way to those I have just now described. On these two beams and on the fourth long wall are fixed seventeen cross-beams, forty-three feet and three palms long, a foot wide, and three palms thick; the first of these is laid upon the second transverse wall, the last lies along the third and fourth transverse walls; the rest are set in the space between them. These cross-beams are three feet apart one from the other.

In the ends of these cross-beams, facing the second long wall, are mortised the ends of the same number of rafters reaching to those timbers which stand upright on the second long wall, and in this manner is made the inclined side of the hood in a similar way to the one described in Book IX. To prevent this from falling toward the vertical wall of the hood, there are iron rods securing it, but only a few, because the four brick chimneys which have to be built in that space

## partly support it. Twelve feet back are likewise mortised into the

cross-beams, which lie upon the two longitudinal beams and the fourth long wall, the lower ends of as many rafters, whose upper ends are mortised into the upper ends of an equal number of similar rafters, whose lower ends are mortised to the ends of the beams at the fourth long wall. From the first set of rafters[4] to the second set of rafters is a distance of twelve feet, in order that a gutter may be well placed in the middle space. Between these two are again erected two sets of rafters, the lower ends of which are likewise mortised into the beams, which lie on the two longitudinal beams and the fourth long wall, and are interdistant a cubit. The upper ends of the ones fifteen feet long rest on the backs of the rafters of the first set; the ends of the others, which are eighteen feet long, rest on the backs of the rafters of the second set, which are longer; in this manner, in the middle of the rafters, is a sub-structure. Upon each alternate cross-beam which is placed upon the two longitudinal beams and the fourth long wall is erected an upright post, and that it may be sufficiently firm it is strengthened by means of a slanting timber. Upon these posts is laid a long beam, upon which rests one set of middle rafters. In a similar manner the other set of middle rafters rests on a long beam which is placed upon other posts. Besides this, two feet above every cross-beam, which is placed on the two longitudinal beams and the fourth long wall, is placed a tie-beam which reaches from the first set of middle rafters to the second set of middle rafters; upon the tie-beams is placed a gutter hollowed out from a tree. Then from the back of each of the first set of middle rafters a beam six feet long reaches almost to the gutter; to the lower end of this beam is attached a piece of wood two feet long; this is repeated with each rafter of the first set of middle rafters. Similarly from the back of each rafter of the second set of middle rafters a little beam, seven feet long, reaches almost to the gutter; to the lower end of it is likewise attached a short piece of wood; this is repeated on each rafter of the second set of middle rafters. Then in the upper part, to the first and second sets of principal rafters are fastened long boards, upon which are fixed the burnt tiles; and in the same manner, in the middle part, they are fastened to the first and second sets of middle rafters, and at the lower part to the little beams which reach from each rafter of the first and second set of middle rafters almost to the gutter; and, finally, to the little boards fastened to the short pieces of wood are fixed shingles of pine-wood extending into the gutter, so that the violent rain or melted snow may not penetrate into the building. The substructures in the interior which support the second set of rafters, and those on the opposite side which support the third, being not unusual, I need not explain.

In that part of the building against the second long wall are the furnaces, in which exhausted liquation cakes which have already been "dried" are smelted, that they may recover once again the appearance and colour of copper, inasmuch as they really are copper. The remainder of the room is occupied by the passage which leads from the door to the furnaces, together with two other furnaces, in one of which the whole cakes of copper are heated, and in the other the exhausted liquation cakes are "dried" by the heat of the fire.

Likewise, in the room between the third and seventh[5] transverse walls, two posts are erected on rock foundation; both of them are eight feet high and two feet wide and thick. The one is at a distance of thirteen feet from the second long wall; the other at the same distance from the third long wall; there is a distance of thirteen feet between them. Upon these two posts and upon the third transverse wall are laid two longitudinal beams, forty-one feet and one palm long, and two feet wide and thick. Two other beams of the same length, width, and thickness are laid upon the upright posts and upon the seventh transverse wall, and the heads of the two long beams, where they meet, are joined with iron staples. On these longitudinal beams are again placed twenty-one transverse beams, thirteen feet long, a foot wide, and three palms thick, of which the first is set on the third transverse wall, and the last on the seventh transverse wall; the rest are laid in the space between these two, and they are distant from one another three feet. Into the ends of the transverse beams which face the second long wall, are mortised the ends of the same number of rafters erected toward the upright posts which are placed upon the second long wall, and in this manner is made the second inclined side wall of the hood. Into the ends of the transverse beams facing the third long wall, are mortised the ends of the same number of rafters rising toward the rafters of the first inclined side of the second hood, and in this manner is made the other inclined side of the second hood. But to prevent this from falling in upon the opposite inclined side of the hood, and that again upon the opposite vertical one, there are many iron rods reaching from some of the rafters to those opposite them; and this is also prevented in part by means of a few tie-beams, extending from the back of the rafters to the back of those which are behind them. These tie-beams are two palms thick and wide, and have holes made through them at each end; each of the rafters is bound round with iron bands three digits wide and half a digit thick, which hold together the ends of the tie-beams of which I have spoken; and so that the joints may be firm, an iron nail, passing through the plate on both sides, is driven through the holes in the ends of the beams. Since one weight counter-balances another, the rafters on the opposite hoods cannot fall. The tie-beams and middle posts which have to support the gutters and the roof, are made in every particular as I stated above, except only that the second set of middle rafters are not longer than the first set of middle rafters, and that the little beams which reach from the back of each rafter of the second set of middle rafters nearly to the gutter are not longer than the little beams which reach from the back of each rafter of the first set of middle rafters almost to the gutter. In this part of the building, against the second long wall, are the furnaces in which copper is alloyed with lead, and in which "slags" are re-smelted. Against the third long wall are the furnaces in which silver and lead are liquated from copper. The interior is also occupied by two cranes, of which one deposits on the ground the cakes of copper lifted out of the moulding pans; the other lifts them from the ground into the second furnace.

On the third and the fourth long walls are set twenty-one beams eighteen feet and three palms long. In mortises in them, two feet behind the third long wall, are set the ends of the same number of rafters erected opposite to the rafters of the other inclined wall of the second furnace hood, and in this manner is made the third inclined wall, exactly similar to the others. The ends of as many rafters are mortised into these beams where they are fixed in the fourth long wall; these rafters are erected obliquely, and rest against the backs of the preceding ones and support the roof, which consists entirely of burnt tiles and has the usual substructures. In this part of the building there are two rooms, in the first of which the cakes of copper, and in the other the cakes of lead, are stored.

In the space enclosed between the ninth and tenth transverse walls and the second and fifth long walls, a post twelve feet high and two feet wide and thick is erected on a rock foundation; it is distant thirteen feet from the second long wall, and six from the fifth long wall. Upon this post and upon the ninth transverse wall is laid a beam thirty-three feet and three palms long, and two palms wide and thick. Another beam, also of the same length, width and thickness, is laid upon the same post and upon the tenth transverse wall, and the ends of these two beams where they meet are joined by means of iron staples. On these beams and on the fifth long wall are placed ten cross-beams, eight feet and three palms long, the first of which is placed on the ninth transverse wall, the last on the tenth, the remainder in the space between them; they are distant from one another three feet. Into the ends of the cross-beams facing the second long wall, are mortised the ends of the same number of rafters inclined toward the posts which stand vertically upon the second long wall. This, again, is the manner in which the inclined side of the furnace hood is made, just as with the others; at the top where the fumes are emitted it is two feet distant from the vertical side. The ends of the same number of rafters are mortised into the cross-beams, where they are set in the fifth long wall; each of them is set up obliquely and rests against the back of one of the preceding set; they support the roof, made of burnt tiles. In this part of the building, against the second long wall, are four furnaces in which lead is separated from silver, together with the cranes by means of which the domes are lifted from the crucibles.

In that part of the building which lies between the first long wall and the break in the second long wall, is the stamp with which the copper cakes are crushed, and the four stamps with which the accretions that are chipped off the walls of the furnace are broken up and crushed to powder, and likewise the bricks on which the exhausted liquation cakes of copper are stood to be "dried." This room has the usual roof, as also has the space between the seventh transverse wall and the twelfth and thirteenth transverse walls.

[Illustration 499 (Hearths for melting lead cakes): A--Hearth. B--Rocks sunk into the ground. C--Walls which protect the fourth long wall from damage by fire. D--Dipping-pot. E--Masses of lead. F--Trolley. G--Its wheels. H--Crane. I--Tongs. K--Wood. L--Moulds. M--Ladle. N--Pick. O--Cakes.]

At the sides of these rooms are the fifth, the sixth, and the third long walls. This part of the building is divided into two parts, in the first of which stand the little furnaces in which the artificer assays metals; and the bone ash, together with the other powders, are kept here. In the other room is prepared the powder from which the hearths and the crucibles of the furnaces are made. Outside the building, at the back of the fourth long wall, near the door to the left as you enter, is a hearth in which smaller masses of lead are melted from large ones, that they may be the more easily weighed; because the masses of lead, just as much as the cakes of copper, ought to be first prepared so that they can be weighed, and a definite weight can be melted and alloyed in the furnaces. To begin with, the hearth in which the masses of lead are liquefied is six feet long and five wide; it is protected on both sides by rocks partly sunk into the earth, but a palm higher than the hearth, and it is lined in the inside with lute. It slopes toward the middle and toward the front, in order that the molten lead may run down and flow out into the dipping-pot. There is a wall at the back of the hearth which protects the fourth long wall from damage by the heat; this wall, which is made of bricks and lute, is four feet high, three palms thick, and five feet long at the bottom, and at the top three feet and two palms long; therefore it narrows gradually, and in the upper part are laid seven bricks, the middle ones of which are set upright, and the end ones inclined; they are all thickly coated with lute. In front of the hearth is a dipping-pot, whose pit is a foot deep, and a foot and three palms wide at the top, and gradually narrows. When the masses of lead are to be melted, the workman first places the wood in the hearth so that one end of each billet faces the wall, and the other end the dipping-pot. Then, assisted by other workmen, he pushes the mass of lead forward with crowbars on to a low trolley, and draws it to the crane. The trolley consists of planks fastened together, is two and one-half feet wide and five feet long, and has two small iron axles, around which at each end revolve small iron wheels, two palms in diameter and as many digits wide. The trolley has a tongue, and attached to this is a rope, by which it is drawn to the crane. The crane is exactly similar to those in the second part of the works, except that the crane-arm is not so long. The tongs in whose jaws[6] the masses of lead are seized, are two feet a palm and two digits long; both of the jaws, when struck with a hammer, impinge upon the mass and are driven into it. The upper part of both handles of the tongs are curved back, the one to the right, the other to the left, and each handle is engaged in one of the lowest links of two short chains, which are three links long. The upper links are engaged in a large round ring, in which is fixed the hook of a chain let down from the pulley of the crane-arm. When the crank of the crane is turned, the mass is lifted and is carried by the crane-arm to the hearth and placed on the wood. The workmen wheel up one mass after another and place them in a similar manner on the wood of the hearth; masses which weigh a total of about a hundred and sixty _centumpondia_[7] are usually placed upon the wood and melted at one time. Then a workman throws charcoal on the masses, and all are made ready in the evening. If he fears that it may rain, he covers it up with a cover, which may be moved here and there; at the back this cover has two legs, so that the rain which it collects may flow down the slope on to the open ground. Early in the morning of the following day, he throws live coals on the charcoal with a shovel, and by this method the masses of lead melt, and from time to time charcoal is added. The lead, as soon as it begins to run into the dipping-pot, is ladled out with an iron ladle into copper moulds such as the refiners generally use. If it does not cool immediately he pours water over it, and then sticks the pointed pick into it and pulls it out. The pointed end of the pick is three palms long and the round end is two digits long. It is necessary to smear the moulds with a wash of lute, in order that, when they have been turned upside down and struck with the broad round end of the pick, the cakes of lead may fall out easily. If the moulds are not washed over with the lute, there is a risk that they may be melted by the lead and let it through. Others take hold of a billet of wood with their left hand, and with the heavy lower end of it they pound the mould, and with the right hand they stick the point of the pick into the cake of lead, and thus pull it out. Then immediately the workman pours other lead into the empty moulds, and this he does until the work of melting the lead is finished. When the lead is melted, something similar to litharge is produced; but it is no wonder that it should be possible to make it in this case, when it used formerly to be produced at Puteoli from lead alone when melted by a fierce fire in the cupellation furnace.[8] Afterward these cakes of lead are carried into the lead store-room.

[Illustration 501 (Stamp-mill for breaking copper cakes): A--Block of wood. B--Upright posts. C--Transverse beams. D--Head of the stamp. E--Its tooth. F--The hole in the stamp-stem. G--Iron bar. H--Masses of lead. I--The bronze saddle. K--Axle. L--Its arms. M--Little iron axle. N--Bronze pipe.]

The cakes of copper, put into wheelbarrows, are carried into the third part of the building, where each is laid upon a saddle, and is broken up by the impact of successive blows from the iron-shod stamp. This machine is made by placing upon the ground a block of oak, five feet long and three feet wide and thick; it is cut out in the middle for a length of two feet and two palms, a width of two feet, and a depth of three palms and two digits, and is open in front; the higher part of it is at the back, and the wide part lies flat in the block. In the middle of it is placed a bronze saddle. Its base is a palm and two digits wide, and is planted between two masses of lead, and extends under them to a depth of a palm on both sides. The whole saddle is three palms and two digits wide, a foot long, and two palms thick. Upon each end of the block stands a post, a cubit wide and thick, the upper end of which is somewhat cut away and is mortised into the beams of the building. At a height of four feet and two digits above the block there are joined to the posts two transverse beams, each of which is three palms wide and thick; their ends are mortised into the upright posts, and holes are bored through them; in the holes are driven iron claves, horned in front and so driven into the post that one of the horns of each points upward and the other downward; the other end of each clavis is perforated, and a wide iron wedge is inserted and driven into the holes, and thus holds the transverse beams in place. These transverse beams have in the middle a square opening three palms and half a digit wide in each direction, through which the iron-shod stamp passes. At a height of three feet and two palms above these transverse beams there are again two beams of the same kind, having also a square opening and holding the same stamp. This stamp is square, eleven feet long, three palms wide and thick; its iron shoe is a foot and a palm long; its head is two palms long and wide, a palm two digits thick at the top, and at the bottom the same number of digits, for it gradually narrows. But the tail is three palms long; where the head begins is two palms wide and thick, and the further it departs from the same the narrower it becomes. The upper part is enclosed in the stamp-stem, and it is perforated so that an iron bolt may be driven into it; it is bound by three rectangular iron bands, the lowest of which, a palm wide, is between the iron shoe and the head of the stamp; the middle band, three digits wide, follows next and binds round the head of the stamp, and two digits above is the upper one, which is the same number of digits wide. At a distance of two feet and as many digits above the lowest part of the iron shoe, is a rectangular tooth, projecting from the stamp for a distance of a foot and a palm; it is two palms thick, and when it has extended to a distance of six digits from the stamp it is made two digits narrower. At a height of three palms upward from the tooth there is a round hole in the middle of the stamp-stem, into which can be thrust a round iron bar two feet long and a digit and a half in diameter; in its hollow end is fixed a wooden handle two palms and the same number of digits long. The bar rests on the lower transverse beam, and holds up the stamp when it is not in use. The axle which raises the stamp has on each side two arms, which are two palms and three digits distant from each other, and which project from the axle a foot, a palm and two digits; penetrating through them are bolts, driven in firmly; the arms are each a palm and two digits wide and thick, and their round heads, for a foot downward on either side, are covered with iron plates of the same width as the arms and fastened by iron nails. The head of each arm has a round hole, into which is inserted an iron pin, passing through a bronze pipe; this little axle has at the one end a wide head, and at the other end a perforation through which is driven an iron nail, lest this little axle should fall out of the arms. The bronze pipe is two palms long and one in diameter; the little iron axle penetrates through its round interior, which is two digits in diameter. The bronze pipe not only revolves round the little iron axle, but it also rotates with it; therefore, when the axle revolves, the little axle and the bronze tube in their turn raise the tooth and the stamp. When the little iron axle and the bronze pipe have been taken out of the arms, the tooth of the stamps is not raised, and other stamps may be raised without this one. Further on, a drum with spindles fixed around the axle of a water-wheel moves the axle of a toothed drum, which depresses the sweeps of the bellows in the adjacent fourth part of the building; but it turns in the contrary direction; for the axis of the drum which raises the stamps turns toward the north, while that one which depresses the sweeps of the bellows turns toward the south.

[Illustration 504 (Hearths for heating copper cakes): A--Back wall. B--Walls at the sides. C--Upright posts. D--Chimney. E--The cakes arranged. F--Iron plates. G--Rocks. H--Rabble with two prongs. I--Hammers.]

Those cakes which are too thick to be rapidly broken by blows from the iron-shod stamp, such as are generally those which have settled in the bottom of the crucible,[9] are carried into the first part of the building. They are there heated in a furnace, which is twenty-eight feet distant from the second long wall and twelve feet from the second transverse wall. The three sides of this furnace are built of rectangular rocks, upon which bricks are laid; the back furnace wall is three feet and a palm high, and the rear of the side walls is the same; the side walls are sloping, and where the furnace is open in front they are only two feet and three palms high; all the walls are a foot and a palm thick. Upon these walls stand upright posts not less thick, in order that they may bear the heavy weight placed upon them, and they are covered with lute; these posts support the sloping chimney and penetrate through the roof. Moreover, not only the ribs of the chimney, but also the rafters, are covered thickly with lute. The hearth of the furnace is six feet long on each side, is sloping, and is paved with bricks. The cakes of copper are placed in the furnace and heated in the following way. They are first of all placed in the furnace in rows, with as many small stones the size of an egg between, so that the heat of the fire can penetrate through the spaces between them; indeed, those cakes which are placed at the bottom of the crucible are each raised upon half a brick for the same reason. But lest the last row, which lies against the mouth of the furnace, should fall out, against the mouth are placed iron plates, or the copper cakes which are the first taken from the crucible when copper is made, and against them are laid exhausted liquation cakes or rocks. Then charcoal is thrown on the cakes, and then live coals; at first the cakes are heated by a gentle fire, and afterward more charcoal is added to them until it is at times three-quarters of a foot deep. A fiercer fire is certainly required to heat the hard cakes of copper than the fragile ones. When the cakes have been sufficiently heated, which usually occurs within the space of about two hours, the exhausted liquation cakes or the rocks and the iron plate are removed from the mouth of the furnace. Then the hot cakes are taken out row after row with a two-pronged rabble, such as the one which is used by those who "dry" the exhausted liquation cakes. Then the first cake is laid upon the exhausted liquation cakes, and beaten by two workmen with hammers until it breaks; the hotter the cakes are, the sooner they are broken up; the less hot, the longer it takes, for now and then they bend into the shape of copper basins. When the first cake has been broken, the second is put on to the other fragments and beaten until it breaks into pieces, and the rest of the cakes are broken up in the same manner in due order. The head of the hammer is three palms long and one wide, and sharpened at both ends, and its handle is of wood three feet long. When they have been broken by the stamp, if cold, or with hammers if hot, the fragments of copper or the cakes are carried into the store-room for copper.

The foreman of the works, according to the different proportions of silver in each _centumpondium_ of copper, alloys it with lead, without which he could not separate the silver from the copper.[10] If there be a moderate amount of silver in the copper, he alloys it fourfold; for instance, if in three-quarters of a _centumpondium_ of copper there is less than the following proportions, _i.e._: half a _libra_ of silver, or half a _libra_ and a _sicilicus_, or half a _libra_ and a _semi-uncia_, or half a _libra_ and _semi-uncia_ and a _sicilicus_, then rich lead--that is, that from which the silver has not yet been separated--is added, to the amount of half a _centumpondium_ or a whole _centumpondium_, or a whole and a half, in such a way that there may be in the copper-lead alloy some one of the proportions of silver which I have just mentioned, which is the first alloy. To this "first" alloy is added such a weight of de-silverized lead or litharge as is required to make out of all of these a single liquation cake that will contain approximately two _centumpondia_ of lead; but as usually from one hundred and thirty _librae_ of litharge only one hundred _librae_ of lead are made, a greater proportion of litharge than of de-silverized lead is added as a supplement. Since four cakes of this kind are placed at the same time into the furnace in which the silver and lead is liquated from copper, there will be in all the cakes three _centumpondia_ of copper and eight _centumpondia_ of lead. When the lead has been liquated from the copper, it weighs six _centumpondia_, in each _centumpondium_ of which there is a quarter of a _libra_ and almost a _sicilicus_ of silver. Only seven _unciae_ of the silver remain in the exhausted liquation cakes and in that copper-lead alloy which we call "liquation thorns"; they are not called by this name so much because they have sharp points as because they are base. If in three-quarters of a _centumpondium_ of copper there are less than seven _uncia_ and a _semi-uncia_ or a _bes_ of silver, then so much rich lead must be added as to make in the copper and lead alloy one of the proportions of silver which I have already mentioned. This is the "second" alloy. To this is again to be added as great a weight of de-silverized lead, or of litharge, as will make it possible to obtain from that alloy a liquation cake containing two and a quarter _centumpondia_ of lead, in which manner in four of these cakes there will be three _centumpondia_ of copper and nine _centumpondia_ of lead. The lead which liquates from these cakes weighs seven _centumpondia_, in each _centumpondium_ of which there is a quarter of a _libra_ of silver and a little more than a _sicilicus_. About seven _unciae_ of silver remain in the exhausted liquation cakes and in the liquation thorns, if we may be allowed to make common the old name (_spinae_ = thorns) and bestow it upon a new substance. If in three-quarters of a _centumpondium_ of copper there is less than three-quarters of a _libra_ of silver, or three-quarters and a _semi-uncia_, then as much rich lead must be added as will produce one of the proportions of silver in the copper-lead alloy above mentioned; this is the "third" alloy. To this is added such an amount of de-silverized lead or of litharge, that a liquation cake made from it contains in all two and three-quarters _centumpondia_ of lead. In this manner four such cakes will contain three _centumpondia_ of copper and eleven _centumpondia_ of lead. The lead which these cakes liquate, when they are melted in the furnace, weighs about nine _centumpondia_, in each _centumpondium_ of which there is a quarter of a _libra_ and more than a _sicilicus_ of silver; and seven _unciae_ of silver remain in the exhausted liquation cakes and in the liquation thorns. If, however, in three-quarters of a _centumpondium_ of copper there is less than ten-twelfths of a _libra_ or ten-twelfths of a _libra_ and a _semi-uncia_ of silver, then such a proportion of rich lead is added as will produce in the copper-lead alloy one of the proportions of silver which I mentioned above; this is the "fourth" alloy. To this is added such a weight of de-silverized lead or of litharge, that a liquation cake made from it contains three _centumpondia_ of lead, and in four cakes of this kind there are three _centumpondia_ of copper and twelve _centumpondia_ of lead. The lead which is liquated therefrom weighs about ten _centumpondia_, in each _centumpondium_ of which there is a quarter of a _libra_ and more than a _semi-uncia_ of silver, or seven _unciae_; a _bes_, or seven _unciae_ and a _semi-uncia_, of silver remain in the exhausted liquation cakes and in the liquation thorns.

[Illustration 508 (Blast Furnaces): A--Furnace in which "slags" are re-smelted. B--Furnace in which copper is alloyed with lead. C--Door. D--Forehearths on the ground. E--Copper moulds. F--Rabble. G--Hook. H--Cleft stick. I--Arm of the crane. K--The hook of its chain.]

Against the second long wall in the second part of the building, whose area is eighty feet long by thirty-nine feet wide, are four furnaces in which the copper is alloyed with lead, and six furnaces in which "slags" are re-smelted. The interior of the first kind of furnace is a foot and three palms wide, two feet three digits long; and of the second is a foot and a palm wide and a foot three palms and a digit long. The side walls of these furnaces are the same height as the furnaces in which gold or silver ores are smelted. As the whole room is divided into two parts by upright posts, the front part must have, first, two furnaces in which "slags" are re-melted; second, two furnaces in which copper is alloyed with lead; and third, one furnace in which "slags" are re-melted. The back part of the room has first, one furnace in which "slags" are re-melted; next, two furnaces in which copper is alloyed with lead; and third, two furnaces in which "slags" are re-melted. Each of these is six feet distant from the next; on the right side of the first is a space of three feet and two palms, and on the left side of the last one of seven feet. Each pair of furnaces has a common door, six feet high and a cubit wide, but the first and the tenth furnace each has one of its own. Each of the furnaces is set in an arch of its own in the back wall, and in front has a forehearth pit; this is filled with a powder compound rammed down and compressed in order to make a crucible. Under each furnace is a hidden receptacle for the moisture,[11] from which a vent is made through the back wall toward the right, which allows the vapour to escape. Finally, to the right, in front, is the copper mould into which the copper-lead alloy is poured from the forehearth, in order that liquation cakes of equal weight may be made. This copper mould is a digit thick, its interior is two feet in diameter and six digits deep. Behind the second long wall are ten pairs of bellows, two machines for compressing them, and twenty instruments for inflating them. The way in which these should be made may be understood from Book IX.

The smelter, when he alloys copper with lead, with his hand throws into the heated furnace, first the large fragments of copper, then a basketful of charcoal, then the smaller fragments of copper. When the copper is melted and begins to run out of the tap-hole into the forehearth, he throws litharge into the furnace, and, lest part of it should fly away, he first throws charcoal over it, and lastly lead. As soon as he has thrown into the furnace the copper and the lead, from which alloy the first liquation cake is made, he again throws in a basket of charcoal, and then fragments of copper are thrown over them, from which the second cake may be made. Afterward with a rabble he skims the "slag" from the copper and lead as they flow into the forehearth. Such a rabble is a board into which an iron bar is fixed; the board is made of elder-wood or willow, and is ten digits long, six wide, and one and a half digits thick; the iron bar is three feet long, and the wooden handle inserted into it is two and a half feet long. While he purges the alloy and pours it out with a ladle into the copper mould, the fragments of copper from which he is to make the second cake are melting. As soon as this begins to run down he again throws in litharge, and when he has put on more charcoal he adds the lead. This operation he repeats until thirty liquation cakes have been made, on which work he expends nine hours, or at most ten; if more than thirty cakes must be made, then he is paid for another shift when he has made an extra thirty.

At the same time that he pours the copper-lead alloy into the copper mould, he also pours water slowly into the top of the mould. Then, with a cleft stick, he takes a hook and puts its straight stem into the molten cake. The hook itself is a digit and a half thick; its straight stem is two palms long and two digits wide and thick. Afterward he pours more water over the cakes. When they are cold he places an iron ring in the hook of the chain let down from the pulley of the crane arm; the inside diameter of this ring is six digits, and it is about a digit and a half thick; the ring is then engaged in the hook whose straight stem is in the cake, and thus the cake is raised from the mould and put into its place.

The copper and lead, when thus melted, yield a small amount of "slag"[12] and much litharge. The litharge does not cohere, but falls to pieces like the residues from malt from which beer is made. _Pompholyx_ adheres to the walls in white ashes, and to the sides of the furnace adheres _spodos_.

In this practical manner lead is alloyed with copper in which there is but a moderate portion of silver. If, however, there is much silver in it, as, for instance, two _librae_, or two _librae_ and a _bes_, to the _centumpondium_,--which weighs one hundred and thirty-three and a third _librae_, or one hundred and forty-six _librae_ and a _bes_,[13]--then the foreman of the works adds to a _centumpondium_ of such copper three _centumpondia_ of lead, in each _centumpondium_ of which there is a third of a _libra_ of silver, or a third of a _libra_ and a _semi-uncia_. In this manner three liquation cakes are made, which contain altogether three _centumpondia_ of copper and nine _centumpondia_ of lead.[14] The lead, when it has been liquated from the copper, weighs seven _centumpondia_; and in each _centumpondium_--if the _centumpondium_ of copper contain two _librae_ of silver, and the lead contain a third of a _libra_--there will be a _libra_ and a sixth and more than a _semi-uncia_ of silver; while in the exhausted liquation cakes, and in the liquation thorns, there remains a third of a _libra_. If a _centumpondium_ of copper contains two _librae_ and a _bes_ of silver, and the lead a third of a _libra_ and a _semi-uncia_, there will be in each liquation cake one and a half _librae_ and a _semi-uncia_, and a little more than a _sicilicus_ of silver. In the exhausted liquation cakes there remain a third of a _libra_ and a _semi-uncia_ of silver.

[Illustration 510 (Furnaces enriching copper bottoms): A--Furnace. B--Forehearth. C--Dipping-Pot. D--Cakes.]

If there be in the copper only a minute proportion of silver, it cannot be separated easily until it has been re-melted in other furnaces, so that in the "bottoms" there remains more silver and in the "tops" less.[15] This furnace, vaulted with unbaked bricks, is similar to an oven, and also to the cupellation furnace, in which the lead is separated from silver, which I described in the last book. The crucible is made of ashes, in the same manner as in the latter, and in the front of the furnace, three feet above the floor of the building, is the mouth out of which the re-melted copper flows into a forehearth and a dipping-pot. On the left side of the mouth is an aperture, through which beech-wood may be put into the furnace to feed the fire. If in a _centumpondium_ of copper there were a sixth of a _libra_ and a _semi-uncia_ of silver, or a quarter of a _libra_, or a quarter of a _libra_ and a _semi-uncia_--there is re-melted at the same time thirty-eight _centumpondia_ of it in this furnace, until there remain in each _centumpondium_ of the copper "bottoms" a third of a _libra_ and a _semi-uncia_ of silver. For example, if in each _centumpondium_ of copper not yet re-melted, there is a quarter of a _libra_ and a _semi-uncia_ of silver, then the thirty-eight _centumpondia_ that are smelted together must contain a total of eleven _librae_ and an _uncia_ of silver. Since from fifteen _centumpondia_ of re-melted copper there was a total of four and a third _librae_ and a _semi-uncia_ of silver, there remain only two and a third _librae_. Thus there is left in the "bottoms," weighing twenty-three _centumpondia_, a total of eight and three-quarter _librae_ of silver. Therefore, each _centumpondium_ of this contains a third of a _libra_ and a _semi-uncia_, a _drachma_, and the twenty-third part of a _drachma_ of silver; from such copper it is profitable to separate the silver. In order that the master may be more certain of the number of _centumpondia_ of copper in the "bottoms," he weighs the "tops" that have been drawn off from it; the "tops" were first drawn off into the dipping-pot, and cakes were made from them. Fourteen hours are expended on the work of thus dividing the copper. The "bottoms," when a certain weight of lead has been added to them, of which alloy I shall soon speak, are melted in the blast furnace; liquation cakes are then made, and the silver is afterward separated from the copper. The "tops" are subsequently melted in the blast furnace, and re-melted in the refining furnace, in order that red copper shall be made[16]; and the "tops" from this are again smelted in the blast furnace, and then again in the refining furnace, that therefrom shall be made _caldarium_ copper. But when the copper, yellow or red or _caldarium_ is re-smelted in the refining furnace, forty _centumpondia_ are placed in it, and from it they make at least twenty, and at most thirty-five, _centumpondia_. About twenty-two _centumpondia_ of exhausted liquation cakes and ten of yellow copper and eight of red, are simultaneously placed in this latter furnace and smelted, in order that they may be made into refined copper.

The copper "bottoms" are alloyed in three different ways with lead.[17] First, five-eighths of a _centumpondium_ of copper and two and three-quarters _centumpondia_ of lead are taken; and since one liquation cake is made from this, therefore two and a half _centumpondia_ of copper and eleven _centumpondia_ of lead make four liquation cakes. Inasmuch as in each _centumpondium_ of copper there is a third of a _libra_ of silver, there would be in the whole of the copper ten-twelfths of a _libra_ of silver; to these are added four _centumpondia_ of lead re-melted from "slags," each _centumpondium_ of which contains a _sicilicus_ and a _drachma_ of silver, which weights make up a total of an _uncia_ and a half of silver. There is also added seven _centumpondia_ of de-silverized lead, in each _centumpondium_ of which there is a _drachma_ of silver; therefore in the four cakes of copper-lead alloy there is a total of a _libra_, a _sicilicus_ and a _drachma_ of silver. In each single _centumpondium_ of lead, after it has been liquated from the copper, there is an _uncia_ and a _drachma_ of silver, which alloy we call "poor" argentiferous lead, because it contains but little silver. But as five cakes of that kind are placed together in the furnace, they liquate from them usually as much as nine and three-quarters _centumpondia_ of poor argentiferous lead, in each _centumpondium_ of which there is an _uncia_ and a _drachma_ of silver, or a total of ten _unciae_ less four _drachmae_. Of the liquation thorns there remain three _centumpondia_, in each _centumpondium_ of which there are three _sicilici_ of silver; and there remain four _centumpondia_ of exhausted liquation cakes, each _centumpondium_ of which contains a _semi-uncia_ or four and a half _drachmae_. Inasmuch as in a _centumpondium_ of copper "bottoms" there is a third of a _libra_ and a _semi-uncia_ of silver, in five of those cakes there must be more than one and a half _unciae_ and half a _drachma_ of silver.

Then, again, from another two and a half _centumpondia_ of copper "bottoms," together with eleven _centumpondia_ of lead, four liquation cakes are made. If in each _centumpondium_ of copper there was a third of a _libra_ of silver, there would be in the whole of the _centumpondia_ of base metal five-sixths of a _libra_ of the precious metal. To this copper is added eight _centumpondia_ of poor argentiferous lead, each _centumpondium_ of which contains an _uncia_ and a _drachma_ of silver, or a total of three-quarters of a _libra_ of silver. There is also added three _centumpondia_ of de-silverized lead, in each _centumpondium_ of which there is a _drachma_ of silver. Therefore, four liquation cakes contain a total of a _libra_, seven _unciae_, a _sicilicus_ and a _drachma_ of silver; thus each _centumpondium_ of lead, when it has been liquated from the copper, contains an _uncia_ and a half and a _sicilicus_ of silver, which alloy we call "medium" silver-lead.

Then, again, from another two and a half _centumpondia_ of copper "bottoms," together with eleven _centumpondia_ of lead, they make four liquation cakes. If in each _centumpondium_ of copper there were likewise a third of a _libra_ of silver, there will be in all the weight of the base metal five-sixths of a _libra_ of the precious metal. To this is added nine _centumpondia_ of medium silver-lead, each _centumpondium_ of which contains an _uncia_ and a half and a _sicilicus_ of silver; or a total of a _libra_ and a quarter and a _semi-uncia_ and a _sicilicus_ of silver. And likewise they add two _centumpondia_ of poor silver-lead, in each of which there is an _uncia_ and a _drachma_ of silver. Therefore the four liquation cakes contain two and a third _librae_ of silver. Each _centumpondium_ of lead, when it has been liquated from the copper, contains a sixth of a _libra_ and a _semi-uncia_ and a _drachma_ of silver. This alloy we call "rich" silver-lead; it is carried to the cupellation furnace, in which lead is separated from silver. I have now mentioned in how many ways copper containing various proportions of silver is alloyed with lead, and how they are melted together in the furnace and run into the casting pan.

[Illustration 514 (Crane for liquation cakes): A--Crane. B--Drum consisting of rundles. C--Toothed drum. D--Trolley and its wheels. E--Triangular board. F--Cakes. G--Chain of the crane. H--Its hook. I--Ring. K--The tongs.]

Now I will speak of the method by which lead is liquated from copper simultaneously with the silver. The liquation cakes are raised from the ground with the crane, and placed on the copper plates of the furnaces. The hook of the chain let down from the arm of the crane, is inserted in a ring of the tongs, one jaw of which has a tooth; a ring is engaged in each of the handles of the tongs, and these two rings are engaged in a third, in which the hook of the chain is inserted. The tooth on the one jaw of the tongs is struck by a hammer, and driven into the hole in the cake, at the point where the straight end of the hook was driven into it when it was lifted out of the copper mould; the other jaw of the tongs, which has no tooth, squeezes the cake, lest the tooth should fall out of it; the tongs are one and a half feet long, each ring is a digit and a half thick, and the inside is a palm and two digits in diameter. Those cranes by which the cakes are lifted out of the copper pans and placed on the ground, and lifted up again from there and placed in the furnaces, are two in number--one in the middle space between the third transverse wall and the two upright posts, and the other in the middle space between the same posts and the seventh transverse wall. The rectangular crane-post of both of these is two feet wide and thick, and is eighteen feet from the third long wall, and nineteen from the second long wall. There are two drums in the framework of each--one drum consisting of rundles, the other being toothed. The crane-arm of each extends seventeen feet, three palms and as many digits from the post. The trolley of each crane is two feet and as many palms long, a foot and two digits wide, and a palm and two digits thick; but where it runs between the beams of the crane-arm it is three digits wide and a palm thick; it has five notches, in which turn five brass wheels, four of which are small, and the fifth much larger than the rest. The notches in which the small wheels turn are two palms long and as much as a palm wide; those wheels are a palm wide and a palm and two digits in diameter; four of the notches are near the four corners of the trolley; the fifth notch is between the two front ones, and it is two palms back from the front. Its pulley is larger than the rest, and turns in its own notch; it is three palms in diameter and one palm wide, and grooved on the circumference, so that the iron chain may run in the groove. The trolley has two small axles, to the one in front are fastened three, and to the one at the back, the two wheels; two wheels run on the one beam of the crane-arm, and two on the other; the fifth wheel, which is larger than the others, runs between those two beams. Those people who have no cranes place the cakes on a triangular board, to which iron cleats are affixed, so that it will last longer; the board has three iron chains, which are fixed in an iron ring at the top; two workmen pass a pole through the ring and carry it on their shoulders, and thus take the cake to the furnace in which silver is separated from copper.

From the vicinity of the furnaces in which copper is mixed with lead and the "slags" are re-melted, to the third long wall, are likewise ten furnaces, in which silver mixed with lead is separated from copper. If this space is eighty feet and two palms long, and the third long wall has in the centre a door three feet and two palms wide, then the spaces remaining at either side of the door will be thirty-eight feet and two palms; and if each of the furnaces occupies four feet and a palm, then the interval between each furnace and the next one must be a foot and three palms; thus the width of the five furnaces and four interspaces will be twenty-eight feet and a palm. Therefore, there remain ten feet and a palm, which measurement is so divided that there are five feet and two digits between the first furnace and the transverse wall, and as many feet and digits between the fifth furnace and the door; similarly in the other part of the space from the door to the sixth furnace, there must be five feet and two digits, and from the tenth furnace to the seventh transverse wall, likewise, five feet and two digits. The door is six feet and two palms high; through it the foreman of the _officina_ and the workmen enter the store-room in which the silver-lead alloy is kept.

[Illustration 517 (Liquation Furnace): A--Sole-stones. B--Rectangular stones. C--Copper plates. D--Front panel. E--Side panels. F--Bar. G--Front end of the long iron rods. H--Short chain. I--Hooked rod. K--Wall which protects the third long wall from injury by fire. L--Third long wall. M--Feet of the panels. N--Iron blocks. O--Cakes. P--Hearth. Q--Receiving-pit.]

Each furnace has a bed, a hearth, a rear wall, two sides and a front, and a receiving-pit. The bed consists of two sole-stones, four rectangular stones, and two copper plates; the sole-stones are five feet and a palm long, a cubit wide, a foot and a palm thick, and they are sunk into the ground, so that they emerge a palm and two digits; they are distant from each other about three palms, yet the distance is narrower at the back than the front. Each of the rectangular stones is two feet and as many palms long, a cubit wide, and a cubit thick at the outer edge, and a foot and a palm thick on the inner edge which faces the hearth, thus they form an incline, so that there is a slope to the copper plates which are laid upon them. Two of these rectangular stones are placed on one sole-stone; a hole is cut in the upper edge of each, and into the holes are placed iron clamps, and lead is poured in; they are so placed on the sole-stones that they project a palm at the sides, and at the front the sole-stones project to the same extent; if rectangular stones are not available, bricks are laid in their place. The copper plates are four feet two palms and as many digits long, a cubit wide, and a palm thick; each edge has a protuberance, one at the front end, the other at the back; these are a palm and three digits long, and a palm wide and thick. The plates are so laid upon the rectangular stones that their rear ends are three digits from the third long wall; the stones project beyond the plate the same number of digits in front, and a palm and three digits at the sides. When the plates have been joined, the groove which is between the protuberances is a palm and three digits wide, and four feet long, and through it flows the silver-lead which liquates from the cakes. When the plates are corroded either by the fire or by the silver-lead, which often adheres to them in the form of stalactites, and is chipped off, they are exchanged, the right one being placed to the left, and the left one, on the contrary, to the right; but the left side of the plates, which, when the fusion of the copper took place, came into contact with the copper, must lie flat; so that when the exchange of the plates has been carried out, the protuberances, which are thus on the underside, raise the plate from the stones, and they have to be partially chipped off, lest they should prove an impediment to the work; and in each of their places is laid a piece of iron, three palms long, a digit thick at both ends, and a palm thick in the centre for the length of a palm and three digits.

The passage under the plates between the rectangular stones is a foot wide at the back, and a foot and a palm wide at the front, for it gradually widens out. The hearth, which is between the sole-stones, is covered with a bed of hearth-lead, taken from the crucible in which lead is separated from silver. The rear end is the highest, and should be so high that it reaches to within six digits of the plates, from which point it slopes down evenly to the front end, so that the argentiferous lead alloy which liquates from the cakes can flow into the receiving-pit. The wall built against the third long wall in order to protect it from injury by fire, is constructed of bricks joined together with lute, and stands on the copper plates; this wall is two feet, a palm and two digits high, two palms thick, and three feet, a palm and three digits wide at the bottom, for it reaches across both of them; at the top it is three feet wide, for it rises up obliquely on each side. At each side of this wall, at a height of a palm and two digits above the top of it, there is inserted in a hole in the third long wall a hooked iron rod, fastened in with molten lead; the rod projects two palms from the wall, and is two digits wide and one digit thick; it has two hooks, the one at the side, the other at the end. Both of these hooks open toward the wall, and both are a digit thick, and both are inserted in the last, or the adjacent, links of a short iron chain. This chain consists of four links, each of which is a palm and a digit long and half a digit thick; the first link is engaged in the first hole in a long iron rod, and one or other of the remaining three links engages the hook of the hooked rod. The two long rods are three feet and as many palms and digits long, two digits wide, and one digit thick; both ends of both of these rods have holes, the back one of which is round and a digit in diameter, and in this is engaged the first link of the chain as I have stated; the hole at the front end is two digits and a half long and a digit and a half wide. This end of each rod is made three digits wide, while for the rest of its length it is only two digits, and at the back it is two and a half digits. Into the front hole of each rod is driven an iron bar, which is three feet and two palms long, two digits wide and one thick; in the end of this bar are five small square holes, two-thirds of a digit square; each hole is distant from the other half a digit, the first being at a distance of about a digit from the end. Into one of these holes the refiner drives an iron pin; if he should desire to make the furnace narrower, then he drives it into the last hole; if he should desire to widen it, then into the first hole; if he should desire to contract it moderately, then into one of the middle holes. For the same reason, therefore, the hook is sometimes inserted into the last link of the chain, and sometimes into the third or the second. The furnace is widened when many cakes are put into it, and contracted when there are but few, but to put in more than five is neither usual nor possible; indeed, it is because of thin cakes that the walls are contracted. The bar has a hump, which projects a digit on each side at the back, of the same width and thickness as itself. These humps project, lest the bar should slip through the hole of the right-hand rod, in which it remains fixed when it, together with the rods, is not pressing upon the furnace walls.

[Illustration 519 (Liquation Furnaces): A--Furnace in which the operation of liquation is being performed. B--Furnace in which it is not being performed. C--Receiving-pit. D--Moulds. E--Cakes. F--Liquation thorns.]

There are three panels to the furnace--two at the sides, one in front and another at the back. Those which are at the sides are three feet and as many palms and two digits long, and two feet high; the front one is two feet and a palm and three digits long, and, like the side ones, two feet high. Each consists of iron bars, of feet, and of iron plates. Those which are at the side have seven bars, the lower and upper of which are of the same length as the panels; the former holds up the upright bars; the latter is placed upon them; the uprights are five in number, and have the same height as the panels; the middle ones are inserted into holes in the upper and lower bars; the outer ones are made of one and the same bar as the lower and upper ones. They are two digits wide and one thick. The front panel has five bars; the lower one holds similar uprights, but there are three of them only; the upper bar is placed on them. Each of these panels has two feet fixed at each end of the lower bar, and these are two palms long, one wide, and a digit thick. The iron plates are fastened to the inner side of the bars with iron wire, and they are covered with lute, so that they may last longer and may be uninjured by the fire. There are, besides, iron blocks three palms long, one wide, and a digit and a half thick; the upper surface of these is somewhat hollowed out, so that the cakes may stand in them; these iron blocks are dipped into a vessel in which there is clay mixed with water, and they are used only for placing under the cakes of copper and lead alloy made in the furnaces. There is more silver in these than in those which are made of liquation thorns, or furnace accretions, or re-melted "slags." Two iron blocks are placed under each cake, in order that, by raising it up, the fire may bring more force to bear upon it; the one is put on the right bed-plate, the other on the left. Finally, outside the hearth is the receiving-pit, which is a foot wide and three palms deep; when this is worn away it is restored with lute alone, which easily retains the lead alloy.

If four liquation cakes are placed on the plates of each furnace, then the iron blocks are laid under them; but if the cakes are made from copper "bottoms," or from liquation thorns, or from the accretions or "slags," of which I have partly written above and will further describe a little later, there are five of them, and because they are not so large and heavy, no blocks are placed under them. Pieces of charcoal six digits long are laid between the cakes, lest they should fall one against the other, or lest the last one should fall against the wall which protects the third long wall from injury by fire. In the middle empty spaces, long and large pieces of charcoal are likewise laid. Then when the panels have been set up, and the bar has been closed, the furnace is filled with small charcoal, and a wicker basket full of charcoal is thrown into the receiving-pit, and over that are thrown live coals; soon afterward the burning coal, lifted up in a shovel, is spread over all parts of the furnace, so that the charcoal in it may be kindled; any charcoal which remains in the receiving-pit is thrown into the passage, so that it may likewise be heated. If this has not been done, the silver-lead alloy liquated from the cakes is frozen by the coldness of the passage, and does not run down into the receiving-pit.

After a quarter of an hour the cakes begin to drip silver-lead alloy,[18] which runs down through the openings between the copper plates into the passage. When the long pieces of charcoal have burned up, if the cakes lean toward the wall, they are placed upright again with a hooked bar, but if they lean toward the front bar they are propped up by charcoal; moreover, if some cakes shrink more than the rest, charcoal is added to the former and not to the others. The silver drips together with the lead, for both melt more rapidly than copper. The liquation thorns do not flow away, but remain in the passage, and should be turned over frequently with a hooked bar, in order that the silver-lead may liquate away from them and flow down into the receiving pit; that which remains is again melted in the blast furnace, while that which flows into the receiving pit is at once carried with the remaining products to the cupellation furnace, where the lead is separated from the silver. The hooked bar has an iron handle two feet long, in which is set a wooden one four feet long. The silver-lead which runs out into the receiving-pit is poured out by the refiner with a bronze ladle into eight copper moulds, which are two palms and three digits in diameter; these are first smeared with a lute wash so that the cakes of silver-lead may more easily fall out when they are turned over. If the supply of moulds fails because the silver-lead flows down too rapidly into the receiving-pit, then water is poured on them, in order that the cakes may cool and be taken out of them more rapidly; thus the same moulds may be used again immediately; if no such necessity urges the refiner, he washes over the empty moulds with a lute wash. The ladle is exactly similar to that which is used in pouring out the metals that are melted in the blast furnace. When all the silver-lead has run down from the passage into the receiving-pit, and has been poured out into copper moulds, the thorns are drawn out of the passage into the receiving-pit with a rabble; afterward they are raked on to the ground from the receiving-pit, thrown with a shovel into a wheelbarrow, and, having been conveyed away to a heap, are melted once again. The blade of the rabble is two palms and as many digits long, two palms and a digit wide, and joined to its back is an iron handle three feet long; into the iron handle is inserted a wooden one as many feet in length.

The residue cakes, after the silver-lead has been liquated from the copper, are called "exhausted liquation cakes" (_fathiscentes_), because when thus smelted they appear to be dried up. By placing a crowbar under the cakes they are raised up, seized with tongs, and placed in the wheelbarrow; they are then conveyed away to the furnace in which they are "dried." The crowbar is somewhat similar to those generally used to chip off the accretions that adhere to the walls of the blast furnace. The tongs are two and a half feet long. With the same crowbar the stalactites are chipped off from the copper plates from which they hang, and with the same instrument the iron blocks are struck off the exhausted liquation cakes to which they adhere. The refiner has performed his day's task when he has liquated the silver-lead from sixteen of the large cakes and twenty of the smaller ones; if he liquates more than this, he is paid separately for it at the price for extraordinary work.

Silver, or lead mixed with silver, which we call _stannum_, is separated by the above method from copper. This silver-lead is carried to the cupellation furnace, in which lead is separated from silver; of these methods I will mention only one, because in the previous book I have explained them in detail. Amongst us some years ago only forty-four _centumpondia_ of silver-lead and one of copper were melted together in the cupellation furnaces, but now they melt forty-six _centumpondia_ of silver-lead and one and a half _centumpondia_ of copper; in other places, usually a hundred and twenty _centumpondia_ of silver-lead alloy and six of copper are melted, in which manner they make about one hundred and ten _centumpondia_ more or less of litharge and thirty of hearth-lead. But in all these methods the silver which is in the copper is mixed with the remainder of silver; the copper itself, equally with the lead, will be changed partly into litharge and partly into hearth-lead.[19] The silver-lead alloy which does not melt is taken from the margin of the crucible with a hooked bar.

[Illustration 522 (Exhausted Liquation Cakes): A--Cakes. B--Hammer.]

The work of "drying" is distributed into four operations, which are performed in four days. On the first--as likewise on the other three days--the master begins at the fourth hour of the morning, and with his assistant chips off the stalactites from the exhausted liquation cakes. They then carry the cakes to the furnace, and put the stalactites upon the heap of liquation thorns. The head of the chipping hammer is three palms and as many digits long; its sharp edge is a palm wide; the round end is three digits thick; the wooden handle is four feet long.

The master throws pulverised earth into a small vessel, sprinkles water over it, and mixes it; this he pours over the whole hearth, and sprinkles charcoal dust over it to the thickness of a digit. If he should neglect this, the copper, settling in the passages, would adhere to the copper bed-plates, from which it can be chipped off only with difficulty; or else it would adhere to the bricks, if the hearth was covered with them, and when the copper is chipped off these they are easily broken. On the second day, at the same time, the master arranges bricks in ten rows; in this manner twelve passages are made. The first two rows of bricks are between the first and the second openings on the right of the furnace; the next three rows are between the second and third openings, the following three rows are between the third and the fourth openings, and the last two rows between the fourth and fifth openings. These bricks are a foot and a palm long, two palms and a digit wide, and a palm and two digits thick; there are seven of these thick bricks in a row, so there are seventy all together. Then on the first three rows of bricks they lay exhausted liquation cakes and a layer five digits thick of large charcoal; then in a similar way more exhausted liquation cakes are laid upon the other bricks, and charcoal is thrown upon them; in this manner seventy _centumpondia_ of cakes are put on the hearth of the furnace. But if half of this weight, or a little more, is to be "dried," then four rows of bricks will suffice. Those who dry exhausted liquation cakes[20] made from copper "bottoms" place ninety or a hundred _centumpondia_[21] into the furnace at the same time. A place is left in the front part of the furnace for the topmost cakes removed from the forehearth in which copper is made, these being more suitable for supporting the exhausted liquation cakes than are iron plates; indeed, if the former cakes drip copper from the heat, this can be taken back with the liquation thorns to the first furnace, but melted iron is of no use to us in these matters. When the cakes of this kind have been placed in front of the exhausted liquation cakes, the workman inserts the iron bar into the holes on the inside of the wall, which are at a height of three palms and two digits above the hearth; the hole to the left penetrates through into the wall, so that the bar may be pushed back and forth. This bar is round, eight feet long and two digits in diameter; on the right side it has a haft made of iron, which is about a foot from the right end; the aperture in this haft is a palm wide, two digits high, and a digit thick. The bar holds the exhausted liquation cakes opposite, lest they should fall down. When the operation of "drying" is completed, a workman draws out this bar with a crook which he inserts into the haft, as I will explain hereafter.

[Illustration 525 (Drying Furnace for Liquation): A--Side walls. B--Front arch. C--Rear arch. D--Wall in the rear arch. E--Inner wall. F--Vent holes. G--Chimney. H--Hearth. I--Tank. K--Pipe. L--Plug. M--Iron door. N--Transverse bars. O--Upright bars. P--Plates. Q--Rings of the bars. R--Chains. S--Rows of bricks. T--Bar. V--Its haft. X--Copper bed-plates.]

In order that one should understand those things of which I have spoken, and concerning which I am about to speak, it is necessary for me to give some information beforehand about the furnace and how it is to be made. It stands nine feet from the fourth long wall, and as far from the wall which is between the second and fourth transverse walls. It consists of walls, an arch, a chimney, an interior wall, and a hearth; the two walls are at the sides; and they are eleven feet three palms and two digits long, and where they support the chimney they are eight feet and a palm high. At the front of the arch they are only seven feet high; they are two feet three palms and two digits thick, and are made either of rock or of bricks; the distance between them is eight feet, a palm and two digits. There are two of the arches, for the space at the rear between the walls is also arched from the ground, in order that it may be able to support the chimney; the foundations of these arches are the walls of the furnace; the span of the arch has the same length as the space between the walls; the top of the arch is five feet, a palm and two digits high. In the rear arch there is a wall made of bricks joined with lime; this wall at a height of a foot and three palms from the ground has five vent-holes, which are two palms and a digit high, a palm and a digit wide, of which the first is near the right interior wall, and the last near the left interior wall, the remaining three in the intervening space; these vent-holes penetrate through the interior of the wall which is in the arch. Half-bricks can be placed over the vent-holes, lest too much air should be drawn into the furnace, and they can be taken out at times, in order that he who is "drying" the exhausted liquation cakes may inspect the passages, as they are called, to see whether the cakes are being properly "dried." The front arch is three feet two palms distant from the rear one; this arch is the same thickness as that of the rear arch, but the span is six feet wide; the interior of the arch itself is of the same height as the walls. A chimney is built upon the arches and the walls, and is made of bricks joined together with lime; it is thirty-six feet high and penetrates through the roof. The interior wall is built against the rear arch and both the side walls, from which it juts out a foot; it is three feet and the same number of palms high, three palms thick, and is made of bricks joined together with lute and smeared thickly with lute, sloping up to the height of a foot above it. This wall is a kind of shield, for it protects the exterior walls from the heat of the fire, which is apt to injure them; the latter cannot be easily re-made, while the former can be repaired with little work.

The hearth is made of lute, and is covered either with copper plates, such as those of the furnaces in which silver is liquated from copper, although they have no protuberances, or it may be covered with bricks, if the owners are unwilling to incur the expense of copper plates. The wider part of the hearth is made sloping in such a manner that the rear end reaches as high as the five vent-holes, and the front end of the hearth is so low that the back of the front arch is four feet, three palms and as many digits above it, and the front five feet, three palms and as many digits. The hearth beyond the furnaces is paved with bricks for a distance of six feet. Near the furnace, against the fourth long wall, is a tank thirteen feet and a palm long, four feet wide, and a foot and three palms deep. It is lined on all sides with planks, lest the earth should fall into it; on one side the water flows in through pipes, and on the other, if the plug be pulled out, it soaks into the earth; into this tank of water are thrown the cakes of copper from which the silver and lead have been separated. The fore part of the front furnace arch should be partly closed with an iron door; the bottom of this door is six feet and two digits wide; the upper part is somewhat rounded, and at the highest point, which is in the middle, it is three feet and two palms high. It is made of iron bars, with plates fastened to them with iron wire, there being seven bars--three transverse and four upright--each of which is two digits wide and half a digit thick. The lowest transverse bar is six feet and two palms long; the middle one has the same length; the upper one is curved and higher at the centre, and thus longer than the other two. The upright bars are two feet distant from one another; both the outer ones are two feet and as many palms high; but the centre ones are three feet and two palms. They project from the upper curved transverse bar and have holes, in which are inserted the hooks of small chains two feet long; the topmost links of these chains are engaged in the ring of a third chain, which, when extended, reaches to one end of a beam which is somewhat cut out. The chain then turns around the beam, and again hanging down, the hook in the other end is fastened in one of the links. This beam is eleven feet long, a palm and two digits wide, a palm thick, and turns on an iron axle fixed in a nearby timber; the rear end of the beam has an iron pin, which is three palms and a digit long, and which penetrates through it where it lies under a timber, and projects from it a palm and two digits on one side, and three digits on the other side. At this point the pin is perforated, in order that a ring may be fixed in it and hold it, lest it should fall out of the beam; that end is hardly a digit thick, while the other round end is thicker than a digit. When the door is to be shut, this pin lies under the timber and holds the door so that it cannot fall; the pin likewise prevents the rectangular iron band which encircles the end of the beam, and into which is inserted the ring of a long hook, from falling from the end. The lowest link of an iron chain, which is six feet long, is inserted in the ring of a staple driven into the right wall of the furnace, and fixed firmly by filling in with molten lead. The hook suspended at the top from the ring should be inserted in one of these lower links, when the door is to be raised; when the door is to be let down, the hook is taken out of that link and put into one of the upper links.

[Illustration 527 (Drying Furnace for Liquation): A--The door let down. B--Bar. C--Exhausted liquation cakes. D--Bricks. E--Tongs.]

On the third day the master sets about the principal operation. First he throws a basketful of charcoals on to the ground in front of the hearth, and kindles them by adding live coals, and having thrown live coals on to the cakes placed within, he spreads them equally all over with an iron shovel. The blade of the shovel is three palms and a digit long, and three palms wide; its iron handle is two palms long, and the wooden one ten feet long, so that it can reach to the rear wall of the furnace. The exhausted liquation cakes become incandescent in an hour and a half, if the copper was good and hard, or after two hours, if it was soft and fragile. The workman adds charcoal to them where he sees it is needed, throwing it into the furnace through the openings on both sides between the side walls and the closed door. This opening is a foot and a palm wide. He lets down the door, and when the "slags" begin to flow he opens the passages with a bar; this should take place after five hours; the door is let down over the upper open part of the arch for two feet and as many digits, so that the master can bear the violence of the heat. When the cakes shrink, charcoal should not be added to them lest they should melt. If the cakes made from poor and fragile copper are "dried" with cakes made from good hard copper, very often the copper so settles into the passages that a bar thrust into them cannot penetrate them. This bar is of iron, six feet and two palms long, into which a wooden handle five feet long is inserted. The refiner draws off the "slags" with a rabble from the right side of the hearth. The blade of the rabble is made of an iron plate a foot and a palm wide, gradually narrowing toward the handle; the blade is two palms high, its iron handle is two feet long, and the wooden handle set into it is ten feet long.

[Illustration 528 (Drying Furnace for Liquation): A--The door raised. B--Hooked bar. C--Two-pronged rake. D--Tongs. E--Tank.]

When the exhausted liquation cakes have been "dried," the master raises the door in the manner I have described, and with a long iron hook inserted into the haft of the bar he draws it through the hole in the left wall from the hole in the right wall; afterward he pushes it back and replaces it. The master then takes out the exhausted liquation cakes nearest to him with the iron hook; then he pulls out the cakes from the bricks. This hook is two palms high, as many digits wide, and one thick; its iron handle is two feet long, and the wooden handle eleven feet long. There is also a two-pronged rake with which the "dried" cakes are drawn over to the left side so that they may be seized with tongs; the prongs of the rake are pointed, and are two palms long, as many digits wide, and one digit thick; the iron part of the handle is a foot long, the wooden part nine feet long. The "dried" cakes, taken out of the hearth by the master and his assistants, are seized with other tongs and thrown into the rectangular tank, which is almost filled with water. These tongs are two feet and three palms long, both the handles are round and more than a digit thick, and the ends are bent for a palm and two digits; both the jaws are a digit and a half wide in front and sharpened; at the back they are a digit thick, and then gradually taper, and when closed, the interior is two palms and as many digits wide.

The "dried" cakes which are dripping copper are not immediately dipped into the tank, because, if so, they burst in fragments and give out a sound like thunder. The cakes are afterward taken out of the tank with the tongs, and laid upon the two transverse planks on which the workmen stand; the sooner they are taken out the easier it is to chip off the copper that has become ash-coloured. Finally, the master, with a spade, raises up the bricks a little from the hearth, while they are still warm. The blade of the spade is a palm and two digits long, the lower edge is sharp, and is a palm and a digit wide, the upper end a palm wide; its handle is round, the iron part being two feet long, and the wooden part seven and a half feet long.

On the fourth day the master draws out the liquation thorns which have settled in the passages; they are much richer in silver than those that are made when the silver-lead is liquated from copper in the liquation furnace. The "dried" cakes drip but little copper, but nearly all their remaining silver-lead and the thorns consist of it, for, indeed, in one _centumpondium_ of "dried" copper there should remain only half an _uncia_ of silver, and there sometimes remain only three _drachmae_.[22] Some smelters chip off the metal adhering to the bricks with a hammer, in order that it may be melted again; others, however, crush the bricks under the stamps and wash them, and the copper and lead thus collected is melted again. The master, when he has taken these things away and put them in their places, has finished his day's work.

[Illustration 530 (Dried Liquation Cakes): A--Tank. B--Board. C--Tongs. D--"Dried" cakes taken out of the tanks. E--Block. F--Rounded hammer. G--Pointed hammer.]

The assistants take the "dried" cakes out of the tank on the next day, place them on an oak block, and first pound them with rounded hammers in order that the ash-coloured copper may fall away from them, and then they dig out with pointed picks the holes in the cakes, which contain the same kind of copper. The head of the round hammer is three palms and a digit long; one end of the head is round and two digits long and thick; the other end is chisel-shaped, and is two digits and a half long. The sharp pointed hammer is the same length as the round hammer, but one end is pointed, the other end is square, and gradually tapers to a point.

The nature of copper is such that when it is "dried" it becomes ash coloured, and since this copper contains silver, it is smelted again in the blast furnaces.[23]

[Illustration 532 (Copper Refining Furnace): A--Hearth of the furnace. B--Chimney. C--Common pillar. D--Other pillars. The partition wall is behind the common pillar and not to be seen. E--Arches. F--Little walls which protect the partition wall from injury by the fire. G--Crucibles. H--Second long wall. I--Door. K--Spatula. L--The other spatula. M--The broom in which is inserted a stick. N--Pestles. O--Wooden mallet. P--Plate. Q--Stones. R--Iron rod.]

I have described sufficiently the method by which exhausted liquation cakes are "dried"; now I will speak of the method by which they are made into copper after they have been "dried." These cakes, in order that they may recover the appearance of copper which they have to some extent lost, are melted in four furnaces, which are placed against the second long wall in the part of the building between the second and third transverse walls. This space is sixty-three feet and two palms long, and since each of these furnaces occupies thirteen feet, the space which is on the right side of the first furnace, and on the left of the fourth, are each three feet and three palms wide, and the distance between the second and third furnace is six feet. In the middle of each of these three spaces is a door, a foot and a half wide and six feet high, and the middle one is common to the master of each of the furnaces. Each furnace has its own chimney, which rises between the two long walls mentioned above, and is supported by two arches and a partition wall. The partition wall is between the two furnaces, and is five feet long, ten feet high, and two feet thick; in front of it is a pillar belonging in common to the front arches of the furnace on either side, which is two feet and as many palms thick, three feet and a half wide. The front arch reaches from this common pillar to another pillar that is common to the side arch of the same furnace; this arch on the right spans from the second long wall to the same pillar, which is two feet and as many palms wide and thick at the bottom. The interior of the front arch is nine feet and a palm wide, and eight feet high at its highest point; the interior of the arch which is on the right side, is five feet and a palm wide, and of equal height to the other, and both the arches are built of the same height as the partition wall. Imposed upon these arches and the

## partition wall are the walls of the chimney; these slope upward, and

thus contract, so that at the upper part, where the fumes are emitted, the opening is eight feet in length, one foot and three palms in width. The fourth wall of the chimney is built vertically upon the second long wall. As the partition wall is common to the two furnaces, so its superstructure is common to the two chimneys. In this sensible manner the chimney is built. At the front each furnace is six feet two palms long, and three feet two palms wide, and a cubit high; the back of each furnace is against the second long wall, the front being open. The first furnace is open and sloping at the right side, so that the slags may be drawn out; the left side is against the partition wall, and has a little wall built of bricks cemented together with lute; this little wall protects the partition wall from injury by the fire. On the contrary, the second furnace has the left side open and the right side is against the partition wall, where also it has its own little wall which protects the partition wall from the fire. The front of each furnace is built of rectangular rocks; the interior of it is filled up with earth. Then in each of the furnaces at the rear, against the second long wall, is an aperture through an arch at the back, and in these are fixed the copper pipes. Each furnace has a round pit, two feet and as many palms wide, built three feet away from the partition wall. Finally, under the pit of the furnace, at a depth of a cubit, is the hidden receptacle for moisture, similar to the others, whose vent penetrates through the second long wall and slopes upward to the right from the first furnace, and to the left from the second. If copper is to be made the next day, then the master cuts out the crucible with a spatula, the blade of which is three digits wide and as many palms long, the iron handle being two feet long and one and a half digits in diameter; the wooden handle inserted into it is round, five feet long and two digits in diameter. Then, with another cutting spatula, he makes the crucible smooth; the blade of this spatula is a palm wide and two palms long; its handle,

## partly of iron, partly of wood, is similar in every respect to the first

one. Afterward he throws pulverised clay and charcoal into the crucible, pours water over it, and sweeps it over with a broom into which a stick is fixed. Then immediately he throws into the crucible a powder, made of two wheelbarrowsful of sifted charcoal dust, as many wheelbarrowsful of pulverised clay likewise sifted, and six basketsful of river sand which has passed through a very fine sieve. This powder, like that used by smelters, is sprinkled with water and moistened before it is put into the crucible, so that it may be fashioned by the hands into shapes similar to snowballs. When it has been put in, the master first kneads it and makes it smooth with his hands, and then pounds it with two wooden pestles, each of which is a cubit long; each pestle has a round head at each end, but one of these is a palm in diameter, the other three digits; both are thinner in the middle, so that they may be held in the hand. Then he again throws moistened powder into the crucible, and again makes it smooth with his hands, and kneads it with his fists and with the pestles; then, pushing upward and pressing with his fingers, he makes the edge of the crucible smooth. After the crucible has been made smooth, he sprinkles in dry charcoal dust, and again pounds it with the same pestles, at first with the narrow heads, and afterward with the wider ones. Then he pounds the crucible with a wooden mallet two feet long, both heads of which are round and three digits in diameter; its wooden handle is two palms long, and one and a half digits in diameter. Finally, he throws into the crucible as much pure sifted ashes as both hands can hold, and pours water into it, and, taking an old linen rag, he smears the crucible over with the wet ashes. The crucible is round and sloping. If copper is to be made from the best quality of "dried" cakes, it is made two feet wide and one deep, but if from other cakes, it is made a cubit wide and two palms deep. The master also has an iron band curved at both ends, two palms long and as many digits wide, and with this he cuts off the edges of the crucible if they are higher than is necessary. The copper pipe is inclined, and projects three digits from the wall, and has its upper end and both sides smeared thick with lute, that it may not be burned; but the underside of the pipe is smeared thinly with lute, for this side reaches almost to the edge of the crucible, and when the crucible is full the molten copper touches it. The wall above the pipe is smeared over with lute, lest that should be damaged. He does the same to the other side of an iron plate, which is a foot and three palms long and a foot high; this stands on stones near the crucible at the side where the hearth slopes, in order that the slag may run out under it. Others do not place the plates upon stones, but cut out of the plate underneath a small piece, three digits long and three digits wide; lest the plate should fall, it is supported by an iron rod fixed in the wall at a height of two palms and the same number of digits, and it projects from the wall three palms.

Then with an iron shovel, whose wooden handle is six feet long, he throws live charcoal into the crucible; or else charcoal, kindled by means of a few live coals, is added to them. Over the live charcoal he lays "dried" cakes, which, if they were of copper of the first quality, weigh all together three _centumpondia_, or three and a half _centumpondia_; but if they were of copper of the second quality, then two and a half _centumpondia_; if they were of the third quality, then two _centumpondia_ only; but if they were of copper of very superior quality, then they place upon it six _centumpondia_, and in this case they make the crucible wider and deeper.[24] The lowest "dried" cake is placed at a distance of two palms from the pipe, the rest at a greater distance, and when the lower ones are melted the upper ones fall down and get nearer to the pipe; if they do not fall down they must be pushed with a shovel. The blade of the shovel is a foot long, three palms and two digits wide, the iron part of the handle is two palms long, the wooden part nine feet. Round about the "dried" cakes are placed large long pieces of charcoal, and in the pipe are placed medium-sized pieces. When all these things have been arranged in this manner, the fire must be more violently excited by the blast from the bellows. When the copper is melting and the coals blaze, the master pushes an iron bar into the middle of them in order that they may receive the air, and that the flame can force its way out. This pointed bar is two and a half feet long, and its wooden handle four feet long. When the cakes are partly melted, the master, passing out through the door, inspects the crucible through the bronze pipe, and if he should find that too much of the "slag" is adhering to the mouth of the pipe, and thus impeding the blast of the bellows, he inserts the hooked iron bar into the pipe through the nozzle of the bellows, and, turning this about the mouth of the pipe, he removes the "slags" from it. The hook on this bar is two digits high; the iron part of the handle is three feet long; the wooden part is the same number of palms long. Now it is time to insert the bar under the iron plate, in order that the "slags" may flow out. When the cakes, being all melted, have run into the crucible, he takes out a sample of copper with the third round bar, which is made wholly of iron, and is three feet long, a digit thick, and has a steel point lest its pores should absorb the copper. When he has compressed the bellows, he introduces this bar as quickly as possible into the crucible through the pipe between the two nozzles, and takes out samples two, three, or four times, until he finds that the copper is perfectly refined. If the copper is good it adheres easily to the bar, and two samples suffice; if it is not good, then many are required. It is necessary to smelt it in the crucible until the copper adhering to the bar is seen to be of a brassy colour, and if the upper as well as the lower part of the thin layer of copper may be easily broken, it signifies that the copper is perfectly melted; he places the point of the bar on a small iron anvil, and chips off the thin layer of copper from it with a hammer.[25]

[Illustration 534 (Copper Refining): A--Pointed bar. B--Thin copper layer. C--Anvil. D--Hammer.]

[Illustration 537 (Copper Refining): A--Crucible. B--Board. C--Wedge-shaped bar. D--Cakes of copper made by separating them with the wedge-shaped bar. E--Tongs. F--Tub.]

If the copper is not good, the master draws off the "slags" twice, or three times if necessary--the first time when some of the cakes have been melted, the second when all have melted, the third time when the copper has been heated for some time. If the copper was of good quality, the "slags" are not drawn off before the operation is finished, but at the time they are to be drawn off, he depresses the bar over both bellows, and places over both a stick, a cubit long and a palm wide, half cut away at the upper part, so that it may pass under the iron pin fixed at the back in the perforated wood. This he does likewise when the copper has been completely melted. Then the assistant removes the iron plate with the tongs; these tongs are four feet three palms long, their jaws are about a foot in length, and their straight part measures two palms and three digits, and the curved a palm and a digit. The same assistant, with the iron shovel, throws and heaps up the larger pieces of charcoal into that part of the hearth which is against the little wall which protects the other wall from injury by fire, and partly extinguishes them by pouring water over them. The master, with a hazel stick inserted into the crucible, stirs it twice. Afterward he draws off the slags with a rabble, which consists of an iron blade, wide and sharp, and of alder-wood; the blade is a digit and a half in width and three feet long; the wooden handle inserted in its hollow part is the same number of feet long, and the alder-wood in which the blade is fixed must have the figure of a rhombus; it must be three palms and a digit long, a palm and two digits wide, and a palm thick. Subsequently he takes a broom and sweeps the charcoal dust and small coal over the whole of the crucible, lest the copper should cool before it flows together; then, with a third rabble, he cuts off the slags which may adhere to the edge of the crucible. The blade of this rabble is two palms long and a palm and one digit wide, the iron part of the handle is a foot and three palms long, the wooden part six feet. Afterward he again draws off the slags from the crucible, which the assistant does not quench by pouring water upon them, as the other slags are usually quenched, but he sprinkles over them a little water and allows them to cool. If the copper should bubble, he presses down the bubbles with the rabble. Then he pours water on the wall and the pipes, that it may flow down warm into the crucible, for, the copper, if cold water were to be poured over it while still hot, would spatter about. If a stone, or a piece of lute or wood, or a damp coal should then fall into it, the crucible would vomit out all the copper with a loud noise like thunder, and whatever it touches it injures and sets on fire. Subsequently he lays a curved board with a notch in it over the front part of the crucible; it is two feet long, a palm and two digits wide, and a digit thick. Then the copper in the crucible should be divided into cakes with an iron wedge-shaped bar; this is three feet long, two digits wide, and steeled on the end for the distance of two digits, and its wooden handle is three feet long. He places this bar on the notched board, and, driving it into the copper, moves it forward and back, and by this means the water flows into the vacant space in the copper, and he separates the cake from the rest of the mass. If the copper is not perfectly smelted the cakes will be too thick, and cannot be taken out of the crucible easily. Each cake is afterward seized by the assistant with the tongs and plunged into the water in the tub; the first one is placed aside so that the master may re-melt it again immediately, for, since some "slags" adhere to it, it is not as perfect as the subsequent ones; indeed, if the copper is not of good quality, he places the first two cakes aside. Then, again pouring water over the wall and the pipes, he separates out the second cake, which the assistant likewise immerses in water and places on the ground together with the others separated out in the same way, which he piles upon them. These, if the copper was of good quality, should be thirteen or more in number; if it was not of good quality, then fewer. If the copper was of good quality, this part of the operation, which indeed is distributed into four parts, is accomplished by the master in two hours; if of mediocre quality, in two and a half hours; if of bad quality, in three. The "dried" cakes are re-melted, first in the first crucible and then in the second. The assistant must, as quickly as possible, quench all the cakes with water, after they have been cut out of the second crucible. Afterward with the tongs he replaces in its proper place the iron plate which was in front of the furnace, and throws the charcoal back into the crucible with a shovel. Meanwhile the master, continuing his work, removes the wooden stick from the bars of the bellows, so that in re-melting the other cakes he may accomplish the third part of his process; this must be carefully done, for if a

## particle from any iron implement should by chance fall into the

crucible, or should be thrown in by any malevolent person, the copper could not be made until the iron had been consumed, and therefore double labour would have to be expended upon it. Finally, the assistant extinguishes all the glowing coals, and chips off the dry lute from the mouth of the copper pipe with a hammer; one end of this hammer is pointed, the other round, and it has a wooden handle five feet long. Because there is danger that the copper would be scattered if the _pompholyx_ and _spodos_, which adhere to the walls and the hood erected upon them, should fall into the crucible, he cleans them off in the meantime. Every week he takes the copper flowers out of the tub, after having poured off the water, for these fall into it from the cakes when they are quenched.[26]

The bellows which this master uses differ in size from the others, for the boards are seven and a half feet long; the back part is three feet wide; the front, where the head is joined on is a foot, two palms and as many digits. The head is a cubit and a digit long; the back part of it is a cubit and a palm wide, and then becomes gradually narrower. The nozzles of the bellows are bound together by means of an iron chain, controlled by a thick bar, one end of which penetrates into the ground against the back of the long wall, and the other end passes under the beam which is laid upon the foremost perforated beams. These nozzles are so placed in a copper pipe that they are at a distance of a palm from the mouth; the mouth should be made three digits in diameter, that the air may be violently expelled through this narrow aperture.

There now remain the liquation thorns, the ash-coloured copper, the "slags," and the _cadmia_.[27] Liquation cakes are made from thorns in the following manner.[28] There are taken three-quarters of a _centumpondium_ of thorns, which have their origin from the cakes of copper-lead alloy when lead-silver is liquated, and as many parts of a _centumpondium_ of the thorns derived from cakes made from once re-melted thorns by the same method, and to them are added a _centumpondium_ of de-silverized lead and half a _centumpondium_ of hearth-lead. If there is in the works plenty of litharge, it is substituted for the de-silverized lead. One and a half _centumpondia_ of litharge and hearth-lead is added to the same weight of primary thorns, and half a _centumpondium_ of thorns which have their origin from liquation cakes composed of thorns twice re-melted by the same method (tertiary thorns), and a fourth part of a _centumpondium_ of thorns which are produced when the exhausted liquation cakes are "dried." By both methods one single liquation cake is made from three _centumpondia_. In this manner the smelter makes every day fifteen liquation cakes, more or less; he takes great care that the metallic substances, from which the first liquation cake is made, flow down properly and in due order into the forehearth, before the material of which the subsequent cake is to be made. Five of these liquation cakes are put simultaneously into the furnace in which silver-lead is liquated from copper, they weigh almost fourteen _centumpondia_, and the "slags" made therefrom usually weigh quite a _centumpondium_. In all the liquation cakes together there is usually one _libra_ and nearly two _unciae_ of silver, and in the silver-lead which drips from those cakes, and weighs seven and a half _centumpondia_, there is in each an _uncia_ and a half of silver. In each of the three _centumpondia_ of liquation thorns there is almost an _uncia_ of silver, and in the two _centumpondia_ and a quarter of exhausted liquation cakes there is altogether one and a half _unciae_; yet this varies greatly for each variety of thorns, for in the thorns produced from primary liquation cakes made of copper and lead when silver-lead is liquated from the copper, and those produced in "drying" the exhausted liquation cakes, there are almost two _unciae_ of silver; in the others not quite an _uncia_. There are other thorns besides, of which I will speak a little further on.

Those in the Carpathian Mountains who make liquation cakes from the copper "bottoms" which remain after the upper part of the copper is divided from the lower, in the furnace similar to an oven, produce thorns when the poor or mediocre silver-lead is liquated from the copper. These, together with those made of cakes of re-melted thorns, or made with re-melted litharge, are placed in a heap by themselves; but those that are made from cakes melted from hearth-lead are placed in a heap separate from the first, and likewise those produced from "drying" the exhausted liquation cakes are placed separately; from these thorns liquation cakes are made. From the first heap they take the fourth part of a _centumpondium_, from the second the same amount, from the third a _centumpondium_,--to which thorns are added one and a half _centumpondia_ of litharge and half a _centumpondium_ of hearth-lead, and from these, melted in the blast furnace, a liquation cake is made; each workman makes twenty such cakes every day. But of theirs enough has been said for the present; I will return to ours.

The ash-coloured copper[29] which is chipped off, as I have stated, from the "dried" cakes, used some years ago to be mixed with the thorns produced from liquation of the copper-lead alloy, and contained in themselves, equally with the first, two _unciae_ of silver; but now it is mixed with the concentrates washed from the accretions and the other material. The inhabitants of the Carpathian Mountains melt this kind of copper in furnaces in which are re-melted the "slags" which flow out when the copper is refined; but as this soon melts and flows down out of the furnace, two workmen are required for the work of smelting, one of whom smelts, while the other takes out the thick cakes from the forehearth. These cakes are only "dried," and from the "dried" cakes copper is again made.

The "slags"[30] are melted continually day and night, whether they have been drawn off from the alloyed metals with a rabble, or whether they adhered to the forehearth to the thickness of a digit and made it smaller and were taken off with spatulas. In this manner two or three liquation cakes are made, and afterward much or little of the "slag," skimmed from the molten alloy of copper and lead, is re-melted. Such liquation cakes should weigh up to three _centumpondia_, in each of which there is half an _uncia_ of silver. Five cakes are placed at the same time in the furnace in which argentiferous lead is liquated from copper, and from these are made lead which contains half an _uncia_ of silver to the _centumpondium_. The exhausted liquation cakes are laid upon the other baser exhausted liquation cakes, from both of which yellow copper is made. The base thorns thus obtained are re-melted with a few baser "slags," after having been sprinkled with concentrates from furnace accretions and other material, and in this manner six or seven liquation cakes are made, each of which weighs some two _centumpondia_. Five of these are placed at the same time in the furnace in which silver-lead is liquated from copper; these drip three _centumpondia_ of lead, each of which contains half an _uncia_ of silver. The basest thorns thus produced should be re-melted with only a little "slag." The copper alloyed with lead, which flows down from the furnace into the forehearth, is poured out with a ladle into oblong copper moulds; these cakes are "dried" with base exhausted liquation cakes. The thorns they produce are added to the base thorns, and they are made into cakes according to the method I have described. From the "dried" cakes they make copper, of which some add a small portion to the best "dried" cakes when copper is made from them, in order that by mixing the base copper with the good it may be sold without loss. The "slags," if they are utilisable, are re-melted a second and a third time, the cakes made from them are "dried," and from the "dried" cakes is made copper, which is mixed with the good copper. The "slags," drawn off by the master who makes copper out of "dried" cakes, are sifted, and those which fall through the sieve into a vessel placed underneath are washed; those which remain in it are emptied into a wheelbarrow and wheeled away to the blast furnaces, and they are re-melted together with other "slags," over which are sprinkled the concentrates from washing the slags or furnace accretions made at this time. The copper which flows out of the furnace into the forehearth, is likewise dipped out with a ladle into oblong copper moulds; in this way nine or ten cakes are made, which are "dried," together with bad exhausted liquation cakes, and from these "dried" cakes yellow[31] copper is made.

[Illustration 543 (Copper Refining): A--Furnace. B--Forehearth. C--Oblong moulds.]

The _cadmia_,[32] as it is called by us, is made from the "slags" which the master, who makes copper from "dried" cakes, draws off together with other re-melted base "slags"; for, indeed, if the copper cakes made from such "slags" are broken, the fragments are called _cadmia_; from this and yellow copper is made _caldarium_ copper in two ways. For either two parts of _cadmia_ are mixed with one of yellow copper in the blast furnaces, and melted; or, on the contrary, two parts of yellow copper with one of _cadmia_, so that the _cadmia_ and yellow copper may be well mixed; and the copper which flows down from the furnace into the forehearth is poured out with a ladle into oblong copper moulds heated beforehand. These moulds are sprinkled over with charcoal dust before the _caldarium_ copper is to be poured into them, and the same dust is sprinkled over the copper when it is poured in, lest the _cadmia_ and yellow copper should freeze before they have become well mixed. With a piece of wood the assistant cleanses each cake from the dust, when it is turned out of the mould. Then he throws it into the tub containing hot water, for the _caldarium_ copper is finer if quenched in hot water. But as I have so often made mention of the oblong copper moulds, I must now speak of them a little; they are a foot and a palm long, the inside is three palms and a digit wide at the top, and they are rounded at the bottom.

The concentrates are of two kinds--precious and base.[33] The first are obtained from the accretions of the blast furnace, when liquation cakes are made from copper and lead, or from precious liquation thorns, or from the better quality "slags," or from the best grade of concentrates, or from the sweepings and bricks of the furnaces in which exhausted liquation cakes are "dried"; all of these things are crushed and washed, as I explained in Book VIII. The base concentrates are made from accretions formed when cakes are cast from base thorns or from the worst quality of slags. The smelter who makes liquation cakes from the precious concentrates, adds to them three wheelbarrowsful of litharge and four barrowsful of hearth-lead and one of ash-coloured copper, from all of which nine or ten liquation cakes are melted out, of which five at a time are placed in the furnace in which silver-lead is liquated from copper; a _centumpondium_ of the lead which drips from these cakes contains one _uncia_ of silver. The liquation thorns are placed apart by themselves, of which one basketful is mixed with the precious thorns to be re-melted. The exhausted liquation cakes are "dried" at the same time as other good exhausted liquation cakes.

The thorns which are drawn off from the lead, when it is separated from silver in the cupellation furnace[34], and the hearth-lead which remains in the crucible in the middle part of the furnaces, together with the hearth material which has become defective and has absorbed silver-lead, are all melted together with a little slag in the blast furnaces. The lead, or rather the silver-lead, which flows from the furnace into the forehearth, is poured out into copper moulds such as are used by the refiners; a _centumpondium_ of such lead contains four _unciae_ of silver, or, if the hearth was defective, it contains more. A small portion of this material is added to the copper and lead when liquation cakes are made from them, if more were to be added the alloy would be much richer than it should be, for which reason the wise foreman of the works mixes these thorns with other precious thorns. The hearth-lead which remains in the middle of the crucible, and the hearth material which absorbs silver-lead, is mixed with other hearth-lead which remains in the cupellation furnace crucible; and yet some cakes, made rich in this manner, may be placed again in the cupellation furnaces, together with the rest of the silver-lead cakes which the refiner has made.

The inhabitants of the Carpathian Mountains, if they have an abundance of finely crushed copper[35] or lead either made from "slags," or collected from the furnace in which the exhausted liquation cakes are dried, or litharge, alloy them in various ways. The "first" alloy consists of two _centumpondia_ of lead melted out of thorns, litharge, and thorns made from hearth-lead, and of half a _centumpondium_ each of lead collected in the furnace in which exhausted liquation cakes are "dried," and of copper _minutum_, and from these are made liquation cakes; the task of the smelter is finished when he has made forty liquation cakes of this kind. The "second" alloy consists of two _centumpondia_ of litharge, of one and a quarter _centumpondia_ of de-silverized lead or lead from "slags," and of half a _centumpondium_ of lead made from thorns, and of as much copper _minutum_. The "third" alloy consists of three _centumpondia_ of litharge and of half a _centumpondium_ each of de-silverized lead, of lead made from thorns, and of copper _minutum contusum_. Liquation cakes are made from all these alloys; the task of the smelters is finished when they have made thirty cakes.

The process by which cakes are made among the Tyrolese, from which they separate the silver-lead, I have explained in Book IX.

Silver is separated from iron in the following manner. Equal portions of iron scales and filings and of _stibium_ are thrown into an earthenware crucible which, when covered with a lid and sealed, is placed in a furnace, into which air is blown. When this has melted and again cooled, the crucible is broken; the button that settles in the bottom of it, when taken out, is pounded to powder, and the same weight of lead being added, is mixed and melted in a second crucible; at last this button is placed in a cupel and the lead is separated from the silver.[36]

There are a great variety of methods by which one metal is separated from other metals, and the manner in which the same are alloyed I have explained partly in the eighth book of _De Natura Fossilium_, and partly I will explain elsewhere. Now I will proceed to the remainder of my subject.

END OF BOOK XI.

FOOTNOTES:

[1] The whole of this Book is devoted to the subject of the separation of silver from copper by liquation, except pages 530-9 on copper refining, and page 544 on the separation of silver from iron. We believe a brief outline of the liquation process here will refresh the mind of the reader, and enable him to peruse the Book with more satisfaction. The fundamental principle of the process is that if a copper-lead alloy, containing a large excess of lead, be heated in a reducing atmosphere, above the melting point of lead but below that of copper, the lead will liquate out and carry with it a large proportion of the silver. As the results are imperfect, the process cannot be carried through in one operation, and a large amount of bye-products is created which must be worked up subsequently. The process, as here described, falls into six stages. 1st, Melting the copper and lead in a blast furnace to form "liquation cakes"--that is, the "leading." If the copper contain too little silver to warrant liquation directly, then the copper is previously enriched by melting and drawing off from a settling pot the less argentiferous "tops" from the metal, liquation cakes being made from the enriched "bottoms." 2nd, Liquation of the argentiferous lead from the copper. This work was carried out in a special furnace, to which the admission of air was prevented as much as possible in order to prevent oxidation. 3rd, "Drying" the residual copper, which retained some lead, in a furnace with a free admission of air. The temperature was raised to a higher degree than in the liquation furnace, and the expelled lead was oxidized. 4th, Cupellation of the argentiferous lead. 5th, Refining of the residual copper from the "drying" furnace by oxidation of impurities and poling in a "refining furnace." 6th, Re-alloy and re-liquation of the bye-products. These consist of: _a_, "slags" from "leading"; _b_, "slags" from "drying"; _c_, "slags" from refining of the copper. All of these "slags" were mainly lead oxides, containing some cuprous oxides and silica from the furnace linings; _d_, "thorns" from liquation; _e_, "thorns" from "drying"; _f_, "thorns" from skimmings during cupellation; these were again largely lead oxides, but contained rather more copper and less silica than the "slags"; _g_, "ash-coloured copper," being scales from the "dried" copper, were cuprous oxides, containing considerable lead oxides; _h_, concentrates from furnace accretions, crushed bricks, &c.

The discussion of detailed features of the process has been reserved to notes attached to the actual text, to which the reader is referred. As to the general result of liquation, Karsten (see below) estimates the losses in the liquation of the equivalent of 100 lbs. of argentiferous copper to amount to 32-35 lbs. of lead and 5 to 6 lbs. of copper. Percy (see below) quotes results at Lautenthal in the Upper Harz for the years 1857-60, showing losses of 25% of the silver, 9.1% of the copper, and 36.37 lbs. of lead to the 100 lbs. of copper, or say, 16% of the lead; and a cost of L8 6s. per ton of copper. The theoretical considerations involved in liquation have not been satisfactorily determined. Those who may wish to pursue the subject will find repeated descriptions and much discussion in the following works, which have been freely consulted in the notes which follow upon particular features of the process. It may be mentioned that Agricola's treatment of the subject is more able than any down to the 18th century. Ercker (_Beschreibung Allerfuernemsten Mineralischen_, etc., Prague, 1574). Lohneys (_Bericht vom Bergwercken_, etc., Zellerfeldt, 1617). Schlueter (_Gruendlicher Unterricht von Huette-Werken_, Braunschweig, 1738). _Karsten_ (_System der Metallurgie V._ and _Archiv fuer Bergbau und Huettenwesen_, 1st series, 1825). Berthier (_Annales des Mines_, 1825, II.). Percy (Metallurgy of Silver and Gold, London, 1880).

NOMENCLATURE.--This process held a very prominent position in German metallurgy for over four centuries, and came to have a well-defined nomenclature of its own, which has never found complete equivalents in English, our metallurgical writers to the present day adopting more or less of the German terms. Agricola apparently found no little difficulty in adapting Latin words to his purpose, but stubbornly adhered to his practice of using no German at the expense of long explanatory clauses. The following table, prepared for convenience in translation, is reproduced. The German terms are spelled after the manner used in most English metallurgies, some of them appear in Agricola's Glossary to _De Re Metallica_.

English. Latin. German.

Blast furnace _Prima fornax_ _Schmeltzofen_

Liquation furnace _Fornax in qua argentum et _Saigernofen_ plumbum ab aere secernuntur_

Drying furnace _Fornax in qua aerei panes _Darrofen_ fathiscentes torrentur_

Refining hearth _Fornax in qua panes aerei _Gaarherd_ torrefacti coquuntur_

Cupellation _Secunda fornax_, or _Treibherd_ furnace _fornax in qua plumbum ab argento separatur_

Leading _Mistura_ _Frischen_

Liquating _Stillare_, or _distillare_ _Saigern_

"Drying" _Torrere_ _Darren_

Refining _Aes ex panibus torrefactis _Gaarmachen_ conficere_ Liquation cakes _Panes ex aere ac plumbo misti_ _Saigerstock_

Exhausted _Panes fathiscentes_ _Kiehnstock_, liquation cakes or _Kinstocke_

"Dried" cakes _Panes torrefacti_ _Darrlinge_

Slags from leading _Recrementa_ _Frischschlacke_ (with explanatory phrases)

Slags from drying _Recrementa_ _Darrost_ (with explanatory phrases)

Slags from refining _Recrementa_ _Gaarschlacke_ (with explanatory phrases)

Liquation thorns _Spinae_ _Saigerdoerner_, (with explanatory phrases) or _Roestdoerner_

Thorns from "drying" _Spinae_ _Darrsoehle_ (with explanatory phrases)

Thorns from _Spinae_ _Abstrich_ cupellation (with explanatory phrases)

Silver-lead or _Stannum_ _Saigerwerk_ or liquated _saigerblei_ silver-lead

Ash-coloured copper _Aes cinereum_ _Pickschiefer_ or _schifer_

Furnace accretions _Cadmiae_ _Offenbrueche_ or "accretions"

HISTORICAL NOTE.--So far as we are aware, this is the first complete discussion of this process, although it is briefly mentioned by one writer before Agricola--that is, by Biringuccio (III, 5, 8), who wrote ten years before this work was sent to the printer. His account is very incomplete, for he describes only the bare liquation, and states that the copper is re-melted with lead and re-liquated until the silver is sufficiently abstracted. He neither mentions "drying" nor any of the bye-products. In his directions the silver-lead alloy was cupelled and the copper ultimately refined, obviously by oxidation and poling, although he omits the pole. In A.D. 1150 Theophilus (p. 305, Hendrie's Trans.) describes melting lead out of copper ore, which would be a form of liquation so far as separation of these two metals is concerned, but obviously not a process for separating silver from copper. This passage is quoted in the note on copper smelting (Note on p. 405). A process of such well-developed and complicated a character must have come from a period long before Agricola; but further than such a surmise, there appears little to be recorded. Liquation has been during the last fifty years displaced by other methods, because it was not only tedious and expensive, but the losses of metal were considerable.

[2] _Paries_,--"Partition" or "wall." The author uses this term throughout in distinction to _murus_, usually applying the latter to the walls of the building and the former to furnace walls, chimney walls, etc. In order to gain clarity, we have introduced the term "hood" in distinction to "chimney," and so far as possible refer to the _paries_ of these constructions and furnaces as "side of the furnace," "side of the hood," etc.

[4] From this point on, the construction of the roofs, in the absence of illustration, is hopeless of intelligent translation. The constant repetition of "_tignum_," "_tigillum_," "_trabs_," for at least fifteen different construction members becomes most hopelessly involved, especially as the author attempts to distinguish between them in a sort of "House-that-Jack-built" arrangement of explanatory clauses.

[5] In the original text this is given as the "fifth," a manifest impossibility.

[6] _Chelae_,--"claws."

[7] If Roman weights, this would be 5.6 short tons, and 7.5 tons if German _centner_ is meant.

[8] This is, no doubt, a reference to Pliny's statement (XXXIII, 35) regarding litharge at Puteoli. This passage from Pliny is given in the footnote on p. 466. Puteoli was situated on the Bay of Naples.

[9] By this expression is apparently meant the "bottoms" produced in enriching copper, as described on p. 510.

[10] The details of the preparation of liquation cakes--"leading"--were matters of great concern to the old metallurgists. The size of the cakes, the proportion of silver in the original copper and in the liquated lead, the proportion of lead and silver left in the residual cakes, all had to be reached by a series of compromises among militant forces. The cakes were generally two and one-half to three and one-half inches thick and about two feet in diameter, and weighed 225 to 375 lbs. This size was wonderfully persistent from Agricola down to modern times; and was, no doubt, based on sound experience. If the cakes were too small, they required proportionately more fuel and labour; whilst if too large, the copper began to melt before the maximum lead was liquated. The ratio of the copper and lead was regulated by the necessity of enough copper to leave a substantial sponge mass the shape of the original cake, and not so large a proportion as to imprison the lead. That is, if the copper be in too small proportion the cakes break down; and if in too large, then insufficient lead liquates out, and the extraction of silver decreases. Ercker (p. 106-9) insists on the equivalent of about 3 copper to 9.5 lead; Lohneys (p. 99), 3 copper to 9 or 10 lead. Schlueter (p. 479, etc.) insists on a ration of 3 copper to about 11 lead. Kerl (_Handbuch Der Metallurgischen Huettenkunde_, 1855; Vol. III., p. 116) gives 3 copper to 6 to 7 parts lead. Agricola gives variable amounts of 3 parts copper to from 8 to 12 parts lead. As to the ratio of silver in the copper, or to the cakes, there does not, except the limit of payability, seem to have been any difficulty on the minimum side. On the other hand, Ercker, Lohneys, Schlueter, and Karsten all contend that if the silver ran above a certain proportion, the copper would retain considerable silver. These authors give the outside ratio of silver permissible for good results in one liquation at what would be equivalent to 45 to 65 ozs. per ton of cakes, or about 190 to 250 ozs. per ton on the original copper. It will be seen, however, that Agricola's cakes greatly exceed these values. A difficulty did arise when the copper ran low in silver, in that the liquated lead was too poor to cupel, and in such case the lead was used over again, until it became rich enough for this purpose. According to Karsten, copper containing less than an equivalent of 80 to 90 ozs. per ton could not be liquated profitably, although the Upper Harz copper, according to Kerl, containing the equivalent of about 50 ozs. per ton, was liquated at a profit. In such a case the cakes would run only 12 to 14 ozs. per ton. It will be noticed that in the eight cases given by Agricola the copper ran from 97 to over 580 ozs. per ton, and in the description of enrichment of copper "bottoms" the original copper runs 85 ozs., and "it cannot be separated easily"; as a result, it is raised to 110 ozs. per ton before treatment. In addition to the following tabulation of the proportions here given by Agricola, the reader should refer to footnotes 15 and 17, where four more combinations are tabulated. It will be observed from this table that with the increasing richness of copper an increased proportion of lead was added, so that the products were of similar value. It has been assumed (see footnote 13 p. 509), that Roman weights are intended. It is not to be expected that metallurgical results of this period will "tie up" with the exactness of the modern operator's, and it has not been considered necessary to calculate beyond the nearest pennyweight. Where two or more values are given by the author the average has been taken.

1ST CHARGE. 2ND CHARGE. 3RD CHARGE. 4TH CHARGE.

Amount of 211.8 lbs. 211.8 lbs. 211.8 lbs. 211.8 lbs. argentiferous copper

Amount of lead 564.8 " 635.4 " 776.6 " 847.2 "

Weight of each cake 193.5 " 211.5 " 247.1 " 264.75 "

Average value of 56 ozs. 62 ozs. 64 ozs. 66 ozs. charge 3dwts. 4dwts. 4dwts. 7dwts.

Per cent. of copper 27.2% 25% 21.4% 20%

Average value of 207 ozs. 251 ozs. 299 ozs. 332 ozs. original copper 4dwts. 3dwts. 15dwts. 3dwts. per ton

Weight of 423.6 lbs. 494.2 lbs. 635.4 lbs. 706 lbs. argentiferous lead liquated out

Average value of 79 ozs. 79 ozs. 79 ozs. 85 ozs. liquated lead per ton

Weight of residues 353 lbs. 353 lbs. 353 lbs. 353 lbs. (residual copper and thorns)

Average value of 34 ozs. 34 ozs. 34 ozs. 34 ozs. to residues per ton 38 ozs.

Extraction of 76.5% 73.4% 79% 85.3% silver into the argentiferous lead

[11] See p. 356.

[12] An analysis of this "slag" by Karsten (_Archiv_. 1st Series IX, p. 24) showed 63.2% lead oxide, 5.1% cuprous oxide, 20.1% silica (from the fuel and furnace linings), together with some iron alumina, etc. The _pompholyx_ and _spodos_ were largely zinc oxide (see note, p. 394).

[13] This description of a _centumpondium_ which weighed either 133-1/3 _librae_, or 146-3/4 _librae_, adds confusion to an already much mixed subject (see Appendix C.). Assuming the German _pfundt_ to weigh 7,219 troy grains, and the Roman _libra_ 4,946 grains, then a _centner_ would weigh 145.95 _librae_, which checks up fairly well with the second case; but under what circumstances a _centner_ can weigh 133-1/3 _librae_ we are unable to record. At first sight it might appear from this statement that where Agricola uses the word _centumpondium_ he means the German _centner_. On the other hand, in the previous five or six pages the expressions one-third, five-sixths, ten-twelfths of a _libra_ are used, which are even divisions of the Roman 12 _unciae_ to one _libra_, and are used where they manifestly mean divisions of 12 units. If Agricola had in mind the German scale, and were using the _libra_ for a _pfundt_ of 16 _untzen_, these divisions would amount to fractions, and would not total the _sicilicus_ and _drachma_ quantities given, nor would they total any of the possibly synonymous divisions of the German _untzen_ (see also page 254).

[14] If we assume Roman weights, the charge in the first case can be tabulated as follows, and for convenience will be called the fifth charge:--

5TH CHARGE (3 cakes). Amount of copper 211.8 lbs. Amount of lead 635.4 lbs. Weight of each cake 282.4 lbs. Average value of charge 218 ozs. 18 dwts. Per cent. of copper 25% Average value of original copper per ton 583 ozs. 6 dwts. 16 grs. Weight of argentiferous lead liquated out 494.2 lbs. Average value of liquated lead per ton 352 ozs. 8 dwts. Weight of residues 353 lbs. Average value of residues per ton 20 ozs. (about). Extraction of silver into the argentiferous lead 94%

The results given in the second case where the copper contains 2 _librae_ and a _bes_ per _centumpondium_ do not tie together at all, for each liquation cake should contain 3 _librae_ 9-1/2 _unciae_, instead of 1-1/2 _librae_ and 1/2 _uncia_ of silver.

[15] In this enrichment of copper by the "settling" of the silver in the molten mass the original copper ran, in the two cases given, 60 ozs. 15 dwts. and 85 ozs. 1 dwt. per ton. The whole charge weighed 2,685 lbs., and contained in the second case 114 ozs. Troy, omitting fractions. On melting, 1,060 lbs. were drawn off as "tops," containing 24 ozs. of silver, or running 45 ozs. per ton, and there remained 1,625 lbs. of "bottoms," containing 90 ozs. of silver, or averaging 110 ozs. per ton. It will be noticed later on in the description of making liquation cakes from these copper bottoms, that the author alters the value from one-third _librae_, a _semi-uncia_ and a _drachma_ per _centumpondium_ to one-third of a _libra_, _i.e._, from 110 ozs. to 97 ozs. 4 dwts. per ton. In the Glossary this furnace is described as a _spleisofen_, _i.e._, a refining hearth.

[16] The latter part of this paragraph presents great difficulties. The term "refining furnace" is given in the Latin as the "second furnace," an expression usually applied to the cupellation furnace. The whole question of refining is exhaustively discussed on pages 530 to 539. Exactly what material is meant by the term red (_rubrum_), yellow (_fulvum_) and _caldarium_ copper is somewhat uncertain. They are given in the German text simply as _rot_, _geel_, and _lebeter kupfer_, and apparently all were "coarse" copper of different characters destined for the refinery. The author states in _De Natura Fossilium_ (p. 334): "Copper has a red colour peculiar to itself; this colour in smelted copper is considered the most excellent. It, however, varies. In some it is red, as in the copper smelted at Neusohl.... Other copper is prepared in the smelters where silver is separated from copper, which is called yellow copper (_luteum_), and is _regulare_. In the same place a dark yellow copper is made which is called _caldarium_, taking its name among the Germans from a caldron.... _Regulare_ differs from _caldarium_ in that the former is not only fusible, but also malleable; while the latter is, indeed, fusible, but is not ductile, for it breaks when struck with the hammer." Later on in _De Re Metallica_ (p. 542) he describes yellow copper as made from "baser" liquation thorns and from exhausted liquation cakes made from thorns. These products were necessarily impure, as they contained, among other things, the concentrates from furnace accretions. Therefore, there was ample source for zinc, arsenic or other metallics which would lighten the colour. _Caldarium_ copper is described by Pliny (see note, p. 404), and was, no doubt, "coarse" copper, and apparently Agricola adopted this term from that source, as we have found it used nowhere else. On page 542 the author describes making _caldarium_ copper from a mixture of yellow copper and a peculiar _cadmia_, which he describes as the "slags" from refining copper. These "slags," which are the result of oxidation and poling, would contain almost any of the metallic impurities of the original ore, antimony, lead, arsenic, zinc, cobalt, etc. Coming from these two sources the _caldarium_ must have been, indeed, impure.

[17] The liquation of these low-grade copper "bottoms" required that the liquated lead should be re-used again to make up fresh liquation cakes, in order that it might eventually become rich enough to warrant cupellation. In the following table the "poor" silver-lead is designated (A) the "medium" (B) and the "rich" (C). The three charges here given are designated sixth, seventh, and eighth for purposes of reference. It will be seen that the data is insufficient to complete the ninth and tenth. Moreover, while the author gives directions for making four cakes, he says the charge consists of five, and it has, therefore, been necessary to reduce the volume of products given to this basis.

6TH CHARGE. 7TH CHARGE. 8TH CHARGE.

Amount of copper 176.5 lbs. 176.5 lbs. 176.5 lbs. bottoms

Amount of lead 282.4 lbs. 564.8 lbs. 635.4 lbs. (slags) of (A) of (B)

Amount of 494.2 lbs. 211.8 lbs. 141.2 lbs. (A) de-silverized lead

Weight of each cake 238.3 lbs. 238.3 lbs. 238.3 lbs.

Average value of 22 ozs. 35 ozs. 50 ozs. charge per ton 5dwts. 15dwts. 5dwts.

Per cent. of copper 18.5% 18.5% 18.5%

Average value per 97 ozs. 97 ozs. 97 ozs. ton original copper 4dwts. 4dwts. 4dwts.

Average value per 90 ozs. 28 ozs. 28 ozs. ton of 2dwts. (slags) 5dwts. (A) 5dwts. (A)

Average value per 3 ozs. 3 ozs. 42 ozs. ton of 1dwt. (lead) 1dwt. (lead) 10dwts. (B)

Weight of liquated 550.6 lbs. lead

Average value of 28 ozs. 42 ozs. 63 ozs. the liquated lead 5dwts. (A) 10dwts. (B) 16dwts. (C) per ton

Weight of exhausted 225.9 lbs. liquation cakes

Average value of 12 ozs. the exhausted 3dwts. liquation cakes per ton

Weight of liquation 169.4 lbs. thorns

Average value of 18 ozs. the liquation 4dwts. thorns per ton

Extraction of 71% silver into the liquated lead

[18] For the liquation it was necessary to maintain a reducing atmosphere, otherwise the lead would oxidize; this was secured by keeping the cakes well covered with charcoal and by preventing the entrance of air as much as possible. Moreover, it was necessary to preserve a fairly even temperature. The proportions of copper and lead in the three liquation products vary considerably, depending upon the method of conducting the process and the original proportions. From the authors consulted (see note p. 492) an average would be about as follows:--The residual copper--exhausted liquation cakes--ran from 25 to 33% lead; the liquated lead from 2 to 3% copper; and the liquation thorns, which were largely oxidized, contained about 15% copper oxides, 80% lead oxides, together with impurities, such as antimony, arsenic, etc. The proportions of the various products would obviously depend upon the care in conducting the operation; too high temperature and the admission of air would increase the copper melted and oxidize more lead, and thus increase the liquation thorns. There are insufficient data in Agricola to adduce conclusions as to the actual ratios produced. The results given for the 6th charge (note 17, p. 512) would indicate about 30% lead in the residual copper, and would indicate that the original charge was divided into about 24% of residual copper, 18% of liquation thorns, and 57% of liquated lead. This, however, was an unusually large proportion of liquation thorns, some of the authors giving instances of as low as 5%.

[19] The first instance given, of 44 _centumpondia_ (3,109 lbs.) lead and one _centumpondium_ (70.6 lbs.) copper, would indicate that the liquated lead contained 2.2% copper. The second, of 46 _centumpondia_ (3,250 lbs.) lead and 1-1/2 _centumpondia_ copper (106 lbs.), would indicate 3% copper; and in the third, 120 _centumpondia_ (8,478 lbs.) lead and six copper (424 lbs.) would show 4.76% copper. This charge of 120 _centumpondia_ in the cupellation furnace would normally make more than 110 _centumpondia_ of litharge and 30 of hearth-lead, _i.e._, saturated furnace bottoms. The copper would be largely found in the silver-lead "which does not melt," at the margin of the crucible. These skimmings are afterward referred to as "thorns." It is difficult to understand what is meant by the expression that the silver which is in the copper is mixed with the remaining (_reliquo_) silver. The coppery skimmings from the cupellation furnace are referred to again in Note 28, p. 539.

[20] A further amount of lead could be obtained in the first liquation, but a higher temperature is necessary, which was more economical to secure in the "drying" furnace. Therefore, the "drying" was really an extension of liquation; but as air was admitted the lead and copper melted out were oxidized. The products were the final residual copper, called by Agricola the "dried" copper, together with lead and copper oxides, called by him the "slags," and the scale of copper and lead oxides termed by him the "ash-coloured copper." The German metallurgists distinguished two kinds of slag: the first and principal one, the _darrost_, and the second the _darrsoehle_, this latter differing only in that it contained more impurities from the floor of the furnace, and remained behind until the furnace cooled. Agricola possibly refers to these as "more liquation thorns," because in describing the treatment of the bye-products he refers to thorns from the process, whereas in the description of "drying" he usually refers to "slags." A number of analyses of these products, given by Karsten, show the "dried" copper to contain from 82.7 to 90.6% copper, and from 9.4 to 17.3% lead; the "slag" to contain 76.5 to 85.1% lead oxide, and from 4.1 to 7.8% cuprous oxide, with 9 to 13% silica from the furnace bottoms, together with some other impurities; the "ash-coloured copper" to contain about 60% cuprous oxide and 30% lead oxide, with some metallic copper and minor impurities. An average of proportions given by various authors shows, roughly, that out of 100 _centners_ of "exhausted" liquation cakes, containing about 70% copper and 30% lead, there were about 63 _centners_ of "dried" copper, 38 _centners_ of "slag," and 6-1/2 _centners_ of "ash-coloured copper." According to Karsten, the process fell into stages; first, at low temperature some metallic lead appeared; second, during an increasing temperature for over 14 to 15 hours the slags ran out; third, there was a period of four hours of lower temperature to allow time for the lead to diffuse from the interior of the cakes; and fourth, during a period of eight hours the temperature was again increased. In fact, the latter portion of the process ended with the economic limit between leaving some lead in the copper and driving too much copper into the "slags." Agricola gives the silver contents of the "dried" copper as 3 _drachmae_ to 1 _centumpondium_, or equal to about 9 ozs. per ton; and assuming that the copper finally recovered from the bye-products ran no higher, then the first four charges (see note on p. 506) would show a reduction in the silver values of from 95 to 97%; the 7th and 8th charges (note on p. 512) of about 90%.

[21] If Roman weights, this would equal from 6,360 lbs. to 7,066 lbs.

[22] One half _uncia_, or three _drachmae_ of silver would equal either 12 ozs. or 9 ozs. per ton. If we assume the values given for residual copper in the first four charges (note p. 506) of 34 ozs., this would mean an extraction of, roughly, 65% of the silver from the exhausted liquation cakes.

[23] See note 29, p. 540.

[24]

Assuming Roman weights: 2 _centumpondia_ = 141.3 lbs. 2-1/2 " = 176.6 " 3 " = 211.9 " 3-1/2 " = 248.2 " 6 " = 423.9 "

[25] This description of refining copper in an open hearth by oxidation with a blast and "poling"--the _gaarmachen_ of the Germans--is so accurate, and the process is so little changed in some parts of Saxony, that it might have been written in the 20th century instead of the 16th. The best account of the old practice in Saxony after Agricola is to be found in Schlueter's _Huette Werken_ (Braunschweig, 1738, Chap. CXVIII.). The process has largely been displaced by electrolytic methods, but is still in use in most refineries as a step in electrolytic work. It may be unnecessary to repeat that the process is one of subjecting the molten mass of impure metal to a strong and continuous blast, and as a result, not only are the impurities to a considerable extent directly oxidized and taken off as a slag, but also a considerable amount of copper is turned into cuprous oxide. This cuprous oxide mostly melts and diffuses through the metallic copper, and readily parting with its oxygen to the impurities further facilitates their complete oxidation. The blast is continued until the impurities are practically eliminated, and at this stage the molten metal contains a great deal of dissolved cuprous oxide, which must be reduced. This is done by introducing a billet of green wood ("poling"), the dry distillation of which generates large quantities of gases, which reduce the oxide. The state of the metal is even to-day in some localities tested by dipping into it the point of an iron rod; if it be at the proper state the adhering copper has a net-like appearance, should be easily loosened from the rod by dipping in water, is of a reddish-copper colour and should be quite pliable; if the metal is not yet refined, the sample is thick, smooth, and detachable with difficulty; if over-refined, it is thick and brittle. By allowing water to run on to the surface of the molten metal, thin cakes are successively formed and taken off. These cakes were the article known to commerce over several centuries as "rosetta copper." The first few cakes are discarded as containing impurities or slag, and if the metal be of good quality the cakes are thin and of a red colour. Their colour and thinness, therefore, become a criterion of purity. The cover of charcoal or charcoal dust maintained upon the surface of the metal tended to retard oxidation, but prevented volatilization and helped to secure the impurities as a slag instead. Karsten (_Archiv._, 1st series, p. 46) gives several analyses of the slag from refining "dried" copper, showing it to contain from 51.7 to 67.4% lead oxide, 6.2 to 19.2% cuprous oxide, and 21.4 to 23.9 silica (from the furnace bottoms), with minor quantities of iron, antimony, etc. The "bubbles" referred to by Agricola were apparently the shower of copper globules which takes place upon the evolution of sulphur dioxide, due to the reaction of the cuprous oxide upon any remaining sulphide of copper when the mass begins to cool.

HISTORICAL NOTE.--It is impossible to say how the Ancients refined copper, beyond the fact that they often re-smelted it. Such notes as we can find are set out in the note on copper smelting (note 42, p. 402). The first authentic reference to poling is in Theophilus (1150 to 1200 A.D., Hendrie's translation, p. 313), which shows a very good understanding of this method of refining copper:--"Of the Purification of Copper. Take an iron dish of the size you wish, and line it inside and out with clay strongly beaten and mixed, and it is carefully dried. Then place it before a forge upon the coals, so that when the bellows act upon it the wind may issue partly within and partly above it, and not below it. And very small coals being placed round it, place the copper in it equally, and add over it a heap of coals. When by blowing a long time this has become melted, uncover it and cast immediately fine ashes of coals over it, and stir it with a thin and dry piece of wood as if mixing it, and you will directly see the burnt lead adhere to these ashes like a glue, which being cast out again superpose coals, and blowing for a long time, as at first, again uncover it, and then do as you did before. You do this until at length by cooking it you can withdraw the lead entirely. Then pour it over the mould which you have prepared for this, and you will thus prove if it be pure. Hold it with the pincers, glowing as it is, before it has become cold, and strike it with a large hammer strongly over the anvil, and if it be broken or split you must liquefy it anew as before. If, however, it should remain sound, you will cool it in water, and you cook other (copper) in the same manner." Biringuccio (III, 8) in 1540 describes the process briefly, but omits the poling, an essential in the production of malleable copper.

[26] _Pompholyx_ and _spodos_ were impure zinc oxides (see note 26, p. 394).

The copper flowers were no doubt cupric oxide. They were used by the Ancients for medicinal purposes. Dioscorides (V, 48) says: "Of flowers of copper, which some call the scrapings of old nails, the best is friable; it is gold-coloured when rubbed, is like millet in shape and size, is moderately bright, and somewhat astringent. It should not be mixed with copper filings, with which it is often adulterated. But this deception is easily detected, for when bitten in the teeth the filings are malleable. It (the flowers) is made when the copper fused in a furnace has run into the receptacle through the spout pertaining to it, for then the workmen engaged in this trade cleanse it from dirt and pour clear water over it in order to cool it; from this sudden condensation the copper spits and throws out the aforesaid flowers." Pliny (XXXIV, 24) says: "The flower, too, of copper (_aeris flos_) is used in medicine. This is made by fusing copper, and then removing it to another furnace, where the repeated blast makes the metal separate into small scales like millet, known as flowers. These scales also fall off when the cakes of metal are cooled in water; they become red, too, like the scales of copper known as '_lepis_,' by use of which the flowers of copper are adulterated, it being also sold for it. These are made when hammering the nails that are made from the cakes of copper. All these methods are carried on in the works of Cyprus; the difference between these substances is that the _squamae_ (copper scales) are detached from hammering the cakes, while the flower falls off spontaneously." Agricola (_De Nat. Fos._, p. 352) notes that "flowers of copper (_flos aeris_) have the same properties as 'roasted copper.'"

[27] It seems scarcely necessary to discuss in detail the complicated "flow scheme" of the various minor bye-products. They are all re-introduced into the liquation circuit, and thereby are created other bye-products of the same kind _ad infinitum_. Further notes are given on:--

Liquation thorns Note 28. Slags " 30. Ash-coloured copper " 29. Concentrates " 33. _Cadmia_ " 32.

There are no data given, either by Agricola or the later authors, which allow satisfactory calculation of the relative quantities of these products. A rough estimate from the data given in previous notes would indicate that in one liquation only about 70% of the original copper came out as refined copper, and that about 70% of the original lead would go to the cupellation furnace, _i.e._, about 30% of the original metal sent to the blast furnace would go into the "thorns," "slags," and "ash-coloured copper." The ultimate losses were very great, as given before (p. 491), they probably amounted to 25% of the silver, 9% copper, and 16% of the lead.

[28] There were the following classes of thorns:--

1st. From liquation. 2nd. From drying. 3rd. From cupellation.

In a general way, according to the later authors, they were largely lead oxide, and contained from 5% to 20% cuprous oxide. If a calculation be made backward from the products given as the result of the charge described, it would appear that in this case they must have contained at least one-fifth copper. The silver in these liquation cakes would run about 24 ozs. per ton, in the liquated lead about 36 ozs. per ton, and in the liquation thorns 24 ozs. per ton. The extraction into the liquated lead would be about 80% of the silver.

[29] The "ash-coloured copper" is a cuprous oxide, containing some 3% lead oxide; and if Agricola means they contained two _unciae_ of silver to the _centumpondium_, then they ran about 48 ozs. per ton, and would contain much more silver than the mass.

[30] There are three principal "slags" mentioned--

1st. Slag from "leading." 2nd. Slag from "drying." 3rd. Slag from refining the copper.

From the analyses quoted by various authors these ran from 52% to 85% lead oxide, 5% to 30% cuprous oxide, and considerable silica from the furnace bottoms. They were reduced in the main into liquation cakes, although Agricola mentions instances of the metal reduced from "slags" being taken directly to the "drying" furnace. Such liquation cakes would run very low in silver, and at the values given only averaged 12 ozs. per ton; therefore the liquated lead running the same value as the cakes, or less than half that of the "poor" lead mentioned in Note 17, p. 512, could not have been cupelled directly.

[31] See Note 16, p. 511, for discussion of yellow and _caldarium_ copper.

[32] This _cadmia_ is given in the Glossary and the German translation as _kobelt_. A discussion of this substance is given in the note on p. 112; and it is sufficient to state here that in Agricola's time the metal cobalt was unknown, and the substances designated _cadmia_ and _cobaltum_ were arsenical-cobalt-zinc minerals. A metal made from "slag" from refining, together with "base" thorns, would be very impure; for the latter, according to the paragraph on concentrates a little later on, would contain the furnace accretions, and would thus be undoubtedly zincky. It is just possible that the term _kobelt_ was used by the German smelters at this time in the sense of an epithet--"black devil" (see Note 21, p. 214).

[33] It is somewhat difficult to see exactly the meaning of base (_vile_) and precious (_preciosum_) in this connection. While "base" could mean impure, "precious" could hardly mean pure, and while "precious" could mean high value in silver, the reverse does not seem entirely _apropos_. It is possible that "bad" and "good" would be more appropriate terms.

[34] The skimmings from the molten lead in the early stages of cupellation have been discussed in Note 28, p. 539. They are probably called thorns here because of the large amount of copper in them. The lead from liquation would contain 2% to 3% of copper, and this would be largely recovered in these skimmings, although there would be some copper in the furnace bottoms--hearth-lead--and the litharge. These "thorns" are apparently fairly rich, four _unciae_ to the _centumpondium_ being equivalent to about 97 ozs. per ton, and they are only added to low-grade liquation material.

[35] _Particulis aeris tusi_. Unless this be the fine concentrates from crushing the material mentioned, we are unable to explain the expression.

[36] This operation would bring down a button of antimony under an iron matte, by de-sulphurizing the antimony. It would seem scarcely necessary to add lead before cupellation. This process is given in an assay method, in the _Probierbuechlein_ (folio 31) 50 years before _De Re Metallica_: "How to separate silver from iron: Take that silver which is in iron _plechen_ (_plachmal_), pulverize it finely, take the same iron or _plec_ one part, _spiesglasz_ (antimony sulphide) one part, leave them to melt in a crucible placed in a closed _windtofen_. When it is melted, let it cool, break the crucible, chip off the button that is in the bottom, and melt it in a crucible with as much lead. Then break the crucible, and seek from the button in the cupel, and you will find what silver it contains."

## BOOK XII.

Previously I have dealt with the methods of separating silver from copper. There now remains the portion which treats of solidified juices; and whereas they might be considered as alien to things metallic, nevertheless, the reasons why they should not be separated from it I have explained in the second book.

Solidified juices are either prepared from waters in which nature or art has infused them, or they are produced from the liquid juices themselves, or from stony minerals. Sagacious people, at first observing the waters of some lakes to be naturally full of juices which thickened on being dried up by the heat of the sun and thus became solidified juices, drew such waters into other places, or diverted them into low-lying places adjoining hills, so that the heat of the sun should likewise cause them to condense. Subsequently, because they observed that in this wise the solidified juices could be made only in summer, and then not in all countries, but only in hot and temperate regions in which it seldom rains in summer, they boiled them in vessels over a fire until they began to thicken. In this manner, at all times of the year, in all regions, even the coldest, solidified juices could be obtained from solutions of such juices, whether made by nature or by art. Afterward, when they saw juices drip from some roasted stones, they cooked these in pots in order to obtain solidified juices in this wise also. It is worth the trouble to learn the proportions and the methods by which these are made.

I will therefore begin with salt, which is made from water either salty by nature, or by the labour of man, or else from a solution of salt, or from lye, likewise salty. Water which is salty by nature, is condensed and converted into salt in salt-pits by the heat of the sun, or else by the heat of a fire in pans or pots or trenches. That which is made salty by art, is also condensed by fire and changed into salt. There should be as many salt-pits dug as the circumstance of the place permits, but there should not be more made than can be used, although we ought to make as much salt as we can sell. The depth of salt-pits should be moderate, and the bottom should be level, so that all the water is evaporated from the salt by the heat of the sun. The salt-pits should first be encrusted with salt, so that they may not suck up the water. The method of pouring or leading sea-water into salt-pits is very old, and is still in use in many places. The method is not less old, but less common, to pour well-water into salt-pits, as was done in Babylon, for which Pliny is the authority, and in Cappadocia, where they used not only well-water, but also spring-water. In all hot countries salt-water and lake-water are conducted, poured or carried into salt-pits, and, being dried by the heat of the sun, are converted into salt.[1] While the salt-water contained in the salt-pits is being heated by the sun, if they be flooded with great and frequent showers of rain the evaporation is hindered. If this happens rarely, the salt acquires a disagreeable[2] flavour, and in this case the salt-pits have to be filled with other sweet water.

[Illustration 547 (Salt Pans): A--Sea. B--Pool. C--Gate. D--Trenches. E--Salt basins. F--Rake. G--Shovel.]

Salt from sea-water is made in the following manner. Near that part of the seashore where there is a quiet pool, and there are wide, level plains which the inundations of the sea do not overflow, three, four, five, or six trenches are dug six feet wide, twelve feet deep, and six hundred feet long, or longer if the level place extends for a longer distance; they are two hundred feet distant from one another; between these are three transverse trenches. Then are dug the principal pits, so that when the water has been raised from the pool it can flow into the trenches, and from thence into the salt-pits, of which there are numbers on the level ground between the trenches. The salt-pits are basins dug to a moderate depth; these are banked round with the earth which was dug in sinking them or in cleansing them, so that between the basins, earth walls are made a foot high, which retain the water let into them. The trenches have openings, through which the first basins receive the water; these basins also have openings, through which the water flows again from one into the other. There should be a slight fall, so that the water may flow from one basin into the other, and can thus be replenished. All these things having been done rightly and in order, the gate is raised that opens the mouth of the pool which contains sea-water mixed with rain-water or river-water; and thus all of the trenches are filled. Then the gates of the first basins are opened, and thus the remaining basins are filled with the water from the first; when this salt-water condenses, all these basins are incrusted, and thus made clean from earthy matter. Then again the first basins are filled up from the nearest trench with the same kind of water, and left until much of the thin liquid is converted into vapour by the heat of the sun and dissipated, and the remainder is considerably thickened. Then their gates being opened, the water passes into the second basins; and when it has remained there for a certain space of time the gates are opened, so that it flows into the third basins, where it is all condensed into salt. After the salt has been taken out, the basins are filled again and again with sea-water. The salt is raked up with wooden rakes and thrown out with shovels.

[Illustration 549 (Salt Wells): A--Shed. B--Painted signs. C--First room. D--Middle room. E--Third room. F--Two little windows in the end wall. G--Third little window in the roof. H--Well. I--Well of another kind. K--Cask. L--Pole. M--Forked sticks in which the porters rest the pole when they are tired.]

Salt-water is also boiled in pans, placed in sheds near the wells from which it is drawn. Each shed is usually named from some animal or other thing which is pictured on a tablet nailed to it. The walls of these sheds are made either from baked earth or from wicker work covered with thick mud, although some may be made of stones or bricks. When of brick they are often sixteen feet high, and if the roof rises twenty-four feet high, then the walls which are at the ends must be made forty feet high, as likewise the interior partition walls. The roof consists of large shingles four feet long, one foot wide, and two digits thick; these are fixed on long narrow planks placed on the rafters, which are joined at the upper end and slope in opposite directions. The whole of the under side is plastered one digit thick with straw mixed with lute; likewise the roof on the outside is plastered one and a half feet thick with straw mixed with lute, in order that the shed should not run any risk of fire, and that it should be proof against rain, and be able to retain the heat necessary for drying the lumps of salt. Each shed is divided into three parts, in the first of which the firewood and straw are placed; in the middle room, separated from the first room by a

## partition, is the fireplace on which is placed the caldron. To the right

of the caldron is a tub, into which is emptied the brine brought into the shed by the porters; to the left is a bench, on which there is room to lay thirty pieces of salt. In the third room, which is in the back part of the house, there is made a pile of clay or ashes eight feet higher than the floor, being the same height as the bench. The master and his assistants, when they carry away the lumps of salt from the caldrons, go from the former to the latter. They ascend from the right side of the caldron, not by steps, but by a slope of earth. At the top of the end wall are two small windows, and a third is in the roof, through which the smoke escapes. This smoke, emitted from both the back and the front of the furnace, finds outlet through a hood through which it makes its way up to the windows; this hood consists of boards projecting one beyond the other, which are supported by two small beams of the roof. Opposite the fireplace the middle partition has an open door eight feet high and four feet wide, through which there is a gentle draught which drives the smoke into the last room; the front wall also has a door of the same height and width. Both of these doors are large enough to permit the firewood or straw or the brine to be carried in, and the lumps of salt to be carried out; these doors must be closed when the wind blows, so that the boiling will not be hindered. Indeed, glass panes which exclude the wind but transmit the light, should be inserted in the windows in the walls.

They construct the greater part of the fireplace of rock-salt and of clay mixed with salt and moistened with brine, for such walls are greatly hardened by the fire. These fireplaces are made eight and a half feet long, seven and three quarters feet wide, and, if wood is burned in them, nearly four feet high; but if straw is burned in them, they are six feet high. An iron rod, about four feet long, is engaged in a hole in an iron foot, which stands on the base of the middle of the furnace mouth. This mouth is three feet in width, and has a door which opens inward; through it they throw in the straw.

[Illustration 551 (Salt Caldron): A--Fireplace. B--Mouth of fireplace. C--Caldron. D--Posts sunk into the ground. E--Cross-beams. F--Shorter bars. G--Iron hooks. H--Staples. I--Longer bars. K--Iron rod bent to support the caldron.]

The caldrons are rectangular, eight feet long, seven feet wide, and half a foot high, and are made of sheets of iron or lead, three feet long and of the same width, all but two digits. These plates are not very thick, so that the water is heated more quickly by the fire, and is boiled away rapidly. The more salty the water is, the sooner it is condensed into salt. To prevent the brine from leaking out at the points where the metal plates are fastened with rivets, the caldrons are smeared over with a cement made of ox-liver and ox-blood mixed with ashes. On each side of the middle of the furnace two rectangular posts, three feet long, and half a foot thick and wide are set into the ground, so that they are distant from each other only one and a half feet. Each of them rises one and a half feet above the caldron. After the caldron has been placed on the walls of the furnace, two beams of the same width and thickness as the posts, but four feet long, are laid on these posts, and are mortised in so that they shall not fall. There rest transversely upon these beams three bars, three feet long, three digits wide, and two digits thick, distant from one another one foot. On each of these hang three iron hooks, two beyond the beams and one in the middle; these are a foot long, and are hooked at both ends, one hook turning to the right, the other to the left. The bottom hook catches in the eye of a staple, whose ends are fixed in the bottom of the caldron, and the eye projects from it. There are besides, two longer bars six feet long, one palm wide, and three digits thick, which pass under the front beam and rest upon the rear beam. At the rear end of each of the bars there is an iron hook two feet and three digits long, the lower end of which is bent so as to support the caldron. The rear end of the caldron does not rest on the two rear corners of the fireplace, but is distant from the fireplace two thirds of a foot, so that the flame and smoke can escape; this rear end of the fireplace is half a foot thick and half a foot higher than the caldron. This is also the thickness and height of the wall between the caldron and the third room of the shed, to which it is adjacent. This back wall is made of clay and ashes, unlike the others which are made of rock-salt. The caldron rests on the two front corners and sides of the fireplace, and is cemented with ashes, so that the flames shall not escape. If a dipperful of brine poured into the caldron should flow into all the corners, the caldron is rightly set upon the fireplace.

The wooden dipper holds ten Roman _sextarii_, and the cask holds eight dippers full[3]. The brine drawn up from the well is poured into such casks and carried by porters, as I have said before, into the shed and poured into a tub, and in those places where the brine is very strong it is at once transferred with the dippers into the caldron. That brine which is less strong is thrown into a small tub with a deep ladle, the spoon and handle of which are hewn out of one piece of wood. In this tub rock-salt is placed in order that the water should be made more salty, and it is then run off through a launder which leads into the caldron. From thirty-seven dippersful of brine the master or his deputy, at Halle in Saxony,[4] makes two cone-shaped pieces of salt. Each master has a helper, or in the place of a helper his wife assists him in his work, and, in addition, a youth who throws wood or straw under the caldron. He, on account of the great heat of the workshop, wears a straw cap on his head and a breech cloth, being otherwise quite naked. As soon as the master has poured the first dipperful of brine into the caldron the youth sets fire to the wood and straw laid under it. If the firewood is bundles of faggots or brushwood, the salt will be white, but if straw is burned, then it is not infrequently blackish, for the sparks, which are drawn up with the smoke into the hood, fall down again into the water and colour it black.

[Illustration 553 (Salt Caldron): A--Wooden dipper. B--Cask. C--Tub. D--Master. E--Youth. F--Wife. G--Wooden spade. H--Boards. I--Baskets. K--Hoe. L--Rake. M--Straw. N--Bowl. O--Bucket containing the blood. P--Tankard which contains beer.]

In order to accelerate the condensation of the brine, when the master has poured in two casks and as many dippersful of brine, he adds about a Roman _cyathus_ and a half of bullock's blood, or of calf's blood, or buck's blood, or else he mixes it into the nineteenth dipperful of brine, in order that it may be dissolved and distributed into all the corners of the caldron; in other places the blood is dissolved in beer. When the boiling water seems to be mixed with scum, he skims it with a ladle; this scum, if he be working with rock-salt, he throws into the opening in the furnace through which the smoke escapes, and it is dried into rock-salt; if it be not from rock-salt, he pours it on to the floor of the workshop. From the beginning to the boiling and skimming is the work of half-an-hour; after this it boils down for another quarter-of-an-hour, after which time it begins to condense into salt. When it begins to thicken with the heat, he and his helper stir it assiduously with a wooden spatula, and then he allows it to boil for an hour. After this he pours in a _cyathus_ and a half of beer. In order that the wind should not blow into the caldron, the helper covers the front with a board seven and a half feet long and one foot high, and covers each of the sides with boards three and three quarters feet long. In order that the front board may hold more firmly, it is fitted into the caldron itself, and the side-boards are fixed on the front board and upon the transverse beam. Afterward, when the boards have been lifted off, the helper places two baskets, two feet high and as many wide at the top, and a palm wide at the bottom, on the transverse beams, and into them the master throws the salt with a shovel, taking half-an-hour to fill them. Then, replacing the boards on the caldron, he allows the brine to boil for three quarters of an hour. Afterward the salt has again to be removed with a shovel, and when the baskets are full, they pile up the salt in heaps.

In different localities the salt is moulded into different shapes. In the baskets the salt assumes the form of a cone; it is not moulded in baskets alone, but also in moulds into which they throw the salt, which are made in the likeness of many objects, as for instance tablets. These tablets and cones are kept in the higher part of the third room of the house, or else on the flat bench of the same height, in order that they may dry better in the warm air. In the manner I have described, a master and his helper continue one after the other, alternately boiling the brine and moulding the salt, day and night, with the exception only of the annual feast days. No caldron is able to stand the fire for more than half a year. The master pours in water and washes it out every week; when it is washed out he puts straw under it and pounds it; new caldrons he washes three times in the first two weeks, and afterward twice. In this manner the incrustations fall from the bottom; if they are not cleared off, the salt would have to be made more slowly over a fiercer fire, which requires more brine and burns the plates of the caldron. If any cracks make their appearance in the caldron they are filled up with cement. The salt made during the first two weeks is not so good, being usually stained by the rust at the bottom where incrustations have not yet adhered.

Although salt made in this manner is prepared only from the brine of springs and wells, yet it is also possible to use this method in the case of river-, lake-, and sea-water, and also of those waters which are artificially salted. For in places where rock-salt is dug, the impure and the broken pieces are thrown into fresh water, which, when boiled, condenses into salt. Some, indeed, boil sea-salt in fresh water again, and mould the salt into the little cones and other shapes.

[Illustration 554 (Salt Boiling): A--Pool. B--Pots. C--Ladle. D--Pans. E--Tongs.]

Some people make salt by another method, from salt water which flows from hot springs that issue boiling from the earth. They set earthenware pots in a pool of the spring-water, and into them they pour water scooped up with ladles from the hot spring until they are half full. The perpetual heat of the waters of the pool evaporates the salt water just as the heat of the fire does in the caldrons. As soon as it begins to thicken, which happens when it has been reduced by boiling to a third or more, they seize the pots with tongs and pour the contents into small rectangular iron pans, which have also been placed in the pool. The interior of these pans is usually three feet long, two feet wide, and three digits deep, and they stand on four heavy legs, so that the water flows freely all round, but not into them. Since the water flows continuously from the pool through the little canals, and the spring always provides a new and copious supply, always boiling hot, it condenses the thickened water poured into the pans into salt; this is at once taken out with shovels, and then the work begins all over again. If the salty water contains other juices, as is usually the case with hot springs, no salt should be made from them.

[Illustration 555 (Salt Boiling): A--Pots. B--Tripod. C--Deep ladle.]

Others boil salt water, and especially sea-water, in large iron pots; this salt is blackish, for in most cases they burn straw under them. Some people boil in these pots the brine in which fish is pickled. The salt which they make tastes and smells of fish.

[Illustration 556 (Salt evaporated on faggots): A--Trench. B--Vat into which the salt water flows. C--Ladle. D--Small bucket with pole fastened into it.]

Those who make salt by pouring brine over firewood, lay the wood in trenches which are twelve feet long, seven feet wide, and two and one half feet deep, so that the water poured in should not flow out. These trenches are constructed of rock-salt wherever it is to be had, in order that they should not soak up the water, and so that the earth should not fall in on the front, back and sides. As the charcoal is turned into salt at the same time as the salt liquor, the Spaniards think, as Pliny writes[5], that the wood itself turns into salt. Oak is the best wood, as its pure ash yields salt; elsewhere hazel-wood is lauded. But with whatever wood it be made, this salt is not greatly appreciated, being black and not quite pure; on that account this method of salt-making is disdained by the Germans and Spaniards.

[Illustration 557 (Lye Making): A--Large vat. B--Plug. C--Small tub. D--Deep ladle. E--Small vat. F--Caldron.]

The solutions from which salt is made are prepared from salty earth or from earth rich in salt and saltpetre. Lye is made from the ashes of reeds and rushes. The solution obtained from salty earth by boiling, makes salt only; from the other, of which I will speak more a little later, salt and saltpetre are made; and from ashes is derived lye, from which its own salt is obtained. The ashes, as well as the earth, should first be put into a large vat; then fresh water should be poured over the ashes or earth, and it should be stirred for about twelve hours with a stick, so that it may dissolve the salt. Then the plug is pulled out of the large vat; the solution of salt or the lye is drained into a small tub and emptied with ladles into small vats; finally, such a solution is transferred into iron or lead caldrons and boiled, until the water having evaporated, the juices are condensed into salt. The above are the various methods for making salt. (Illustration p. 557.)

[Illustration 559 (Nitrum-pits): A--Nile. B--Nitrum-pits, such as I conjecture them to be.[7]]

_Nitrum_[6] is usually made from _nitrous_ waters, or from solutions or from lye. In the same manner as sea-water or salt-water is poured into salt-pits and evaporated by the heat of the sun and changed into salt, so the _nitrous_ Nile is led into _nitrum_ pits and evaporated by the heat of the sun and converted into _nitrum_. Just as the sea, in flowing of its own will over the soil of this same Egypt, is changed into salt, so also the Nile, when it overflows in the dog days, is converted into _nitrum_ when it flows into the _nitrum_ pits. The solution from which _nitrum_ is produced is obtained from fresh water percolating through _nitrous_ earth, in the same manner as lye is made from fresh water percolating through ashes of oak or hard oak. Both solutions are taken out of vats and poured into rectangular copper caldrons, and are boiled until at last they condense into _nitrum_.

[Illustration 561 (Soda Making): A--Vat in which the soda is mixed. B--Caldron. C--Tub in which _chrysocolla_ is condensed. D--Copper wires. E--Mortar.]

Native as well as manufactured _nitrum_ is mixed in vats with urine and boiled in the same caldrons; the decoction is poured into vats in which are copper wires, and, adhering to them, it hardens and becomes _chrysocolla_, which the Moors call _borax_. Formerly _nitrum_ was compounded with Cyprian verdigris, and ground with Cyprian copper in Cyprian mortars, as Pliny writes. Some _chrysocolla_ is made of rock-alum and sal-ammoniac.[8]

[Illustration 563 (Saltpetre Making): A--Caldron. B--Large vat into which sand is thrown. C--Plug. D--Tub. E--Vat containing the rods.]

Saltpetre[9] is made from a dry, slightly fatty earth, which, if it be retained for a while in the mouth, has an acrid and salty taste. This earth, together with a powder, are alternately put into a vat in layers a palm deep. The powder consists of two parts of unslaked lime and three parts of ashes of oak, or holmoak, or Italian oak, or Turkey oak, or of some similar kind. Each vat is filled with alternate layers of these to within three-quarters of a foot of the top, and then water is poured in until it is full. As the water percolates through the material it dissolves the saltpetre; then, the plug being pulled out from the vat, the solution is drained into a tub and ladled out into small vats. If when tested it tastes very salty, and at the same time acrid, it is good; but, if not, then it is condemned, and it must be made to percolate again through the same material or through a fresh lot. Even two or three waters may be made to percolate through the same earth and become full of saltpetre, but the solutions thus obtained must not be mixed together unless all have the same taste, which rarely or never happens. The first of these solutions is poured into the first vat, the next into the second, the third into the third vat; the second and third solutions are used instead of plain water to percolate through fresh material; the first solution is made in this manner from both the second and third. As soon as there is an abundance of this solution it is poured into the rectangular copper caldron and evaporated to one half by boiling; then it is transferred into a vat covered with a lid, in which the earthy matter settles to the bottom. When the solution is clear it is poured back into the same pan, or into another, and re-boiled. When it bubbles and forms a scum, in order that it should not run over and that it may be greatly purified, there is poured into it three or four pounds of lye, made from three parts of oak or similar ash and one of unslaked lime. But in the water, prior to its being poured in, is dissolved rock-alum, in the proportion of one hundred and twenty _librae_ of the former to five _librae_ of the latter. Shortly afterward the solution will be found to be clear and blue. It is boiled until the waters, which are easily volatile (_subtiles_), are evaporated, and then the greater part of the salt, after it has settled at the bottom of the pan, is taken out with iron ladles. Then the concentrated solution is transferred to the vat in which rods are placed horizontally and vertically, to which it adheres when cold, and if there be much, it is condensed in three or four days into saltpetre. Then the solution which has not congealed, is poured out and put on one side or re-boiled. The saltpetre being cut out and washed with its own solution, is thrown on to boards that it may drain and dry. The yield of saltpetre will be much or little in proportion to whether the solution has absorbed much or little; when the saltpetre has been obtained from lye, which purifies itself, it is somewhat clear and pure.

The purest and most transparent, because free from salt, is made if it is drawn off at the thickening stage, according to the following method. There are poured into the caldron the same number of _amphorae_ of the solution as of _congii_ of the lye of which I have already spoken, and into the same caldron is thrown as much of the already made saltpetre as the solution and lye will dissolve. As soon as the mixture effervesces and forms scum, it is transferred to a vat, into which on a cloth has been thrown washed sand obtained from a river. Soon afterward the plug is drawn out of the hole at the bottom, and the mixture, having percolated through the sand, escapes into a tub. It is then reduced by boiling in one or another of the caldrons, until the greater part of the solution has evaporated; but as soon as it is well boiled and forms scum, a little lye is poured into it. Then it is transferred to another vat in which there are small rods, to which it adheres and congeals in two days if there is but little of it, or if there is much in three days, or at the most in four days; if it does not condense, it is poured back into the caldron and re-boiled down to half; then it is transferred to the vat to cool. The process must be repeated as often as is necessary.

Others refine saltpetre by another method, for with it they fill a pot made of copper, and, covering it with a copper lid, set it over live coals, where it is heated until it melts. They do not cement down the lid, but it has a handle, and can be lifted for them to see whether or not the melting has taken place. When it has melted, powdered sulphur is sprinkled in, and if the pot set on the fire does not light it, the sulphur kindles, whereby the thick, greasy matter floating on the saltpetre burns up, and when it is consumed the saltpetre is pure. Soon afterward the pot is removed from the fire, and later, when cold, the purest saltpetre is taken out, which has the appearance of white marble, the earthy residue then remains at the bottom. The earths from which the solution was made, together with branches of oak or similar trees, are exposed under the open sky and sprinkled with water containing saltpetre. After remaining thus for five or six years, they are again ready to be made into a solution.

Pure saltpetre which has rested many years in the earth, and that which exudes from the stone walls of wine cellars and dark places, is mixed with the first solution and evaporated by boiling.

Thus far I have described the methods of making _nitrum_, which are not less varied or multifarious than those for making salt. Now I propose to describe the methods of making alum,[10] which are likewise neither all alike, nor simple, because it is made from boiling aluminous water until it condenses to alum, or else from boiling a solution of alum which is obtained from a kind of earth, or from rocks, or from pyrites, or other minerals.

[Illustration 567 (Vitriol Making): A--Tanks. B--Stirring poles. C--Plug. D--Trough. E--Reservoir. F--Launder. G--lead caldron. H--Wooden tubs sunk into the earth. I--Vats in which twigs are fixed.]

This kind of earth having first been dug up in such quantity as would make three hundred wheelbarrow loads, is thrown into two tanks; then the water is turned into them, and if it (the earth) contains vitriol it must be diluted with urine. The workmen must many times a day stir the ore with long, thick sticks in order that the water and urine may be mixed with it; then the plugs having been taken out of both tanks, the solution is drawn off into a trough, which is carved out of one or two trees. If the locality is supplied with an abundance of such ore, it should not immediately be thrown into the tanks, but first conveyed into open spaces and heaped up, for the longer it is exposed to the air and the rain, the better it is; after some months, during which the ore has been heaped up in open spaces into mounds, there are generated veinlets of far better quality than the ore. Then it is conveyed into six or more tanks, nine feet in length and breadth and five in depth, and afterward water is drawn into them of similar solution. After this, when the water has absorbed the alum, the plugs are pulled out, and the solution escapes into a round reservoir forty feet wide and three feet deep. Then the ore is thrown out of the tanks into other tanks, and water again being run into the latter and the urine added and stirred by means of poles, the plugs are withdrawn and the solution is run off into the same reservoir. A few days afterward, the reservoirs containing the solution are emptied through a small launder, and run into rectangular lead caldrons; it is boiled in them until the greater part of the water has evaporated. The earthy sediment deposited at the bottom of the caldron is composed of fatty and aluminous matter, which usually consists of small incrustations, in which there is not infrequently found a very white and very light powder of asbestos or gypsum. The solution now seems to be full of meal. Some people instead pour the partly evaporated solution into a vat, so that it may become pure and clear; then pouring it back into the caldron, they boil it again until it becomes mealy. By whichever process it has been condensed, it is then poured into a wooden tub sunk into the earth in order to cool it. When it becomes cold it is poured into vats, in which are arranged horizontal and vertical twigs, to which the alum clings when it condenses; and thus are made the small white transparent cubes, which are laid to dry in hot rooms.

If vitriol forms part of the aluminous ore, the material is dissolved in water without being mixed with urine, but it is necessary to pour that into the clear and pure solution when it is to be re-boiled. This separates the vitriol from the alum, for by this method the latter sinks to the bottom of the caldron, while the former floats on the top; both must be poured separately into smaller vessels, and from these into vats to condense. If, however, when the solution was re-boiled they did not separate, then they must be poured from the smaller vessels into larger vessels and covered over; then the vitriol separating from the alum, it condenses. Both are cut out and put to dry in the hot room, and are ready to be sold; the solution which did not congeal in the vessels and vats is again poured back into the caldron to be re-boiled. The earth which settled at the bottom of the caldron is carried back to the tanks, and, together with the ore, is again dissolved with water and urine. The earth which remains in the tanks after the solution has been drawn off is emptied in a heap, and daily becomes more and more aluminous in the same way as the earth from which saltpetre was made, but fuller of its juices, wherefore it is again thrown into the tanks and percolated by water.

[Illustration 571 (Alum Making): A--Furnace. B--Enclosed space. C--Aluminous rock. D--Deep ladle. E--Caldron. F--Launder. G--Troughs.]

Aluminous rock is first roasted in a furnace similar to a lime kiln. At the bottom of the kiln a vaulted fireplace is made of the same kind of rock; the remainder of the empty part of the kiln is then entirely filled with the same aluminous rocks. Then they are heated with fire until they are red hot and have exhaled their sulphurous fumes, which occurs, according to their divers nature, within the space of ten, eleven, twelve, or more hours. One thing the master must guard against most of all is not to roast the rock either too much or too little, for on the one hand they would not soften when sprinkled with water, and on the other they either would be too hard or would crumble into ashes; from neither would much alum be obtained, for the strength which they have would be decreased. When the rocks are cooled they are drawn out and conveyed into an open space, where they are piled one upon the other in heaps fifty feet long, eight feet wide, and four feet high, which are sprinkled for forty days with water carried in deep ladles. In spring the sprinkling is done both morning and evening, and in summer at noon besides. After being moistened for this length of time the rocks begin to fall to pieces like slaked lime, and there originates a certain new material of the future alum, which is soft and similar to the _liquidae medullae_ found in the rocks. It is white if the stone was white before it was roasted, and rose-coloured if red was mixed with the white; from the former, white alum is obtained, and from the latter, rose-coloured. A round furnace is made, the lower part of which, in order to be able to endure the force of the heat, is made of rock that neither melts nor crumbles to powder by the fire. It is constructed in the form of a basket, the walls of which are two feet high, made of the same rock. On these walls rests a large round caldron made of copper plates, which is concave at the bottom, where it is eight feet in diameter. In the empty space under the bottom they place the wood to be kindled with fire. Around the edge of the bottom of the caldron, rock is built in cone-shaped, and the diameter of the bottom of the rock structure is seven feet, and of the top ten feet; it is eight feet deep. The inside, after being rubbed over with oil, is covered with cement, so that it may be able to hold boiling water; the cement is composed of fresh lime, of which the lumps are slaked with wine, of iron-scales, and of sea-snails, ground and mixed with the white of eggs and oil. The edges of the caldron are surmounted with a circle of wood a foot thick and half a foot high, on which the workmen rest the wooden shovels with which they cleanse the water of earth and of the undissolved lumps of rock that remain at the bottom of the caldron. The caldron, being thus prepared, is entirely filled through a launder with water, and this is boiled with a fierce fire until it bubbles. Then little by little eight wheelbarrow loads of the material, composed of roasted rock moistened with water, are gradually emptied into the caldron by four workmen, who, with their shovels which reach to the bottom, keep the material stirred and mixed with water, and by the same means they lift the lumps of undissolved rock out of the caldron. In this manner the material is thrown in, in three or four lots, at intervals of two or three hours more or less; during these intervals, the water, which has been cooled by the rock and material, again begins to boil. The water, when sufficiently purified and ready to congeal, is ladled out and run off with launders into thirty troughs. These troughs are made of oak, holm oak, or Turkey oak; their interior is six feet long, five feet deep, and four feet wide. In these the water congeals and condenses into alum, in the spring in the space of four days, and in summer in six days. Afterward the holes at the bottom of the oak troughs being opened, the water which has not congealed is drawn off into buckets and poured back into the caldron; or it may be preserved in empty troughs, so that the master of the workmen, having seen it, may order his helpers to pour it into the caldron, for the water which is not altogether wanting in alum, is considered better than that which has none at all. Then the alum is hewn out with a knife or a chisel. It is thick and excellent according to the strength of the rock, either white or pink according to the colour of the rock. The earthy powder, which remains three to four digits thick as the residue of the alum at the bottom of the trough is again thrown into the caldron and boiled with fresh aluminous material. Lastly, the alum cut out is washed, and dried, and sold.

Alum is also made from crude pyrites and other aluminous mixtures. It is first roasted in an enclosed area; then, after being exposed for some months to the air in order to soften it, it is thrown into vats and dissolved. After this the solution is poured into the leaden rectangular pans and boiled until it condenses into alum. The pyrites and other stones which are not mixed with alum alone, but which also contain vitriol, as is most usually the case, are both treated in the manner which I have already described. Finally, if metal is contained in the pyrites and other rock, this material must be dried, and from it either gold, silver, or copper is made in a furnace.

Vitriol[11] can be made by four different methods; by two of these methods from water containing vitriol; by one method from a solution of _melanteria_, _sory_ and _chalcitis_; and by another method from earth or stones mixed with vitriol.

[Illustration 574 (Vitriol Making): A--Tunnel. B--Bucket. C--Pit.]

The vitriol water is collected into pools, and if it cannot be drained into them, it must be drawn up and carried to them in buckets by a workman. In hot regions or in summer, it is poured into out-of-door pits which have been dug to a certain depth, or else it is extracted from shafts by pumps and poured into launders, through which it flows into the pits, where it is condensed by the heat of the sun. In cold regions and in winter these vitriol waters are boiled down with equal parts of fresh water in rectangular leaden caldrons; then, when cold, the mixture is poured into vats or into tanks, which Pliny calls wooden fish-tanks. In these tanks light cross-beams are fixed to the upper part, so that they may be stationary, and from them hang ropes stretched with little stones; to these the contents of the thickened solutions congeal and adhere in transparent cubes or seeds of vitriol, like bunches of grapes.

[Illustration 575 (Vitriol Making): A--Caldron. B--Tank. C--Cross-bars. D--Ropes. E--Little stones.]

By the third method vitriol is made out of _melanteria_ and _sory_. If the mines give an abundant supply of _melanteria_ and _sory_, it is better to reject the _chalcitis_, and especially the _misy_, for from these the vitriol is impure, particularly from the _misy_. These materials having been dug and thrown into the tanks, they are first dissolved with water; then, in order to recover the pyrites from which copper is not rarely smelted and which forms a sediment at the bottom of the tanks, the solution is transferred to other vats, which are nine feet wide and three feet deep. Twigs and wood which float on the surface are lifted out with a broom made of twigs, and afterward all the sediment settles at the bottom of this vat. The solution is poured into a rectangular leaden caldron eight feet long, three feet wide, and the same in depth. In this caldron it is boiled until it becomes thick and viscous, when it is poured into a launder, through which it runs into another leaden caldron of the same size as the one described before. When cold, the solution is drawn off through twelve little launders, out of which it flows into as many wooden tubs four and a half feet deep and three feet wide. Upon these tubs are placed perforated crossbars distant from each other from four to six digits, and from the holes hang thin laths, which reach to the bottom, with pegs or wedges driven into them. The vitriol adheres to these laths, and within the space of a few days congeals into cubes, which are taken away and put into a chamber having a sloping board floor, so that the moisture which drips from the vitriol may flow into a tub beneath. This solution is re-boiled, as is also that solution which was left in the twelve tubs, for, by reason of its having become too thin and liquid, it did not congeal, and was thus not converted into vitriol.

[Illustration 576 (Vitriol Making): A--Wooden tub. B--Cross-bars. C--Laths. D--Sloping floor of the chamber. E--Tub placed under it.]

[Illustration 577 (Vitriol Making): A--Caldron. B--Moulds. C--Cakes.]

The fourth method of making vitriol is from vitriolous earth or stones. Such ore is at first carried and heaped up, and is then left for five or six months exposed to the rain of spring and autumn, to the heat of summer, and to the rime and frost of winter. It must be turned over several times with shovels, so that the part at the bottom may be brought to the top, and it is thus ventilated and cooled; by this means the earth crumbles up and loosens, and the stone changes from hard to soft. Then the ore is covered with a roof, or else it is taken away and placed under a roof, and remains in that place six, seven, or eight months. Afterward as large a portion as is required is thrown into a vat, which is half-filled with water; this vat is one hundred feet long, twenty-four feet wide, eight feet deep. It has an opening at the bottom, so that when it is opened the dregs of the ore from which the vitriol comes may be drawn off, and it has, at the height of one foot from the bottom, three or four little holes, so that, when closed, the water may be retained, and when opened the solution flows out. Thus the ore is mixed with water, stirred with poles and left in the tank until the earthy portions sink to the bottom and the water absorbs the juices. Then the little holes are opened, the solution flows out of the vat, and is caught in a vat below it; this vat is of the same length as the other, but twelve feet wide and four feet deep. If the solution is not sufficiently vitriolous it is mixed with fresh ore; but if it contains enough vitriol, and yet has not exhausted all of the ore rich in vitriol, it is well to dissolve the ore again with fresh water. As soon as the solution becomes clear, it is poured into the rectangular leaden caldron through launders, and is boiled until the water is evaporated. Afterward as many thin strips of iron as the nature of the solution requires, are thrown in, and then it is boiled again until it is thick enough, when cold, to congeal into vitriol. Then it is poured into tanks or vats, or any other receptacle, in which all of it that is apt to congeal does so within two or three days. The solution which does not congeal is either poured back into the caldron to be boiled again, or it is put aside for dissolving the new ore, for it is far preferable to fresh water. The solidified vitriol is hewn out, and having once more been thrown into the caldron, is re-heated until it liquefies; when liquid, it is poured into moulds that it may be made into cakes. If the solution first poured out is not satisfactorily thickened, it is condensed two or three times, and each time liquefied in the caldron and re-poured into the moulds, in which manner pure cakes, beautiful to look at, are made from it.

The vitriolous pyrites, which are to be numbered among the mixtures (_mistura_), are roasted as in the case of alum, and dissolved with water, and the solution is boiled in leaden caldrons until it condenses into vitriol. Both alum and vitriol are often made out of these, and it is no wonder, for these juices are cognate, and only differ in the one point,--that the former is less, the latter more, earthy. That pyrites which contains metal must be smelted in the furnace. In the same manner, from other mixtures of vitriolic and metalliferous material are made vitriol and metal. Indeed, if ores of vitriolous pyrites abound, the miners split small logs down the centre and cut them off in lengths as long as the drifts and tunnels are wide, in which they lay them down transversely; but, that they may be stable, they are laid on the ground with the wide side down and the round side up, and they touch each other at the bottom, but not at the top. The intermediate space is filled with pyrites, and the same crushed are scattered over the wood, so that, coming in or going out, the road is flat and even. Since the drifts or tunnels drip with water, these pyrites are soaked, and from them are freed the vitriol and cognate things. If the water ceases to drip, these dry and harden, and then they are raised from the shafts, together with the pyrites not yet dissolved in the water, or they are carried out from the tunnels; then they are thrown into vats or tanks, and boiling water having been poured over them, the vitriol is freed and the pyrites are dissolved. This green solution is transferred to other vats or tanks, that it may be made clear and pure; it is then boiled in the lead caldrons until it thickens; afterward it is poured into wooden tubs, where it condenses on rods, or reeds, or twigs, into green vitriol.

Sulphur is made from sulphurous waters, from sulphurous ores, and from sulphurous mixtures. These waters are poured into the leaden caldrons and boiled until they condense into sulphur. From this latter, heated together with iron-scales, and transferred into pots, which are afterward covered with lute and refined sulphur, another sulphur is made, which we call _caballinum_.[12]

[Illustration 579 (Sulphur Making): A--Pots having spouts. B--Pots without spouts. C--Lids.]

The ores[13] which consist mostly of sulphur and of earth, and rarely of other minerals, are melted in big-bellied earthenware pots. The furnaces, which hold two of these pots, are divided into three parts; the lowest part is a foot high, and has an opening at the front for the draught; the top of this is covered with iron plates, which are perforated near the edges, and these support iron rods, upon which the firewood is placed. The middle part of the furnace is one and a half feet high, and has a mouth in front, so that the wood may be inserted; the top of this has rods, upon which the bottom of the pots stand. The upper part is about two feet high, and the pots are also two feet high and one digit thick; these have below their mouths a long, slender spout. In order that the mouth of the pot may be covered, an earthenware lid is made which fits into it. For every two of these pots there must be one pot of the same size and shape, and without a spout, but having three holes, two of which are below the mouth and receive the spouts of the two first pots; the third hole is on the opposite side at the bottom, and through it the sulphur flows out. In each furnace are placed two pots with spouts, and the furnace must be covered by plates of iron smeared over with lute two digits thick; it is thus entirely closed in, but for two or three vent-holes through which the mouths of the pots project. Outside of the furnace, against one side, is placed the pot without a spout, into the two holes of which the two spouts of the other pots penetrate, and this pot should be built in at both sides to keep it steady. When the sulphur ore has been placed in the pots, and these placed in the furnace, they are closely covered, and it is desirable to smear the joint over with lute, so that the sulphur will not exhale, and for the same reason the pot below is covered with a lid, which is also smeared with lute. The wood having been kindled, the ores are heated until the sulphur is exhaled, and the vapour, arising through the spout, penetrates into the lower pot and thickens into sulphur, which falls to the bottom like melted wax. It then flows out through the hole, which, as I said, is at the bottom of this pot; and the workman makes it into cakes, or thin sticks or thin pieces of wood are dipped in it. Then he takes the burning wood and glowing charcoal from the furnace, and when it has cooled, he opens the two pots, empties the residues, which, if the ores were composed of sulphur and earth, resemble naturally extinguished ashes; but if the ores consisted of sulphur and earth and stone, or sulphur and stone only, they resemble earth completely dried or stones well roasted. Afterward the pots are re-filled with ore, and the whole work is repeated.

[Illustration 581 (Sulphur Making): A--Long wall. B--High walls. C--Low walls. D--Plates. E--Upper pots. F--Lower pots.]

The sulphurous mixture, whether it consists of stone and sulphur only, or of stone and sulphur and metal, may be heated in similar pots, but with perforated bottoms. Before the furnace is constructed, against the "second" wall of the works two lateral partitions are built seven feet high, three feet long, one and a half feet thick, and these are distant from each other twenty-seven feet. Between them are seven low brick walls, that measure but two feet and the same number of digits in height, and, like the other walls, are three feet long and one foot thick; these little walls are at equal distances from one another, consequently they will be two and one half feet apart. At the top, iron bars are fixed into them, which sustain iron plates three feet long and wide and one digit thick, so that they can bear not only the weight of the pots, but also the fierceness of the fire. These plates have in the middle a round hole one and a half digits wide; there must not be more than eight of these, and upon them as many pots are placed. These pots are perforated at the bottom, and the same number of whole pots are placed underneath them; the former contain the mixture, and are covered with lids; the latter contain water, and their mouths are under the holes in the plates. After wood has been arranged round the upper pots and ignited, the mixture being heated, red, yellow, or green sulphur drips from it and flows down through the hole, and is caught by the pots placed underneath the plates, and is at once cooled by the water. If the mixture contains metal, it is reserved for smelting, and, if not, it is thrown away. The sulphur from such a mixture can best be extracted if the upper pots are placed in a vaulted furnace, like those which I described among other metallurgical subjects in Book VIII., which has no floor, but a grate inside; under this the lower pots are placed in the same manner, but the plates must have larger holes.

[Illustration 582 (Bitumen Making): A--Lower pot. B--Upper pot. C--Lid.]

Others bury a pot in the ground, and place over it another pot with a hole at the bottom, in which pyrites or _cadmia_, or other sulphurous stones are so enclosed that the sulphur cannot exhale. A fierce fire heats the sulphur, and it drips away and flows down into the lower pot, which contains water. (Illustration p. 582).

[Illustration 583 (Bitumen Making): A--Bituminous spring. B--Bucket. C--Pot. D--Lid.]

Bitumen[14] is made from bituminous waters, from liquid bitumen, and from mixtures of bituminous substances. The water, bituminous as well as salty, at Babylon, as Pliny writes, was taken from the wells to the salt works and heated by the great heat of the sun, and condensed partly into liquid bitumen and partly into salt. The bitumen being lighter, floats on the top, while the salt being heavier, sinks to the bottom. Liquid bitumen, if there is much floating on springs, streams and rivers, is drawn up in buckets or other vessels; but, if there is little, it is collected with goose wings, pieces of linen, _ralla_, shreds of reeds, and other things to which it easily adheres, and it is boiled in large brass or iron pots by fire and condensed. As this bitumen is put to divers uses, some mix pitch with the liquid, others old cart-grease, in order to temper its viscosity; these, however long they are boiled in the pots, cannot be made hard. The mixtures containing bitumen are also treated in the same manner as those containing sulphur, in pots having a hole in the bottom, and it is rare that such bitumen is not highly esteemed.

[Illustration 585 (Chrysocolla Making): A--Mouth of the tunnel. B--Trough. C--Tanks. D--Little trough.]

Since all solidified juices and earths, if abundantly and copiously mixed with the water, are deposited in the beds of springs, streams or rivers, and the stones therein are coated by them, they do not require the heat of the sun or fire to harden them. This having been pondered over by wise men, they discovered methods by which the remainder of these solidified juices and unusual earths can be collected. Such waters, whether flowing from springs or tunnels, are collected in many wooden tubs or tanks arranged in consecutive order, and deposit in them such juices or earths; these being scraped off every year, are collected, as _chrysocolla_[15] in the Carpathians and as ochre in the Harz.

There remains glass, the preparation of which belongs here, for the reason that it is obtained by the power of fire and subtle art from certain solidified juices and from coarse or fine sand. It is transparent, as are certain solidified juices, gems, and stones; and can be melted like fusible stones and metals. First I must speak of the materials from which glass is made; then of the furnaces in which it is melted; then of the methods by which it is produced.

It is made from fusible stones and from solidified juices, or from other juicy substances which are connected by a natural relationship. Stones which are fusible, if they are white and translucent, are more excellent than the others, for which reason crystals take the first place. From these, when pounded, the most excellent transparent glass was made in India, with which no other could be compared, as Pliny relates. The second place is accorded to stones which, although not so hard as crystal, are yet just as white and transparent. The third is given to white stones, which are not transparent. It is necessary, however, first of all to heat all these, and afterward they are subjected to the pestle in order to break and crush them into coarse sand, and then they are passed through a sieve. If this kind of coarse or fine sand is found by the glass-makers near the mouth of a river, it saves them much labour in burning and crushing. As regards the solidified juices, the first place is given to soda; the second to white and translucent rock-salt; the third to salts which are made from lye, from the ashes of the musk ivy, or from other salty herbs. Yet there are some who give to this latter, and not to the former, the second place. One part of coarse or fine sand made from fusible stones should be mixed with two parts of soda or of rock-salt or of herb salts, to which are added minute particles of _magnes_.[16] It is true that in our day, as much as in ancient times, there exists the belief in the singular power of the latter to attract to itself the vitreous liquid just as it does iron, and by attracting it to purify and transform green or yellow into white; and afterward fire consumes the _magnes_. When the said juices are not to be had, two parts of the ashes of oak or holmoak, or of hard oak or Turkey oak, or if these be not available, of beech or pine, are mixed with one part of coarse or fine sand, and a small quantity of salt is added, made from salt water or sea-water, and a small particle of _magnes_; but these make a less white and translucent glass. The ashes should be made from old trees, of which the trunk at a height of six feet is hollowed out and fire is put in, and thus the whole tree is consumed and converted into ashes. This is done in winter when the snow lies long, or in summer when it does not rain, for the showers at other times of the year, by mixing the ashes with earth, render them impure; for this reason, at such times, these same trees are cut up into many pieces and burned under cover, and are thus converted into ashes.

[Illustration 587 (Glass-making Furnace): A--Lower chamber of the first furnace. B--Upper chamber. C--Vitreous mass.]

Some glass-makers use three furnaces, others two, others only one. Those who use three, melt the material in the first, re-melt it in the second, and in the third they cool the glowing glass vessels and other articles. Of these the first furnace must be vaulted and similar to an oven. In the upper chamber, which is six feet long, four feet wide, and two feet high, the mixed materials are heated by a fierce fire of dry wood until they melt and are converted into a vitreous mass. And if they are not satisfactorily purified from dross, they are taken out and cooled and broken into pieces; and the vitreous pieces are heated in pots in the same furnace.

[Illustration 588 (Glass-making Furnace): A--Arches of the second furnace. B--Mouth of the lower chamber. C--Windows of the upper chamber. D--Big-bellied pots. E--Mouth of the third furnace. F--Recesses for the receptacles. G--Openings in the upper chamber. H--Oblong receptacles.]

The second furnace is round, ten feet in diameter and eight feet high, and on the outside, so that it may be stronger, it is encompassed by five arches, one and one half feet thick; it consists in like manner of two chambers, of which the lower one is vaulted and is one and one half feet thick. In front this chamber has a narrow mouth, through which the wood can be put into the hearth, which is on the ground. At the top and in the middle of its vault, there is a large round hole which opens to the upper chamber, so that the flames can penetrate into it. Between the arches in the walls of the upper chamber are eight windows, so large that the big-bellied pots may be placed through them on to the floor of the chamber, around the large hole. The thickness of these pots is about two digits, their height the same number of feet, and the diameter of the belly one and a half feet, and of the mouth and bottom one foot. In the back part of the furnace is a rectangular hole, measuring in height and width a palm, through which the heat penetrates into a third furnace which adjoins it.

This third furnace is rectangular, eight feet long and six feet wide; it also consists of two chambers, of which the lower has a mouth in front, so that firewood may be placed on the hearth which is on the ground. On each side of this opening in the wall of the lower chamber is a recess for oblong earthenware receptacles, which are about four feet long, two feet high, and one and a half feet wide. The upper chamber has two holes, one on the right side, the other on the left, of such height and width that earthenware receptacles may be conveniently placed in them. These latter receptacles are three feet long, one and a half feet high, the lower part one foot wide, and the upper part rounded. In these receptacles the glass articles, which have been blown, are placed so that they may cool in a milder temperature; if they were not cooled slowly they would burst asunder. When the vessels are taken from the upper chamber, they are immediately placed in the receptacles to cool.

[Illustration 589 (Glass-making Furnaces): A--Lower chamber of the other second furnace. B--Middle one. C--Upper one. D--Its opening. E--Round opening. F--Rectangular opening.]

Some who use two furnaces partly melt the mixture in the first, and not only re-melt it in the second, but also replace the glass articles there. Others partly melt and re-melt the material in different chambers of the second furnace. Thus the former lack the third furnace, and the latter, the first. But this kind of second furnace differs from the other second furnace, for it is, indeed, round, but the interior is eight feet in diameter and twelve feet high, and it consists of three chambers, of which the lowest is not unlike the lowest of the other second furnace. In the middle chamber wall there are six arched openings, in which are placed the pots to be heated, and the remainder of the small windows are blocked up with lute. In the middle top of the middle chamber is a square opening a palm in length and width. Through this the heat penetrates into the upper chamber, of which the rear part has an opening to receive the oblong earthenware receptacles, in which are placed the glass articles to be slowly cooled. On this side, the ground of the workshop is higher, or else a bench is placed there, so that the glass-makers may stand upon it to stow away their products more conveniently.

Those who lack the first furnace in the evening, when they have accomplished their day's work, place the material in the pots, so that the heat during the night may melt it and turn it into glass. Two boys alternately, during night and day, keep up the fire by throwing dry wood on to the hearth. Those who have but one furnace use the second sort, made with three chambers. Then in the evening they pour the material into the pots, and in the morning, having extracted the fused material, they make the glass objects, which they place in the upper chamber, as do the others.

The second furnace consists either of two or three chambers, the first of which is made of unburnt bricks dried in the sun. These bricks are made of a kind of clay that cannot be easily melted by fire nor resolved into powder; this clay is cleaned of small stones and beaten with rods. The bricks are laid with the same kind of clay instead of lime. From the same clay the potters also make their vessels and pots, which they dry in the shade. These two parts having been completed, there remains the third.

[Illustration 591 (Glass Making): A--Blow-pipe. B--Little window. C--Marble. D--Forceps. E--Moulds by means of which the shapes are produced.]

The vitreous mass having been made in the first furnace in the manner I described, is broken up, and the assistant heats the second furnace, in order that the fragments may be re-melted. In the meantime, while they are doing this, the pots are first warmed by a slow fire in the first furnace, so that the vapours may evaporate, and then by a fiercer fire, so that they become red in drying. Afterward the glass-makers open the mouth of the furnace, and, seizing the pots with tongs, if they have not cracked and fallen to pieces, quickly place them in the second furnace, and they fill them up with the fragments of the heated vitreous mass or with glass. Afterward they close up all the windows with lute and bricks, with the exception that in each there are two little windows left free; through one of these they inspect the glass contained in the pot, and take it up by means of a blow-pipe; in the other they rest another blow-pipe, so that it may get warm. Whether it is made of brass, bronze, or iron, the blow-pipe must be three feet long. In front of the window is inserted a lip of marble, on which rests the heaped-up clay and the iron shield. The clay holds the blow-pipe when it is put into the furnace, whereas the shield preserves the eyes of the glass-maker from the fire. All this having been carried out in order, the glass-makers bring the work to completion. The broken pieces they re-melt with dry wood, which emits no smoke, but only a flame. The longer they re-melt it, the purer and more transparent it becomes, the fewer spots and blisters there are, and therefore the glass-makers can carry out their work more easily. For this reason those who only melt the material from which glass is made for one night, and then immediately make it up into glass articles, make them less pure and transparent than those who first produce a vitreous mass and then re-melt the broken pieces again for a day and a night. And, again, these make a less pure and transparent glass than do those who melt it again for two days and two nights, for the excellence of the glass does not consist solely in the material from which it is made, but also in the melting. The glass-makers often test the glass by drawing it up with the blowpipes; as soon as they observe that the fragments have been re-melted and purified satisfactorily, each of them with another blow-pipe which is in the pot, slowly stirs and takes up the glass which sticks to it in the shape of a ball like a glutinous, coagulated gum. He takes up just as much as he needs to complete the article he wishes to make; then he presses it against the lip of marble and kneads it round and round until it consolidates. When he blows through the pipe he blows as he would if inflating a bubble; he blows into the blow-pipe as often as it is necessary, removing it from his mouth to re-fill his cheeks, so that his breath does not draw the flames into his mouth. Then, twisting the lifted blow-pipe round his head in a circle, he makes a long glass, or moulds the same in a hollow copper mould, turning it round and round, then warming it again, blowing it and pressing it, he widens it into the shape of a cup or vessel, or of any other object he has in mind. Then he again presses this against the marble to flatten the bottom, which he moulds in the interior with his other blow-pipe. Afterward he cuts out the lip with shears, and, if necessary, adds feet and handles. If it so please him, he gilds it and paints it with various colours. Finally, he lays it in the oblong earthenware receptacle, which is placed in the third furnace, or in the upper chamber of the second furnace, that it may cool. When this receptacle is full of other slowly-cooled articles, he passes a wide iron bar under it, and, carrying it on the left arm, places it in another recess.

The glass-makers make divers things, such as goblets, cups, ewers, flasks, dishes, plates, panes of glass, animals, trees, and ships, all of which excellent and wonderful works I have seen when I spent two whole years in Venice some time ago. Especially at the time of the Feast of the Ascension they were on sale at Morano, where are located the most celebrated glass-works. These I saw on other occasions, and when, for a certain reason, I visited Andrea Naugerio in his house which he had there, and conversed with him and Francisco Asulano.

END OF BOOK XII.

FOOTNOTES:

[1] The history of salt-making in salt-pans, from sea-water or salt springs, goes further back than human records. From an historical point of view the real interest attached to salt lies in the bearing which localities rich in either natural salt or salt springs, have had upon the movements of the human race. Many ancient trade routes have been due to them, and innumerable battles have been fought for their possession. Salt has at times served for currency, and during many centuries in nearly every country has served as a basis of taxation. These subjects do not, however, come within the scope of this text. For the quotation from Pliny referred to, see Note 14 below, on bitumen.

[2] The first edition gives _graviorem_, the latter editions _gratiorem_, which latter would have quite the reverse meaning from the above.

[3] The following are approximately the English equivalents:--

Pints. Quarts. Gallons. 1 _Cyathus_ .08 3 _Cyathi_ = 1 _Quartarius_ .24 4 _Quartarii_ = 1 _Sextarius_ .99 6 _Sextarii_ = 1 _Congius_ 5.94 2.97 16 _Sextarii_ = 1 _Modius_ 15.85 7.93 1.98 8 _Congii_ = 1 _Amphora_ 47.57 23.78 5.94

The dipper mentioned would thus hold about one and one quarter gallons, and the cask ten gallons.

[4] The salt industry, founded upon salt springs, is still of importance to this city. It was a salt centre of importance to the Germanic tribes before Charles, the son of Charlemagne, erected a fortress here in 806. Mention of the salt works is made in the charter by Otto I., conveying the place to the Diocese of Magdeburg, in 968.

[5] Pliny XXXI., 39-40. "In the Gallic provinces in Germany they pour salt water upon burning wood. The Spaniards in a certain place draw the brine from wells, which they call _Muria_. They indeed think that the wood turns to salt, and that the oak is the best, being the kind which is itself salty. Elsewhere the hazel is praised. Thus the charcoal even is turned into salt when it is steeped in brine. Whenever salt is made with wood it is black."

[6] We have elsewhere in this book used the word "soda" for the Latin term _nitrum_, because we believe as used by Agricola it was always soda, and because some confusion of this term with its modern adaptation for saltpetre (nitre) might arise in the mind of the reader. Fortunately, Agricola usually carefully mentions other alkalis, such as the product from lixiviation of ashes, separately from his _nitrum_. In these paragraphs, however, he has soda and potash hopelessly mixed, wherefore we have here introduced the Latin term. The actual difference between potash and soda--the _nitrum_ of the Ancients, and the _alkali_ of Geber (and the glossary of Agricola), was not understood for two hundred years after Agricola, when Duhamel made his well-known determinations; and the isolation of sodium and potassium was, of course, still later by fifty years. If the reeds and rushes described in this paragraph grew near the sea, the salt from lixiviation would be soda, and likewise the Egyptian product was soda, but the lixiviation of wood-ash produces only potash; as seen above, all are termed _nitrum_ except the first.

HISTORICAL NOTES.--The word _nitrum_, _nitron_, _nitri_, _neter_, _nether_, or similar forms, occurs in innumerable ancient writings. Among such references are Jeremiah (II., 22) Proverbs (XXV., 20), Herodotus (II., 86, 87), Aristotle (_Prob._ I., 39, _De Mirab._ 54), Theophrastus (_De Igne_ 435 ed. Heinsii, Hist. Plants III., 9), Dioscorides (V., 89), Pliny (XIV., 26, and XXXI., 46). A review of disputations on what salts this term comprised among the Ancients would itself fill a volume, but from the properties named it was no doubt mostly soda, more rarely potash, and sometimes both mixed with common salt. There is every reason to believe from the properties and uses mentioned, that it did not generally comprise nitre (saltpetre)--into which superficial error the nomenclature has led many translators. The preparation by way of burning, and the use of _nitrum_ for purposes for which we now use soap, for making glass, for medicines, cosmetics, salves, painting, in baking powder, for preserving food, embalming, etc., and the descriptions of its taste in "nitrous" waters,--all answer for soda and potash, but not for saltpetre. It is possible that the common occurrence of saltpetre as an efflorescence on walls might naturally lead to its use, but in any event its distinguishing characteristics are nowhere mentioned. As sal-ammoniac occurred in the volcanoes in Italy, it also may have been included in the _nitrum_ mentioned. _Nitrum_ was in the main exported from Egypt, but Theophrastus mentions its production from wood-ash, and Pliny very rightly states that burned lees of wine (argol) had the nature of _nitrum_. Many of the ancient writers understood that it was rendered more caustic by burning, and still more so by treatment with lime. According to Beckmann (Hist. of Inventions II., p. 488), the form of the word _natron_ was first introduced into Europe by two travellers in Egypt, Peter Ballon and Prosper Alpinus, about 1550. The word was introduced into mineralogy by Linnaeus in 1736. In the first instance _natron_ was applied to soda and potash in distinction to _nitre_ for saltpetre, and later _natron_ was applied solely to soda.

It is desirable to mention here two other forms of soda and potash which are frequently mentioned by Agricola. "Ashes which wool dyers use" (_cineres quo infectores lanarum utuntur_).--There is no indication in any of Agricola's works as to whether this was some special wood-ash or whether it was the calcined residues from wool washing. The "yolk" or "suint" of wool, originating from the perspiration of the animal, has long been a source of crude potash. The water, after washing the wool, is evaporated, and the residue calcined. It contains about 85% K_{2}CO_{3}, the remainder being sodium and potassium sulphates. Another reason for assuming that it was not a wood-ash product, is that these products are separately mentioned. In either event, whether obtained from wool residues or from lixiviation of wood-ash, it would be an impure potash. In some methods of wool dyeing, a wash of soda was first given, so that it is barely possible that this substance was sodium carbonate.

"Salt made from the ashes of musk ivy" (_sal ex anthyllidis cinere factus_,--Glossary, _salalkali_). This would be largely potash.

[7] This wondrous illustration of soda-making from Nile water is no doubt founded upon Pliny (XXXI., 46). "It is made in almost the same manner as salt, except that sea-water is put into salt pans, whereas in the nitrous pans it is water of the Nile; these, with the subsidence of the Nile during the forty days, are impregnated with _nitrum_."

[8] This paragraph displays hopeless ignorance. Borax was known to Agricola and greatly used in his time; it certainly was not made from these compounds, but was imported from Central Asia. Sal-ammoniac was also known in his time, and was used like borax as a soldering agent. The reaction given by Agricola would yield free ammonia. The following historical notes on borax and sal-ammoniac may be of service.

BORAX.--The uncertainties of the ancient distinctions in salts involve borax deeply. The word _Baurach_ occurs in Geber and the other early Alchemistic writings, but there is nothing to prove that it was modern borax. There cannot be the slightest doubt, however, that the material referred to by Agricola as _borax_ was our borax, because of the characteristic qualities incidentally mentioned in Book VII. That he believed it was an artificial product from _nitrum_ is evident enough from his usual expression "_chrysocolla_ made from _nitrum_, which the Moors call _borax_." Agricola, in _De Natura Fossilium_ (p. 206-7), makes the following statements, which could leave no doubt on the subject:--"Native _nitrum_ is found in the earth or on the surface.... It is from this variety that the Venetians make _chrysocolla_, which I call _borax_.... The second variety of artificial _nitrum_ is made at the present day from the native _nitrum_, called by the Arabs _tincar_, but I call it usually by the Greek name _chrysocolla_; it is really the Arabic _borax_.... This _nitrum_ does not decrepitate nor fly out of the fire; however, the native variety swells up from within." The application of the word _chrysocolla_ (_chrysos_, gold; _colla_, solder) to soldering materials, and at the same time to the copper mineral, is of Greek origin. If any further proof were needed as to the substance meant by Agricola, it lies in the word _tincar_. For a long time the borax of Europe was imported from Central Asia, through Constantinople and Venice, under the name of _tincal_ or _tincar_. When this trade began, we do not know; evidently before Agricola's time. The statement here of making borax from alum and sal-ammoniac is identical with the assertion of Biringuccio (II., 9).

SAL-AMMONIAC.--The early history of this--ammonium chloride--is also under a cloud. Pliny (XXXI., 39) speaks of a _sal-hammoniacum_, and Dioscorides (V., 85) uses much the same word. Pliny describes it as from near the temple of Ammon in Egypt. None of the distinctive characteristics of sal-ammoniac are mentioned, and there is every reason to believe it was either common salt or soda. Herodotus, Strabo, and others mention common salt sent from about the same locality. The first authentic mention is in Geber, who calls it _sal-ammoniacum_, and describes a method of making, and several characteristic reactions. It was known in the Middle Ages under various names, among them _sal-aremonicum_. Agricola (_De Nat. Fos._, III., p. 206) notes its characteristic quality of volatilization. "Sal-ammoniac ... in the fire neither crackles nor flies out, but is totally consumed." He also says (p. 208): "Borax is used by goldsmiths to solder gold, likewise silver. The artificers who make iron needles (tacks?) similarly use sal-ammoniac when they cover the heads with tin." The statement from Pliny mentioned in this paragraph is from XXXIII., 29, where he describes the _chrysocolla_ used as gold solder as made from verdigris, _nitrum_, and urine in the way quoted. It is quite possible that this solder was sal-ammoniac, though not made in quite this manner. Pliny refers in several places (XXXIII., 26, 27, 28, and 29, XXXV., 28, etc.) to _chrysocolla_, about which he is greatly confused as between gold-solder, the copper mineral, and a green pigment, the latter being of either mineral origin.

[9] Saltpetre was secured in the Middle Ages in two ways, but mostly from the treatment of calcium nitrate efflorescence on cellar and similar walls, and from so-called saltpetre plantations. In this description of the latter, one of the most essential factors is omitted until the last sentence, _i.e._, that the nitrous earth was the result of the decay of organic or animal matter over a long period. Such decomposition, in the presence of potassium and calcium carbonates--the lye and lime--form potassium and calcium nitrates, together with some magnesium and sodium nitrates. After lixiviation, the addition of lye converts the calcium and magnesium nitrates into saltpetre, _i.e._, Ca(NO_{3})_{2} + K_{2}CO_{3} = CaCO_{3} + 2KNO_{3}. The carbonates precipitate out, leaving the saltpetre in solution, from which it was evaporated and crystallized out. The addition of alum as mentioned would scarcely improve the situation.

The purification by repeated re-solution and addition of lye, and filtration, would eliminate the remaining other salts. The purification with sulphur, however, is more difficult to understand. In this case the saltpetre is melted and the sulphur added and set alight. Such an addition to saltpetre would no doubt burn brilliantly. The potassium sulphate formed would possibly settle to the bottom, and if the "greasy matter" were simply organic impurities, they might be burned off. This method of refining appears to have been copied from Biringuccio (X., 1), who states it in almost identical terms.

HISTORICAL NOTE.--As mentioned in Note 6 above, it is quite possible that the Ancients did include efflorescence of walls under _nitrum_; but, so far as we are aware, no specific mention of such an occurrence of _nitrum_ is given, and, as stated before, there is every reason to believe that all the substances under that term were soda and potash. Especially the frequent mention of the preparation of _nitrum_ by way of burning, argues strongly against saltpetre being included, as they would hardly have failed to notice the decrepitation. Argument has been put forward that Greek fire contained saltpetre, but it amounts to nothing more than argument, for in those receipts preserved, no salt of any kind is mentioned. It is most likely that the leprosy of house-walls of the Mosaic code (Leviticus XIV., 34 to 53) was saltpetre efflorescence. The drastic treatment by way of destruction of such "unclean" walls and houses, however, is sufficient evidence that this salt was not used. The first certain mention of saltpetre (_sal petrae_) is in Geber. As stated before, the date of this work is uncertain; in any event it was probably as early as the 13th Century. He describes the making of "solvative water" with alum and saltpetre, so there can be no doubt as to the substance (see Note on p. 460, on nitric acid). There is also a work by a nebulous Marcus Graecus, where the word _sal petrosum_ is used. And it appears that Roger Bacon (died 1294) and Albertus Magnus (died 1280) both had access to that work. Bacon uses the term _sal petrae_ frequently enough, and was the first to describe gunpowder (_De Mirabili Potestate Artis et Naturae_ 1242). He gives no mention of the method of making his _sal petrae_. Agricola uses throughout the Latin text the term _halinitrum_, a word he appears to have coined himself. However, he gives its German equivalent in the _Interpretatio_ as _salpeter_. The only previous description of the method of making saltpetre, of which we are aware, is that of Biringuccio (1540), who mentions the boiling of the excrescences from walls, and also says a good deal about boiling solutions from "nitrous" earth, which may or may not be of "plantation" origin. He also gives this same method of refining with sulphur. In any event, this statement by Agricola is the first clear and complete description of the saltpetre "plantations." Saltpetre was in great demand in the Middle Ages for the manufacture of gunpowder, and the first record of that substance and of explosive weapons necessarily involves the knowledge of saltpetre. However, authentic mention of such weapons only begins early in the 14th Century. Among the earliest is an authority to the Council of Twelve at Florence to appoint persons to make cannon, etc., (1326), references to cannon in the stores of the Tower of London, 1388, &c.

[10] There are three methods of manufacturing alum described by Agricola, the first and third apparently from shales, and the second from alum rock or "alunite." The reasons for assuming that the first process was from shales, are the reference to the "aluminous earth" as ore (_venae_) coming from "veins," and also the mixture of vitriol. In this process the free sulphuric acid formed by the oxidation of pyrites reacts upon the argillaceous material to form aluminium sulphate. The decomposed ore is then placed in tanks and lixiviated. The solution would contain aluminium sulphate, vitriol, and other impurities. By the addition of urine, the aluminium sulphate would be converted into ammonia alum. Agricola is, of course, mistaken as to the effect of the addition, being under the belief that it separated the vitriol from the alum; in fact, this belief was general until the latter part of the 18th Century, when Lavoisier determined that alum must have an alkali base. Nor is it clear from this description exactly how they were separated. In a condensed solution allowed to cool, the alum would precipitate out as "alum meal," and the vitriol would "float on top"--in solution. The reference to "meal" may represent this phenomenon, and the re-boiling referred to would be the normal method of purification by crystallization. The "asbestos" and gypsum deposited in the caldrons were no doubt feathery and mealy calcium sulphate. The alum produced would, in any event, be mostly ammonia alum.

The second process is certainly the manufacture from "alum rock" or "alunite" (the hydrous sulphate of aluminium and potassium), such as that mined at La Tolfa in the Papal States, where the process has been for centuries identical with that here described. The alum there produced is the double basic potassium alum, and crystallizes into cubes instead of octahedra, _i.e._, the Roman alum of commerce. The presence of much ferric oxide gives the rose colour referred to by Agricola. This account is almost identical with that of Biringuccio (II., 4), and it appears from similarity of details that Agricola, as stated in his preface, must have "refreshed his mind" from this description; it would also appear from the preface that he had himself visited the locality.

The third process is essentially the same as the first, except that the decomposition of the pyrites was hastened by roasting. The following obscure statement of some interest occurs in Agricola's _De Natura Fossilium_, p. 209:--"... alum is made from vitriol, for when oil is made from the latter, alum is distilled out (_expirat_). This absorbs the clay which is used in cementing glass, and when the operation is complete the clay is macerated with pure water, and the alum is soon afterward deposited in the shape of small cubes." Assuming the oil of vitriol to be sulphuric acid and the clay "used in cementing glass" to be kaolin, we have here the first suggestion of a method for producing alum which came into use long after.

"Burnt alum" (_alumen coctum_).--Agricola frequently uses this expression, and on p. 568, describes the operation, and the substance is apparently the same as modern dehydrated alum, often referred to as "burnt alum."

HISTORICAL NOTES.--Whether the Ancients knew of alum in the modern sense is a most vexed question. The Greeks refer to a certain substance as _stypteria_, and the Romans refer to this same substance as _alumen_. There can be no question as to their knowledge and common use of vitriol, nor that substances which they believed were entirely different from vitriol were comprised under the above names. Beckmann (Hist. of Inventions, Vol. I., p. 181) seems to have been the founder of the doctrine that the ancient _alumen_ was vitriol, and scores of authorities seem to have adopted his arguments without inquiry, until that belief is now general. One of the strongest reasons put forward was that alum does not occur native in appreciable quantities. Apart from the fact that the weight of this argument has been lost by the discovery that alum does occur in nature to some extent as an aftermath of volcanic action, and as an efflorescence from argillaceous rocks, we see no reason why the Ancients may not have prepared it artificially. One of the earliest mentions of such a substance is by Herodotus (II., 180) of a thousand talents of _stypteria_, sent by Amasis from Egypt as a contribution to the rebuilding of the temple of Delphi. Diodorus (V., 1) mentions the abundance which was secured from the Lipari Islands (Stromboli, etc.), and a small quantity from the Isle of Melos. Dioscorides (V., 82) mentions Egypt, Lipari Islands, Melos, Sardinia, Armenia, etc., "and generally in any other places where one finds red ochre (_rubrica_)." Pliny (XXXV., 52) gives these same localities, and is more explicit as to how it originates--"from an earthy water which exudes from the earth." Of these localities, the Lipari Islands (Stromboli, etc.), and Melos are volcanic enough, and both Lipari and Melos are now known to produce natural alum (Dana. Syst. Min., p. 95; and Tournefort, "_Relation d'un voyage du Levant_." London, 1717, _Lettre_ IV., Vol. 1.). Further, the hair-like alum of Dioscorides, repeated by Pliny below, was quite conceivably fibrous _kalinite_, native potash alum, which occurs commonly as an efflorescence. Be the question of native alum as it may--and vitriol is not much more common--our own view that the ancient _alumen_ was alum, is equally based upon the artificial product. Before entering upon the subject, we consider it desirable to set out the properties of the ancient substance, a complete review of which is given by Pliny (XXXV., 52), he obviously quoting also from Dioscorides, which, therefore, we do not need to reproduce. Pliny says:--

"Not less important, or indeed dissimilar, are the uses made of _alumen_; by which name is understood a sort of salty earth. Of this, there are several kinds. In Cyprus there is a white _alumen_, and a darker kind. There is not a great difference in their colour, though the uses made of them are very dissimilar,--the white _alumen_ being employed in a liquid state for dyeing wool bright colours, and the dark-coloured _alumen_, on the other hand, for giving wool a sombre tint. Gold is purified with black _alumen_. Every kind of _alumen_ is from a _limus_ water which exudes from the earth. The collection of it commences in winter, and it is dried by the summer sun. That portion of it which first matures is the whitest. It is obtained in Spain, Egypt, Armenia, Macedonia, Pontus, Africa, and the islands of Sardinia, Melos, Lipari, and Strongyle; the most esteemed, however, is that of Egypt, the next best from Melos. Of this last there are two kinds, the liquid _alumen_, and the solid. Liquid _alumen_, to be good, should be of a limpid and milky appearance; when rubbed, it should be without roughness, and should give a little heat. This is called _phorimon_. The mode of detecting whether it has been adulterated is by pomegranate juice, for, if genuine, the mixture turns black. The other, or solid, is pale and rough and turns dark with nut-galls; for which reason it is called _paraphoron_. Liquid _alumen_ is naturally astringent, indurative, and corrosive; used in combination with honey, it heals ulcerations.... There is one kind of solid _alumen_, called by the Greeks _schistos_, which splits into filaments of a whitish colour; for which reason some prefer calling it _trichitis_ (hair like). _Alumen_ is produced from the stone _chalcitis_, from which copper is also made, being a sort of coagulated scum from that stone. This kind of _alumen_ is less astringent than the others, and is less useful as a check upon bad humours of the body.... The mode of preparing it is to cook it in a pan until it has ceased being a liquid. There is another variety of _alumen_ also, of a less active nature, called _strongyle_. It is of two kinds. The fungous, which easily dissolves, is utterly condemned. The better kind is the pumice-like kind, full of small holes like a sponge, and is in round pieces, more nearly white in colour, somewhat greasy, free from grit, friable, and does not stain black. This last kind is cooked by itself upon charcoal until it is reduced to pure ashes. The best kind of all is that called _melinum_, from the Isle of Melos, as I have said, none being more effectual as an astringent, for staining black, and for indurating, and none becomes more dry.... Above all other properties of _alumen_ is its remarkable astringency, whence its Greek name.... It is injected for dysentry and employed as a gargle." The lines omitted refer entirely to medical matters which have no bearing here. The following paragraph (often overlooked) from Pliny (XXXV., 42) also has an important bearing upon the subject:--"In Egypt they employ a wonderful method of dyeing. The white cloth, after it is pressed, is stained in various places, not with dye stuffs, but with substances which absorb colours. These applications are not apparent on the cloth, but when it is immersed in a caldron of hot dye it is removed the next moment brightly coloured. The remarkable circumstance is that although there be only one dye in the caldron yet different colours appear in the cloth."

It is obvious from Pliny's description above, and also from the making of vitriol (see Note 11, p. 572), that this substance was obtained from liquor resulting from natural or artificial lixiviation of rocks--in the case of vitriols undoubtedly the result of decomposition of pyritiferous rocks (such as _chalcitis_). Such liquors are bound to contain aluminum sulphate if there is any earth or clay about, and whether they contained alum would be a question of an alkali being present. If no alkali were present in this liquor, vitriol would crystallize out first, and subsequent condensation would yield aluminum sulphate. If alkali were present, the alum would crystallize out either before or with the vitriol. Pliny's remark, "that portion of it which first matures is whitest", agrees well enough with this hypothesis. No one will doubt that some of the properties mentioned above belong peculiarly to vitriol, but equally convincing are properties and uses that belong to alum alone. The strongly astringent taste, white colour, and injection for dysentry, are more peculiar to alum than to vitriol. But above all other properties is that displayed in dyeing, for certainly if we read this last quotation from Pliny in conjunction with the statement that white _alumen_ produces bright colours and the dark kind, sombre colours, we have the exact reactions of alum and vitriol when used as mordants. Therefore, our view is that the ancient salt of this character was a more or less impure mixture ranging from alum to vitriol--"the whiter the better." Further, considering the ancient knowledge of soda (_nitrum_), and the habit of mixing it into almost everything, it does not require much flight of imagination to conceive its admixture to the "water," and the absolute production of alum.

Whatever may have been the confusion between alum and vitriol among the Ancients, it appears that by the time of the works attributed to Geber (12th or 13th Century), the difference was well known. His work (_Investigationes perfectiones_, IV.) refers to _alumen glaciale_ and _alumen jameni_ as distinguished from vitriol, and gives characteristic reactions which can leave no doubt as to the distinction. We may remark here that the repeated statement apparently arising from Meyer (History of Chemistry, p. 51) that Geber used the term _alum de rocca_ is untrue, this term not appearing in the early Latin translations. During the 15th Century alum did come to be known in Europe as _alum de rocca_. Various attempts have been made to explain the origin of this term, ranging from the Italian root, a "rock," to the town of Rocca in Syria, where alum was supposed to have been produced. In any event, the supply for a long period prior to the middle of the 15th Century came from Turkey, and the origin of the methods of manufacture described by Agricola, and used down to the present day, must have come from the Orient.

In the early part of the 15th Century, a large trade in alum was done between Italy and Asia Minor, and eventually various Italians established themselves near Constantinople and Smyrna for its manufacture (Dudae, _Historia Byzantina Venetia_, 1729, p. 71). The alum was secured by burning the rock, and lixiviation. With the capture of Constantinople by the Turks (1453), great feeling grew up in Italy over the necessity of buying this requisite for their dyeing establishments from the infidel, and considerable exertion was made to find other sources of supply. Some minor works were attempted, but nothing much eventuated until the appearance of one John de Castro. From the Commentaries of Pope Pius II. (1614, p. 185), it appears that this Italian had been engaged in dyeing cloth in Constantinople, and thus became aware of the methods of making alum. Driven out of that city through its capture by the Turks, he returned to Italy and obtained an office under the Apostolic Chamber. While in this occupation he discovered a rock at Tolfa which appeared to him identical with that used at Constantinople in alum manufacture. After experimental work, he sought the aid of the Pope, which he obtained after much vicissitude. Experts were sent, who after examination "shed tears of joy, they kneeling down three times, worshipped God and praised His kindness in conferring such a gift on their age." Castro was rewarded, and the great papal monopoly was gradually built upon this discovery. The industry firmly established at Tolfa exists to the present day, and is the source of the Roman alum of commerce. The Pope maintained this monopoly strenuously, by fair means and by excommunication, gradually advancing the price until the consumers had greater complaint than against the Turks. The history of the disputes arising over the papal alum monopoly would alone fill a volume.

By the middle of the 15th Century alum was being made in Spain, Holland, and Germany, and later in England. In her efforts to encourage home industries and escape the tribute to the Pope, Elizabeth (see Note on p. 283) invited over "certain foreign chymistes and mineral masters" and gave them special grants to induce them to "settle in these realmes." Among them was Cornelius Devoz, to whom was granted the privilege of "mining and digging in our Realm of England for allom and copperas." What Devoz accomplished is not recorded, but the first alum manufacture on a considerable scale seems to have been in Yorkshire, by one Thomas Chaloner (about 1608), who was supposed to have seduced workmen from the Pope's alum works at Tolfa, for which he was duly cursed with all the weight of the Pope and Church. (Pennant, Tour of Scotland, 1786).

[11] The term for vitriol used by the Roman authors, followed by Agricola, is _atramentum sutorium_, literally shoemaker's blacking, the term no doubt arising from its ancient (and modern) use for blackening leather. The Greek term was _chalcanthon_. The term "vitriol" seems first to appear in Albertus Magnus (_De Mineralibus_, _Liber_ V.), who died in 1280, where he uses the expression "_atramentum viride a quibusdam vitreolum vocatur_." Agricola (_De Nat. Foss._, p. 213) states, "In recent years the name _vitriolum_ has been given to it." The first adequate description of vitriol is by Dioscorides (V., 76), as follows:--"Vitriol (_chalcanthon_) is of one genus, and is a solidified liquid, but it has three different species. One is formed from the liquids which trickle down drop by drop and congeal in certain mines; therefore those who work in the Cyprian mines call it _stalactis_. Petesius calls this kind _pinarion_. The second kind is that which collects in certain caverns; afterward it is poured into trenches, where it congeals, whence it derives its name _pectos_. The third kind is called _hephthon_ and is mostly made in Spain; it has a beautiful colour but is weak. The manner of preparing it is as follows: dissolving it in water, they boil it, and then they transfer it to cisterns and leave it to settle. After a certain number of days it congeals and separates into many small pieces, having the form of dice, which stick together like grapes. The most valued is blue, heavy, dense, and translucent." Pliny (XXXIV., 32) says:--"By the name which they have given to it, the Greeks indicate the similar nature of copper and _atramentum sutorium_, for they call it _chalcanthon_. There is no substance of an equally miraculous nature. It is made in Spain from wells of this kind of water. This water is boiled with an equal quantity of pure water, and is then poured into wooden tanks (fish ponds). Across these tanks there are fixed beams, to which hang cords stretched by little stones. Upon these cords adheres the _limus_ (Agricola's 'juice') in drops of a vitreous appearance, somewhat resembling a bunch of grapes. After removal, it is dried for thirty days. It is of a blue colour, and of a brilliant lustre, and is very like glass. Its solution is the blacking used for colouring leather. _Chalcanthon_ is made in many other ways: its kind of earth is sometimes dug from ditches, from the sides of which exude drops, which solidify by the winter frosts into icicles, called _stalagmia_, and there is none more pure. When its colour is nearly white, with a slight tinge of violet, it is called _leukoion_. It is also made in rock basins, the rain water collecting the _limus_ into them, where it becomes hardened. It is also made in the same way as salt by the intense heat of the sun. Hence it is that some distinguish two kinds, the mineral and the artificial; the latter being paler than the former and as much inferior to it in quality as it is in colour."

While Pliny gives prominence to blue vitriol, his solution for colouring leather must have been the iron sulphate. There can be no doubt from the above, however, that both iron and copper sulphates were known to the Ancients. From the methods for making vitriol given here in _De Re Metallica_, it is evident that only the iron sulphate would be produced, for the introduction of iron strips into the vats would effectually precipitate any copper. It is our belief that generally throughout this work, the iron sulphate is meant by the term _atramentum sutorium_. In _De Natura Fossilium_ (p. 213-15) Agricola gives three varieties of _atramentum sutorium_,--_viride_, _caeruleum_, and _candidum_, _i.e._, green, blue, and white. Thus the first mention of white vitriol (zinc sulphate) appears to be due to him, and he states further (p. 213): "A white sort is found, especially at Goslar, in the shape of icicles, transparent like crystals." And on p. 215: "Since I have explained the nature of vitriol and its relatives, which are obtained from cupriferous pyrites, I will next speak of an acrid solidified juice which commonly comes from _cadmia_. It is found at Annaberg in the tunnel driven to the Saint Otto mine; it is hard and white, and so acrid that it kills mice, crickets, and every kind of animal. However, that feathery substance which oozes out from the mountain rocks and the thick substance found hanging in tunnels and caves from which saltpetre is made, while frequently acrid, does not come from _cadmia_." Dana (Syst. of Min., p. 939) identifies this as _Goslarite_--native zinc sulphate. It does not appear, however, that artificial zinc vitriol was made in Agricola's time. Schlueter (_Huette-Werken_, Braunschweig 1738, p. 597) states it to have been made for the first time at Rammelsberg about 1570.

It is desirable here to enquire into the nature of the substances given by all of the old mineralogists under the Latinized Greek terms _chalcitis_, _misy_, _sory_, and _melanteria_. The first mention of these minerals is in Dioscorides, who (V., 75-77) says: "The best _chalcitis_ is like copper. It is friable, not stony, and is intersected by long brilliant veins.... _Misy_ is obtained from Cyprus; it should have the appearance of gold, be hard, and when pulverised it should have the colour of gold and sparkle like stars. It has the same properties as _chalcitis_.... The best is from Egypt.... One kind of _melanteria_ congeals like salt in the entries to copper mines. The other kind is earthy and appears on the surface of the aforesaid mines. It is found in the mines of Cilicia and other regions. The best has the colour of sulphur, is smooth, pure, homogenous, and upon contact with water immediately becomes black.... Those who consider _sory_ to be the same as _melanteria_, err greatly. _Sory_ is a species of its own, though it is not dissimilar. The smell of _sory_ is oppressive and provokes nausea. It is found in Egypt and in other regions, as Libya, Spain, and Cyprus. The best is from Egypt, and when broken is black, porous, greasy, and astringent." Pliny (XXXIV., 29-31) says:--"That is called _chalcitis_ from which, as well as itself copper (?) is extracted by heat. It differs from _cadmia_ in that this is obtained from rocks near the surface, while that is taken from rocks below the surface. Also _chalcitis_ is immediately friable, being naturally so soft as to appear like compressed wool. There is also this other distinction; _chalcitis_ contains three other substances, copper, _misy_, and _sory_. Of each of these we shall speak in their appropriate places. It contains elongated copper veins. The most approved kind is of the colour of honey; it is streaked with fine sinuous veins and is friable and not stony. It is considered most valuable when fresh.... The _sory_ of Egypt is the most esteemed, being much superior to that of Cyprus, Spain, and Africa; although some prefer the _sory_ from Cyprus for affections of the eyes. But from whatever nation it comes, the best is that which has the strongest odour, and which, when ground up, becomes greasy, black, and spongy. It is a substance so unpleasant to the stomach that some persons are nauseated by its smell. Some say that _misy_ is made by the burning of stones in trenches, its fine yellow powder being mixed with the ashes of pine-wood. The truth is, as I said above, that though obtained from the stone, it is already made and in solid masses, which require force to detach them. The best comes from the works of Cyprus, its characteristics being that when broken it sparkles like gold, and when ground it presents a sandy appearance, but on the contrary, if heated, it is similar to _chalcitis_. _Misy_ is used in refining gold...."

Agricola's views on the subject appear in _De Natura Fossilium_. He says (p. 212):--"The cupriferous pyrites (_pyrites aerosus_) called _chalcitis_ is the mother and cause of _sory_--which is likewise known as mine _vitriol_ (_atramentum metallicum_)--and _melanteria_. These in turn yield vitriol and such related things. This may be seen especially at Goslar, where the nodular lumps of dark grey colour are called vitriol stone (_lapis atramenti_). In the centre of them is found greyish pyrites, almost dissolved, the size of a walnut. It is enclosed on all sides, sometimes by _sory_, sometimes by _melanteria_. From them start little veinlets of greenish vitriol which spread all over it, presenting somewhat the appearance of hairs extending in all directions and cohering together.... There are five species of this solidified juice, _melanteria_, _sory_, _chalcitis_, _misy_, and vitriol. Sometimes many are found in one place, sometimes all of them, for one originates from the other. From pyrites, which is, as one might say, the root of all these juices, originates the above-mentioned _sory_ and _melanteria_. From _sory_, _chalcitis_, and _melanteria_ originate the various kinds of vitriol.... _Sory_, _melanteria_, _chalcitis_, and _misy_ are always native; vitriol alone is either native or artificial. From them vitriol effloresces white, and sometimes green or blue. _Misy_ effloresces not only from _sory_, _melanteria_, and _chalcitis_, but also from all the vitriols, artificial as well as natural.... _Sory_ and _melanteria_ differ somewhat from the others, but they are of the same colours, grey and black; but _chalcitis_ is red and copper-coloured; _misy_ is yellow or gold-coloured. All these native varieties have the odour of lightning (brimstone), but _sory_ is the most powerful. The feathery vitriol is soft and fine and hair-like, and _melanteria_ has the appearance of wool and it has a similarity to salt; all these are rare and light; _sory_, _chalcitis_, and _misy_ have the following relations. _Sory_ because of its density has the hardness of stone, although its texture is very coarse. _Misy_ has a very fine texture. _Chalcitis_ is between the two; because of its roughness and strong odour it differs from _melanteria_, although they do not differ in colour. The vitriols, whether natural or artificial, are hard and dense ... as regarding shape, _sory_, _chalcitis_, _misy_, and _melanteria_ are nodular, but _sory_ is occasionally porous, which is peculiar to it. _Misy_ when it effloresces in no great quantity from the others is like a kind of pollen, otherwise it is nodular. _Melanteria_ sometimes resembles wool, sometimes salt."

The sum and substance, therefore, appears to be that _misy_ is a yellowish material, possibly ochre, and _sory_ a blackish stone, both impregnated with vitriol. _Chalcitis_ is a partially decomposed pyrites; and _melanteria_ is no doubt native vitriol. From this last term comes the modern _melanterite_, native hydrous ferrous sulphate. Dana (System of Mineralogy, p. 964) considers _misy_ to be in part _copiapite_--basic ferric sulphate--but any such part would not come under Agricola's objection to it as a source of vitriol. The disabilities of this and _chalcitis_ may, however, be due to their copper content.

[12] Agricola (_De Nat. Fos._, 221) says:--"There is a species of artificial sulphur made from sulphur and iron hammer-scales, melted together and poured into moulds. This, because it heals scabs of horses, is generally called _caballinum_." It is difficult to believe such a combination was other than iron sulphide, but it is equally difficult to understand how it was serviceable for this purpose.

[13] Inasmuch as pyrites is discussed in the next paragraph, the material of the first distillation appears to be native sulphur. Until the receiving pots became heated above the melting point of the sulphur, the product would be "flowers of sulphur," and not the wax-like product. The equipment described for pyrites in the next paragraph would be obviously useful only for coarse material.

But little can be said on the history of sulphur; it is mentioned often enough in the Bible and also by Homer (Od. XXII., 481). The Greeks apparently knew how to refine it, although neither Dioscorides nor Pliny specifically describes such an operation. Agricola says (_De Nat. Fos._, 220): "Sulphur is of two kinds; the mineral, which the Latins call _vivum_, and the Greeks _apyron_, which means 'not exposed to the fire' (_ignem non expertum_) as rightly interpreted by Celsius; and the artificial, called by the Greeks _pepyromenon_, that is, 'exposed to the fire.'" In Book X., the expression _sulfur ignem non expertum_ frequently appears, no doubt in Agricola's mind for native sulphur, although it is quite possible that the Greek distinction was between "flowers" of sulphur and the "wax-like" variety.

[14] The substances referred to under the names _bitumen_, _asphalt_, _maltha_, _naphtha_, _petroleum_, _rock-oil_, etc., have been known and used from most ancient times, and much of our modern nomenclature is of actual Greek and Roman ancestry. These peoples distinguished three related substances,--the Greek _asphaltos_ and Roman _bitumen_ for the hard material,--Greek _pissasphaltos_ and Roman _maltha_ for the viscous, pitchy variety--and occasionally the Greek _naphtha_ and Roman _naphtha_ for petroleum proper, although it is often enough referred to as liquid _bitumen_ or liquid _asphaltos_. The term _petroleum_ apparently first appears in Agricola's _De Natura Fossilium_ (p. 222), where he says the "oil of bitumen ... now called _petroleum_." Bitumen was used by the Egyptians for embalming from pre-historic times, _i.e._, prior to 5000 B.C., the term "mummy" arising from the Persian word for bitumen, _mumiai_. It is mentioned in the tribute from Babylonia to Thotmes III., who lived about 1500 B.C. (Wilkinson, Ancient Egyptians I., p. 397). The Egyptians, however, did not need to go further afield than the Sinai Peninsula for abundant supplies. Bitumen is often cited as the real meaning of the "slime" mentioned in Genesis (XI., 3; XIV., 10), and used in building the Tower of Babel. There is no particular reason for this assumption, except the general association of Babel, Babylon, and Bitumen. However, the Hebrew word _sift_ for pitch or bitumen does occur as the cement used for Moses's bulrush cradle (Exodus II., 3), and Moses is generally accounted about 1300 B.C. Other attempts to connect Biblical reference to petroleum and bitumen revolve around Job XXIX., 6, Deut. XXXII., 13, Maccabees II., I, 18, Matthew V., 13, but all require an unnecessary strain on the imagination.

The plentiful occurrence of bitumen throughout Asia Minor, and

## particularly in the Valley of the Euphrates and in Persia, is the

subject of innumerable references by writers from Herodotus (484-424 B.C.) down to the author of the company prospectus of recent months. Herodotus (I., 179) and Diodorus Siculus (I) state that the walls of Babylon were mortared with bitumen--a fact partially corroborated by modern investigation. The following statement by Herodotus (VI., 119) is probably the source from which Pliny drew the information which Agricola quotes above. In referring to a well at Ardericca, a place about 40 miles from ancient Susa, in Persia, Herodotus says:--"For from the well they get bitumen, salt, and oil, procuring it in the way that I will now describe: they draw with a swipe, and instead of a bucket they make use of the half of a wine-skin; with this the man dips and, after drawing, pours the liquid into a reservoir, wherefrom it passes into another, and there takes three different shapes. The salt and bitumen forthwith collect and harden, while the oil is drawn off into casks. It is called by the Persians _rhadinace_, is black, and has an unpleasant smell." (Rawlinson's Trans. III., p. 409). The statement from Pliny (XXXI., 39) here referred to by Agricola, reads:--"It (salt) is made from water of wells poured into salt-pans. At Babylon the first condensed is a bituminous liquid like oil which is burned in lamps. When this is taken off, salt is found beneath. In Cappadocia also the water from both wells and springs is poured into salt-pans." When petroleum began to be used as an illuminant it is impossible to say. A passage in Aristotle's _De Mirabilibus_ (127) is often quoted, but in reality it refers only to a burning spring, a phenomenon noted by many writers, but from which to its practical use is not a great step. The first really definite statement as to the use of petroleum as an illuminant is Strabo's quotation (XVI., 1, 15) from Posidonius: "Asphaltus is found in great abundance in Babylonia. Eratosthenes describes it as follows:--The liquid _asphaltus_, which is called _naphtha_, is found in Susa; the dry kind, which can be made solid, in Babylonia. There is a spring of it near the Euphrates.... Others say that the liquid kind is also found in Babylonia.... The liquid kind, called _naphtha_, is of a singular nature. When it is brought near the fire, the fire catches it.... Posidonius says that there are springs of _naphtha_ in Babylonia, some of which produce white, others black _naphtha_; the first of these, I mean white _naphtha_, which attracts flame, is liquid sulphur; the second or black _naphtha_ is liquid _asphaltus_, and is burnt in lamps instead of oil." (Hamilton's Translation, Vol. III., p. 151). Eratosthenes lived about 200 B.C., and Posidonius about 100 years later. Dioscorides (I., 83), after discussing the usual sources of bitumen says: "It is found in a liquid state in Agrigentum in Sicily, flowing on streams; they use it for lights in lanterns in place of oil. Those who call the Sicilian kind oil are under a delusion, for it is agreed that it is a kind of liquid bitumen." Pliny adds nothing much new to the above quotations, except in regard to these same springs (XXXV., 51) that "The inhabitants collect it on the panicles of reeds, to which it quickly adheres and they use it for burning in lamps instead of oil." Agricola (_De Natura Fossilium_, Book IV.) classifies petroleum, coal, jet, and obsidian, camphor, and amber as varieties of bitumen, and devotes much space to the refutation of the claims that the last two are of vegetable origin.

[15] Agricola (_De Natura Fossilium_, p. 215) in discussing substances which originate from copper, gives among them green _chrysocolla_ (as distinguished from borax, etc., see Note 8 above), and says: "Native _chrysocolla_ originates in veins and veinlets, and is found mostly by itself like sand, or adhering to metallic substances, and when scraped off from this appears similar to its own sand. Occasionally it is so thin that very little can be scraped off. Or else it occurs in waters which, as I have said, wash these minerals, and afterward it settles as a powder. At Neusohl in the Carpathians, green water flowing from an ancient tunnel wears away this _chrysocolla_ with it. The water is collected in thirty large reservoirs, where it deposits the _chrysocolla_ as a sediment, which they collect every year and sell,"--as a pigment. This description of its occurrence would apply equally well to modern _chrysocolla_ or to malachite. The solution from copper ores would deposit some sort of green incrustation, of carbonates mostly.

[16] The statement in Pliny (XXXVI., 66) to which Agricola refers is as follows: "Then as ingenuity was not content with the mixing of _nitrum_, they began the addition of _lapis magnes_, because of the belief that it attracts liquefied glass as well as iron. In a similar manner many kinds of brilliant stones began to be added to the melting, and then shells and fossil sand. Authors tell us that the glass of India is made of broken crystal, and in consequence nothing can compare with it. Light and dry wood is used for fusing, _cyprium_ (copper?) and _nitrum_ being added, particularly _nitrum_ from Ophir etc."

A great deal of discussion has arisen over this passage, in connection with what this _lapis magnes_ really was. Pliny (XXXVI., 25) describes the lodestone under this term, but also says: "There (in Ethiopia) also is _haematites magnes_, a stone of blood colour, which shows a red colour if crushed, or of saffron. The _haematites_ has not the same property of attracting iron as _magnes_." Relying upon this sentence for an exception to the ordinary sort of _magnes_, and upon the impossible chemical reaction involved, most commentators have endeavoured to show that lodestone was not the substance meant by Pliny, but manganese, and thus they find here the first knowledge of this mineral. There can be little doubt that Pliny assumed it to be the lodestone, and Agricola also. Whether the latter had any independent knowledge on this point in glass-making or was merely quoting Pliny--which seems probable--we do not know. In any event, Biringuccio, whose work preceded _De Re Metallica_ by fifteen years, does definitely mention manganese in this connection. He dismisses this statement of Pliny with the remark (p. 37-38): "The Ancients wrote about lodestones, as Pliny states, and they mixed it together with _nitrum_ in their first efforts to make glass." The following passage from this author (p. 36-37), however, is not only of interest in this connection, but also as possibly being the first specific mention of manganese under its own name. Moreover, it has been generally overlooked in the many discussions of the subject. "Of a similar nature (to _zaffir_) is also another mineral called _manganese_, which is found, besides in Germany, at the mountain of Viterbo in Tuscany ... it is the colour of _ferrigno scuro_ (iron slag?). In melting it one cannot obtain any metal ... but it gives a very fine colour to glass, so that the glass workers use it in their pigments to secure an azure colour.... It also has such a property that when put into melted glass it cleanses it and makes it white, even if it were green or yellow. In a hot fire it goes off in a vapour like lead, and turns into ashes."

To enter competently into the discussion of the early history of glass-making would employ more space than can be given, and would lead but to a sterile end. It is certain that the art was pre-Grecian, and that the Egyptians were possessed of some knowledge of making and blowing it in the XI Dynasty (according to Petrie 3,500 B.C.), the wall painting at Beni Hassen, which represents glass-blowing, being attributed to that period. The remains of a glass factory at Tel el Amarna are believed to be of the XVIII Dynasty. (Petrie, 1,500 B.C.). The art reached a very high state of development among the Greeks and Romans. No discussion of this subject omits Pliny's well-known story (XXXVI, 65), which we also add: "The tradition is that a merchant ship laden with _nitrum_ being moored at this place, the merchants were preparing their meal on the beach, and not having stones to prop up their pots, they used lumps of _nitrum_ from the ship, which fused and mixed with the sands of the shore, and there flowed streams of a new translucent liquid, and thus was the origin of glass."

APPENDIX A.

AGRICOLA'S WORKS.

Georgius Agricola was not only the author of works on Mining and allied subjects, usually associated with his name, but he also interested himself to some extent in political and religious subjects. For convenience in discussion we may, therefore, divide his writings on the broad lines of (1) works on mining, geology, mineralogy, and allied subjects; (2) works on other subjects, medical, religious, critical, political, and historical. In respect especially to the first division, and partially with regard to the others, we find three principal cases: (_a_) Works which can be authenticated in European libraries to-day; (_b_) references to editions of these in bibliographies, catalogues, etc., which we have been unable to authenticate; and (_c_) references to works either unpublished or lost. The following are the short titles of all of the published works which we have been able to find on the subjects allied to mining, arranged according to their present importance:--_De Re Metallica_, first edition, 1556; _De Natura Fossilium_, first edition, 1546; _De Ortu et Causis Subterraneorum_, first edition, 1546; _Bermannus_, first edition, 1530; _Rerum Metallicarum Interpretatio_, first edition, 1546; _De Mensuris et Ponderibus_, first edition, 1533; _De Precio Metallorum et Monetis_, first edition, 1550; _De Veteribus et Novis Metallis_, first edition, 1546; _De Natura eorum quae Effluunt ex Terra_, first edition, 1546; _De Animantibus Subterraneis_, first edition, 1549.

Of the "lost" or unpublished works, on which there is some evidence, the following are the most important:--_De Metallicis et Machinis_, _De Ortu Metallorum Defensio ad Jacobum Scheckium_, _De Jure et Legibus Metallicis_, _De Varia Temperie sive Constitutione Aeris_, _De Terrae Motu_, and _Commentariorum, Libri VI_.

The known published works upon other subjects are as follows:--Latin Grammar, first edition, 1520; Two Religious Tracts, first edition, 1522; _Galen_ (Joint Revision of Greek Text), first edition, 1525; _De Bello adversus Turcam_, first edition, 1528; _De Peste_, first edition, 1554.

The lost or partially completed works on subjects unrelated to mining, of which some trace has been found, are:--_De Medicatis Fontibus_, _De Putredine solidas partes_, etc., _Castigationes in Hippocratem_, _Typographia Mysnae et Toringiae_, _De Traditionibus Apostolicis_, _Oratio de rebus gestis Ernesti et Alberti_, _Ducum Saxoniae_.

REVIEW OF PRINCIPAL WORKS.

Before proceeding with the bibliographical detail, we consider it desirable to review briefly the most important of the author's works on subjects related to mining.

_De Natura Fossilium._ This is the most important work of Agricola, excepting _De Re Metallica_. It has always been printed in combination with other works, and first appeared at Basel, 1546. This edition was considerably revised by the author, the amended edition being that of 1558, which we have used in giving references. The work comprises ten "books" of a total of 217 folio pages. It is the first attempt at systematic mineralogy, the minerals[1] being classified into (1) "earths" (clay, ochre, etc.), (2) "stones properly so-called" (gems, semi-precious and unusual stones, as distinguished from rocks), (3) "solidified juices" (salt, vitriol, alum, etc.), (4) metals, and (5) "compounds" (homogeneous "mixtures" of simple substances, thus forming such minerals as galena, pyrite, etc.). In this classification Agricola endeavoured to find some fundamental basis, and therefore adopted solubility, fusibility, odour, taste, etc., but any true classification without the atomic theory was, of course, impossible. However, he makes a very creditable performance out of their properties and obvious characteristics. All of the external characteristics which we use to-day in discrimination, such as colour, hardness, lustre, etc., are enumerated, the origin of these being attributed to the proportions of the Peripatetic elements and their binary properties. Dana, in his great work[2], among some fourscore minerals which he identifies as having been described by Agricola and his predecessors, accredits a score to Agricola himself. It is our belief, however, that although in a few cases Agricola has been wrongly credited, there are still more of which priority in description might be assigned to him. While a greater number than fourscore of so-called species are given by Agricola and his predecessors, many of these are, in our modern system, but varieties; for instance, some eight or ten of the ancient species consist of one form or another of silica.

## Book I. is devoted to mineral characteristics--colour, brilliance,

taste, shape, hardness, etc., and to the classification of minerals;

## Book II., "earths"--clay, Lemnian earth, chalk, ochre, etc.; Book III.,

"solidified juices"--salt, _nitrum_ (soda and potash), saltpetre, alum, vitriol, chrysocolla, _caeruleum_ (part azurite), orpiment, realgar, and sulphur; Book IV., camphor, bitumen, coal, bituminous shales, amber;

## Book V., lodestone, bloodstone, gypsum, talc, asbestos, mica, calamine,

various fossils, geodes, emery, touchstones, pumice, fluorspar, and quartz; Book VI., gems and precious stones; Book VII., "rocks"--marble, serpentine, onyx, alabaster, limestone, etc.; Book VIII., metals--gold, silver, quicksilver, copper, lead, tin, antimony, bismuth, iron, and alloys, such as electrum, brass, etc.; Book IX., various furnace operations, such as making brass, gilding, tinning, and products such as slags, furnace accretions, _pompholyx_ (zinc oxide), copper flowers, litharge, hearth-lead, verdigris, white-lead, red-lead, etc.; Book X., "compounds," embracing the description of a number of recognisable silver, copper, lead, quicksilver, iron, tin, antimony, and zinc minerals, many of which we set out more fully in Note 8, page 108.

_De Ortu et Causis Subterraneorum._ This work also has always been published in company with others. The first edition was printed at Basel, 1546; the second at Basel, 1558, which, being the edition revised and added to by the author, has been used by us for reference. There are five "books," and in the main they contain Agricola's philosophical views on geologic phenomena. The largest portion of the actual text is occupied with refutations of the ancient philosophers, the alchemists, and the astrologers; and these portions, while they exhibit his ability in observation and in dialectics, make but dull reading. Those sections of the book which contain his own views, however, are of the utmost importance in the history of science, and we reproduce extensively the material relating to ore deposits in the footnotes on pages 43 to 52. Briefly, Book I. is devoted to discussion of the origin and distribution of ground waters and juices. The latter part of this book and a portion of Book II. are devoted to the origin of subterranean heat, which he assumes is in the main due to burning bitumen--a genus which with him embraced coal--and also, in a minor degree, to friction of internal winds and to burning sulphur. The remainder of Book II. is mainly devoted to the discussion of subterranean "air", "vapour", and "exhalations", and he conceives that volcanic eruptions and earthquakes are due to their agency, and in these hypotheses he comes fairly close to the modern theory of eruptions from explosions of steam. "Vapour arises when the internal heat of the earth or some hidden fire burns earth which is moistened with vapour. When heat or subterranean fire meets with a great force of vapour which cold has contracted and encompassed in every direction, then the vapour, finding no outlet, tries to break through whatever is nearest to it, in order to give place to the insistent and urgent cold. Heat and cold cannot abide together in one place, but expel and drive each other out of it by turns".

As he was, we believe, the first to recognise the fundamental agencies of mountain sculpture, we consider it is of sufficient interest to warrant a reproduction of his views on this subject: "Hills and mountains are produced by two forces, one of which is the power of water, and the other the strength of the wind. There are three forces which loosen and demolish the mountains, for in this case, to the power of the water and the strength of the wind we must add the fire in the interior of the earth. Now we can plainly see that a great abundance of water produces mountains, for the torrents first of all wash out the soft earth, next carry away the harder earth, and then roll down the rocks, and thus in a few years they excavate the plains or slopes to a considerable depth; this may be noticed in mountainous regions even by unskilled observers. By such excavation to a great depth through many ages, there rises an immense eminence on each side. When an eminence has thus arisen, the earth rolls down, loosened by constant rain and split away by frost, and the rocks, unless they are exceedingly firm, since their seams are similarly softened by the damp, roll down into the excavations below. This continues until the steep eminence is changed into a slope. Each side of the excavation is said to be a mountain, just as the bottom is called a valley. Moreover, streams, and to a far greater extent rivers, effect the same results by their rushing and washing; for this reason they are frequently seen flowing either between very high mountains which they have created, or close by the shore which borders them.... Nor did the hollow places which now contain the seas all formerly exist, nor yet the mountains which check and break their advance, but in many parts there was a level plain, until the force of winds let loose upon it a tumultuous sea and a scathing tide. By a similar process the impact of water entirely overthrows and flattens out hills and mountains. But these changes of local conditions, numerous and important as they are, are not noticed by the common people to be taking place at the very moment when they are happening, because, through their antiquity, the time, place, and manner in which they began is far prior to human memory. The wind produces hills and mountains in two ways: either when set loose and free from bonds, it violently moves and agitates the sand; or else when, after having been driven into the hidden recesses of the earth by cold, as into a prison, it struggles with a great effort to burst out. For hills and mountains are created in hot countries, whether they are situated by the sea coasts or in districts remote from the sea, by the force of winds; these no longer held in check by the valleys, but set free, heap up the sand and dust, which they gather from all sides, to one spot, and a mass arises and grows together. If time and space allow, it grows together and hardens, but if it be not allowed (and in truth this is more often the case), the same force again scatters the sand far and wide.... Then, on the other hand, an earthquake either rends and tears away part of a mountain, or engulfs and devours the whole mountain in some fearful chasm. In this way it is recorded the Cybotus was destroyed, and it is believed that within the memory of man an island under the rule of Denmark disappeared. Historians tell us that Taygetus suffered a loss in this way, and that Therasia was swallowed up with the island of Thera. Thus it is clear that water and the powerful winds produce mountains, and also scatter and destroy them. Fire only consumes them, and does not produce at all, for part of the mountains--usually the inner part--takes fire."

The major portion of Book III. is devoted to the origin of ore channels, which we reproduce at some length on page 47. In the latter part of Book III., and in Books IV. and V., he discusses the principal divisions of the mineral kingdom given in _De Natura Fossilium_, and the origin of their characteristics. It involves a large amount of what now appears fruitless tilting at the Peripatetics and the alchemists; but nevertheless, embracing, as Agricola did, the fundamental Aristotelian elements, he must needs find in these same elements and their subordinate binary combinations cause for every variation in external character.

_Bermannus._ This, Agricola's first work in relation to mining, was apparently first published at Basel, 1530. The work is in the form of a dialogue between "Bermannus," who is described as a miner, mineralogist, and "a student of mathematics and poetry," and "Nicolaus Ancon" and "Johannes Naevius," both scholars and physicians. Ancon is supposed to be of philosophical turn of mind and a student of Moorish literature, Naevius to be particularly learned in the writings of Dioscorides, Pliny, Galen, etc. "Bermannus" was probably an adaptation by Agricola of the name of his friend Lorenz Berman, a prominent miner. The book is in the main devoted to a correlation of the minerals mentioned by the Ancients with those found in the Saxon mines. This phase is interesting as indicating the natural trend of Agricola's scholastic mind when he first comes into contact with the sciences to which he devoted himself. The book opens with a letter of commendation from Erasmus, of Rotterdam, and with the usual dedication and preface by the author. The three conversationalists are supposed to take walks among the mines and to discuss, incidentally, matters which come to their attention; therefore the book has no systematic or logical arrangement. There are occasional statements bearing on the history, management, titles, and methods used in the mines, and on mining lore generally. The mineralogical part, while of importance from the point of view of giving the first description of several minerals, is immensely improved upon in _De Natura Fossilium_, published 15 years later. It is of interest to find here the first appearance of the names of many minerals which we have since adopted from the German into our own nomenclature. Of importance is the first description of bismuth, although, as pointed out on page 433, the metal had been mentioned before. In the revised collection of collateral works published in 1558, the author makes many important changes and adds some new material, but some of the later editions were made from the unrevised older texts.

_Rerum Metallicarum Interpretatio._ This list of German equivalents for Latin mineralogical terms was prepared by Agricola himself, and first appears in the 1546 collection of _De Ortu et Causis_, _De Natura Fossilium_, etc., being repeated in all subsequent publications of these works. It consists of some 500 Latin mineralogical and metallurgical terms, many of which are of Agricola's own coinage. It is of great help in translation and of great value in the study of mineralogic nomenclature.

_De Mensuris et Ponderibus._ This work is devoted to a discussion of the Greek and Roman weights and measures, with some correlation to those used in Saxony. It is a careful work still much referred to by students of these subjects. The first edition was published at Paris in 1533, and in the 1550 edition at Basel appears, for the first time, _De Precio Metallorum et Monetis_.

_De Veteribus et Novis Metallis._ This short work comprises 31 folio pages, and first appears in the 1546 collection of collateral works. It consists mainly of historical and geographical references to the occurrence of metals and mines, culled from the Greek and Latin classics, together with some information as to the history of the mines in Central Europe. The latter is the only original material, and unfortunately is not very extensive. We have incorporated some of this information in the footnotes.

_De Animantibus Subterraneis._ This short work was first printed in Basel, 1549, and consists of one chapter of 23 folio pages. Practically the whole is devoted to the discussion of various animals who at least a portion of their time live underground, such as hibernating, cave-dwelling, and burrowing animals, together with cave-dwelling birds, lizards, crocodiles, serpents, etc. There are only a few lines of remote geological interest as to migration of animals imposed by geologic phenomena, such as earthquakes, floods, etc. This book also discloses an occasional vein of credulity not to be expected from the author's other works, in that he apparently believes Aristotle's story of the flies which were born and lived only in the smelting furnace; and further, the last paragraph in the book is devoted to underground gnomes. This we reproduce in the footnote on page 217.

_De Natura eorum quae Effluunt ex Terra._ This work of four books, comprising 83 folio pages, first appears in the 1546 collection. As the title indicates, the discussion is upon the substances which flow from the earth, such as water, bitumen, gases, etc. Altogether it is of microscopic value and wholly uninteresting. The major part refers to colour, taste, temperature, medicinal uses of water, descriptions of rivers, lakes, swamps, and aqueducts.

BIBLIOGRAPHICAL NOTES.

For the following we have mainly to thank Miss Kathleen Schlesinger, who has been employed many months in following up every clue, and although the results display very considerable literary activity on the part of the author, they do not by any means indicate Miss Schlesinger's labours. Agricola's works were many of them published at various times in combination, and therefore to set out the title and the publication of each work separately would involve much repetition of titles, and we consequently give the titles of the various volumes arranged according to dates. For instance, _De Natura Fossilium_, _De Ortu et Causis_, _De Veteribus et Novis Metallis_, _De Natura eorum quae Effluunt ex Terra_, and _Interpretatio_ have always been published together, and the Latin and Italian editions of these works always include _Bermannus_ as well. Moreover, the Latin _De Re Metallica_ of 1657 includes all of these works.

We mark with an asterisk the titles to editions which we have been able to authenticate by various means from actual books. Those unmarked are editions which we are satisfied do exist, but the titles of which are possibly incomplete, as they are taken from library catalogues, etc. Other editions to which we find reference and of which we are not certain are noted separately in the discussion later on.[3]

*1530 (8vo):

_Georgii Agricolae Medici, Bermannus sive de re Metallica._

(Froben's mark).

_Basileae in aedibus Frobenianis Anno. MDXXX._

Bound with this edition is (p. 131-135), at least occasionally, _Rerum metallicarum appellationes juxta vernaculam Germanorum linguam, autori Plateano_.

_Basileae in officina Frobeniana_, Anno. MDXXX.

*1533 (8vo):

_Georgii Agricolae Medici libri quinque de Mensuris et Ponderibus: in quibus plaeraque a Budaeo et Portio parum animadversa diligenter excutiuntur. Opus nunc primum in lucem aeditum._

(Wechelus's Mark).

_Parisiis. Excudebat Christianus Wechelus, in vico Iacobaeo, sub scuto Basileiensi, Anno MDXXXIII._

261 pages and index of 5 pages.

*1533 (4to):

_Georgii Agricolae Medici Libri quinque. De Mensuris et Ponderibus: In quibus pleraque a Budaeo et Portio parum animadversa diligenter excutiuntur._

(Froben's Mark).

_Basileae ex Officina Frobeniana Anno MDXXXIII. Cum gratia et privilegio Caesareo ad sex annos._

1534 (4to):

_Georgii Agricolae. Epistola ad Plateanum, cui sunt adiecta aliquot loca castigata in libris de mensuris et ponderibus nuper editis._

Froben, Basel, 1534.

*1535 (8vo):

_Georgii Agricolae Medici libri V. de Mensuris et Ponderibus: in quibus pleraque a Budaeo et Portio parum animadversa diligenter excutiuntur._

(Printer's Mark).

At the end of Index: _Venitues per Juan Anto. de Nicolinis de Sabio, sumptu vero et requisitione Dni Melchionis Sessae. Anno. Dni MDXXXV. Mense Julii._ 116 folios.

On back of title page is given: _Liber primus de mensuris Romanis, Secundus de mensuris Graecis, Tertius de rerum quas metimur pondere, Quartus de ponderibus Romanis, Quintus de ponderibus Graecis._

*1541 (8vo):

_Georgii Agricolae Medici Bermannus sive de re metallica._

_Parisiis. Apud Hieronymum Gormontiu. In Vico Jacobeo sub signotrium coronarum._ 1541.

*1546 (8vo):

_Georgii Agricolae medici Bermannus, sive de metallica ab accurata autoris recognitione et emendatione nunc primum editus cum nomenclatura rerum metallicarum. Eorum Lipsiae In officina Valentini Papae Anno. MDXLVI._

*1546 (folio):

_Georgii Agricolae De ortu et causis subterraneorum Lib. V. De natura eorum quae effluunt ex terra Lib. IIII. De natura fossilium Lib. X. De veteribus et novis metallis, Lib. II. Bermannus sive De re Metallica dialogus. Interpretatio Germanica vocum rei metallicae addito Indice faecundissimo._

_Apud Hieron Frobenium et Nicolaum Episcopium Basileae, MDXLVI. Cum privilegio Imp. Maiestatis ad quinquennium._

*1549 (8vo):

_Georgii Agricolae de animantibus subterraneis Liber._

Froben, Basel, MDXLIX.

*1550 (8vo):

_Di Georgio Agricola De la generatione de le cose, che sotto la terra sono, e de le cause de' loro effetti e natura, Lib. V. De La Natura di quelle cose, che de la terra scorrono Lib. IIII. De La Natura de le cose Fossili, e che sotto la terra si Cavano Lib. X. De Le Minere antiche e moderne Lib. II. Il Bermanno, o de le cose Metallice Dialogo, Recato tutto hora dal Latino in Buona Lingua volgare._

(Vignette of Sybilla surrounded by the words)--_Qv Al Piv Fermo E Il Mio Foglio E Il Mio Presaggio._

_Col Privilegio del Sommo Pontefice Papa Giulio III. Et del Illustriss. Senato Veneto per anni. XX._

(Colophon). _In Vinegia per Michele Tramezzino, MDL._

*1550 (folio):

_Georgii Agricolae. De Mensuris et ponderibus Rom. atque Graec. lib. V. De externis mensuris et ponderibus Lib. II. Ad ea quae Andreas Alciatus denuo disputavit De Mensuris et Ponderibus brevis defensio Lib. I. De Mensuris quibus intervalla metimur Lib. I. De restituendis ponderibus atque mensuris. Lib. I. De precio metallorum et monetis. Lib. III._

_Basileae._ Froben. MDL. _Cum privilegio Imp. Maiestatis ad quinquennium._[4]

*1556 (folio):

_Georgii Agricolae De Re Metallica Libri XII. quibus Officia, Instrumenta, Machinae, ac omnia denique ad Metallicam spectantia, non modo luculentissime describuntur, sed et per effigies, suis locis insertas, adjunctis Latinis, Germanicisque appellationibus ita ob oculos ponuntur, ut clarius tradi non possint Eiusdem De Animantibus Subterraneis Liber, ab Autore recognitus: cum Indicibus diversis, quicquid in opere tractatum est, pulchre demonstrantibus._

(Froben's Mark).

_Basileae MDLVI. Cum Privilegio Imperatoris in annos V. et Galliarum Regis ad Sexennium._

Folio 538 pages and preface, glossary and index amounting to 86 pages. This is the first edition of _De Re Metallica_. We reproduce this title-page on page XIX.

*1557 (folio):

_Vom Bergkwerck xii Buecher darinn alle Empter, Instrument, Gezeuge, unnd Alles zu disem Handel gehoerig, mitt schoenen figuren vorbildet, und Klaerlich beschriben seindt erstlich in Lateinischer Sprach durch den Hochgelerten und weittberuempten Herrn Georgium Agricolam, Doctorn und. Buergermeistern der Churfuerstlichen statt Kempnitz, jezundt aber verteuescht durch den Achtparen. unnd Hochgelerten Herrn Philippum Bechium, Philosophen, Artzer und in der Loblichen Universitet zu Basel Professorn._

_Gedruckt zu Basel durch Jeronymus Froben Und Niclausen Bischoff im 1557 Jar mitt Keiserlicher Freyheit._

*1558 (folio):

_Georgii Agricolae De ortu et causis subterraneorum Lib. V. De natura eorum quae effluunt ex terra Lib. IV. De natura fossilium Lib. X. De veteribus et novis metallis Lib. II. Bermannus, sive De Re Metallica Dialogus Liber. Interpretatio Germanica vocum rei metallicae, addito duplici Indice, altero rerum, altero locorum Omnia ab ipso authore, cum haud poenitenda accessione, recens recognita._

_Froben, et Episcop. Basileae MDLVIII. Cum Imp. Maiestatis renovato privilegio ad quinquennium._

270 pages and index. As the title states, this is a revised edition by the author, and as the changes are very considerable it should be the one used. The Italian translation and the 1612 Wittenberg edition, mentioned below, are taken from the 1546 edition, and are, therefore, very imperfect.

*1561 (folio):

Second edition of _De Re Metallica_ including _De Animantibus Subterraneis_, with same title as the first edition except the addition, after the body of the title, of the words _Atque omnibus nunc iterum ad archetypum diligenter restitutis et castigatis_ and the year MDLXI. 502 pages and 72 pages of glossary and index.

*1563 (folio):

_Opera di Giorgio Agricola de L'arte de Metalli Partita in XII. libri, ne quali si descrivano tutte le sorti, e qualita de gli uffizii, de gli strumenti, delle macchine, e di tutte l'altre cose attenenti a cotal arte, non pure con parole chiare ma eziandio si mettano a luoghi loro le figure di dette cose, ritratte al naturale, con l'aggiunta de nomi di quelle, cotanto chiari, e spediti, che meglio non si puo desiderare, o havere._

_Aggiugnesi il libro del medesimo autore, che tratta de gl' Animali di sottoterra da lui stesso corretto et riveduto. Tradotti in lingua Toscana da M. Michelangelo Florio Fiorentino._

_Con l'Indice di tutte le cose piu notabili alla fine_ (Froben's mark) _in Basilea per Hieronimo Frobenio et Nicolao Episcopio, MDLXIII._

542 pages with 6 pages of index.

*1580 (folio):

_Bergwerck Buch: Darinn nicht Allain alle Empte Instrument Gezeug und alles so zu diesem Handel gehoerig mit figuren vorgebildet und klaerlich beschriben, etc. Durch den Hochgelehrten ... Herrn Georgium Agricolam der Artzney Doctorn und Burgermeister der Churfuerstlichen Statt Kemnitz erstlich mit grossem fleyss muehe und arbeit in Latein beschriben und in zwoelff Buecher abgetheilt: Nachmals aber durch den Achtbarn und auch Hochgelehrten Philippum Bechium Philosophen Artzt und in der Loeblichen Universitet zu Basel Professorn mit sonderm fleyss Teutscher Nation zu gut verteutscht und an Tag geben. Allen Berckherrn Gewercken Berckmeistern Geschwornen Schichtmeistern Steigern Berckheuwern Waeschern und Schmeltzern nicht allein nuetzlich und dienstlich sondern auch zu wissem hochnotwendig._

_Mit Roemischer Keys. May Freyheit nicht nachzutrucken._

_Getruckt in der Keyserlichen Reichsstatt, Franckfort am Mayn, etc. Im Jahr MDLXXX._

*1612 (12mo):

_Georgii Agricolae De ortu et causis subterraneorum Lib. V. De natura eorum quae effluunt ex terra, Lib. IV. De natura fossilium Lib. X. De veteribus et novis metallis Lib. II. Bermannus, sive de re metallica Dialogus. Interpretatio Germanica vocum rei metallicae._

_Addito Indice faecundissimo, Plurimos jam annos a Germanis, et externarum quoque nationum doctissimis viris, valde desiderati et expetiti._

_Nunc vero in rei metallicae studiosorum gratiam recensiti, in certa capita distributi, capitum argumentis, et nonnullis scholiis marginalibus illustrati a Johanne Sigfrido Philos: et Medicinae Doctore et in illustri Julia Professore ordinario._

_Accesserunt De metallicis rebus et nominibus observationes variae et eruditae, ex schedis Georgii Fabricii, quibus ea potissimum explicantur, quae Georgius Agricola praeteriit_.

_Wittebergae Sumptibus Zachariae Schuereri Bibliopolae Typis Andreae Ruedingeri, 1612._

There are 970 pages in the work of Agricola proper, the notes of Fabricius comprising a further 44 pages, and the index 112 pages.

*1614 (8vo):

_Georgii Agricolae De Animantibus Subterraneis Liber Hactenus a multis desideratus, nunc vero in gratiam studiosorum seorsim editus, in certa capita divisus, capitum argumentis et nonnullis marginalibus exornatus a Johanne Sigfrido, Phil. & Med. Doctore_, etc.

_Wittebergae. Typis Meisnerianis: Impensis Zachariae. Schureri Bibliop. Anno. MDCXIV._

*1621 (folio):

_Georgii Agricolae Kempnicensis Medici ac Philosophi Clariss. De Re Metallica Libri XII Quibus Officia, Instrumenta, Machinae, ac omnia denique ad metallicam spectantia, non modo Luculentissime describuntur; sed et per effigies, suis locis insertas adjunctis Latinis, Germanicisque; appellationibus, ita ob oculos ponuntur, ut clarius tradi non possint._

_Ejusdem De Animantibus Subterraneis Liber, ab Autore recognitus cum Indicibus diversis quicquid in Opere tractatum est, pulchre demonstrantibus._

(Vignette of man at assay furnace).

_Basileae Helvet. Sumptibus itemque typis chalcographicis Ludovici Regis Anno MDCXXI._

502 pages and 58 pages glossary and indices.

*1621 (folio):

_Bergwerck Buch Darinnen nicht allein alle Empter Instrument Gezeug und alles so zu disem Handel gehoerig mit Figuren vorgebildet und klaerlich beschrieben:.... Durch den Hochgelehrten und weitberuehmten Herrn Georgium Agricolam, der Artzney Doctorn und Burgermeister der Churfuerstlichen Statt Kemnitz Erstlich mit grossem fleiss muehe und arbeit in Latein beschrieben und in zwoelff Buecher abgetheilt: Nachmals aber durch den Achtbarn und auch Hochgelehrten Philippum Bechium. Philosophen, Artzt, und in der loblichen Universitet zu Basel Professorn mit sonderm fleiss Teutscher Nation zu gut verteutscht und an Tag geben und nun zum andern mal getruckt._

_Allen Bergherrn Gewercken Bergmeistern Geschwornen Schichtmeistern Steigern Berghaewern Waeschern unnd Schmeltzern nicht allein nutzlich und dienstlich sondern auch zu wissen hochnohtwendig._

(Vignette of man at assay furnace).

_Getruckt zu Basel inverlegung Ludwig Koenigs Im Jahr, MDCXXI._

491 pages 5 pages glossary--no index.

*1657 (folio):

_Georgii Agricolae Kempnicensis Medici ac Philosophi Clariss. De Re Metallica Libri XII. Quibus Officia, instrumenta, machinae, ac omnia denique ad metallicam spectantia, non modo luculentissime describuntur: sed et per effigies, suis locis insertas, adjunctis Latinis, Germanicisque appellationibus, ita ob oculos ponuntur, ut clarius tradi non possint. Quibus accesserunt hac ultima editione, Tractatus ejusdem argumenti, ab eodem conscripti, sequentes._

_De Animantibus Subterraneis Lib. I., De Ortu et Causis Subterraneorum Lib. V., De Natura eorum quae effluunt ex Terra Lib. IV., De Natura Fossilium Lib. X., De Veteribus et Novis Metallis Lib. II., Bermannus sive de Re Metallica, Dialogus Lib. I._

_Cum Indicibus diversis, quicquid in Opere tractatum est, pulchre demonstrantibus._

(Vignette of assayer and furnace).

_Basileae Sumptibus et Typis Emanuelis Koenig. Anno MDCLVII._

Folio, 708 pages and 90 pages of glossary and indices. This is a very serviceable edition of all of Agricola's important works, and so far as we have noticed there are but few typographical errors.

*1778 (8vo):

_Gespraech vom Bergwesen, wegen seiner Fuertrefflich keit aus dem Lateinischen in das Deutsche uebersetzet, mit nuetzl. Anmerkungen erlaeutert. u. mit einem ganz neuen Zusatze von Zlueglicher Anstellung des Bergbaues u. von der Zugutemachung der Erze auf den Huettenwerken versehen von Johann Gottlieb Stoer._

_Rotenburg a. d. Fulda, Hermstaedt 1778._ 180 pages.

*1806 (8vo):

_Georg Agricola's Bermannus eine Einleitung in die metallurgischen Schriften desselben, uebersetzt und mit Exkursionen herausgegeben von Friedrich August Schmid. Haushalts- und Befahrungs-Protokollist im Churf. vereinigten Bergamte zu St. Annaberg._

_Freyberg 1806. Bey Craz und Gerlach._

*1807-12 (8vo).

_Georg Agrikola's Mineralogische Schriften uebersetzt und mit erlaeuternden Anmerkungen. Begleitet von Ernst Lehmann Bergamts-Assessor, Berg- Gegen- und Receszschreiber in Dem Koenigl. Saechs. Bergamte Voigtsberg der jenaischen Societaet fuer die gesammte Mineralogie Ehrenmitgliede._

_Freyberg, 1807-12. Bey Craz und Gerlach._

This German translation consists of four parts: the first being _De Ortu et Causis_, the second _De Natura eorum quae effluunt ex terra_, and the third in two volumes _De Natura Fossilium_, the fourth _De Veteribus et Novis Metallis_; with glossary and index to the four parts.

We give the following notes on other possible prints, as a great many references to the above works occur in various quarters, of date other than the above. Unless otherwise convinced it is our belief that most of these refer to the prints given above, and are due to error in giving titles or dates. It is always possible that such prints do exist and have escaped our search.

_De Re Metallica._ Leupold, Richter, Schmid, van der Linden, Mercklinus and Eloy give an 8vo edition of _De Re Metallica_ without illustrations, Schweinfurt, 1607. We have found no trace of this print. Leupold, van der Linden, Richter, Schmid and Eloy mention an 8vo edition, Wittenberg, 1614. It is our belief that this refers to the 1612 Wittenberg edition of the selected works, which contains a somewhat similar title referring in reality to _Bermannus_, which was and is still continually confused with _De Re Metallica_. Ferguson mentions a German edition, Schweinfurt, 8vo, 1687. We can find no trace of this; it may refer to the 1607 Schweinfurt edition mentioned above.

_De Natura Fossilium._ Leupold and Gatter refer to a folio edition of 1550. This was probably an error for either the 1546 or the 1558 editions. Watt refers to an edition of 1561 combined with _De Medicatis Fontibus_. We find no trace of such edition, nor even that the latter work was ever actually printed. He also refers to an edition of 1614 and one of 1621, this probably being an error for the 1612 edition of the subsidiary works and the _De Re Metallica_ of 1621. Leupold also refers to an edition of 1622, this probably being an error for 1612.

_De Ortu et Causis._ Albinus, Hofmann, Jacobi, Schmid, Richter, and Reuss mention an edition of 1544. This we believe to be an error in giving the date of the dedication instead of that of the publication (1546). Albinus and Ferguson give an edition of 1555, which date is, we believe, an error for 1558. Ferguson gives an edition of the Italian translation as 1559; we believe this should be 1550. Draud gives an edition of 1621; probably this should be 1612.

_Bermannus._ Albinus, Schmid, Reuss, Richter, and Weinart give the first edition as 1528. We have been unable to learn of any actual copy of that date, and it is our belief that the date is taken from the dedication instead of from the publication, and should be 1530. Leupold, Schmid, and Reuss give an edition by Froben in 1549; we have been unable to confirm this. Leupold also gives an edition of 1550 (folio), and Joecher gives an edition of Geneva 1561 (folio); we have also been unable to find this, and believe the latter to be a confusion with the _De Re Metallica_ of 1561, as it is unlikely that _Bermannus_ would be published by itself in folio. The catalogue of the library at Siena (Vol. III., p. 78) gives _Il Bermanno, Vinegia_, 1550, 8vo. We have found no trace of this edition elsewhere.

_De Mensuris et Ponderibus._ Albinus and Schmid mention an edition of 1539, and one of 1550. The Biographie Universelle, Paris, gives one of 1553, and Leupold one of 1714, all of which we have been unable to find. An epitome of this work was published at various times, sometimes in connection with editions of Vitruvius; so far as we are aware on the following dates, 1552, 1585, 1586, 1829. There also appear extracts in relation to liquid measures in works entitled _Vocabula rei numariae ponderum et mensurarum_, etc. Paul Eber and Caspar Peucer, _Lipsiae_, 1549, and in same Wittenberg, 1552.

_De Veteribus et Novis Metallis._ Watt gives an edition, Basel, 1530, and Paris, 1541; we believe this is incorrect and refers to _Bermannus_. Reuss mentions a folio print of Basel, 1550. We consider this very unlikely.

_De Natura eorum quae Effluunt ex Terra._ Albinus, Hofmann, Schmid, Jacobi, Richter, Reuss, and Weinart give an edition of 1545. We believe this is again the dedication instead of the publication date (1546).

_De Animantibus Subterraneis._ Van der Linden gives an edition at Schweinfurt, 8vo, 1607. Although we have been unable to find a copy, this slightly confirms the possibility of an octavo edition of _De Re Metallica_ of this date, as they were usually published together. Leupold gives assurance that he handled an octavo edition of Wittenberg, 1612, _cum notis Johann Sigfridi_. We think he confused this with _Bermannus sive de re metallica_ of that date and place. Schmid, Richter, and Draud all refer to an edition similarly annotated, Leipzig, 1613, 8vo. We have no trace of it otherwise.

UNPUBLISHED WORKS ON SUBJECTS RELATED TO MINING.

Agricola apparently projected a complete series of works covering the whole range of subjects relating to minerals: geology, mineralogy, mining, metallurgy, history of metals, their uses, laws, etc. In a letter[5] from Fabricius to Meurer (March, 1553), the former states that Agricola intended writing about 30 books (chapters) in addition to those already published, and to the twelve books _De Re Metallica_ which he was about to publish. Apparently a number of these works were either unfinished or unpublished at Agricola's death, for his friend George Fabricius seems to have made some effort to secure their publication, but did not succeed, through lack of sympathy on the part of Agricola's family. Hofmann[6] states on this matter: "His intentions were frustrated mainly through the lack of support with which he was met by the heirs of the Mineralogist. These, as he complains to a Councillor of the Electorate, Christopher von Carlovitz, in 1556, and to Paul Eber in another letter, adopted a grudging and ungracious tone with regard to his proposal to collect all Agricola's works left behind, and they only consented to communicate to him as much as they were obliged by express command of the Prince. At the Prince's command they showed him a little, but he supposed that there was much more that they had suppressed or not preserved. The attempt to purchase some of the works--the Elector had given Fabricius money for the purpose (30 nummos unciales)--proved unavailing, owing to the disagreeableness of Agricola's heirs. It is no doubt due to these regrettable circumstances that all the works of the industrious scholar did not come down to us." The "disagreeableness" was probably due to the refusal of the Protestant townsfolk to allow the burial of Agricola in the Cathedral at Chemnitz. So far as we know the following are the unpublished or lost works.

_De Jure et Legibus Metallicis._ This work on mining law is mentioned at the end of Book IV. of _De Re Metallica_, and it is referred to by others apparently from that source. We have been unable to find any evidence that it was ever published.

_De Varia temperie sive Constitutione Aeris._ In a letter[7] to Johann Naevius, Agricola refers to having a work in hand of this title.

_De Metallis et Machinis._ Hofmann[8] states that a work of this title by Agricola, dated Basel 1543, was sold to someone in America by a Frankfort-on-Main bookseller in 1896. This is apparently the only reference to it that we know of, and it is possibly a confusion of titles or a "separate" of some chapters from _De Re Metallica_.

_De Ortu Metallorum Defensio ad Jacobum Scheckium._ Referred to by Fabricius in a letter[9] to Meurer. If published was probably only a tract.

_De Terrae Motu._ In a letter[10] from Agricola to Meurer (Jan. 1, 1544) is some reference which might indicate that he was formulating a work on earthquakes under this title, or perhaps may be only incidental to the portions of _De Ortu et Causis_ dealing with this subject.

_Commentariorum in quibus utriusque linguae scriptorum locos difficiles de rebus subterraneis explicat, Libri VI._ Agricola apparently partially completed a work under some such title as this, which was to embrace chapters entitled _De Methodis_ and _De Demonstratione_. The main object seems to have been a commentary on the terms and passages in the classics relating to mining, mineralogy, etc. It is mentioned in the Preface of _De Veteribus et Novis Metallis_, and in a letter[11] from one of Froben's firm to Agricola in 1548, where it is suggested that Agricola should defer sending his new commentaries until the following spring. The work is mentioned by Albinus[12], and in a letter from Georg Fabricius to Meurer on the 2nd Jan. 1548,[13] in another from G. Fabricius, to his brother Andreas on Oct. 28, 1555,[14] and in a third from Fabricius to Melanchthon on December 8th, 1555[15], in which regret is expressed that the work was not completed by Agricola.

WRITINGS NOT RELATED TO MINING, INCLUDING LOST OR UNPUBLISHED WORKS.

_Latin Grammar._ This was probably the first of Agricola's publications, the full title to which is _Georgii Agricolae Glaucii Libellus de prima ac simplici institutione grammatica. Excusum Lipsiae in Officina Melchioris Lottheri. Anno MDXX._ (4to), 24 folios.[16] There is some reason to believe that Agricola also published a Greek grammar, for there is a letter[17] from Agricola dated March 18th, 1522, in which Henicus Camitianus is requested to send a copy to Stephan Roth.

_Theological Tracts._ There are preserved in the Zwickau Rathsschul Library[18] copies by Stephan Roth of two tracts, the one entitled, _Deum non esse auctorem Peccati_, the other, _Religioso patri Petri Fontano, sacre theologie Doctori eximio Georgius Agricola salutem dicit in Christo_. The former was written from Leipzig in 1522, and the latter, although not dated, is assigned to the same period. Both are printed in _Zwei theologische Abhandlungen des Georg Agricola_, an article by Otto Clemen, _Neuen Archiv fur Saechsische Geschichte_, etc., Dresden, 1900. There is some reason (from a letter of Fabricius to Melanchthon, Dec. 8th, 1555) to believe that Agricola had completed a work on the unwritten traditions concerning the Church. There is no further trace of it.

_Galen._ Agricola appears to have been joint author with Andreas Asulanus and J. B. Opizo of a revision of this well-known Greek work. It was published at Venice in 1525, under the title of _Galeni Librorum_, etc., etc. Agricola's name is mentioned in a prefatory letter to Opizo by Asulanus.

_De Bello adversus Turcam._ This political tract, directed against the Turks, was written in Latin and first printed by Froben, Basel, 1528. It was translated into German apparently by Agricola's friend Laurenz Berman, and published under the title _Oration Anrede Und Vormanunge ... widder den Tuercken_ by Frederich Peypus, Nuremberg, in 1531 (8vo), and either in 1530 or 1531 by Wolfgang Stoeckel, Dresden, 4to. It was again printed in Latin by Froben, Basel, 1538, 4to; by H. Grosius, Leipzig, 1594, 8vo; it was included among other works published on the same subject by Nicholas Reusnerus, Leipzig, 1595; by Michael Lantzenberger, Frankfurt-am-Main, 1597, 4to. Further, there is reference by Watt to an edition at Eisleben, 1603, of which we have no confirmation. There is another work on the subject, or a revision by the author mentioned by Albinus[19] as having been, after Agricola's death, sent to Froben by George Fabricius to be printed; nothing further appears in this matter however.

_De Peste._ This work on the Plague appears to have been first printed by Froben, Basel, 1554, 8vo. The work was republished at Schweinfurt, 1607, and at Augsburg in 1614, under various editors. It would appear from Albinus[20] that the work was revised by Agricola and in Froben's hands for publication after the author's death.

_De Medicatis Fontibus._ This work is referred to by Agricola himself in _De Natura Eorum_,[21] in the prefatory letter in _De Veteribus et Novis Metallis_; and Albinus[22] quotes a letter of Agricola to Sebastian Munster on the subject. Albinus states (_Bergchronik_, p. 193) that to his knowledge it had not yet been published. Conrad Gesner, in his work _Excerptorum et observationum de Thermis_, which is reprinted in _De Balneis_, Venice, 1553, after Agricola's _De Natura Eorum_, states[23] concerning Agricola _in libris quos de medicatis fontibus instituerit copiosus se dicturum pollicetur_. Watt mentions it as having been published in 1549, 1561, 1614, and 1621. He, however, apparently confuses it with _De Natura Eorum_. We are unable to state whether it was ever printed or not. A note of inquiry to the principal libraries in Germany gave a negative result.

_De Putredine solidas partes humani corporis corrumpente._ This work, according to Albinus was received by Fabricius a year after Agricola's death, but whether it was published or not is uncertain.[24]

_Castigationes in Hippocratem et Galenum._ This work is referred to by Agricola in the preface of _Bermannus_, and Albinus[25] mentions several letters referring to the preparation of the work. There is no evidence of publication.

_Typographia Mysnae et Toringiae._ It seems from Agricola's letter[26] to Munster that Agricola prepared some sort of a work on the history of Saxony and of the Royal Family thereof at the command of the Elector and sent it to him when finished, but it was never published as written by Agricola. Albinus, Hofmann, and Struve give some details of letters in reference to it. Fabricius in a letter[27] dated Nov. 11, 1536 asks Meurer to send Agricola some material for it; in a letter from Fabricius to Meurer dated Oct. 30, 1554, it appears that the Elector had granted Agricola 200 thalers to assist in the work. After Agricola's death the material seems to have been handed over to Fabricius, who made use of it (as he states in the preface) in preparing the work he was commissioned by the Elector to write, the title of which was, _Originum illustrissimae stirpis Saxonicae Libri_, and was published in Leipzig, 1597. It includes on page 880 a fragment of a work entitled _Oratio de rebus Gestis Ernesti et Alberti Ducum Saxoniae_, by Agricola.

WORKS WRONGLY ATTRIBUTED TO GEORGIUS AGRICOLA.

The following works have been at one time or another wrongly attributed to Georgius Agricola:--

_Galerazeya sive Revelator Secretorum De Lapide Philosophorum_, Cologne, 1531 and 1534, by one Daniel Agricola, which is merely a controversial book with a catch-title, used by Catholics for converting heretics.

_Rechter Gebrauch der Alchimey_, a book of miscellaneous receipts which treats very slightly of transmutation.[28]

_Chronik der Stadt Freiberg_ by a Georg Agricola (died 1630), a preacher at Freiberg.

_Dominatores Saxonici_, by the same author.

_Breviarum de Asse_ by Guillaume Bude.

_De Inventione Dialectica_ by Rudolph Agricola.

FOOTNOTES:

[1] See footnote 4, page 1.

[2] System of Mineralogy.

[3] The following are the titles of the works referred to in this discussion:--

Petrus Albinus: _Meissnische Land und Berg Chronica In welcher ein wollnstendige description des Landes_, etc., Dresden, 1590 (contains

## part I, _Commentatorium de Mysnia_). _Newe Chronica und Beschreibung des

Landes zu Meissen_, pp. 1 to 449, besides preface and index, and Part II. _Meissnische Bergk Chronica_, Dresden, 1590, pp. 1 to 205, besides preface and index.

Adam Daniel Richter: _Umstaendliche ... Chronica der ... Stadt Chemnitz nebst beygefuegten Urkunden_, 2 pts. 4to, Zittau & Leipzig, 1767.

Ben. G. Weinart: _Versuch einer Litteratur d. Saechsischen Geschichte und Staats kunde_, Leipzig, 1885.

Friedrich August Schmid: _Georg Agrikola's Bermannus: Einleitung in die metallurgischen Schriften desselben_, Freyberg, Craz & Gerlach. 1806, pp. VIII., 1-260.

Franz Ambros Reuss: _Mineralogische Geographie van Boehmen_. 2 vols. 4to, Dresden, 1793-97. (Agricola Vol. I, p. 2).

Jacob Leupold: _Prodromus Bibliothecae Metallicae_, corrected, continued, and augmented by F. E. Brueckmann. Wolfenbuettel, 1732, s.v. Agricola.

Christian Gottlieb Goecher: _Allgemeines Gelehrten-Lexicon_, with continuation and supplements by Adelung, Leipzig, 1750, s.v. Agricola.

John Anton Van der Linden: _De Scriptis medicis, Libri duo_, Amsterdam, 1662, s.v. Georgius Agricola.

Nicolas Francois Joseph Eloy: _Dictionnaire Historique de la Medecine_, Liege & Francfort (chez J. F. Bassompierre), 1755, 8vo (Agricola p. 28, vol. I).

Georg Abraham Mercklinus: _Lindenius Renovatus de scriptis medicis continuati ... amplificati_, etc., Amsterdam, 1686, s.v. Georgius Agricola.

John Ferguson: _Bibliotheca Chemica_: A catalogue of the Alchemical, Chemical, and Pharmaceutical books in the collection of the late James Young of Kelly & Durris, Esq., L.L.D., F.R.S., F.R.S.E. Glasgow, 1906, 4to, 2 vols., s.v. Agricola.

Christoph Wilhelm Gatterer: _Allgemeines Repertorium der mineralogischen, bergwerks und Salz werkswissenschaftlichen Literatur_, Goettingen, 1798, vol. I.

Dr. Reinhold Hofmann: _Dr. Georg Agricola, Ein Gelehrtenleben aus dem Zeitalter der Reformation_, 8vo, Gotha, 1905.

Georg Heinrich Jacobi: _Der Mineralog Georgius Agricola und sein Verhaeltnis zur wissenschaft seiner Zeit_, etc., 8vo. Zwickau (1889), (_Dissertation_--Leipzig).

Georg Draud: _Bibliotheca Classica_, Frankfurt-am-Main, 1611.

B. G. Struve: _Bibliotheca Saxonica_, 8vo, Halle, 1736.

[4] Albinus states (p. 354): _Omnes simul editi Anno. 1549, iterum 1550, Basileae_, as though two separate editions.

[5] _G. Fabricii epistolae ad W. Meurerum et alios aequales_, by Baumgarten-Crusius, Leipzig, 1845, p. 83.

[6] _Dr. Georg Agricola_, Gotha, 1905, pp. 60-61.

[7] Albinus, _Landchronik_, pp. 354-5.

[8] _Dr. Georg Agricola_, p. 63.

[9] _Baumgarten-Crusius_, p. 115.

[10] _Virorum Clarorum Saec. XVI. et XVII._ _Epistolae Selectae_ by Ernst Weber, Leipzig, 1894, p. 2.

[11] Nicholas Episcopius to Georg Agricola, Sept. 17, 1548, published in Schmid's _Bermannus_ p. 38. See also Hofmann, op. cit. pp. 62 and 140.

[12] _Meissnische Landchronik_, Dresden, 1589, p. 354.

[13] Printed in Baumgarten-Crusius, pp. 48-49, letter XLVIII.

[14] Printed in Hermann Peter's _Meissner Jahresbericht der Fuerstenschule_, 1891, p. 24.

[15] Baumgarten-Crusius. _Georgii Fabricii Chemnicensis Epistolae_, Leipzig, 1845, p. 139.

[16] There is a copy of this work in the Rathsschul Library at Zwickau.

[17] In the Rathsschul Library at Zwickau.

[18] Contained in Vols. XXXVII. and XL. of Stephan Roth's _Kollectanenbaende_ Volumes of Transcripts.

[19] _Landchronik_, p. 354.

[20] Op. cit., p. 354.

[21] Book IV.

[22] Op. cit., p. 355.

[23] Page 291.

[24] See Baumgarten-Crusius, p. 114, letter from Georg Fabricius.

[25] Op. cit., p. 354.

[26] Albinus, Op. cit., p. 355.

[27] Baumgarten-Crusius, p. 2.

[28] See Ferguson, _Bibliotheca Chemica_, s.v. Daniel Agricola.

APPENDIX B.

ANCIENT AUTHORS.

We give the following brief notes on early works containing some reference to mineralogy, mining, or metallurgy, to indicate the literature available to Agricola and for historical notes bearing upon the subject. References to these works in the footnotes may be most easily consulted through the personal index.

GREEK AUTHORS.--Only a very limited Greek literature upon subjects allied to mining or natural science survives. The whole of the material of technical interest could be reproduced on less than twenty of these pages. Those of most importance are: Aristotle (384-322 B.C.), Theophrastus (371-288 B.C.), Diodorus Siculus (1st Century B.C.), Strabo (64 B.C.-25 A.D.), and Dioscorides (1st Century A.D.).

Aristotle, apart from occasional mineralogical or metallurgical references in _De Mirabilibus_, is mostly of interest as the author of the Peripatetic theory of the elements and the relation of these to the origin of stones and metals. Agricola was, to a considerable measure, a follower of this school, and their views colour much of his writings. We, however, discuss elsewhere[1] at what point he departed from them. Especially in _De Ortu et Causis_ does he quote largely from Aristotle's _Meteorologica_, _Physica_, and _De Coelo_ on these subjects. There is a spurious work on stones attributed to Aristotle of some interest to mineralogists. It was probably the work of some Arab early in the Middle Ages.

Theophrastus, the principal disciple of Aristotle, appears to have written at least two works relating to our subject--one "On Stones", and the other on metals, mining or metallurgy, but the latter is not extant. The work "On Stones" was first printed in Venice in 1498, and the Greek text, together with a fair English translation by Sir John Hill, was published in London in 1746 under the title "Theophrastus on Stones"; the translation is, however, somewhat coloured with Hill's views on mineralogy. The work comprises 120 short paragraphs, and would, if reproduced, cover but about four of these pages. In the first paragraphs are the Peripatetic view of the origin of stones and minerals, and upon the foundation of Aristotle he makes some modifications. The principal interest in Theophrastus' work is the description of minerals; the information given is, however, such as might be possessed by any ordinary workman, and betrays no particular abilities for natural philosophy. He enumerates various exterior characteristics, such as colour, tenacity, hardness, smoothness, density, fusibility, lustre, and transparence, and their quality of reproduction, and then proceeds to describe various substances, but usually omits his enumerated characteristics. Apart from the then known metals and certain "earths" (ochre, marls, clay, etc.), it is possible to identify from his descriptions the following rocks and minerals:--marble, pumice, onyx, gypsum, pyrites, coal, bitumen, amber, azurite, chrysocolla, realgar, orpiment, cinnabar, quartz in various forms, lapis lazuli, emerald, sapphire, diamond, and ruby. Altogether there are some sixteen distinct mineral species. He also describes the touchstone and its uses, the making of white-lead and verdigris, and of quicksilver from cinnabar.

Diodorus Siculus was a Greek native of Sicily. His "historical library" consisted of some 40 books, of which parts of 15 are extant. The first print was in Latin, 1472, and in Greek in 1539; the first translation into English was by Thomas Stocker, London, 1568, and later by G. Booth, 1700. We have relied upon Booth's translation, but with some amendments by friends, to gain more literal statement. Diodorus, so far as relates to our subject, gives merely the occasional note of a traveller. The most interesting paragraphs are his quotation from Agatharchides on Egyptian mining and upon British tin.

Strabo was also a geographer. His work consists of 17 books, and practically all survive. We have relied upon the most excellent translation of Hamilton and Falconer, London, 1903, the only one in English. Mines and minerals did not escape such an acute geographer, and the matters of greatest interest are those with relation to Spanish mines.

Dioscorides was a Greek physician who wrote entirely from the standpoint of materia medica, most of his work being devoted to herbs; but Book V. is devoted to minerals and rocks, and their preparation for medicinal purposes. The work has never been translated into English, and we have relied upon the Latin translation of Matthioli, Venice, 1565, and notes upon the Greek text prepared for us by Mr. C. Katopodes. In addition to most of the substances known before, he, so far as can be identified, adds schist, _cadmia_ (blende or calamine), _chalcitis_ (copper sulphide), _misy_, _melanteria_, _sory_ (copper or iron sulphide oxidation minerals). He describes the making of certain artificial products, such as copper oxides, vitriol, litharge, _pompholyx_, and _spodos_ (zinc and/or arsenical oxides). His principal interest for us, however, lies in the processes set out for making his medicines.

Occasional scraps of information relating to the metals or mines in some connection are to be found in many other Greek writers, and in quotations by them from others which are not now extant, such as Polybius, Posidonius, etc. The poets occasionally throw a gleam of light on ancient metallurgy, as for instance in Homer's description of Vulcan's foundry; while the historians, philosophers, statesmen, and physicians, among them Herodotus, Xenophon, Demosthenes, Galen, and many others, have left some incidental references to the metals and mining, helpful to gleaners from a field, which has been almost exhausted by time. Even Archimedes made pumps, and Hero surveying instruments for mines.

ROMAN AUTHORS.--Pre-eminent among all ancient writers on these subjects is, of course, Pliny, and in fact, except some few lines by Vitruvius, there is practically little else in extant Roman literature of technical interest, for the metallurgical metaphors of the poets and orators were threadbare by this time, and do not excite so much interest as upon their first appearance among the Greeks and Hebrews.

Pliny (Caius Plinius Secundus) was born 23 A.D., and was killed by eruption of Vesuvius 79 A.D. His Natural History should be more properly called an encyclopaedia, the whole comprising 37 books; but only portions of the last four books relate to our subject, and over one-half of the material there is upon precious stones. To give some rough idea of the small quantity of even this, the most voluminous of ancient works upon our subject, we have made an estimate that the portions of metallurgical character would cover, say, three pages of this text, on mining two pages, on building and precious stones about ten pages. Pliny and Dioscorides were contemporaries, and while Pliny nowhere refers to the Greek, internal evidence is most convincing, either that they drew from the same source, or that Pliny drew from Dioscorides. We have, therefore, throughout the text given precedence in time to the Greek author in matters of historical interest. The works of Pliny were first printed at Venice in 1469. They have passed dozens of editions in various languages, and have been twice translated into English. The first translation by Philemon Holland, London, 1601, is quite impossible. The second translation, by Bostock and Riley, London, 1855, was a great advance, and the notes are most valuable, but in general the work has suffered from a freedom justifiable in the translation of poetry, but not in science. We have relied upon the Latin edition of Janus, Leipzig, 1870. The frequent quotations in our footnotes are sufficient indication of the character of Pliny's work. In general it should be remembered that he was himself but a compiler of information from others, and, so far as our subjects are concerned, of no other experience than most travellers. When one considers the reliability of such authors to-day on technical subjects, respect for Pliny is much enhanced. Further, the text is no doubt much corrupted through the generations of transcription before it was set in type. So far as can be identified with any assurance, Pliny adds but few distinct minerals to those enumerated by Theophrastus and Dioscorides. For his metallurgical and mining information we refer to the footnotes, and in general it may be said that while those skilled in metallurgy can dimly see in his statements many metallurgical operations, there is little that does not require much deduction to arrive at a conclusion. On geology he offers no new philosophical deductions of consequence; the remote connection of building stones is practically all that can be enumerated, lest one build some assumption of a knowledge of ore-deposits on the use of the word "vein". One point of great interest to this work is that in his search for Latin terms for technical purposes Agricola relied almost wholly upon Pliny, and by some devotion to the latter we have been able to disentangle some very puzzling matters of nomenclature in _De Re Metallica_, of which the term _molybdaena_ may be cited as a case in point.

Vitruvius was a Roman architect of note of the 1st Century B.C. His work of ten books contains some very minor references to pumps and machinery, building stones, and the preparation of pigments, the latter involving operations from which metallurgical deductions can occasionally be safely made. His works were apparently first printed in Rome in 1496. There are many editions in various languages, the first English translation being from the French in 1692. We have relied upon the translation of Joseph Gwilt, London, 1875, with such alterations as we have considered necessary.

MEDIAEVAL AUTHORS.--For convenience we group under this heading the writers of interest from Roman times to the awakening of learning in the early 16th Century. Apart from Theophilus, they are mostly alchemists; but, nevertheless, some are of great importance in the history of metallurgy and chemistry. Omitting a horde of lesser lights upon whom we have given some data under the author's preface, the works principally concerned are those ascribed to Avicenna, Theophilus, Geber, Albertus Magnus, Roger Bacon, and Basil Valentine. Judging from the Preface to _De Re Metallica_, and from quotations in his subsidiary works, Agricola must have been not only familiar with a wide range of alchemistic material, but also with a good deal of the Arabic literature, which had been translated into Latin. The Arabs were, of course, the only race which kept the light of science burning during the Dark Ages, and their works were in considerable vogue at Agricola's time.

Avicenna (980-1037) was an Arabian physician of great note, a translator of the Greek classics into Arabic, and a follower of Aristotle to the extent of attempting to reconcile the Peripatetic elements with those of the alchemists. He is chiefly known to the world through the works which he compiled on medicine, mostly from the Greek and Latin authors. These works for centuries dominated the medical world, and were used in certain European Universities until the 17th century. A great many works are attributed to him, and he is copiously quoted by Agricola, principally in his _De Ortu et Causis_, apparently for the purpose of exposure.

Theophilus was a Monk and the author of a most illuminating work, largely upon working metal and its decoration for ecclesiastical purposes. An excellent translation, with the Latin text, was published by Robert Hendrie, London, 1847, under the title "An Essay upon various Arts, in three books, by Theophilus, called also Rugerus, Priest and Monk." Hendrie, for many sufficient reasons, places the period of Theophilus as the latter half of the 11th century. The work is mainly devoted to preparing pigments, making glass, and working metals, and their conversion into ecclesiastical paraphernalia, such as mural decoration, pictures, windows, chalices, censers, bells, organs, etc. However, he incidentally describes the making of metallurgical furnaces, cupellation, parting gold and silver by cementation with salt, and by melting with sulphur, the smelting of copper, liquating lead from it, and the refining of copper under a blast with poling.

Geber was until recent years considered to be an Arab alchemist of a period somewhere between the 7th and 12th centuries. A mere bibliography of the very considerable literature which exists in discussion of who, where, and at what time the author was, would fill pages. Those who are interested may obtain a start upon such references from Hermann Kopp's _Beitraege zur Geschichte der Chemie_, Braunschweig, 1875, and in John Ferguson's _Bibliotheca Chemica_, Glasgow, 1906. Berthelot, in his _Chimie au Moyen Age_, Paris, 1893, considers the works under the name of Geber were not in the main of Arabic origin, but composed by some Latin scholar in the 13th century. In any event, certain works were, under this name, printed in Latin as early as 1470-80, and have passed innumerable editions since. They were first translated into English by Richard Russell, London, 1678, and we have relied upon this and the Nuremberg edition in Latin of 1541. This work, even assuming Berthelot's view, is one of the most important in the history of chemistry and metallurgy, and is characterised by a directness of statement unique among alchemists. The making of the mineral acids--certainly nitric and _aqua regia_, and perhaps hydrochloric and sulphuric--are here first described. The author was familiar with saltpetre, sal-ammoniac, and alkali, and with the acids he prepared many salts for the first time. He was familiar with amalgamation, cupellation, the separation of gold and silver by cementation with salt and by nitric acid. His views on the primary composition of bodies dominated the alchemistic world for centuries. He contended that all metals were composed of "spiritual" sulphur (or arsenic, which he seems to consider a special form of sulphur) and quicksilver, varying proportions and qualities yielding different metals. The more the quicksilver, the more "perfect" the metal.

Albertus Magnus (Albert von Bollstadt) was a Dominican Monk, afterwards Bishop, born about 1205, and died about 1280. He was rated the most learned man of his time, and evidence of his literary activities lies in the complete edition of his works issued by Pierre Jammy, Lyons, 1651, which comprises 21 folio volumes. However, there is little doubt that a great number of works attributed to him, especially upon alchemy, are spurious. He covered a wide range of theology, logic, alchemy, and natural science, and of the latter the following works which concern our subject are considered genuine:--_De Rebus Metallicis et Mineralibus_, _De Generatione et Corruptione_, and _De Meteoris_. They are little more than compilations and expositions of the classics muddled with the writings of the Arabs, and in general an attempt to conciliate the Peripatetic and Alchemistic schools. His position in the history of science has been greatly over-estimated. However, his mineralogy is, except for books on gems, the only writing of any consequence at all on the subject between Pliny and Agricola, and while there are but two or three minerals mentioned which are not to be found in the ancient authors, this work, nevertheless, deserves some place in the history of science, especially as some attempt at classification is made. Agricola devotes some thousands of words to the refutation of his "errors."

Roger Bacon (1214-1294) was a Franciscan Friar, a lecturer at Oxford, and a man of considerable scientific attainments for his time. He was the author of a large number of mathematical, philosophical, and alchemistic treatises. The latter are of some importance in the history of chemistry, but have only minute bearing upon metallurgy, and this chiefly as being one of the earliest to mention saltpetre.

Basil Valentine is the reputed author of a number of alchemistic works, of which none appeared in print until early in the 17th century. Internal evidence seems to indicate that the "Triumphant Chariot of Antimony" is the only one which may possibly be authentic, and could not have been written prior to the end of the 15th or early 16th century, although it has been variously placed as early as 1350. To this work has been accredited the first mention of sulphuric and hydrochloric acid, the separation of gold and silver by the use of antimony (sulphide), the reduction of the antimony sulphide to the metal, the extraction of copper by the precipitation of the sulphate with iron, and the discovery of various antimonial salts. At the time of the publication of works ascribed to Valentine practically all these things were well known, and had been previously described. We are, therefore, in much doubt as to whether this author really deserves any notice in the history of metallurgy.

EARLY 16th CENTURY WORKS.--During the 16th century, and prior to _De Re Metallica_, there are only three works of importance from the point of view of mining technology--the _Nuetzlich Bergbuechlin_, the _Probierbuechlein_, and Biringuccio's _De La Pirotechnia_. There are also some minor works by the alchemists of some interest for isolated statements, particularly those of Paracelsus. The three works mentioned, however, represent such a stride of advance over anything previous, that they merit careful consideration.

_Eyn Nuetzlich Bergbuechlin._ Under this title we frequently refer to a little booklet on veins and ores, published at the beginning of the 16th century. The title page of our copy is as below:--

[Illustration 610 (Title page)]

This book is small 8vo, comprises 24 folios without pagination, and has no typographical indications upon the title page, but the last line in the book reads: _Gedruckt zu Erffurd durch Johan Loersfelt, 1527_. Another edition in our possession, that of "Frankfurt am Meyn", 1533, by Christian Egenolph, is entitled _Bergwerk und Probierbuechlin_, etc., and contains, besides the above, an extract and plates from the _Probierbuechlein_ (referred to later on), and a few recipes for assay tests. All of these booklets, of which we find mention, comprise instructions from Daniel, a skilled miner, to Knappius, "his mining boy". Although the little books of this title are all anonymous, we are convinced, largely from the statement in the Preface of _De Re Metallica_, that one Calbus of Freiberg was the original author of this work. Agricola says: "Two books have been written in our tongue: the one on the assaying of mineral substances and metals, somewhat confused, whose author is unknown; the other 'On Veins', of which Pandulfus Anglus is also said to have written, _although the German book was written by Calbus of Freiberg, a well-known doctor; but neither of them accomplished the task he had begun_." He again refers to Calbus at the end of Book III.[2] of _De Re Metallica_, and gives an almost verbatim quotation from the _Nuetzlich Bergbuechlin_. Jacobi[3] says: "Calbus Fribergius, so called by Agricola himself, is certainly no other than the Freiberg doctor, Ruehlein von C(K)albe." There are also certain internal evidences that support Agricola's statement, for the work was evidently written in Meissen, and the statement of Agricola that the book was unfinished is borne out by a short dialogue at the end of the earlier editions, designed to introduce further discussion. Calbus (or Dr. Ulrich Ruehlein von Kalbe) was a very active citizen of Freiberg, having been a town councillor in 1509, burgomaster in 1514, a mathematician, mining surveyor, founder of a school of liberal arts, and in general a physician. He died in 1523.[4] The book possesses great literary interest, as it is, so far as we are aware, undoubtedly the first work on mining geology, and in consequence we have spent some effort in endeavour to find the date of its first appearance. Through the courtesy of M. Polain, who has carefully examined for us the _Nuetzlich Bergbuechlein_ described in Marie Pellechet's _Catalogue General des Incunables des Bibliotheques Publiques de France_,[5] we have ascertained that it is similar as regards text and woodcuts to the Erfurt edition, 1527. This copy in the Bibliotheque Nationale is without typographical indications, and M. Polain considers it very possible that it is the original edition printed at the end of the fifteenth or beginning of the sixteenth centuries. Mr. Bennett Brough,[6] quoting Hans von Dechen,[7] states that the first edition was printed at Augsburg in 1505, no copy of which seems to be extant. The Librarian at the School of Mines at Freiberg has kindly furnished us with the following notes as to the titles of the copies in that Institution:--(1) _Eyn Wolgeordent und Nuetzlich Bergbuechlein_, etc., Worms, 1512[8] and 1518[9] (the place and date are written in), (2) the same as ours (1527); (3) the same, Heinrich Steyner, Augsburg, 1534; (4) the same, 1539. On comparing these various editions (to which may be added one probably published in Nuernberg by Friedrich Peypus in 1532[10]) we find that they fall into two very distinct groups, characterised by their contents and by two entirely different sets of woodcuts.

Group I.

(_a_) _Eyn Nuetzlich Bergbuechlein_ (in _Bibl. Nat._, Paris) before 1500 (?).

(_b_) Ditto, Erfurt, 1527.

Group II.

(_c_) _Wolgeordent Nuetzlich Bergbuechlein_, Worms, Peter Schoefern, 1512.

(_d_) _Wolgeordent Nuetzlich Bergbuechlein_, Worms, Peter Schoefern, 1518.

(_e_) _Bergbuechlin von Erkantnus der Berckwerck_, Nuernberg, undated, 1532 (?).

(_f_) _Bergwerckbuch & Probirbuch_, Christian Egenolph, Frankfurt-am-Meyn, 1533.

(_g_) _Wolgeordent Nuetzlich Bergbuechlein_, Augsburg, Heinrich Steyner, 1534.

(_h_) _Wolgeordent Nuetzlich Bergbuechlein_, Augsburg, Heinrich Steyner, 1539.

There are also others of later date toward the end of the sixteenth century.

The _Buechlein_ of Group I. terminate after the short dialogue between Daniel and Knappius with the words: _Mitt welchen das kleinspeissig ertz geschmeltzt soil werden_; whereas in those of Group II. these words are followed by a short explanation of the signs used in the woodcuts, and by directions for colouring the woodcuts, and in some cases by several pages containing definitions of some 92 mining terms. In the editions of Group I. the woodcut on the title page represents a miner hewing ore in a vein and two others working a windlass. In those of Group II. the woodcut on the title page represents one miner hewing on the surface, another to the right carting away ore in a handcart, and two others carrying between them a heavy timber. In our opinion Group I. represents the older and original work of Calbus; but as we have not seen the copy in the _Bibliotheque Nationale_, and the Augsburg edition of 1505 has only so far been traced to Veith's catalogue,[11] the question of the first edition cannot be considered settled at present. In any event, it appears that the material grafted on in the second group was later, and by various authors.

The earliest books comprise ten chapters, in which Daniel delivers about 6,000 words of instruction. The first four chapters are devoted to the description of veins and the origin of the metals, of the remaining six chapters one each to silver, gold, tin, copper, iron, lead, and quicksilver. Among the mining terms are explained the meaning of country rock (_zechstein_), hanging and footwalls (_hangends_ and _liegends_), the strike (_streichen_), dip (_fallen_), and outcrop (_ausgehen_). Of the latter two varieties are given, one of the "whole vein," the other of the _gesteins_, which may be the ore-shoot. Various veins are illustrated, and also for the first time a mining compass. The account of the origin of the metals is a muddle of the Peripatetics, the alchemists, and the astrologers, for which acknowledgment to Albertus Magnus is given. They are represented to originate from quicksilver and sulphur through heat, cold, dampness, and dryness, and are drawn out as exhalations through the veins, each metal owing its origin to the special influence of some planet; the Moon for silver, Saturn for lead, etc. Two types of veins are mentioned, "standing" (_stehendergang_) and flat (_flachgang_). Stringers are given the same characteristics as veins, but divided into hanging, footwall, and other varieties. Prominence is also given to the _geschick_ (selvage seams or joints?). The importance of the bearing of the junctions of veins and stringers on enrichment is elaborated upon, and veins of east-west strike lying upon a south slope are considered the best. From the following notes it will be seen that two or three other types of deposits besides veins are referred to.

In describing silver veins, of peculiar interest is the mention of the association of bismuth (_wismuth_), this being, we believe, the first mention of that metal, galena (_glantz_), quartz (_quertz_), spar (_spar_), hornstone (_hornstein_), ironstone and pyrites (_kies_), are mentioned as gangue materials, "according to the mingling of the various vapours." The term _glasertz_ is used, but it is difficult to say if silver glance is meant; if so, it is the first mention of this mineral. So far as we know, this is the first use of any of the terms in print. Gold alluvial is described, part of the gold being assumed as generated in the gravel. The best alluvial is in streams running east and west. The association of gold with pyrites is mentioned, and the pyrites is found "in some places as a complete stratum carried through horizontally, and is called a _schwebender gang_." This sort of occurrence is not considered very good "because the work of the heavens can be but little completed on account of the unsuitability of the position." Gold pyrites that comes in veins is better. Tin is mentioned as found in alluvial, and also in veins, the latter being better or worse, according to the amount of pyrites, although the latter can be burned off. Tin-stone is found in masses, copper ore in schist and in veins sometimes with pyrites. The ore from veins is better than schist. Iron ore is found in masses, and sometimes in veins; the latter is the best. "The iron veins with good hanging- and foot-walls are not to be despised, especially if their strike be from east to west, their dip to the south, the foot-wall and outcrop to the north, then if the ironstone is followed down, the vein usually reveals gold or other valuable ore". Lead ore is found in _schwebenden gang_ and _stehenden gang_. Quicksilver, like other ore, is sometimes found in brown earth, and sometimes, again, in caves where it has run out like water. The classification of veins is the same as in _De Re Metallica_.[12] The book generally, however, seems to have raised Agricola's opposition, for the quotations are given in order to be demolished.

_Probierbuechlein._ Agricola refers in the Preface of _De Re Metallica_ to a work in German on assaying and refining metals, and it is our belief that it was to some one of the little assay books published early in the 16th century. There are several of them, seemingly revised editions of each other; in the early ones no author's name appears, although among the later editions various names appear on the title page. An examination of these little books discloses the fact that their main contents are identical, for they are really collections of recipes after the order of cookery books, and intended rather to refresh the memory of those already skilled than to instruct the novice. The books appear to have grown by accretions from many sources, for a large number of methods are given over and over again in the same book with slight variations. We reproduce the title page of our earliest copy.

[Illustration 612 (Title page)]

The following is a list of these booklets so far as we have been able to discover actual copies:--

_Date._ _Place._ _Publisher._ _Title (Short)._ _Author._

Unknown Unknown Unknown _Probierbuechlein_ Anon. (Undated; but catalogue of British Museum suggests Augsburg, 1510.)

1524 Magdeburg _Probirbuechleyn Anon. tzu Gotteslob_

1531 Augsburg Unknown _Probierbuch aller Anon. Sachsischer Ertze_

1533 Frankfurt a. _Bergwerck und Anon. Meyn Probierbuechlein_

1534 Augsburg Heinrich _Probirbuechlein_ Anon. Steyner, 8vo.

1546 Augsburg Ditto, ditto _Probirbuechlein_ Anon.

1549 Augsburg Ditto, ditto _Probirbuechlein_ Anon.

1564 Augsburg Math. Francke, _Probirbuechlein_ Zach. Lochner 4to

1573 Augsburg 8vo. _Probirbuch_ Sam. Zimmermann

1574 Franckfurt _Probierbuechlein_ Anon. a. Meyn

1578 Ditto _Probierbuechlein Fremde Cyriacus und subtile Kunst_ Schreittmann

1580 Ditto _Probierbuechlein_ Anon.

1595 Ditto _Probierbuechlein darinn Modestin Fachs gruendlicher Bericht_

1607 Dresden 4to _Metallische Probier C. C. Schindler Kunst_ _Bericht vom Ursprung und Erkenntniss der Metallischen erze_

1669 Amsterdam _Probierbuechlein darinn Modestin Fachs gruendlicher Bericht_

1678 Leipzig _Probierbuechlein darinn Modestin Fachs gruendlicher Bericht_

1689 Leipzig _Probierbuechlein darinn Modestin Fachs gruendlicher Bericht_

1695 Nuernberg 12mo. _Deutliche Vorstellung Anon. der Probier Kunst_

1744 Luebeck 8vo. _Neu-eroeffnete Probier Anon. Buch_

1755 Frankfurt 8vo. _Scheid-Kuenstler ... Anon. and Leipzig alle Ertz und Metalle ... probiren_

1782 Rotenburg an 8vo. _Probierbuch aus K. A. Scheidt der Fulde Erfahrung aufgesetzt_

As mentioned under the _Nuetzlich Bergbuechlein_, our copy of that work, printed in 1533, contains only a portion of the _Probierbuechlein_. Ferguson[13] mentions an edition of 1608, and the Freiberg School of Mines Catalogue gives also Frankfort, 1608, and Nuernberg, 1706. The British Museum copy of earliest date, like the title page reproduced, contains no date. The title page woodcut, however, in the Museum copy is referred from that above, possibly indicating an earlier date of the Museum copy.

The booklets enumerated above vary a great deal in contents, the successive prints representing a sort of growth by accretion. The first portion of our earliest edition is devoted to weights, in which the system of "lesser weights" (the principle of the "assay ton") is explained. Following this are exhaustive lists of touch-needles of various composition. Directions are given with regard to assay furnaces, cupels, muffles, scorifiers, and crucibles, granulated and leaf metals, for washing, roasting, and the preparation of assay charges. Various reagents, including glass-gall, litharge, salt, iron filings, lead, "alkali", talc, argol, saltpetre, sal-ammoniac, alum, vitriol, lime, sulphur, antimony, _aqua fortis_, or _scheidwasser_, etc., are made use of. Various assays are described and directions given for crucible, scorification, and cupellation tests. The latter part of the book is devoted to the refining and parting of precious metals. Instructions are given for the separation of silver from iron, from lead, and from antimony; of gold from silver with antimony (sulphide) and sulphur, or with sulphur alone, with "_scheidwasser_," and by cementation with salt; of gold from copper with sulphur and with lead. The amalgamation of gold and silver is mentioned.

The book is diffuse and confused, and without arrangement or system, yet a little consideration enables one of experience to understand most statements. There are over 120 recipes, with, as said before, much repetition; for instance, the parting of gold and silver by use of sulphur is given eight times in different places. The final line of the

## book is: "Take this in good part, dear reader, after it, please God,

there will be a better." In truth, however, there are books on assaying four centuries younger that are worse. This is, without doubt, the first written word on assaying, and it displays that art already full grown, so far as concerns gold and silver, and to some extent copper and lead; for if we eliminate the words dependent on the atomic theory from modern works on dry assaying, there has been but very minor progress. The art could not, however, have reached this advanced stage but by slow accretion, and no doubt this collection of recipes had been handed from father to son long before the 16th century. It is of wider interest that these booklets represent the first milestone on the road to quantitative analysis, and in this light they have been largely ignored by the historians of chemistry. Internal evidence in Book VII. of _De Re Metallica_, together with the reference in the Preface, leave little doubt that Agricola was familiar with these booklets. His work, however, is arranged more systematically, each operation stated more clearly, with more detail and fresh items; and further, he gives methods of determining copper and lead which are but minutely touched upon in the _Probierbuechlein_, while the directions as to tin, bismuth, quicksilver, and iron are entirely new.

Biringuccio (Vanuccio). We practically know nothing about this author. From the preface to the first edition of his work it appears he was styled a mathematician, but in the text[14] he certainly states that he was most of his time engaged in metallurgical operations, and that in pursuit of such knowledge he had visited Germany. The work was in Italian, published at Venice in 1540, the title page of the first edition as below:--

[Illustration 614 (Title page)]

It comprises ten chapters in 168 folios demi-octavo. Other Italian editions of which we find some record are the second at Venice, 1552; third, Venice, 1558; fourth, Venice, 1559; fifth, Bologna, 1678. A French translation, by Jacques Vincent, was published in Paris, 1556, and this translation was again published at Rouen in 1627. Of the ten chapters the last six are almost wholly devoted to metal working and founding, and it is more largely for this description of the methods of making artillery, munitions of war and bells that the book is celebrated. In any event, with the exception of a quotation which we give on page 297 on silver amalgamation, there is little of interest on our subject in the latter chapters. The first four chapters are undoubtedly of importance in the history of metallurgical literature, and represent the first work on smelting. The descriptions are, however, very diffuse, difficult to follow, and lack arrangement and detail. But like the _Probierbuechlein_, the fact that it was written prior to _De Re Metallica_ demands attention for it which it would not otherwise receive. The ores of gold, silver, copper, lead, tin, and iron are described, but much interrupted with denunciations of the alchemists. There is little of geological or mineralogical interest, he too holding to a muddle of the classic elements astrology and alchemy. He has nothing of consequence to say on mining, and dismisses concentration with a few words. Upon assaying his work is not so useful as the _Probierbuechlein_. On ore smelting he describes the reduction of iron and lead ores and cupriferous silver or gold ores with lead. He gives the barest description of a blast furnace, but adds an interesting account of a _reverbero_ furnace. He describes liquation as consisting of one operation; the subsequent treatment of the copper by refining with an oxidizing blast, but does not mention poling; the cupellation of argentiferous lead and the reduction of the litharge; the manufacture of nitric acid and that method of parting gold and silver. He also gives the method of parting with antimony and sulphur, and by cementation with common salt. Among the side issues, he describes the method of making brass with calamine; of making steel; of distilling quicksilver; of melting out sulphur; of making vitriol and alum. He states that _arsenico_ and _orpimento_ and _etrisagallio_ (realgar) are the same substance, and are used to colour copper white.

In general, Biringuccio should be accredited with the first description (as far as we are aware) of silver amalgamation, of a reverberatory furnace, and of liquation, although the description is not complete. Also he is, so far as we are aware, the first to mention cobalt blue (_Zaffre_) and manganese, although he classed them as "half" metals. His descriptions are far inferior to Agricola's; they do not compass anything like the same range of metallurgy, and betray the lack of a logical mind.

_Other works._ There are several works devoted to mineralogy, dating from the fifteenth and early sixteenth centuries, which were, no doubt, available to Agricola in the compilation of his _De Natura Fossilium_. They are, however, practically all compiled from the jeweller's point of view rather than from that of the miner. Among them we may mention the poem on precious stones by Marbodaeus, an author who lived from 1035 to 1123, but which was first printed at Vienna in 1511; _Speculum Lapidum_, a work on precious stones, by Camilli Leonardi, first printed in Venice in 1502. A work of wider interest to mineralogists is that by Christoph Entzelt (or Enzelius, Encelio, Encelius, as it is variously given), entitled _De Re Metallica_, and first printed in 1551. The work is five years later than _De Natura Fossilium_, but contains much new material and was available to Agricola prior to his revised editions.

FOOTNOTES:

[1] See pages 44 and 46.

[2] Page 75.

[3] _Der Mineralog Georgius Agricola_, Zwickau, 1889, p. 46.

[4] Andreas Moeller, _Theatrum Freibergense Chronicum_, etc., Freiberg, 1653.

[5] Paris, 1897, Vol. I. p. 501.

[6] Cantor Lectures, London, April 1892.

[7] Hans von Dechen, _Das aelteste deutsche Bergwerksbuch_, reprint from _Zts. fuer Bergrecht Bd. XXVI._, Bonn, 1885.

[8] Panzer's _Annalen_, Nuernberg, 1782, p. 422, gives an edition Worms _bei_ Peter Schoefern, 1512.

[9] The Royal Library at Dresden and the State Library at Munich have each a copy, dated 1518, Worms.

[10] Hans von Decken _op. cit._, p. 48-49.

[11] _Annales typographiae augustanae ab ejus origine, MCCCLXVI. usque ad. an. M.D.XXX. Accedit dom Franc. Ant. Veith. Diatribe de origine ... artis typographicae in urbe augusta vindelica edidit...._ Georgius G. Zapf., Augsburg, 1778, X. p. 23.

[12] See p. 44.

[13] _Bibliotheca Chemica_.

[14] Book I., Chap. 2.

APPENDIX C.

WEIGHTS AND MEASURES.

As stated in the preface, the nomenclature to be adopted for weights and measures has presented great difficulty. Agricola uses, throughout, the Roman and the Romanized Greek scales, but in many cases he uses these terms merely as lingual equivalents for the German quantities of his day. Moreover the classic language sometimes failed him, whereupon he coined new Latin terms adapted from the Roman scale, and thus added further confusion. We can, perhaps, make the matter clearer by an illustration of a case in weights. The Roman _centumpondium_, composed of 100 _librae_, the old German _centner_ of 100 _pfundt_, and the English hundredweight of 112 pounds can be called lingual equivalents. The first weighs about 494,600 Troy grains, the second 721,900, and the third 784,000. While the divisions of the _centumpondium_ and the _centner_ are the same, the _libra_ is divided into 12 _unciae_ and the _pfundt_ into 16 _untzen_, and in most places a summation of the units given proves that the author had in mind the Roman ratios. However, on p. 509 he makes the direct statement that the _centumpondium_ weighs 146 _librae_, which would be about the correct weight if the _centumpondium_ referred to was a _centner_. If we take an example such as "each _centumpondium_ of lead contains one _uncia_ of silver", and reduce it according to purely lingual equivalents, we should find that it runs 24.3 Troy ounces per short ton, on the basis of Roman values, and 18.25 ounces per short ton, on the basis of old German. If we were to translate these into English lingual equivalents of one ounce per hundredweight, then the value would be 17.9 ounces per short ton.

Several possibilities were open in translation: first, to calculate the values accurately in the English units; second, to adopt the nearest English lingual equivalent; third, to introduce the German scale of the period; or, fourth, to leave the original Latin in the text. The first would lead to an indefinite number of decimals and to constant doubt as to whether the values, upon which calculations were to be based, were Roman or German. The second, that is the substitution of lingual equivalents, is objectionable, not only because it would indicate values not meant by the author, but also because we should have, like Agricola, to coin new terms to accommodate the lapses in the scales, or again to use decimals. In the third case, that is in the use of the old German scale, while it would be easier to adapt than the English, it would be more unfamiliar to most readers than the Latin, and not so expressive in print, and further, in some cases would present the same difficulties of calculation as in using the English scale. Nor does the contemporary German translation of _De Re Metallica_ prove of help, for its translator adopted only lingual equivalents, and in consequence the summation of his weights often gives incorrect results. From all these possibilities we have chosen the fourth, that is simply to reproduce the Latin terms for both weights and measures. We have introduced into the footnotes such reductions to the English scale as we considered would interest readers. We have, however, digressed from the rule in two cases, in the adoption of "foot" for the Latin _pes_, and "fathom" for _passus_. Apart from the fact that these were not cases where accuracy is involved, Agricola himself explains (p. 77) that he means the German values for these particular terms, which, fortunately, fairly closely approximate to the English. Further, we have adopted the Anglicized words "digit", "palm", and "cubit", instead of their Latin forms.

For purposes of reference, we reproduce the principal Roman and old German scales, in so far as they are used by Agricola in this work, with their values in English. All students of weights and measures will realize that these values are but approximate, and that this is not an occasion to enter upon a discussion of the variations in different periods or by different authorities. Agricola himself is the author of one of the standard works on Ancient Weights and Measures (see Appendix A), and further gives fairly complete information on contemporary scales of weight and fineness for precious metals in Book VII. p. 262 etc., to which we refer readers.

ROMAN SCALES OF WEIGHTS.

Troy Grains. 1 _Siliqua_ = 2.87 6 _Siliquae_ = 1 _Scripulum_ 17.2 4 _Scripula_ = 1 _Sextula_ 68.7 6 _Sextulae_ = 1 _Uncia_ 412.2 12 _Unciae_ = 1 _Libra_ 4946.4 100 _Librae_ = 1 _Centumpondium_ 494640.0

Also

1 _Scripulum_ = 17.2 3 _Scripula_ = 1 _Drachma_ 51.5 2 _Drachmae_ = 1 _Sicilicus_ 103.0 4 _Sicilici_ = 1 _Uncia_ 412.2 8 _Unciae_ = 1 _Bes_ 3297.6

SCALE OF FINENESS (AGRICOLA'S ADAPTATION).

4 _Siliquae_ = 1 Unit of _Siliquae_ 3 _Units of Siliquae_ = 1 _Semi-sextula_ 4 _Semi-sextulae_ = 1 _Duella_ 24 _Duellae_ = 1 _Bes_

OLD GERMAN SCALE OF WEIGHTS. Troy Grains. 1 _Pfennig_ = 14.1 4 _Pfennige_ = 1 _Quintlein_ 56.4 4 _Quintlein_ = 1 _Loth_ 225.6 2 _Loth_ = 1 _Untzen_ 451.2 8 _Untzen_ = 1 _Mark_ 3609.6 2 _Mark_ = 1 _Pfundt_ 7219.2 100 _Pfundt_ = 1 _Centner_ 721920.0

SCALE OF FINENESS.

3 _Grenlin_ = 1 _Gran_ 4 _Gran_ = 1 _Krat_ 24 _Krat_ = 1 _Mark_

ROMAN LONG MEASURE. Inches. 1 _Digitus_ = .726 4 _Digiti_ = 1 _Palmus_ 2.90 4 _Palmi_ = 1 _Pes_ 11.61 1-1/2 _Pedes_ = 1 _Cubitus_ 17.41 5 _Pedes_ = 1 _Passus_ 58.1

Also

1 Roman _Uncia_ = .97 12 _Unciae_ = Pes 11.61

GREEK LONG MEASURE. Inches. 1 _Dactylos_ = .758 4 _Dactyloi_ = 1 _Palaiste_ 3.03 4 _Palaistai_ = 1 _Pous_ 12.135 1-1/2 _Pous_ = 1 _Pechus_ 18.20 6 _Pous_ = 1 _Orguia_ 72.81

OLD GERMAN LONG MEASURE. Inches. 1 _Querfinger_ = .703 16 _Querfinger_ = 1 _Werckschuh_ 11.247 2 _Werckschuh_ = 1 _Elle_ 22.494 3 _Elle_ = 1 _Lachter_ 67.518

Also

1 _Zoll_ = .85 12 _Zoll_ = 1 _Werkschuh_

ROMAN LIQUID MEASURE. Cubic inches. Pints. 1 _Quartarius_ = 8.6 .247 4 _Quartarii_ = 1 _Sextarius_ 31.4 .991 6 _Sextarii_ = 1 _Congius_ 206.4 5.947 16 _Sextarii_ = 1 _Modius_ 550.4 15.867 8 _Congii_ = 1 _Amphora_ 1650.0 47.577

(Agricola nowhere uses the Saxon liquid measures, nor do they fall into units comparable with the Roman).

GENERAL INDEX.

NOTE.--The numbers in heavy type refer to the Text; those in plain type to the Footnotes, Appendices, etc.

Abandonment of Mines, =217=

Abertham. Mines at, =74=; =92=; 74

Abolite, 113

_Abstrich_, 465; 492

Abydos. Gold mines of, =26=; 27 Lead figure from, 390

_Abzug_, 464; 465; 475

_Achates_ (_see_ Agate).

Accidents To Miners, =214-218=

Accounts (Mining), =96-98=

Adit, 101

_Aeris flos_ (_see_ Copper Flowers).

_Aeris squama_ (_see_ Copper Scales).

_Aes caldarium_, 109

_Aes luteum_, 109

_Aes nigrum_, 109

_Aes purum fossile_ (_see_ Native Copper).

_Aes rude plumbei coloris_ (_see_ Copper Glance).

_Aes ustum_ (_see_ Roasted Copper).

_Aetites_, 2

Africa. Iron, 420 Tin, 412

Agate, 114

Agriculture. Mining compared with, =5=

Ailments of Miners (_see_ Maladies of Miners).

Air Currents in Mines, =121=; =200=

Alabaster, 114

Alchemists, XXVII-XXX; 44; 608 Agricola's opinion of, XII; =XXVII.= Amalgamation, 297 Assaying, =248=; 219 Discovery of acids, 439; 460 Distillation, 441

Aljustrel Tablet, 83-84

Alkali, 558

Alloys, Assaying of, =247-252=

Alluvial Mining, =321-348=; 330-332

Alston Moor, 84

Altenberg, =XXXI=; VI. Collapse of mine, =216= Miners poisoned, =214= Tin working appliances, =290=; =304=; =318=

Alum, =564-568=; 564-570 A solidified juice, 1 Elizabethan Charter, 283 In roasted pyrites, =350= In _Sal artificiosus_, =463= Latin and German terms, 220; 221 Papal monopoly, 570 Use in making nitric acid, =439=; 460

Amalgam.

## Parting the gold from, =298=; 297

Amalgamation, 297 Of gilt objects, =461= Mills, =295-299=

Amber, =34=; 35

Amethyst, 114

_Amiantus_ (_see_ Asbestos).

Ampulla, =445-447=; 220

Annaberg, VI; =XXXI=; =42=; =75=; 75 Profits, =92=

Ant, venomous, =216=

Antimony, 220; 428; 354 Minerals, 110 Smelting of, =400=; =428= Use as type-metal, 2; 429

Antimony Sulphide, 220; 428; 451

## Parting gold and silver with, =451=; 451; 461

## Parting gold from copper, =463=

## Parting silver and iron, =544=

Antwerp, Scale of Weights, =263=

Apex Law, 81; 83-86

_Aqua regia_, 439; 441; 354

_Aqua valens_ (_see also_ Nitric Acid), =439-443=; 439; 220 Clarification with silver, =443=; 443 Cleansing gold-dust with, =396=

## Parting precious metals with, =443-447=

_Arbores dissectae_ (Lagging), 101

Archimedes, Screw of, 149

Architecture. Knowledge necessary for miners, =4=

_Area fodinarum_ (_see_ Meer).

Argentiferous Copper Ores, Smelting of, =404-407=

Argentite, 109

_Argentum purum in venis_ (_see_ Native Silver).

_Argentum rude plumbei coloris_ (_see_ Silver Glance).

_Argentum rude rubrum translucidum_ (_see_ Ruby Silver).

Argol, 234; 220 As a flux, =234=; =238=; =243= Use in melting silver nitrate, =447= Use in smelting gold dust, =396-398=

Argonauts, 330

Arithmetical Science. Knowledge necessary for miners, =4=

Armenia, Stone of, 115

Arsenic (_see also_ Orpiment _and_ Realgar), 111; 214

_Arsenicum_, 111

Arsenopyrite, 111

Asbestos, =440=; 440; 114

Ash-coloured Copper, =539-540=; 540; 523-524; 492 From liquation, =529-530=

Ashes which Wool Dyers use (_see also_ Potash), 233; 559; 220 Use in assaying, =236-238=

Ash of Lead, =237-238=; 237; 220

Ash of Musk Ivy (_see also_ Potash and _Nitrum_), =236-238=; 220

Asphalt, 581

_Asphaltites_ (_see_ Dead Sea).

Assay Balances (_see_ Balances).

Assay Fluxes (_see_ Fluxes).

Assay Furnaces, =224-228=; 220 Crucible, =226-227= Muffle, =224-228=; =239=

Assaying (_see also_ _Probierbuechlein_), =219=; 219; 220; 354 Amalgamation, =243= Bismuth, =247= Copper, =244= Cupellation, =240= Gold and silver alloys, =248= Gold ore, =242-244= Iron ore, =247= Lead, =245-246= Silver, =242-245= Silver and copper alloys, =249-250= Tin, =246= Tin and silver alloys, =251=

Assay Muffles (_see_ Muffles).

Assay Ton, =261=; 242

Assyrian Copper, 402

Asthma, =214=

Astronomy. Knowledge necessary for miners, =4=

Atarnea. Mines near, =26=; 27

Athens. Mining law, 83 Sea power and mines, 27 Silver mines (_see_ Mt. Laurion, Mines of).

_Atramentum Sutorium_ (_see also_ Vitriol), 572; 110

_Atramentum Sutorium candidum_, 113

_Atramentum Sutorium rubrum_, =274=; 274

_Aurichalcum_, 409; 404

_Auripigmentum_ (_see_ Orpiment).

Azure, 1; 109; 220 An indication of copper, =116= An indication of gold, =117= Colour of flame, =235=

Azurite 109; 220; 402

Babel, Tower of, 582

Babylonia. Bitumen in, 582 Use of lead, 391

Babytace. Gold buried by inhabitants, =9=; =15=

Baebelo, =42=; 42

Balances, =224=; =264-265=

Barite, 115

Barmaster, of High Peak, 77

Bars, for Furnace Work, =382=

Baskets, for Hoisting, =153=

Batea, =156=

Beer, =230=; 220

Bell, to call Workmen, =100=

Bellows, =362-373=; =419= Ancient use of, 354; 355; 362 Assay furnace, =226=; =245= Mine ventilation with, =207-210=

Beni Hassen, Inscriptions at, 586

_Berg-geel_, 111

Bergmeister, =33=; =81=; =95=; =77=; 77; 78 Deals with forfeited shares, =92-93= Jurors, =96=

Bergmeister's Clerk, =95=; 78

_Bergzinober_ (_see_ Quicksilver).

Bermius (Bermium), Mt. (_see_ Mt. Bermius).

Bismuth, =433=; 354; 220 Assaying ores of, =247= Indication of silver, =116= Minerals, 2; 111 Smelting of, =433-437=; =400= The "roof of silver," =117=; 433 _Zaffre_, 112

Bitumen. Ancient knowledge of, 220; 581-582; 354 Colour of fumes, =235= Dead Sea, =33= Distillation, =581= From springs, =582= Harmful to metals, =273= Roasting from ore, =273=; =276=; =351= Solidified juice, =1=

_Bituminosa cadmia_ (_see_ _Cadmia bituminosa_).

Blast, Regulation of, =380=; =386=

Blasting, 119

Blende, 113

Bleyberg, 239

Bloodstone, 111; 2

Bloom, 420

_Bluetstein_ (_see_ Ironstone).

Bohemia. Antimony sulphide, 428 Pestilential vapours, =216= Sifting ore in, =293= Smelting, =384=

Bone-ash, =230=; 466

Borax, 560; 221; 110 Method of manufacture, =560= Use in gold smelting, =444=; =457=; =464= Use in assaying, =245=; =246=

Bornite, 109

Boundary Stones, =87=; 129

Boundaries, =77=; =147=

Bowls for Alluvial Washing, =322=; =324=; =334=; =336=

Brass, 410; 354; 2 Ancient methods of making, 404-405; 112

Breaking Ore, =117-119=

Brick Dust. Used in cementation, =454=; 454 Used in making nitric acid, =440=

Brine (_see also_ Salt). Evaporation of, =547-548=

Britain. Lead-silver smelting, 392 Miners mentioned by Pliny, 83 Tin trade, 411-413

British Museum. Egyptian gold-mining, 399 Egyptian lead, 390 Egyptian steel, 402

Bromyrite, 109

Bronze. Historical notes, 411; 402; 354

Bronze Age, 355; =402=; 411

Bryle (Outcrop), 101

Buckets, for Hoisting Ore, =153-154=; =157=

Buddle, 281; 282; 267 Divided, =302-303= Simple, =300-302=; =312-315=

Bullion, Pouring into Bars, =382=

Burning Ore, =231=; =273=; 267

Burnt Alum, =233=; 565; 221

_Cadmia_ (_see also_ Zinc, _Pompholyx_, _and_ Cobalt), =542=; 542; 112-113 Ancient ore of brass, 410 From dust chambers, =394= From liquation, =539=; 542 From roasting matte, =349= Poisonous to miners, =214=; 214 Roasting, =276= Smelting for gold and silver, =410=

_Cadmia bituminosa_, =276=; 273; 113

_Cadmia fornacis_ (_see_ Furnace Accretions).

_Cadmia fossilis_ (_see_ Calamine _and_ Blende).

_Cadmia metallica_ (_see also_ Cobalt), =403=; 113

_Caeruleum_ (_see_ Azure).

Cakes of Melted Pyrites, 379; 222 A flux, =234= Roasting of, =349-351= Use in smelting, =379=

Calaem (_see also_ Zinc), =409=

Calamine, 112; 113; 409; 410

Calcite, 114

Calcspar, =116=; 114

_Caldarium_ Copper, =512=; =542=; 404; 511

Caldrons, for Evaporating Salts, =548=

_Calmei_ (_see_ Calamine).

Cameros. Zinc found at, 409

Camphor, =238=; 238; 221

Cam-shaft, =282-283=; 267

_Canales_ (Ore Channels), 43; 46; 47 Ore shoots in, =117=

Cannon, =11=

Cardinal Points, =57=; =58=

Carnelian, 114

_Carneol_ (_see_ Carnelian).

_Carni_, 390 Cupellation, =483= Smelting of lead ores, =390=

Carpathian Mountains. Liquation practice in, =540=; =544= Sieves, =289= Stamp-milling, =319=

Carthage. Mines in Spain, =27=

Castulo (Cazlona), 42

Cementation (_see also_ Parting Gold from Silver), =453-457=; 453; 458

_Centumpondium_, 616; 242; 509 Scale of weights, =260-261=

Cerargurite, 109

_Cerussa_ (_see_ White-lead).

Cerussite, 110

Chain Pumps, =171-175=

Chalcanthite, 110

_Chalcanthum_ (_see also_ Vitriol), 109; 572

Chalcedony, 114

_Chalcitis_, 573; 109 Indication of copper, =116=

Chalcocite, 109; 402

Chalcopyrite, 109

Chaldean Antimony, 429

Chemistry. Origin, XXVII; 220

Chemnitz. Agricola appointed city physician, VII. Agricola elected burgomaster, VIII; IX. Quarrel over Agricola's burial, XI.

China, Grand Canal of, 129

Chinese. Early copper smelting, 402 Early iron, 421 Early silver metallurgy, 391 Early zinc smelting, 409

_Chrysocolla_ (_see also_ Borax), 110; 221; 584; 1 Collection in vats, =584= Colour of fumes, =235= Indication of copper, =116= Indication of gold, =117= Mineral, 109 Smelting of, =401=

Church, Share in Mines, =91=

Cimolite, 31

Cinnabar (_see_ Quicksilver _and_ _Minium_).

Claim, in American Title, 77

Cloth. Lining sluices, =322= Ventilation by shaking, =210=

Coal, 34

Cobalt, 354; 542; 112-113 Cobalt-blue, 112; 433 From lead smelting, 408 King Hiram's experience with, 214 Poisonous to miners, 214 Relation to _cadmia_, 112 Relation to bismuth, 435 Smelting ores of, 401

Cobalt-Arsenic Minerals (_see_ Arsenic).

Cobaltite, 113

_Cobaltum cineraceum_ (_see_ Smallite).

_Cobaltum ferri colore_ (_see_ Cobaltite).

_Cobaltum nigrum_ (_see_ Abolite).

Coiners, =95=; 78

Coins, =251-253=; =457=

Colchis. Alluvial gold washing, =330=

Cologne. Scale of weights, =263=

Companies, Mining, =89-93=; 90 Fraudulent dealing, =22= Investment in, =29=

Compass, =141-142=; 56; 129 Divisions of the, =56=; =57= Swiss, =145=; 137

Concentrates. From washing liquation products, =542= Sintering of, =401= Smelting of, =394=; =396-399=; =401=

Concentration, =267-348=; 279; 354

_Congius_, 153; 172, 617

Constantinople, Alum Trade, 569

Consumption. Miners liable to, =214=

_Conterfei_ (_see_ Zinc).

Contracts, Method of Setting, =96=

Copiapite, 111

Copper (_see also_ Liquation), 109; 402; 511 Assay of, =244=; =249= Granulation of, =250= Indications of, =116=

## Parting from gold, =462-464=

## Parting gold from silver, =448-451=; 448

Ratio in liquation cakes, 505; 506 Residues from liquation, =521= Rosette, =538=

Copper-filings, =233=; 233; 221

Copper flowers, =538=; 110; 233; 538 Pliny's description, 404

Copper Glance, =401=; 109

Copper Matte. Roasting, =350= Smelting, =404-407=

Copper Ore (_see also_ Copper Smelting, _etc._), 109 Assaying, =244-245=

Copper Pyrites, =117=; 109

Copper Refining, =530-538=; 354; 492; 535-536 Breaking cakes, =501-503= Enrichment of silver by settling, 510 Roman method, 404 Rosette copper, 535

Copper Scales, 110; 221; 233; 539 Use in assaying, =245=

Copper Schists (_see also_ Mannsfeld Copper Slates), 127 Method of smelting, =408=

Copper Smelting, =388-390=; =401=; =404=; 402 Invention of appliances, 353-354

Cornwall. Ancient tin mining, 413 Early German miners, 282 Early mining law, 85 Early ore dressing, 282 Influence on German mining, 283 "Knockers," 217 Mining terms, 77; 101; 267; 282 Royal Geol. Soc. Transactions, 84

_Coticula_ (_see_ Touchstone).

_Counterfeht_ (_see_ Zinc).

Crane. For cupellation furnaces, =476-477= For lead cakes, =500= For liquation cakes, =514=

Cremnitz. Age of mines, =5= Width of veins, =52=

Crinoid Stems, 115

Croppings, =37=; 37

Crosscuts, =106=

Crowbars, =152=

Crucible. Assay, =228=; =230=; =241=; =245=; 221 Of blast furnaces, =376=; =377=

_Crudaria_, 65

Crushing Mills (_see_ Stamp-mill _and_ Mills).

Crushing Ore, =231=; =279-287=; 279

Crystal (_Crystallum_), 114

Cumberland. Early report on ores of, 267 Roman lead furnaces, 392

Cup-Bearer. Right to a meer, =81=

Cupellation, =464-483=; 465-466 Buildings and furnaces, =464-472=; 492 Brightening of the silver, =241=, =475= In assaying, =240= In "tests," =483= Latin and German terms, 221; 492 Litharge, =475=

Cupels, =228-230=; 221; 466 Drying of, =240= Moulds, =231=

Cupric Oxide, 221

Cuprite, 109; 402

_Cyanus_ (_see also_ Azurite), 110

Cyprus. Ancient copper smelting, 402

_Dach_, 127

_Dactylos_, 617; 78

Dangers to Miners, =214-218=

_Darrlinge_, 492

_Darrofen_, 492

_Darrsoehle_, 492

Dawling, of a Vein, 101

Dead Sea. Bitumen in, =33=

Decemviral College, =96=

_Decumanus_ (_see_ Tithe Gatherer).

_Demensum_ (_see_ Measure).

Demons (_see also_ Gnomes), =217=; 217

Derbyshire (_see also_ High Peak). Early ore washing, 281 Introduction jigging sieve, 283 Mining law, 77; 84-85

Descent into Mines, =212=

Devon. Mining law, 85

Dilleugher, 267

Dioptra, 129

_Diphrygum_, 404

Dip of Veins, =65-75=

Dippas, 101

Dippers, =157= Of pumps, =172=

_Discretores_ (_see_ Sorters).

Distillation, 441 For making nitric acid, =441= Of amalgam, =244= Of quicksilver, =426-432=

_Distributor_, 78

Divining Rod, =38-40=; 38; 40

Divisions of the Compass, =56=; =57=

Drainage of Mines, =121=; =171-198= With buckets, =171= With chain pumps, =172= With rag and chain pumps, =188= With suction pumps, =172= With water bags, =198=

Drawing. Knowledge necessary for miners, =4=

Drifts, =104=; =105=; 101 Timbering of, =125=

Drusy Veins, =107=; 107

"Drying" Liquation Residues (_see also_ Liquation), =527-529=; 491; 492 Furnaces for, =521=; =526=; 492 Silver extracted by, =529= Slags from, 523

Dumps, Working of, =30=

Dust Chambers, =394=; =416=; 354

Dutins, (Timbers), 101

Dynamite, 119

"Earths." Agricola's view of, 1; 46; 48 Extraordinary, =115= Peripatetic view of, 46; 47

Egyptians. Alluvial mining, 330 Antimony, 428 Bronze, 402; 411 Copper smelting, 402 Crushing and concentration, 279 Furnaces, 355 Glass making, 586 Gold mining, 399 Iron, 421 Maps, 129 Mining law, 83 Silver and lead metallurgy, 390 Tin, 411; 412

Egyptian Screw (_see_ Archimedes, Screw of).

Eifel. Spalling ore, =272=

_Eisenertz_ (_see_ Ironstone).

_Eisenglantz_ (_see_ Ironstone).

Eisleben. Heap roasting, =279=; 274

_Electrum_, 458; 2; 35

Elements, Peripatetic Theory of, 44

Emery, 115

Erbisdorff. Tin strakes, =304=

_Excoctores_ (_see_ Smelters).

Exhalations. From veins, =38=; =44=

Exhausted Liquation Cakes (_see_ Liquation Cakes, Exhausted).

Fans, Ventilation, =203-207=

Fathom, 616; =77=; 78

_Federwis_, (_see also_ Asbestos), 114; 274

Feldspar, 114

_Ferrugo_ (_see_ Iron-rust).

_Ferrum purum_ (_see_ Native Iron).

_Fibrae_ (_see_ Stringers).

Fineness, Scales of, 253; 617

Fire-setting, =118-120=; 118-119

Firstum Mines (_see_ Fuerst).

Fissure Vein (_see_ _Vena profunda_).

Flame. Determination of metal by, =235= Determination of required flux by, =235=

Flint, as a Flux, 380

Float, from Veins, =37=

Flookan, 101

Flue-dust, =394-396=

_Fluores_ (_see_ Fluorspar).

Fluorspar, 115; 380; 381 Indication of ore, =116=

_Fluesse_ (_see_ Fluorspar).

Fluxes (_see also_ Argol, Saltpetre, Limestone, Stones which easily melt, _etc._), =232-239=; 232; 237; 380; 221 Basic, 237 De-sulphurizing, =236=; 237 For smelting, =379=; =380=; =386=; =390= Reducing, =236=; 237 Stock fluxes for assaying, =236= Sulphurizing, =236=; 237

Footwall, =68=; =117=

Forehearth, =356=; =375-378=; =386=; 355 For tin furnaces, =411=; =413=

Foreman (_see_ Mining Foreman).

Forest-Fires, =36=; 36

Forest of Dean, 84

Forest of Mendip, 84

_Formae_, 101

_Fossa latens_ (_see also_ Drifts), 101

_Fossa latens transversa_ (_see also_ Crosscuts), 101

_Fossores_ (_see_ Miners).

Founders' Hoards, 355; 402

Fractional Meers, =80=

France. Mediaeval mining law, 84

Free Mining Cities, 84

Freiberg, =XXXI.= Age of the mines, =5= Bergmeister, =95= Division of shares, =81=; =90=; =91= First discovery of veins, =35=; 36 Flooding of mines, =218= Method of cupellation, =482=

Fullers' Earth, 115

Fumes. From heated ore, =235= Poisonous, =215-216=

_Fundamentum_ (_see also_ Footwall), 101

_Fundgrube_ (_see also_ Meer), 77

Furnaces, =374-378=; =386=; =388=; 355; 492 Assaying (_see_ Assay Furnaces). Bismuth smelting, =433-437= Burning tin concentrates, =349= Cementation, =455= Copper smelting, =401-408= Cupellation, =467-468=; =482-483= "Drying" liquated copper, =522-526= Enriching copper bottoms, =510= Gold and silver ores, =382-384= Heating copper cakes, =503= Iron smelting, =420-421=; 420 Latin and German terms, 220 Lead ores, =408-410= Liquation of silver, =515= Melting lead cakes, =498= Nitric acid making, =441=

## Parting precious metals with antimony, =452-453=

Quicksilver distillation, =426-432= Refining copper, =531-533= Refining silver, =483=; =489= Refining tin, =418= Roasting, =276-277= Smelting liquation slags, =507= Tin smelting, =411-413=; =419=

Furnace Accretions, 113; 221; 492 Removal of, =376=

Furnace Hoods, =494=

Fuerst. Mines of, =24=; 24

_Gaarherd_ (_see_ Refining-hearth).

_Gaarmachen_ (_see_ Copper Refining).

Gad, 150

Galena, 51; 109; 110; 221 Bismuth distinguished from, 3 Smelting of, =400-401=

Gangue Minerals, 48

Garlic. Magnet weakened by, =39=

Garnets, =334=

Gases (_see also_ Fumes) From fire-setting, =120=

_Gedigen eisen, silber_, etc. (_see_ Native Iron, Silver, etc.).

_Gel atrament_ (_see_ _Misy_).

Gems, =115=; 1

Geology. Agricola's views, 595

Germans. English mining influenced by, 283 Mining men imported into England, 282 Ore-dressing methods, 281-282

_Geschwornen_ (in Saxon mines), 77

Geyer, =XXXI=; =42=; VI. Shafts, 102 Tin-strakes, =304=

Gilding, 460 Removal from objects, =460=; =464=

Gips (_see_ Gypsum).

Gittelde. Smelting of lead ore, =391=

_Glantz_ (_see_ Galena).

_Glasertz_ (_see_ Silver Glance).

_Glaskoepfe_ (_see_ Ironstone).

Glass, =584-592= Blowing, =592= Furnaces, =586-590= From sand, 380

Glass-galls, 235; 221 As a flux, =235=; =238=; =243=; =246= Use in parting gold from copper, =464= Use in smelting gold concentrates, =397=; =398=

_Glette_ (_see_ Litharge).

_Glimmer_ (_see_ Mica).

Gnomes. In mines, =217=; 112; 214; 217

Goblins (_see_ Gnomes).

God's Gift Mine (_see_ Gottsgaab Mine).

Gold (_see also_ Gold Ores, Parting, Smelting, Stamp-Mill, _etc._). Alluvial mining, =321-336=; 330 Alluvial streams, =75= Amalgamation, 297 Gold-dust, =396= Historical notes, 399; 354 Indications of, =108=; =116= Lust for, not the fault of the metal, =16= Minerals, 108 Minerals associated with, =108-109= Smelting of ores, =381-382=; =386=; =388=; =390=; =396= Wickedness caused by, =9-10=

Gold Concentrates, =396-399=; 398

Golden Fleece, =330=; 330

Gold Ores, =107-108= Amalgamation, =295-299=; 297 Assay by amalgamation, =243-244= Assay by fire, =242-243= Flux used in assaying, =235= Flux used in smelting, =398= Smelting in blast furnace, =398-400= Smelting cupriferous ores, =404-407= Smelting in lead bath, =399= Smelting pyritiferous ore, =398-401= Stamp-milling, =321=

_Goldstein_ (_see_ Touchstone).

Goslar, =5=; =37=; 37 Lead smelting, =408= Native zinc vitriol, 572 Roasting ores, =274=; 274 Spalling hard ore, =271=

Goslarite, 113; 572

Gottsgaab Mine, VI; VII; =74=; 74

Gounce, 267

Grand Canal of China, 129

Granulation Methods for Bullion, =444=

Granulation of Copper, =250=

Greeks. Antimony, 428 Brass making, 410 Copper smelting, 403 Iron and steel making, 421 Metallurgy from Egypt, 402 Mining law, 83 Ore dressing, 281 Quicksilver, 432 Silver-lead smelting, 391 Smelting appliances, 355

Grey Antimony (_see also_ _Stibium_), 110; 221; 428

Griffins, 331

Groom of the Chamber. Right to a meer, =81=

Groove (_see also_ Shafts), 101

Ground Sluices, =336-337=

Ground Waters, 46-48

_Gruenspan_ (_see_ Verdigris).

_Gulden_, 92; 419

Gunpowder. First use for blasting in mines, 119 Invention of, 562

Gypsum, 114

Hade, 101

_Haematites_ (_see_ Ironstone).

_Halinitrum_ (_see_ Saltpetre).

Halle, Salt Industry, =552=

Hammers, =151= With water power, =423=

Hangingwall, =68=; =117=

Harz Miners. Agricola consulted, VII. Antimony sulphide, 428 First mining charter, 84 First stamp-mill, 282 Pumps, =194=

Hauling Appliances (_see also_ Whims _and_ Windlasses), =160-168=; 149

Heap Roasting, =274-276=

Hearth-lead (_see also_ _Molybdaena_), =475=; 476; 110; 221 As a flux, =232= Use in smelting, =379=; =398=; =400=

Hearths. For bismuth smelting, =433-437= For melting lead, =390=; =498=

Heavenly Host Mine (_see_ _Himmelisch Hoez_ Mine).

Heavy Spar, 115

Hebrews. Knowledge of antimony, 428 Silver-lead smelting, 391 Term for tin, 412

Hematite, 111

Hemicycle (_Hemicyclium_), =137-138=

_Heraclion_ (_see_ Lodestone).

_Herdplei_ (_see_ Hearth-Lead).

Hiero, King, =247=; 247

High Peak (Derbyshire). Mining law, 84 Nomenclature in mines, 77 Saxon customs, connection with, 77; 85

_Himmelisch Hoez_ mine, =74=; =92=; 75

Hoe, =152=

Holidays of Miners, =99=

Horn Silver, 109

Horns of Deer, =230=

Hornstone, =116=; 114

Hungary. Cupellation, =483=

_Huettenrauch_ (_see_ _Pompholyx_).

Iglau, Charter of, 84

Incense in Cupellation Furnaces, =472=

Indications of Ore, =106=; =107=; =116=

_Ingestores_ (_see_ Shovellers).

India. Steel, 423 Zinc, 409

_Intervenium_, =51=; =50=

Investment in Mines, =26-29=

Iron, 420; 354; 111 Cast, 420 Censure of, =11= Indications of, =116= Malleable, 420 Smelting, =420-426= Sulphur harmful to, =273=

Iron Age, 420

Iron Filings (_see also_ Iron-Scales), 221 Use in assaying, =234=; =238=; =246=

Iron Ore. Assaying of, =247= Smelting of, =420-426=

Iron-rust, =116=; =474=; 1; 111

Iron-scales, 221 Flux, =234= Use in smelting gold, =398= Use in smelting silver, =400= Use in making nitric acid, =440= Use in parting gold from copper, =464=

Iron-slag, 221 As a flux, =234=; =235=

Ironstone, =390=; 111

Italians. Alluvial mining in Germany, =334=

Italy. Mining formerly forbidden, =8=

Jade, 114

Japan. Steel, 423

Jasper, 111; 2

_Jaspis_, 114

Jet, 34

Jigging Sieve, =310=; 267; 283

Joachimsthal, VI. First stamp-mill, 281 Mining shares and profits, =91=; =92=

_Juedenstein_ (_see_ _Lapis Judaicus_).

Juices, 1; 47 Agricola's theory, 46; 52 From springs and streams, =33= Stone juice, 46; 49 Tastes of, =34=

Juices, Solidified. Agricola's view of, 1; 49 Extraction of metals from, =350= Preparation of, =545=

Julian Alps. Stamp-milling in, =319=

Junctions (_see_ Veins, Intersections of).

_Jurati_ (_see_ Jurors).

Jurors, =22=; =92=; =96=; 78 In English mining custom, 85 Relations to Bergmeister, =95=; 77

Justinian Code. Mines, 84

_Kalchstein_ (_see_ Limestone).

_Kammschale_, 127

Kaolinite (_see_ Porcelain Clay).

_Katzensilber_ (_see_ Mica).

King. Deputy, =94= Right to a meer, =81=

_Kinstock_ (_see_ Liquation Cakes, Exhausted).

_Kis_ (_see_ Pyrites).

Knockers (_see_ Gnomes).

_Kobelt_ (_see_ Cobalt).

Koelergang Vein, =42=

Koenigsberg. Fire-setting, 119

_Kupferglas ertz_ (_see_ Copper Glance).

_Kupferschiefer_ (_see_ Copper Schists).

Kuttenberg. Depths of shafts, 102

Labour Condition in Mining Title, =92=; 83-85

Lacedaemonians (_see_ Spartans).

_Lachter_ (_see_ Fathom).

Ladderways in Shafts, =124=; =212=

Ladle for Bullion, =382=

_Lapis aerarius_ (_see_ Copper Ore).

_Lapis alabandicus_, 380

_Lapis Judaicus_, =115=; 115

_Lapis specularis_ (_see_ Gypsum).

Laths (Lagging), 101

La Tolfa. Alum manufacture, 565 Discovery of, 570

Laurion (Laurium), Mt. (_see_ Mt. Laurion, Mines of).

Lautental, Liquation at, 491

Law (_see_ Mining Law).

Law-suits over Shares in Mines, =94=

Lead, 354; 390; 110 Censure of, =11= Cupellation, =464-483= Melting prior to liquation, =500= In liquation cakes, =505-506=; 505; 506 Refining silver, =483-490= Smelting of ores, =388-392=; =400= Use in assaying, =232=; =239=; =242=; =244=; =249=; =251= Washing in sluices, =347=

Lead-ash, =237=; 237; 221 As a flux, =234= Use in parting gold from copper, =463=

Lead Bath, =381=

Lead-glass, 236

Lead Granules, =239=; =463=; 221

Leading (in liquation), =304=; =507=; =513=; 491; 492; 504 Components of the charge, =505-509=

Lead Ochre, 232; 110; 221

Lead Ore. Assay methods, =245-246= Roasting, =275= Smelting in blast furnace, =390=; =408=

Lease, in Australian Title, 77

Leaves, Preparation of Bullion into, =444=

Leberthal, 24

Lees of _aqua_ which separates Gold from Silver, 234; 443; 221 As a flux, =234=; =238=

Lees of Vinegar (_see also_ Argol), 221 As a flux, =234=; =236=; =243=; 234

Lees of Wine (_see_ Argol).

Lemnos, Island of, =31=

Lemnian Earth, 31

Leprosy of House Walls (_see_ Saltpetre).

Level (_see also_ Drift), 101

Level, Plummet (_see_ Plummet Level).

Limestone, 114; 221 As a flux, =236=; =390=

Limonite, 111

Limp, 267

Linares. Hannibal's mines near, 42

Lipari Islands. Alum from, 566

Liquated Silver-lead (_see_ _Stannum_ _and_ Silver-lead).

Liquation, =519-521=; 491; 519 Ash-coloured copper from, =529= Buildings for, 491 Furnace, =515-518=; 492 Historical note on, 494 Losses, 491; 539 Nomenclature, 492

Liquation Cakes, =505-509=; 492; 505; 506 Enrichment of the lead, =512=; 512 Extraction of silver from, 512 From bye-products of liquation, =539-540= From copper bottoms, =512=; 512 Proportion of lead in rich silver copper, =509=

Liquation Cakes, Exhausted, =521-526=; =406=; 492; 520

Liquation Slags, 509; 492; 541 Furnaces for, =507= Treatment of, =541=

Liquation Thorns, =522=; =539=; 492; 539; 540 From cupellation, =543=; 543 From "drying" copper residues, =529=

Litharge (_see also_ Cupellation), =475=; =232-238=; 466; 476; 110; 222 Use in reducing silver nitrate, =447= Use in smelting, =379=; =398=; =400=

_Lithargyrum_ (_see_ Litharge).

Lodestone, =115=; 111; 115; 2 Compass, 57

_Los Pozos de Anibal_, 42

_Lotores_ (_see_ Washers).

Lusitania. Gold alluvial, =347= Sluices for gold washing, =325= Tin smelting, =419=

Lute, 1 Preparation of for furnace linings, =375-376=

Lydia. Mining law, 83 The King's mines, 27

Lye, =558=; 221; 233 Use in making fluxes, =236= Use in parting, =463=

_Magister Metallicorum_ (_see_ Bergmeister).

_Magister Monetariorum_ (_see_ Master of the Mint).

_Magnes_ (_see also_ Lodestone _and_ Manganese), =585=; 111; 115; 585

Magnet, =247= Garlic, =39=

_Magnetis_ (_see_ Mica).

Magnetite, 111

Malachite, 109; 221

Maladies of Miners, =214-217=

Maltha, 581

Manager (_see_ Mine Manager).

Manganese, 586; 354

Mannsfeld Copper Slates, =126-127=; =279=; 127; 273

Map-making, 129

Marble, =115=; 2; 114

Marcasite, 111; 112; 409

_Marga_ (_see_ Marl).

Marienberg, =XXXI=; VI.

Marl, 114

Marmelstein (_see_ Marble).

_Marmor_ (_see_ Marble).

_Marmor alabastrites_ (_see_ Alabaster).

_Marmor glarea_, 114

Massicot (_see also_ Lead Ochre), 110; 221; 232

Master of the Horse, =81=

Master of the Mint, =95=; 78

Matte (_see_ Cakes of Melted Pyrites).

Matte Smelting, =404-407=

Measure (unit of mining area), =78=; 78

Measures, 616-617; 78; 550

Medicine. Knowledge necessary for miners, =3=

_Medulla saxorum_ (_see_ Porcelain Clay).

Meer, =77-89= Boundary stones, =87= On _vena cumulata_, =87= On _vena dilatata_, =86=

Meissen. Dumps from mines, =312=

_Melanteria_, =117=; 112; 573 Indication of copper, =116=

Melanterite, 111

Melos, Island of, 566

_Menning_ (_see_ Red-lead).

_Mergel_ (_see_ Marl).

Metals, 2; 44; 51 Advantages and uses, =19=; =20= Necessity to man, =XXV=; =12-13= Not responsible for evil passions, =15=

_Metreta_, 153

Mexico. Patio process, 297

Mica, 114

Middle Ages, Mining Law of, 84

Mills for Grinding Ore, =294-299=; 280

Mimes (_see also_ Gnomes), 217

Mine Captain, =26=; 77

Mine Manager, =97=; =98=; 77; 78

Mineral Kingdom, Agricola's Divisions of, 1

Minerals, 594; 108; 48; 51 Compound, 2; 51 Mixed, 2; 51

Miners, =1-4=; =25=; 78 Duties and punishments, =100=; =22= Law (_see_ Mining Law). Litigation among, =21= Slaves as, =23=

Mines. Abandonment of, =217= Conditions desirable, =30-33= Investments in, =26-29= Management of, =25=; =26= Names of, =42=

Mines Royal, Company of, 283

Mining (_see also_ Sett, Lease, Claim, Meer, _etc._). Criticisms of, =4-12= Harmless and honourable, =14=; =20=; =23= Methods of breaking ore, =117-118= Stoping, =125=

Mining Clerk, =93=; =95=; =96=; 78

Mining Companies (_see_ Companies, Mining).

Mining Foreman, =98-99=; 78 Frauds by, =21-22=

Mining Law, 82-86 Boundary stones, =87= Drainage requirements, =92-93= England, 84-86 Europe, 84 Forfeiture of title, =92-93= France, 84 Greek and Roman, 83 Middle Ages, 84-85 Right of Overlord, Landowner, State and Miner, 82 Tunnels, =88-89=

Mining Prefect, =26=; =94=; 78

Mining Rights (_see_ Mining Law _and_ Meer).

Mining Terms, Old English, 77; 101

Mining Tools, =149-153= Buckets for ore, =153-154= Buckets for water, =157= Trucks, =156= Wheelbarrows, =155=

_Minium_, 111 Quicksilver from, 433 Red-lead, 232

_Minium secundarium_ (_see_ Red-lead).

Mispickel (_Mistpuckel_), 111

_Misy_ (the mineral), 573; 111; 403 An indication of copper, =116= Use in parting gold and silver, 459

_Mitlere und obere offenbrueche_ (_see_ Furnace Accretions).

_Modius_, 617; 405

Moglitz. Tin working, =318=

Moil, 150

_Molybdaena_, 110; 221; 476; 400; 408 Term for lead carbonates, 400; 408

Molybdenite, 477

_Monetarius_ (_see_ Coiners).

Money, Assaying of, =251-252=

Morano Glass Factories, =592=

Moravia. Cupellation, =483= Stamp-milling, =321= Washing gold ore, =324=

Mordants, 569

Mortar-box, =279-280=; =312=; =319=; 267

Mountains. Formation of, =595=

Mt. Bermius. Gold Mines of, =26=; 27

Mt. Laurion, Mines of, =27=; 27-29; 391 Crushing and concentration of ores, 281 Cupellation, 465 Mining law, 83 Smelting appliances, 355 Xenophon on, =6=

Mt. Sinai. Ancient copper smelting, 355; 402

Muffle Furnaces, =224-228=; =239=

Muffles, =227=; =239=; 222 Refining silver, =489-490=

Muehlberg, Battle of, X.

_Murrhina_ (_see_ Chalcedony).

Muskets, =11=

Mycenae. Copper, 402 Silver-lead smelting, 391

Names of Mines, =42=

Naphtha, 581

Native Copper, 109

Native Iron, 111

Native Minerals, =107=

Native Silver, =269=; 109

Natron (_see_ _Nitrum_).

Neolithic Furnaces, 355

Neusohl, Method of Screening Ore, =290=

Newbottle Abbey, 35

Nitocris, Bridge of, 391

Nitric Acid (_see also_ _Aqua valens_), =439-443=; 460; 439; 354 Assay parting gold and silver, =248= Testing silver regulus with, =449= Use in cleaning gold dust, =396=

_Nitrum_ (_see also_ Soda), 558; 110

Nomenclature, I; 267 Mining law, 77; 78 Mining officials, 77; 78

_Norici_, 388 Conveyance of ore, =169=

Normans. Mining Law in England, 85

Notary, =94=; 78

Nubia. Early gold-mining, 399

Nuremberg, Scale of Weights, =263=

_Obolus_, 25

_Ochra nativa_, 111

Ochre Yellow, 111

_Offenbrueche_ (_see_ Furnace Accretions).

Olynthus. Betrayal to Philip of Macedon, =9=

Operculum, =441=; 222

Orbis, =141=; 137

Ore (_see various metals_, Assaying, Mining, _etc._).

Ore Channels (_see_ Canales).

Ore Deposits, Theory of, XIII; 43-53

Ore Dressing, =267-351= Burning, =273= Hand spalling, =271-272= Sorting, =268-271=

_Orguia_, =78=; 78; 617

_Orichalcum_ (_see_ _Aurichalcum_).

Orpiment, 111; 1; 222 Colour of fumes, =235= Harmful to metals, =273= Indication of gold, etc., =116= Roasted from ore, =273= Use in assaying, =237=

Outcrops, 68; 43

Ox-blood in Salt Making, =552=

Pactolus, Gold Sands of, 27

Park's Process, 465

## Parting Gold from Copper, =462-464=

## Parting Gold from Silver, =443-460=; 458-463

Antimony sulphide, =451-452=; 451-452; 461 Cementation, =453-457=; =453-454=; =458= Chlorine gas, 458; 462 Electrolysis, 458; 462 Nitric acid, =443-447=; 443; 447; 460 Nitric acid (in assaying), =247-249= Sulphur and copper, =448-451=; 448; 461 Sulphuric acid, 458; 462

## Partitions, 493

Passau, Peace of, IX.

_Passus_, 616; 78

Patio Process, 297-298

Pattinson's Process, 465

Peak, The (_see_ High Peak).

_Pentremites_, 115

Pergamum. Brazen ox of, =11= Mines near, =26=; 27

Peripatetics, XII. Theory of ore deposits, =47=; 44 View of wealth, =18=

Persians. Ancient mining law, 83

_Pes_, 616; 78

Pestles, =231=; =483=

Petroleum, 581-582

Phalaris, Brazen Bull of, =11=

Philosophy. Knowledge necessary for miners, =3=

Phoenicians. Copper and bronze, 402 In Thasos, 24 Tin, 411-412

Picks, =152-153=

_Pickschiefer_ (_see_ Ash-coloured Copper).

Placer Mining, =321-348=

_Pleigeel_ (_see_ Lead Ochre).

_Pleiweis_ (_see_ White-lead).

Pleygang Vein, =42=

_Plumbago_, 110

_Plumbum candidum_, 110; 3; 473

_Plumbum cinereum_, 111; 3

_Plumbum nigrum lutei coloris_, 110; 3

Plummet Level. Standing, =143=; 137 Suspended, =145=; =146=; 137

Pockets in Alluvial Sluices, =322-330=

Poisonous Fumes (_see_ Fumes).

Poland. Cupellation, =483= Lead ore washing, =347= Lead smelting, =392=

_Poletae_, Tablets of the, 83

Poling Copper, =531-538=; 535-536

Pompeiopolis. Arsenic mine at, 111

_Pompholyx_, 394; 113-114; 403 From copper refinings, =538= From cupellation, =476= From dust-chambers, =394= From roasting ore, =278= Poisonous, =214=; 215 Used for brass making, 410

Porcelain Clay, 115

Potash, =558-559=; 558; 233; 220 In _Sal artificiosus_, =463=

Pottery, Egyptian, 391

Potosi, 298

Pozos de Anibal, Los, 42

_Pous_, 617; 78

_Praefectus cuniculi_, 78

_Praefectus fodinae_ (_see_ Mine Manager).

_Praefectus metallorum_ (_see_ Mining Prefect).

_Praeses cuniculi_, 78

_Praeses fodinae_ (_see_ Mining Foreman).

Precious and Base Metals, 439

Primgap, 80

_Procurator metallorum_, 83

Prospecting, =35=

Proustite, 108

Pumps, =171-200=; 149 Chain, =171-175= Rag and chain, =188-200= Suction, =175-188=

_Purgator argenti_ (_see_ Silver Refiner).

Purser, 77

Puteoli, =501=

Pyrargyrite, 108

_Pyriten argentum_, 408

Pyrites (_see also_ Cakes of Melted Pyrites), 51; 111; 112; 1 As a flux, =234= Assay for gold, =243= In tin concentrates, =348= Latin and German terms, 222 Roasting, =273-274= Roasting cakes of, =349-351= Smelting for gold and silver, =399=; =401= Used in making vitriol, 578

_Pyrites aerosus_ (_see_ Copper Pyrites).

_Pyrites aurei coloris_ (_see_ Copper Pyrites).

Quartz (_see also_ Stones which easily melt), 114 As a flux, 380 An indication of ore, =116= Material of glass, 380 Silver ore, =113= Smelting of, =401=

_Quarzum_ (_see_ Quartz).

Quertze, 380

Quicksilver, 432; 2; 354; 110 Amalgamation of gilt objects, =461= Amalgamation of gold dust, =396= Amalgamation of gold ores, =297=; 297 Assaying methods, =247= Ore, 426-432 Use in assaying gold ore, =243=

Rag and Chain Pumps, =188-200=

Rake Veins, 101

Rammelsberg. Collapse of mines, =216= Discovery, 37 Early vitriol making, 572

_Rauchstein_, 127

Realgar, 1; 111; 222 Colour of fumes, =235= Harmful to metals, =273= Indication of ore, =116= Roasted from ore, =273=

_Rederstein_ (_see_ _Trochitis_).

Red-lead, 232; 110; 222 Use in parting gold from copper, =463= Use in parting gold from silver, =459=

Refined Salt, =454=; =463=; 233

Refinery for Silver and Copper, =491-498=

Refining Gold from Copper, =462-464=

Refining Gold from Silver, =443-458=

Refining-hearth, 492

Refining Silver, =483-490=; 465; 484

Refining Silver from Lead, =464=

Reformation, The, V; VIII.

Re-opening of Old Mines, =217=

Revival of Learning. Agricola's position in, XIII.

Reward Lease, in Australian Law, 77

Rhaetia, 388

Rhaetian Alps. Stamp milling in, =319=

Ring-fire, =448=

Rio Tinto Mines. Roman methods of smelting, 405 Roman water-wheels, 149

Risks of Mining, =28-29=

Rither (a horse), 101

Roasted Copper, =233=; 233; 222

Roasting, =273-279=; 267 Heap roasting, =274-275= In furnaces, =276= Mattes, =349-351= Prior to assaying, =231=

Rocks, =119=; 2

Rock-salt, =548=; 222 Use in cementation, =454=

Roman Alum, 565

Romans. Amalgamation, 297 Antimony, 428 Brass making, 410 Companies, 90 Copper smelting, 404-405 Mining law, 83 Minium Company, 232 Quicksilver, 433 Roasting, 267 Silver-lead smelting, 392 Washing of ore, 281

Rosette Copper, =538=; 535

_Rosgeel_ (_see_ Realgar).

Ruby Copper, 109; 402

Ruby Silver, 51; 108 Assaying of, =244= Cupellation, =473=

_Rudis_ Ores, 108

Rust (_see_ Iron-rust).

Sabines, =9=

_Saigerdoerner_ (_see_ Liquation Thorns).

_Saigerwerk_ (_see_ _Stannum_).

_Salamander har_ (_see_ Asbestos).

Salamis, Battle of, 27

Sal-ammoniac, =560=; 560; 222 In cements for parting gold and silver, =454-457= In making _aqua valens_, =441= Uses in cupellation, =474= Uses in making _aqua regia_, 460 Uses in parting gold from copper, =463=

_Sal artificiosus_, =236=; =463=; 236 In assaying, =242= As a flux, =234=

Salt, =545=; =556=; 546; 233; 222 As a flux, =234-238= Pans, =545=; =546= Solidified juice, 1 Use in cementation, =454=; 454 Use in parting gold from copper, =463=; =464= Use in smelting ores, =396=; =400= Wells, =546-547=

Salt made from Ashes of Musk Ivy, 560; 233

_Sal torrefactus_, =242=; 222; 233

_Sal tostus_, =233=; 233; 222

Saltpetre, =561-564=; 561; 562; 222 As a flux, =233=; =236-238=; =245=; =247= In smelting gold concentrates, =398= Uses in cementation, =454=; 454 Uses in making nitric acid, =439=; =440=; =447=; =454= Uses in melting silver nitrate, =447=

Sampling Copper Bullion, =249=

Sand, =117=

_Sandaraca_ (_see_ Realgar).

Sandiver (_see_ Glass-galls).

_Sarda_ (_see_ Carnelian).

Saxony. High Peak customs from, 77; 85 Political state in Agricola's time, VIII; IX. Reformation, IX.

_Saxum calcis_ (_see_ Limestone).

Scales of Fineness, 253; 617

Scapte-Hyle, Mines of, 23

Schemnitz. Age of mines, =5= Gunpowder for blasting, 119 Pumps, =194=

Schist, 222

_Schistos_ (_see_ Ironstone).

Schlackenwald. Ore washing, =304=

Schmalkalden League, IX.

Schmalkalden War, IX; X.

Schneeberg, =XXXI=; VI. Cobalt, =435= Depth of shafts, 102 Ore stamping, 281 Shares, =91= St. George mine, =91=; 74; 75

_Schwartz-atrament_ (_see_ _Melanteria_ _and_ _Sory_).

Scorification Assay, =239=

Scorifier, =228=; =230=; 222 Assays in, =238=; =239=

Screening Ore (_see_ Sifting Ore).

Screens (_see also_ Screening), 267 In stamp-mill, =315=

_Scriba fodinarum_ (_see_ Mining Clerk).

_Scriba magistri metallicorum_ (_see_ Bergmeister's Clerk).

_Scriba partium_ (_see_ Share Clerk).

Scum of Lead from Cupellation, =475=

Scythians. Wealth condemned, =9=; =15=

Seams in the Rocks, =72=; 43; 47 Indications of ore, =67=; =107=

Sea-Water, Salt from, =545-546=

_Sesterce_, 448

Sett, 77

Settling Pits, =316=; 267

Shaft-houses, =102=

Shafts, =102-107=; =122-124= Surveys of, =129-135= _Venae cumulatae_, =128=

Shakes, 101

Share Clerk, =97=; =93=; 78

Share in Mines (_see_ Companies, Mining).

Shears for Cutting Native Silver, =269=

Shift, =99=; 92

Shoes (stamp), =285-286=; 267

Shovellers, =153=; =169=; 78

_Sideritis_ (_see_ Lodestone).

_Siegelstein_ (_see_ Lodestone).

Sieves. For charcoal, =375= For crushed ore, =287-293=; =341=

Sifting Ore, =287-293=

_Signator publicus_ (_see_ Notary).

_Silberweis_ (_see_ Mica).

_Silex_, 114; 118

Silver (_see also_ Assaying, Liquation, Parting, Refining, _etc._), 390; 354; 108 Amalgamation, 297; 300 Assaying, =248-251= Cupellation, =464-483=; =241= "Drying" copper residues from liquation, 529 Enrichment in copper bottoms, =510=; 510 Exhausted liquation cakes, 524 Indicated by bismuth, etc., =116= Liquation, =505-507=; 506; 509; 512

## Parting from gold (_see_ Parting Gold and Silver).

## Parting from iron, =544=; 544

Precipitation from solution in copper bowl, =444= Refining, =483-490=; 465; 484 Smelting of ores, =381-382=; =386=; =388=; =390=; =400=; =402= Use in clarification of nitric acid, =443=; 443

Silver, Ruby (_see_ Ruby Silver).

Silver Glance, 108 Assaying, =244= Cupellation, =473= Dressing, =269=

Silver-Lead Alloy (_see_ _Stannum_, _etc._).

Silver Ores, =108=; 108 Assaying, =242-244= Assaying cupriferous ores, =245= Fluxes required in assaying, =235= Smelting cupriferous ores, =404-407=

Silver-Plating, 460

Silver Refiner, =95=; 78

Silver Refining (_see_ Refining).

Silver Veins, =117=

Singing by Miners, =118=

Sintering Concentrates, =401=

Slags (_see also_ Liquation Slags), 222 From blast furnace, =379=; =381= From liquation, 491; 492; 523

Slaves as Miners, =23=; 83 In Greek mines, =25=; 25; 28

Slough (tunnel), 101

Sluices, =319=; =322-348=

Smallite, 113

Smalt, 112

_Smega_, 404

Smelters, 78

Smelting (_see also various metals_), =379-390=; 353-355 Assaying compared, =220= Building for, =355-361= Objects of, =353=

_Smirgel_ (_see_ Emery).

_Smiris_ (_see_ Emery).

Smyrna. Mines near, 27

Snake-Bites, 31

Soda (_see also_ _Nitrum_), =558=; =559=; 233; 222 As a flux, =233=; =234= Historical notes, 558; 354 Solidified juice, 1

Sole, 101

Solidified Juices (_see_ Juices, Solidified).

_Solifuga_, =216=; 216

Sorters, 78

Sorting Ore, =268-271=

_Sory_, 112; 403; 573

Sows, =376=; =386=; 376

Spain (_see also_ Lusitania). Ancient silver-lead mines, 149; 392 Ancient silver mines of Carthage, =27= Ancient tin mines, 411-412

Spalling Ore, =271-272=

_Spangen_ (_see_ _Trochitis_).

_Spanschgruen_ (_see_ Verdigris).

Spartans. Gold and silver forbidden, =9=; =15= Interference with Athenian mines, 27

Spat (_see_ Heavy Spar).

Spelter, 409

Sphalerite, 113

_Spiauter_, 409

_Spiesglas_ (_see_ _Stibium_).

Spines of Fishes for Cupels, =230=

_Spodos_, =538=; 394; 113; 114

_Spuma argenti_ (_see_ Litharge).

Staffordshire. First pumping engine, 149

Stalagmites, 114

Stall Roasting, =350-351=

Stamp, 267 For breaking copper cakes, =501-503= For crushing crucible lining, =373-375=

Stamping Refined Silver, =489=

Stamp-mill, =279-287=; 281-282; 267 Wet ore, =312-314=; =319-321=

Standing Plummet Level (_see_ Plummet Level).

Stannaries, 85

_Stannum_, 473; 2; 384; 492

Steel, =423-426=; 422-423; 354

_Steiger_, 77

_Steinmarck_ (_see_ Porcelain Clay).

Stemple (stull), 101

Stephanite, 109

Sternen Mine, =92=; 75

Steward (of High Peak mines), 77

St. George Mine (Schneeberg), =91=; 74; 75

_Stibium_ (_see also_ Antimony _and_ Antimony Sulphide), 110; 428; 2; 221 Flux to be added to, =235= In assaying, =237-239= In cementation, =458-460= Indication of silver, =116= In making nitric acid, =440= In parting gold and silver, =451-452=; =459= In parting gold from copper, =464= In treatment of gold concentrates, =396=; =397=

Stibnite, 428; 451

St. Lorentz Mine, =74=; =92=

Stockwerke (_see_ _Vena cumulata_).

Stoics. Views on wealth, =18=

_Stomoma_, =423=

Stone Juice, 46; 49

Stones. Agricola's view of, 2; 46; 49 Various orders of fusibility, =380=

"Stones which Easily Melt" (_see also_ Quartz), 380; 222 As a flux, =233=; =236=; 233 In making nitric acid, =440= In smelting, =379=; =380=; =390= Smelting of, =401=

Stool (of a drift), 101

Stope, =126=

Stoping, =125= _Venae cumulatae_, =128= _Venae dilatatae_, =126=; =127=

Strake, =303-310=; 267; 282 Canvas, =307-310=; =314=; =316=; 267 Egyptians, 280 Greeks, 281 Short, =306-307=; 267 Washing tin concentrates, =341-343=

Strata, =126=

Streaming, =316-318=

Stringers, =70=; 43; 47; 70 Indication of ore, =106= Mining method, =128=

Styria, =388=

Subterranean Heat, 46; 595

Suction Pumps, =175-188=

Sulphides, 267; 355

Sulphur, =578-581=; 579; 222 Colour of fumes, =235= Harmful to metals, =273= In assaying, =235-238= In parting gold from copper, =463=; 462 In parting gold from silver, =448-451=; 448; 461 In smelting gold dust, =396= Roasted from ores, =273=; =276= Solidified juice, 1

Sulphur "not exposed to the fire," =458=; =463=; 579

Surveyor's Field, =137=; =144=; 142

Surveying, =128-148=; 129 Necessary for miners, =4= Rod, =137-138=

Suspended Plummet Level (_see_ Plummet Level).

Swiss Compass, =145=; 137

Swiss Surveyors, =145=

_Symposium_, =91=

Tap-hole, =378=; =386=

Tappets, =282=; =319=; 267

Tapping-bar, =381=

Tarshish, Tin Trade, 412

Tartar (Cream of), 220; 234

_Tectum_ (Hangingwall), 101

_Terra sigillata_ (_see_ Lemnian Earth).

"Tests", refining silver in, =483-490=; 465; 484

_Thaler_, 92

Thasos, Mines of, =23=; =95=; 23

_Theamedes_, 115

Theodosian Code. Mines, 84

Thorns (_see_ Liquation Thorns).

Thuringia. Roasting pyrites, =276= Sluices of gold washing, =327=

Tigna (Wall plate), 101

Timbering. Of ladderways and shafts, =122=; =123=; =124= Of stopes, =126= Of tunnels and drifts, =124-125=

Tin, 411-413; 354; 110 Alluvial mining, =336-340= Assaying ore, =246= Assaying for silver, =251= Colour of fumes, =235= Concentrates, =340-342=; =348-349= Cornish treatment, 282 Refining, =418-419= Smelting, =411-420= Stamp-milling, =312-317= Streaming, =316-318= Washing, =298=; =302=; =304=

_Tincar_ or _Tincal_ (_see_ Borax).

Tithe Gatherer, =81=; =95=; =98=; 78

Tithe on Metals, =81=; 82

_Toden Kopff_, 235

_Tofstein_ (_see_ _Tophus_).

Tolfa, La (_see_ La Tolfa).

Tools, =149-153=

_Topfstein_ (_see_ _Tophus_).

_Tophus_, 233; 114; 222 As a flux, =233=; =237=; =390=

Tortures. With metals, =11= Without metals, =17=

Touch-needles, =253-260=; 253

Touchstone, =252-253=; 252; 354; 458; 222 Mineral, 114 Uses, =243=; =248=; =447=

Trade-routes. Salt-deposits influence on, 546

Transport of Ore, =168-169=

Trent, Bishop of. Charter (1185), 84

Triangles in Surveying, =129-137=

Tripoli, 115

_Trochitis_, =115=; 115

Trolley, =480=; =500=; =514=

Troy. Lead found in, 391

Troy Weights, 616; 617; 242

Trucks, =156=

Tunnels, =102=; 101 Law, =88-93= Surveys of, =130-141= Timbering, =124=

Turin Papyrus, 129; 399

Turn (winze), 101

_Tuteneque_, 409

_Tuttanego_, 409

Tutty, 394

Twitches of the Vein, 101

Twyer, 376

Tye, 267

Type. _Stibium_ used for, 2; 429

Tyrants. Inimical to miners, =32=

Tyrolese. Smelting, =388=; =404=

Ulcers, =214=; 31

_Uncia_ (length), =78=; 616; 78

_Uncia_ (weight), 616; 242

Undercurrents (_see_ Sluices).

United States. Apex law, 82

_Vectiarii_ (_see_ Windlass Men).

Veins, =43=; =64-69=; =106-107=; 47 Barren, =72=; =107= Direction of, =54-58= Drusy, =72=; =73=; =107= Hardness variable, =117= Indications, =35-38= Intersections of, =65=; =66=; =67=; =106=; =107=

_Vena_. Use of term, 43; 47

_Vena cumulata_, =46=; =49=; =70=; 43; 47 Mining method, =128= Mining rights, =87=

_Vena dilatata_, =41=; =45=; =53=; =60-61=; 43; 47 Junctions with _vena profunda_, =67=; =68= Mining method, =126-127= Mining rights, =83-86= Washing lead ore from, =347=

_Vena profunda_, =44=; =51=; =60=; =62=; =63=; =68=; =69=; 43; 47 Cross veins, =65= Functions, =65=; =66=; =67=; =68= Mining rights, =79-83=

Venetian Glass, 222 Factories, =592= In assaying, =238=; =245=; =246= In cupellation, =474=

Venice. Glass-factories, =592=

## Parting with nitric acid, 461

Scale of weights, =263=

Ventilation, =200-212=; =121= With bellows, =207-210= With fans, =203-207= With linen cloths, =210= With windsails, =200-203=

Verdigris, 440; 1; 110; 222 In cementation, =454=; =457= Indication of ore, =116= In making nitric acid, =440= In parting gold from copper, =464=

Vermilion. Adulteration with red-lead, 232 Poisonous, =215=

Villacense Lead, =239=; 239

Vinegar. Use in breaking rocks, =119=; 118 Use in cleansing quicksilver, =426= Use in roasting matte, =349= Use in softening ore, =231=

_Virgula divina_ (_see_ Divining Rod).

Vitriol, =571=; 572; 403; 222; 1 In assaying, =237-238= In cementation, =454=; 454 Indication of copper, =116= In making nitric acid, =439-440= In roasted ores, =350= In _sal artificiosus_, =463= Native, 111 Native blue, 109 Native white, 113 Red, 274 White, 454

Volcanic Eruptions, 595

Washers, 78

Washing Ore (_see also_ Concentration, Screening Ore, _etc._), =300-310=

Water-Bags, =157-159=; =198=

Water-Buckets, =157-158=

Water-Wheels, =187=; =283=; =286=; =319=

Water-Tank, under Blast Furnaces, =356-357=

Wealth, =7-20=

Wedges, =150=

Weights, =260-264=; 616-617; 242; 253

_Weisser Kis_, 111

_Werckschuh_, 617; 78

Westphalia. Smelting lead ore, =391= Spalling ore, =272=

Wheelbarrows, =154=

Whims, =164-167=

White-Lead, 440; 354; 110; 232

White Schist, =234=; =390=; 234; 222

Winding Appliances (_see_ Hauling Appliances).

Windlasses, =160=; =171=; 149

Windlass Men, =160=; 78

Winds. Greek and Roman names, =58= Sailors' names, =59=; =60=

Winds (winze), 101

Windsails, =200-203=

Winzes, 102

Wittenberg, Capitulation of, IX.

Wizards. Divining rods, =40=

Workmen, =98=; =100=

Woughs, 101

_Zaffre_, 112

Zeitz, XI.

Zinc (_see also_ _Cadmia_ _and_ Cobalt). Historical notes, 408-410; 354 Minerals, 112-113

Zinck (_see_ Zinc).

Zinc Oxides, 113; 354

Zinc Sulphate (_see_ Vitriol).

_Zincum_ (_see_ Zinc).

_Zoll_, 617; 78

Zwickau, VI.

_Zwitter_, 110

INDEX TO PERSONS AND AUTHORITIES.

NOTE.--The numbers in heavy type refer to the Text; those in plain type to the Footnotes, Appendices, etc.

Acosta, Joseph De, 298

Aeschylus. Amber, 35

Aesculapius. Love of gold, =9=

Africanus (alchemist), =XXVII=; XXVIII

Agatharchides. Cupellation, 465 Egyptian gold mining, 279; 391; 399 Fire-setting, 118

Agathocles. Money, =21=

Agathodaemon (alchemist), =XXVII=; XXVIII

Agricola, Daniel, 606

Agricola, Georg (a preacher at Freiberg), 606

Agricola, Georgius. Assaying, 220 Biography, V-XVI Founder of Science, XIV Geologist, XII; 46; 53 Interest in _Gottsgaab_ mine, VII; 74 Mineralogist, XII; 108; 594 Paracelsus compared with, XIV Real name, V Works, Appendix A See also: _Bermannus._ _De Animantibus._ _De Natura eorum_, etc. _De Natura Fossilium._ _De Ortu et Causis._ _De Peste._ _De Precio Metallorum._ _De Re Metallica._ _De Veteribus Metallis._ Etc.

Agricola, Rudolph, 606

Albert the Brave, Duke of Meissen, VIII

Albertus Magnus (Albert von Bollstadt), XXX; 609 Alluvial gold, =76= Cementation, 460 Metallic arsenic, 111 Metals, 44 Saltpetre, 562 Zinc, 409

Albinus, Petrus, V; 599 Cuntz von Glueck, 24

Alpinus, Prosper, 559

Alyattes, King of Lydia. Mines owned by, =26=; 27

American Institute of Mining Engineers, 38; 53

Anacharsis. Invention of bellows, 362

Anacreon of Teos. Money despised by, =9=; =15=

Anaxagoras. Money despised by, =15=

Anna, Daughter of Agricola, VII

Anna, Wife of Agricola, VII

Antiphanes. On wealth, =19=

Apollodorus, 26

Apulejus (alchemist), =XXVII=; XXIX

Archimedes. King Hiero's crown, =247= Machines, 149

Ardaillon, Edouard. Mt. Laurion, 28; 281; 391

Aristippus. Gold, =9=; =14=

Aristodemus. Money, =8=

Aristotle, XII; 607 Amber, 35 Athenian mines, 27; 83 Burning springs, 583 Coal, 34 Cupellation, 465 Distillation, 441 Lodestone, 115 Nitrum, 558 Ores of brass, 410 Quicksilver, 432 Silver from forest fires, 36 Theory of ore deposits, 44 Wealth of, =15=

Arnold de Villa Nova. (_see_ Villa Nova, Arnold de).

Athenaeus. Silver from forest fires, 36

Augurellus, Johannes Aurelius (alchemist), =XXVII=; XXX

Augustinus Pantheus (alchemist), =XXVII=

Augustus, Elector of Saxony, =IX= Dedication of _De Re Metallica_, =XXV= Letter to Agricola, =XV=

Avicenna, XXX; 608

Bacon, Roger, XXX; 609 Saltpetre, 460; 562

Badoarius, Franciscus, =XXVII=

Balboa, V. N. de, V

Ballon, Peter, 559

Barba, Alonso, 300; 1

Barbarus, Hermolaus, =XXVII=

Barrett, W. F., 38

Becher, J. J., 53

Bechius, Philip, XV

Beckmann, Johann. _Alumen_, 565 Amalgamation, 297 _Nitrum_, 559

## Parting with nitric acid, 461

Stamp-mills, 281 _Stannum_, 473 Tin, 412

_Bergbuechlein_ (_see_ _Nuetzlich Bergbuechlin_).

_Bergwerks lexicon_, 37; 80; 81

Berman, Lorenz, VI; 597

_Bermannus_, 596; 599; VI Arsenical minerals, 111 Bismuth, 3; 433 _Cadmia_, 113 Cobalt, 112 Fluorspar, 381 _Molybdaena_, 477 Schist, 234 Shafts, 102 Zinc, 409

Berthelot, M. P. E., 429; 609

Berthier, 492

Bias of Priene. Wealth, =8=; =14=

Biringuccio, Vannuccio, 614 Agricola indebted to, =XXVII= Amalgamation of silver ores, 297 Assaying, 220 Assay ton, 242 Brass making, 410 Clarifying nitric acid, 443 Copper refining, 536 Copper smelting, 405 Cupellation, 466 Liquation, 494 Manganese, 586

## Parting precious metals, 451; 461; 462

Roasting, 267 Steel making, 420 _Zaffre_, 112

Boeckh, August, 28

Boerhaave, Hermann, XXIX

Borlase, W. C. Bronze celts, 411

Borlase, William. Cornish miners in Germany, 283

Born, Ignaz Edler von, 300

Boussingault, J. B., 454

Boyle, Robert. Divining rod, 38

Brough, Bennett, 129

Bruce, J. C., 392

Brunswick, Duke Henry of (_see_ Henry, Duke of Brunswick).

Budaeus, William (Guillaume Bude), 461; 606

Cadmus, 27

Calbus (_see also_ _Nuetzlich Bergbuechlin_), 610; =XXVI=; XXVII Alluvial gold, =75=

Caligula. Gold from _auripigmentum_, 111

Callides (alchemist), =XXVII=; XXVIII

Callimachus. On wealth, =19=

Camerarius, =VIII=

Canides (alchemist), =XXVII=; XXVIII

Carew, Richard. Cornish mining law, 85 Cornish ore-dressing, 282

Carlyle, W. A. Ancient Rio Tinto smelting, 405

Carne, Joseph. Cornish cardinal points, 57

Casibrotius, Leonardus, VI

_Castigationes in Hippocratem et Galenum_, 605

Castro, John de, 570

Chabas, F. J., 129

Chaloner, Thomas, 570

Chanes (alchemist), =XXVII=; XXVIII

Charles V. of Spain, =IX= Agricola sent on mission to, =X=

Chevreul, M. E., 38

_Chronik der Stadt Freiberg_, 606

Cicero. Divining rod, 38 Wealth of, =15=

Cincinnatus L. Quintius, =23=

Circe. Magic rod, =40=

Cleopatra. As an alchemist, =XXVII=; XXIX

Collins, A. L. 119

Columbus, Christopher, V

Columella, Moderatus, =XXV=; =XXVI=

Comerius, =XXVII=; XXIX

_Commentariorum ... Libri VI._, 604

Conrad (Graf Cuntz von Glueck), =23=; 24

Corduba, Don Juan De, 300

Cortes, Hernando, =V=

Cramer, John, 236

Crassus, Marcus. Love of gold, =9=

Crates, the Theban. Money despised by, =15=

Croesus, King of Lydia. Mines owned by, =26=; 27

Ctesias. Divining rod, 38

Ctesibius. Machines, 149

Curio, Claudius. Love of gold, =9=

Curius, Marcus. Gold of Samnites, =9=; =15=

Dana, J. D., 108 Alum, 566 Copiapite, 574 Emery, 115 Lemnian earth, 31 Minerals of Agricola, 594 Zinc vitriol, 572

Danae. Jove and, =10=

D'Arcet, J.

## Parting with sulphuric acid, 462

Day, St. John V. Ancient steel making, 423

_De Animantibus Subterraneis_, 597; =VII= Editions, 600 Gnomes, =217=; 217

_De Bello adversus Turcam_, 605

_De Inventione Dialectica_, 606

_De Jure et Legibus Metallicis_, =100=; 604

_De Medicatis Fontibus_, 605

_De Mensuris et Ponderibus_, 597 Editions, 599 Weights and measures, =263=; 78

_De Metallis et Machinis_, 604

Democritus (alchemist), =XXVII=; XXVIII

Demosthenes. Mt. Laurion mines, 27; 83

_De Natura eorum quae Effluunt ex Terra_, 598; =32= Dedication, VII Editions, 600

_De Natura Fossilium_, 594; 600; III; XII Alum, 565 Amber, 35 Antimony, 429 Argol, 234 Arsenical minerals, 111 Asbestos, 440 Bismuth, 110 Bitumen, 581 Borax, 560 Brass making, 410 _Cadmia_, 113 _Caldarium_ copper, 511 Camphor, 238 _Chrysocolla_, 584 Coal, 35 Cobalt, 112 Copper flowers, 539; 233 Copper scales, 233 Crinoid stems, 115 Emery, 115 Fluorspar, 380 Goslar ores, 273 Goslar smelting, 408 Iron ores, 111 Iron smelting, 420 Jet, 34 _Lapis judaicus_, 115 Lead minerals, 110 Mannsfeld ores, 273 _Melanteria_, 573 Mineral Kingdom, 1 _Misy_, 573 _Molybdaena_, 476 Native metals, 108 Petroleum, 581 _Pompholyx_, 114; 278 Pyrites, 112 Quicksilver, 110 _Rudis_ minerals, 108 Sal-ammoniac, 560 Silver glance, 109 _Sory_, 573 _Spodos_, 114 _Stannum_, 473 Stones which easily melt, 380 Sulphur, 578 _Tophus_, 233 Touchstone, 253 White schist, 234 Zinc, 409

_De Ortu et Causis Subterraneorum_, 594; 600; III; VII; XII; XIII Earths, 48 Gangue minerals, 48 Gold in alluvial, =76= Ground waters, 48 Juices, 52 Metals, 51 Solidified juices, 49 Stones, 49 Touchstone, 253 Veins, 47

_De Ortu Metallorum Defensio ad J. Scheckium_, 604

_De Peste_, 605; VIII

_De Precio Metallorum et Monetis_, 597; 600 Mention by Agricola, =252=; =263=

_De Putredine solidas partes_, etc., 605

_De Re Metallica_, I; XIII; XIV-XVI Editions, 600; XIV Title page, =XIX=

De Soto, Fernandes, V

_De Terrae Motu_, 604

_De Varia temperie sive Constitutione Aeris_, 604

_De Veteribus et Novis Metallis_, 597; 600; VII; =XXVI=; 5 Agricola's training, VI Conrad, 24 Discovery of mines, =36=; 5; 37 _Gottsgaab_ mine, 74

Devoz (de Voz), Cornelius, 570; 283

Diodorus Siculus, 607 Alum, 566 Bitumen, 582 Cupellation, 465 Drainage of Spanish mines, 149 Egyptian gold mining, 279 Fire-setting, 118 Lead, 391 Silver from forest fires, =36= Tin, 412

Diogenes Laertius, 7; 9; 10

Dioscorides, 607; 608 Alum, 566 Antimony, 428 Argol, 234 Arsenic minerals, 111 Asbestos, 440 Bitumen, 584 Brass making, 410 Burned lead, 237 _Cadmia_, 112 _Chalcitis_, 573 Copper flowers, 233; 538 Copper smelting, 403 Cupellation, 465 Distillation apparatus, 355 Dust-chambers, 355; 394 Emery, 115 Lead, 392 Lead minerals, 477 Lemnian earth, 31 Litharge, 465 Lodestone, 115 _Melanteria_, 573 _Misy_, 573 Naphtha, 584 _Pompholyx_, 394; 410 Quicksilver, 297; 432 Red-lead, 232 Sal-ammoniac, 560 _Sory_, 573 _Spodos_, 394 Verdigris, 440 Vitriol, 572 White-lead, 440

Diphilos, 27; 83

Diphilus (poet). Gold, =10=

_Dominatores Saxonici_, 606

Draud, G., 599

Dudae. Alum trade, 569

Elizabeth, Queen of England. Charters to alum makers, 283; 570 Dedication of Italian _De Re Metallica_ to, XV Importation of German miners, 283; 570

Eloy, N. F. J., 599

Entzelt (Enzelius, Encelio), 615

Erasmus, VI; VIII; XIV

Ercker, Lazarus. Amalgamation, 300 Liquation, 491; 505 Nitric acid preparation, 443

## Parting gold and silver, 444; 451

Eriphyle. Love of gold, =9=

Ernest, Elector of Saxony, VIII

Euripides. Amber mentioned by, 35 Plutus, =8=; =7=

Ezekiel, Prophet. Antimony, 428 Cupellation, 465 Tin, 412

Fabricius, George. Agricola's death, X Friendship with Agricola, VIII Laudatory poem on Agricola, =XXI= Letters, IX; X; XIV; XV Posthumous editor of Agricola, 603; 606

Fairclough, H. R., III

Farinator, Mathias, XXVI

Ferdinand, King of Austria. Agricola sent on mission to, X Badoarius sent on mission to, =XXVII=

Ferguson, John. Editions of _De Re Metallica_, XVI; 599

Feyrabendt, Sigmundi, XV

Figuier, L., 38

Flach, Jacques. Aljustrel tablet, 83

Florio, Michelangelo, XV

Foerster, Johannes, VI

Francis, Col. Grant, 267; 283

Francis I., King of France, IX

Frederick, Elector of Saxony, VIII; IX

Froben, Publisher of _De Re Metallica_, XIV; XV

Frontinus, Sextus Julius, 87

Galen. Agricola's revision of, 605; VI Lemnian earth, 31 Mention by Agricola, 2

_Galerazeya sive Revelator Secretorum_, etc., 606

Gama, Vasco da, V

Ganse (Gaunse), Joachim, 267; 283

Gatterer, C. W., 599

Geber, =XXVII=; XXX; 609 Alum, =569= Assaying, 219 Cementation, 459 Cupels, 466 Nitric acid, 460 Origin of metals, 44 Precipitation of silver nitrate, 443

_Genesis, Book of_, XII; 43

George, Duke of Saxony, IX; =310=; 310

Gesner, Conrad, 52

Gibbon, Edward, 119

Glauber, J. R., 410

Glueck, Cuntz von (_see_ Conrad).

Gmelin, J. F., 84

Goecher, C. G., 599

Godolphin, Sir Francis, 282

Gowland, William. Ancient bronze, 410; 411; 421 Early smelting, 402

Graecus, Marcus. Saltpetre, 562

Grommestetter, Paul, 281

Grymaldo, Leodigaris, XVI

Gyges, King of Lydia. Mines owned by, =26=; 27

Hannibal. Alps broken by vinegar, 119 Spanish mines, =42=; 42

Hardy, William, 85

Heath, Thomas. On Hero, 129

Heliodorus (alchemist), =XXVII=; XXIX

Henckel, J. F., 53; 112; 410

Hendrie, R., 609

Hennebert, E., 119

Henry, Duke of Brunswick, VII

Henry, Duke of Meissen, IX

Hermes (alchemist), =XXVI=; XXVIII

Hermes (Mercury). Magic rod, 40

Hero. Underground surveying, 129

Herodotus. Alum, 566 Bitumen, 582 Lead, 391 Mines of Thrace, 23 _Nitrum_, 558

Hertel, Valentine, XIV

Hiero, King of Syracuse. Crown, 247

Hill, John, 607 _Auripigmentum_, 111

Himilce, wife of Hannibal, 42

Hippocrates. Cupellation, 391; 465 Lodestone, 115

Hiram, King of Tyre. Mines, 214

Hofmann, Dr. R. Biography of Agricola, V; XI; 599; 603

Homer. Amber, 35 Divining rod, =40=; 40 Lead, 391 Smelting, 402 Steel, 421 Sulphur, 579 Tin, 412

Hommel, W. Early zinc smelting, 409

Horace. Metals, =11= Wealth, =15=; =17=

Hordeborch, Johannes, VII

Houghstetter, Daniel, 283

Houghton, Thomas, 85

Humphrey, William. Jigging sieve, 283

Hunt, Robert. Roman lead smelting, 392

Inama-Sternegg, K. T. von, 84

_Interpretatio Rerum Metallicarum_ (_see_ _Rerum Metall. Interpretatio_).

Irene, Daughter of Agricola, VII

Jacobi, G. H. Biography of Agricola, V; 599 Calbus, XXVII; 610

Jagnaux, Raoul. Ancient zinc, 409

Jason. Golden fleece, 330

Jeremiah. Bellows, 362 Cupellation, 465 Lead smelting, 391 _Nitrum_, 558

Jezebel. Use of antimony, 428

Job. Refining silver, 465

Johannes (alchemist), =XXVII=; XXVIII

John, Elector of Saxony, IX

John, King of England. Mining claims, 85

John Frederick, Elector of Saxony, IX

Josephus. Dead Sea bitumen, 33

Jove. Danae legend, =10=

Justin, =36=

Juvenal. Money, =10=

Karsten, K. J. B. Liquation, 491; 492; 505; 509; 523; 535

Kerl, Bruno. Liquation, 505

Koenig, Emanuel, XV

Koenig, Ludwig, XV

Kopp, Dr. Hermann, 609; 441

Lampadius, G. A., 462

Lasthenes. Love of gold, =9=

_Latin Grammar_ (Agricola), 605

Leonardi, Camilli, 615

Leupold, Jacob, XV; 599

_Leviticus_. Leprosy of walls, 562

Lewis, G. R, 84

Lewis, 454

Libavis, Andrew, 410

Lieblein, J. D. C., 129

Linnaeus, Charles, 559

Livy. Hannibal's march over the Alps, 119

Lohneys, G. E. Liquation, 491; 505

## Parting with antimony, 451

Zinc, 409; 410

Lucretia, daughter of Agricola, VII

Lucretius. Forest fires melting veins, =36=

Lully, Raymond, =XXVII=; XXX

Luscinus, Fabricius. Gold, =9=; =15=

Luther, Martin, V; VI; VIII; IX

Lycurgus (Athenian orator). Prosecution of Diphilos, 27; 83

Lycurgus (Spartan legislator). Wealth prohibited by, =9=; =15=

Magellan, F. de, V

Maltitz, Sigismund, 312

Manlove, Edward, 70; 85

Marbodaeus, 615

Marcellinus, Ammianus. On Thucydides, 23

Marcellus, Nonius, XXXI

Maria the Jewess, =XXVII=; XXVIII

Mathesius, Johann. Cobalt, 214 Conrad mentioned by, 24 _De Re Metallica_, XIV King Hiram's mines, 214

Matthew Paris. Cornish miners in Germany, 283

Maurice, Elector of Saxony, =XXV=; VIII; IX; X

Mawe, J., 70

Maximilian, Emperor, =23=; 24

Meissen, Dukes of (_see under personal names_: Albert, Henry, _etc._).

Melanchthon. Relations with Agricola, VIII; X

Menander. Riches, =8=

Mercklinus, G. A., 599

Mercury (_see_ Hermes).

Merlin (magician), =XXVII=; XXX

Meurer, Wolfgang. Letters, IX; X

Meyer, Ernst von, 248; 569

Meyner, Matthias, VII

Midas, King of Lydia. Mines owned by, =26=; 27

Miller, F. B., 462

Minerva. Magic rod, =40=

Morris, W. O'C., 119

Mosellanus, Petrus, VI

Moses. Bitumen, 582 Lead, 391 Refining gold, 399 Rod of Horeb, 38; =40=

Mueller, Max. Ancient iron, 421

Naevius. Money, =20=

Nash, W. G. Rio Tinto mine, 149

Naumachius. Gold and silver, =8=

Neckam, Alexander. Compass, 57

Newcomen, Thomas, 149

Nicander. On coal, 34

Nicias. Sosias and slaves of, =25=; 25

_Nuetzlich Bergbuechlin_, 610; =XXVI=; XXVII Alluvial gold, 75 Bismuth, 110; 433 Compass, 57; 129 Ore-deposits, 44 Ore-shoots, 43 Veins, 43; 46; 73

Olympiodorus (alchemist), =XXVII=; XXX

Oppel, van (_see_ Van Oppel).

Orus Chrysorichites (alchemist), =XXVII=; XXVIII

Osthanes (alchemist), =XXVII=; XXIX

Otho the Great, 6

Otho, Prince, 6

Ovid. Mining censured by, =7=

Pandulfus Anglus, =XXVI=

Pantaenetus. Demosthenes' oration against, 27; 83

Pantheus, Augustinus (alchemist), =XXVII=

Paracelsus, XIV; XXX Divining rod, 38 Zinc, 112; 409

Paris, Matthew (_see_ Matthew Paris).

Pebichius (alchemist), =XXVII=; XXVIII

Pelagius (alchemist), =XXVII=

Pennent, Thomas, 570

Percy, John. Cementation, 454; 459 Cupellation, 465 Liquation, 491

## Parting with antimony, 451; 452

Peregrinus, Petrus. Compass, 57

Petasius (alchemist), =XXVII=; XXVIII

Petrie, W. M. F. Egyptian iron, 421 Mt. Sinai copper, 402

Pettus, Sir John, XVI; 283

Phaenippus. Demosthenes' oration against, 27; 83

Phaeton's sisters, 35

Pherecrates, =XXVI=

Philemon. Riches, 7

Philip of Macedonia, 27

Philip, Peter, 282

Phillips, J. A., 410

Philo. Lost work on mining, =XXVI=

Phocion. Bribe of Alexander, =9=; =15=

Phocylides. Gold, =7=

Photius, 279 Fire-setting, 118

Pindar. Wealth, =19=; 252

Pius II, Pope. Alum maker, 570

Pizarro, F., =V=

Plateanus, Petrus, XIV

Plautus. Gold, =10=

Pliny (Caius Plinius Secundus), =XXVI=; 608 Alluvial mining, 331; 333 Alum, 566 Amalgamation, 297 Amber, 35 Antimony, 428 Argol, 234 _Arrhenicum_, 111 Asbestos, 440 Bitumen, =33=; 583 Brass, 410 British miners, 83 Cadmia, 112 Cementation, 459 Chrysocolla, 560 Copper flowers and scales, 233; 538 Copper smelting, 404 Cupellation, 466 Drainage of Spanish mines, 149 _Electrum_, 458 Fire-setting, 118 Galena, 476 Glass, 585; 586 Hannibal's silver mine, =42=; 42 Hoisting ore, =157=; 157 Iron, 11 Jew-stone, 115 Lead, 392 Lemnian earth, 31 Litharge, =475=; 466; 501 Lodestone, 115 Manganese (?), 586 Metallurgical appliances, 355 _Misy_, 573 _Molybdaena_, 466; 476 Naphtha, 583 _Nitrum_, 560 Ore-dressing, 281 Outcrops, 65 _Pompholyx_, 396 Protection from poison, 215 Quicksilver, 433 Red-lead, 232 Roasting, 267 Sal-ammoniac, 560 Salt from wood, 558 Silver-lead smelting, 392 _Sory_, 573 _Spodos_, 396 _Stannum_, 473 Tin, Spanish, 412 _Tophus_, 233 Touchstone, =256=; 253 Turfs in sluices, =331=; 332 _Vena_, 43 Ventilation with wet cloths, =210=; 210 Verdigris, 440 Vitriol, 572 White-lead, 440

Plutarch, 25

Pluto, =216=

Polybius. Ore washing, 281 Silver-lead smelting, 392; 465

Polymnestor, King of Thrace. Love of gold, =9=; =16=

Poertner, Hans, 281

Posepny, Franz, 53

Posidonius. Asphalt and naphtha, 584 Drainage of Spanish mines, 149 Silver from forest fires, 36

Priam, King of Troy. Gold mines of, =26=; 27

_Probierbuechlein_, 612; =XXVI= Amalgamation, 297 Antimony, 420 Assaying, 220 Assay ton, 242 Bismuth, 433 Cementation, 454 Nitric acid, 439

## Parting, 461; 462; 463

Precipitation of silver nitrate, 443 Residues from distillation of nitric acid, 235; 443 Roasting, 267 Stock fluxes, 235; 236 Touchstone, 253

Propertius. Gold, =10=

Pryce, William. Adam's fall, 353 Divining rod, 38 Juices, 1 Ore-deposits, 53 Stamp-mill, 282 Stringers, 70

Psalms. Silver refining, 465

Pulsifer, Wm. H., 391

Pygmalion. Love of gold, =9=; =16=

Rachaidibus (alchemist), =XXVII=

Rameses I. Map of mines, 129

Rameses III. Leaden objects dating from, 391

Raspe, R. E., 300

Rawlinson, George, 583

Ray, P. Chandra. Indian zinc, 409

Raymond, Rossiter W., 38

_Rechter Gebrauch der Alchimey_, 606

_Rerum Metallicarum Interpretatio_, 597; VII; 600

Reuss, F. A., 599

Richter, A. D., V; 599

Rodianus (alchemist), =XXVII=; XXVIII

Roessler, B., 53

Royal Geological Society of Cornwall, 84

Ruehlein von Kalbe (_see_ Calbus).

Salmoneus. Lightning, =11=

Sandwich, Earl of, trans. Barba's book, 300

Sappho. Wealth, =19=

Savery, Thomas, 149

Saxony, Dukes and Electors of. (_See under personal names_: Albert, Ernest, _etc._).

Schliemann, H., 391

Schlueter, C. A. Artificial zinc vitriol, 572 Copper refining, 535 Cupellation, 464 Liquation, 491; 505

## Parting with sulphur, 462

Schmid, F. A., V; XV; 599

Schnabel and Lewis, 465

Scott, Sir Walter. "Antiquary," 300

Seneca. Wealth of, =15=

Seneferu. Copper mines, 402

Seti I. Map of mine, 129

Shaw, Peter, XXVIII

Shoo King. Copper and lead, 391; 402 Iron, 421

Shutz, Christopher, 283

Sigfrido, Joanne. Ed. Agricola's works, XV

Socrates. Riches, =7=; =9=; =14=; =18=

Solinus, C. Julius. _Solifuga_, =216=; 216

Solomon, King. Cobalt in mines, 214

Solon. Scarcity of silver under, 27

Sosias, the Thracian. Slaves employed by, =25=

Stahl, G. E., 53

Staunton, Sir George, 409

Stephanus (alchemist), =XXVII=; XXX

Stephenson, George, 149

Strabo, 607 Arsenical minerals, 111 Asbestos, 440 Asphalt, 584; 33 Bellows, 362 Cementation, 458 Cupellation, 465 Drainage of Spanish mines, 149 Forest fires melting veins, 36 High stacks, 355 Lydian mines, 26; 27 Mt. Laurion, 27 Silver-lead smelting, 391 Spanish ore-washing, 281 Zinc (?), 409

Strato. Lost work on mines, =XXVI=; =XXVII=; XII

Struve, B. G., 599

Synesius (alchemist), =XXVII=; XXIX

Tantalus, 27

Taphnutia (alchemist), =XXVII=; XXVIII

Tapping, Thomas, 85

Thales of Miletus. Amber, 35

Themistocles. Athenian mine royalties, 27

Theodor, son of Agricola, VII

Theognis. Cupellation, 465 On greed, =18= Plutus, =8= Refining gold, 399

_Theological Tracts_ (Agricola), 605

Theophilus (alchemist), =XXVII=; XXVIII

Theophilus the Monk, 609 Brass making, 410 Calamine, 112 Cementation, 459 Copper refining, 536 Copper smelting, 405 Cupels, 466 Divining rod, 38 Liquation, 494 Metallurgical appliances, 355

## Parting with sulphur, 461

Roasting, 267

Theophrastus, XII; 607 Amber, 35 Arsenical minerals, 111 Asbestos, 440 Assaying, 219 Coal, 34 Copper minerals, 110 Copper ore, 403 Emery, 115 Lodestone, 115 Lost works, =XXVI=; 403 Origin of minerals, 44

## Parting precious metals, 458

Quicksilver, 297; 432 Touchstone, 252 Verdigris, 440 Vermilion, 232 White-lead, 391; 440

Thompson, Lewis, 462

Thoth. Hermes Trismegistos, XXIX

Thotmes III. Lead, 391; 582

Thucydides. Mining prefect, =23=; 23; 95

Tibullus. Wealth condemned by, =16=

Timocles. Riches, =8=

Timocreon of Rhodes. Plutus, =7=

Tournefort, Joseph P. De, 566

Tubal Cain. Instructor in metallurgy, 353

Tursius, =24=

Twain, Mark. Merlin, XXX

_Typographia Mysnae et Toringiae_, 605

Ulloa, Don Antonio De, 298

Ulysses. Magic rod, =40=

Valentine, Basil, XXX; 609 Antimony, 429 Divining rod, 38

## Parting with antimony, 461

Zinc, 409

Valerius, son of Agricola, VII

Van der Linden, J. A., 599

Van Oppel, XIII; 52

Varro, Marcus, =XXVI=

Vasco da Gama (_see_ Gama, Vasco da).

Veiga, Estacia de, 83

Velasco, Dom Pedro De, 298

Veradianus (alchemist), =XXVII=; XXVIII

Villa Nova, Arnold De (alchemist), =XXVII=; XXX

Virgil. Avarice condemned by, =16=

Vitruvius, 608 Amalgamation, 297 Hiero's Crown, 248 Pumps, 174; 149 Red-lead, 232 Surveying, 129 Verdigris, 440 White-lead, 440

Vladislaus III., King of Poland, =24=

Von Oppel (_see_ Van Oppel).

Voz, Cornelius de (_see_ Devoz, Cornelius).

Wallerius, J. G., 234; 273

Watt, James, 149

Watt, Robert, XXVII

Wefring, Basilius, XIV

Weindle, Caspar, 119

Weinart, B. G., 599

Weller, J. G., V

Werner, A. G., XIII; 53

Wilkinson, J. Gardner. Bitumen, 582 Egyptian bellows, 362 Egyptian gold-washing, 279

Williams, John, 53

Winkler, K. A., 464

Wrotham, William de, 85; 413; 473

Xenophon. Athenian mines, =28=; =83=; 27; 29 Fruitfulness of mines, =6= Mining companies, 90 Mine slaves, 25; 28 Quoted by Agricola, =26=; =28=

Zimmerman, C. F., 53

Zosimus (alchemist), =XXVII=; XXIX

INDEX TO ILLUSTRATIONS.

Alum Making, =571=

Amalgamation Mill, =299=

Ampulla, =442=; =446=

Argonauts, =330=

Assay Balances (_see_ Balances).

Assay Crucible, =229=

Assay Furnaces. Crucible, =227= Muffle, =223=; =224=

Balances, =265=

Baling Water, =199=

Bars, for Furnace Work, =377=; =389=

Batea, =157=

Bellows. For blast furnaces, =359=; =365=; =368=; =370=; =372= For mine ventilation, =208=; =209=; =211= For tin furnace, =419=

Bismuth Smelting, =434=; =435=; =436=; =437=

Bitumen Making, =582=

Bitumen Spring, =583=

Bowls for Alluvial Washing (_see also_ Batea), =336=

Buckets. For hoisting ore, =154= For hoisting water, =158=

Buddle, =301=; =302=; =314=; =315=

Building Plan for Refinery, =493=

Building Plan for Smelter, =361=

Chain Pumps, =173=; =174=; =175=

_Chrysocolla_ Making, =585=

Circular Fire (_see_ Ring-Fire).

Clay Washing, =374=; =375=

Compass, =57=; =59=; =142=; =147=

Copper Mould for Assaying, =250=

Copper Refining, =534=; =537=

Copper Refining Furnace, =532=

Crane. For cupellation furnace, =479= For liquation cakes, =514=

Crowbars, =152=

Cupel, =229= Mould, =231=

Cupellation Furnace, =468=; =470=; =474= At Freiberg, =481= In Poland, =482=

Cutting Metal, =269=

Descent into Mines, =213=

Dipping-pots, =385=; =387=; =389=; =393=; =415=; =417=

Distillation (_see_ Nitric Acid _and_ Quicksilver).

Divining Rod, =40=

Dogs Packing Ore, =168=

Drifts, =105=

Drying Furnace for Liquation, =525=; =527=; =528=

Dust Chambers, =395=; =417=

Fans, Ventilation, =204=; =205=; =206=; =207=

Fire-Buckets, =377=

Fire Pump, =377=

Fire-Setting, =120=

Forehearth, =357=; =358=; =383=; =385=; =387=; =389=; =417=

Frames (or Sluices) for Washing Ore or Alluvial, =322-324=; =326-329=; =331-333=

Furnaces. Assaying (_see_ Assay Furnaces). Blast, =357=; =358=; =373=; =377=; =383=; =385=; =387=; =389=; =395=; =419=; =424=; =508= Copper refining, =537= Cupellation, =468=; =470=; =474=; =481=; =482= Distilling sulphur, =277= Enriching copper bottoms, =510= Glass-making, =587=; =588=; =589=; =591= Iron smelting, =422=; =424= Lead smelting (_see also_ Furnaces, blast), =393= Liquation, =517=; =519=; =525=; =527=; =528= Nitric acid making, =442= Nitric acid parting, =446=

## Parting precious metals with antimony, =453=

Ditto cementation, =455= Quicksilver distillation, =427-432= Refining silver, =485=; =486=; =489= Roasting, =276= Steel making, =425= Tin burning, =349= Tin smelting, =415=

Gad, =150=

Glass Making, =591= Furnaces, =587=; =588=; =589=

Ground Sluicing, =337=; =340=; =343=; =346=; =347=

Hammers, =151= With water-power, =422=; =425=

Heap Roasting, =275=; =278=

Hearths. For bismuth smelting, =436=; =437= For heating copper cakes, =504= For melting lead, =393= For melting lead cakes, =499= For refining tin, =418= For roasting, =277=

Hemicycle, =138=

Hoe, =152=

_Intervenium_, =50=

Iron Fork for Metal, =387=

Iron Hook for Assaying, =240=

Iron Smelting, =422=; =424=

Iron Tools, =150=

Jigging Sieve, =311=

Ladders, =213=

Ladle for Metal, =383=

Lead Mould for Assaying, =240=

Liquation Cakes. Dried, =530=

Liquation Cakes, Exhausted, =522=

Liquation Furnaces, =517=; =519=; =525=; =527=; =528=

Lye Making, =557=

Matte Roasting, =350=; =351=

Meers, Shape of, =79=; =80=; =86=; =87=; =89=

Mills for Grinding Ore, =294=; =296=

Muffle Furnaces, =223=; =489=

Muffles, =228=

Nitric Acid Making, =442=

_Nitrum_ Pits, =559=

_Operculum_, =446=

_Orbis_, =142A=

## Parting Precious Metals.

With antimony, =453= By cementation, =455= With nitric acid, =446= With sulphur, =449=

Picks, =152=

Plummet level. Standing, =143= Suspended, =146=

Pumps. Chain, =173=; =174=; =175= Duplex suction, =180=; =185=; =189= Rag and chain, =191=; =193=; =194=; =195= Suction, =177=; =178=; =179=; =182=; =183=; =187=

Quicksilver Distillation, =427=; =429=; =430=; =431=; =432=

Rag and Chain Pumps, =191=; =193=; =194=; =195=; =197=

Rammers for Fire-Clay, =377=; =383=

Ring-Fire, for Parting with Sulphur, =449=

Roasting (_see also_ Heap _and_ Stall Roasting), =278=; =350=; =351=; =274=; =275=; =276=

Rosette Copper Making, =537=

Salt. Boiling, =549=; =554=; =555= Caldron, =551=; =553= Evaporated on faggots, =556= Pans, =547= Wells, =549=

Saltpetre Making, =563=

Saxon Lead Furnace, =393=

Scorifier, =229=

Seams in the Rocks, =54=; =55=; =56=; =60=; =72=

Shafts. Inclined, =104= Timbering, =123= Vertical, =103=; =105=

Shears for Cutting Metal, =269=

Shield for Muffle Furnace, =241=

Sifting Ore, =287=; =288=; =289=; =291=; =292=; =293=; =311=; =342=

Silver. Cakes, Cleansing of, =476=; =488= Refining, =484=; =485=; =486=; =489=

Sleigh for Ore, =168=

Sluicing Tin, =337=; =338=; =340=; =343=

Smelter, Plan of Building, =361=

Soda Making, =561=

Sorting Ore, =268=; =270=

Spalling Ore, =270=; =271=; =272=

Stall Roasting. Matte, =350=; =351= Ore, =274=; =276=

Stamp-mill, =284=; =286=; =287=; =299=; =313=; =320=; =321=; =373= For breaking copper cakes, =501=

Stamps, =285=

Steel Furnace, =425=

Strake, =302=; =303=; =305=; =306=; =307=; =341=; =342=; =345= Canvas, =308=; =309=; =317=; =321=; =329=

Streaming for Tin, =318=

Stringers. Associated, =71= _Fibra dilatata_, =71= _Fibra incumbens_, =71= Oblique, =71= Transverse, =71=

Surveying. Rods, =138A= Shafts and Tunnels, =131= Triangles, =133=; =134=; =135=; =136=; =137=; =139=; =140=

Suction Pumps (_see_ Pumps).

Sulphur Making, =579=; =581=

Tap-holes in Furnaces, =389=

Tapping-bar, =383=; =385=

"Tests" for Refining Silver, =484=; =485=

Timbering. Shafts, =123= Tunnels, =125=

Tin. Bars, =415= Burning, =349= Refining, =418= Smelting, =415=; =419=

Touch-needles, =255=

Trays for Washing Alluvial, =334=

Tread Whim, =163=

Trough, =159= For washing alluvial, =335=; =348=

Trucks, =156=

Tunnels, =103=; =104=; =105=; =120= Timbering, =125=

Veins. Barren, =73= Beginning of, =69= Cavernous, =73= Curved, =61= End of, =69= Head of, =69= Horizontal, =61= Intersections of, =64=; =65=; =66=; =67=; =68= Solid, =73= Strike of, =62=; =63=

_Vena cumulata_, =49=; =70=

_Vena dilatata_, =45=; =50=; =54=; =60=; =61=; =68=; =69=

_Vena profunda_, =45=; =50=; =53=; =61=; =62=; =63=; =64=; =68=

Ventilating with Damp Cloth (_see also_ Bellows, Fans, and Windsails), =212=

Vitriol Making, =567=; =574=; =575=; =576=; =577=

Wagons, for Hauling Ore, =170=

Washing Ore (_see_ Sifting Ore).

Water Tanks, under Furnaces, =358=

Wedges, =150=

Weights, for Assay Balances, =262=

Westphalian Lead Smelting, =393=

Wheelbarrows, =155=

Whims. Horse, =165=; =167= Tread, =163=

Windlasses, =161=; =162=; =171=

Winds, Direction of, =59=

Windsails for Ventilation, =201=; =202=; =203=

Transcriber's Notes.

This document includes quotes from very early authors. As such, it's no surprise that there are many spelling and punctuation irregularities. Also the authors were American, but writing for a British journal. In addition, whether "ae" and "oe" appear as ligatures or separate characters seems to be fairly random. Unless there was a clearly preferred spelling choice, variants were kept as is. All changes are explicitly documented below. Noted spelling variants that were preserved include: "aluminum" and "aluminium;" "ampullas" and "ampullae;" "beechwood" and "beech-wood;" "Bluetstein" and "Bluet stein;" "brick dust" and "brickdust;" "calcspar," "calc spar" and "calc-spar;" derivatives of "crossbar" and "cross-bar," and similarly for "crosscut," "crosspiece," etc.; (Hans von) "Dechen" and "Decken;" "desulphurizing" and "de-sulphurizing;" "dissension" and "dissention" (and their plurals); "distill" and "distil" (and derivatives); "encrusted" and "incrusted;" "enquire" and "inquire" (and derivatives); "ensure" and "insure;" (Lazarus) "Ercker" and "Erckern;" "flavor" and "flavour;" "fluor-spar" and "fluorspar;" "Flusse" and "Fluesse;" (Rotenburg an der) "Fulda" and "Fulde;" "Gatter" and "Gatterer" may be the same person; "gold workers," "goldworkers" and "gold-workers;" "gray" and "grey" (and derivatives); "grove" and "groove" (English mining term for a shaft); "halitum" and "halitus;" "Henckel" and "Henkel;" "holm oak" and "holmoak;" "homogenous" and "homogeneous;" Daniel "Houghsetter," "Houghstetter" and "Hochstetter;" "Joannes" and "Johannes" (the alchemist); "Johanes" and "Johannes" (Aurelius Augurellus), a.k.a. "John Aurelio Augurello;" "Juedenstein" and "Jueden stein;" "Kinstock" and "Kinstocke;" "Lautental" and "Lautenthal;" "lawsuit" and "law-suit;" "Leipsic" and "Leipzig;" "Krat" and "Kratt;" "Mosaic" and "Mosaick;" "mineralogic" and "mineralogical;" "Nuetzlich Bergbuechlin," "Nuetzliche Bergbuechlin," "Nuetzlich Bergbuechlein," and "Nuetzliche Bergbuechlein;" "organisation" and "organization;" (Thomas) "Pennant" and "Pennent;" "Probier Buechlein," "Probierbuechlin," "Probierbuechlein," "Probirbuechlein," and "Probirbuechleyn" (which may be different books in some cases); derivatives of "pulverise" and "pulverize;" "reagent" and "re-agent" (and their plurals); derivatives of "recognise" and "recognize;" "republished" and "re-published;" "salamander har" and "salamanderhar;" "seashore" and "sea-shore;" "semicircle" and "semi-circle" (and derivatives); "shovelful" and "shovel-ful;" "spiesglas," "spiesglass," and "spiesglasz;" "Turkey oak" and "turkey-oak;" "Vannucci," "Vannuccio" and "Vanuccio" (Biringuccio); "Vectarii" and "Vectiarii;" derivatives of "volatilise" and "volatilize."

There appears to be no rule whether punctuation following a quote should be inside or outside the quotation marks. The text was simply left as is.

There appears to be no rule whether Roman numerals have periods after them or not; even references to the same document may differ. The text was simply left as is.

For the text version of the document, replaced the oe-ligature with the separate characters "oe." Also removed the macron from the "e" in "pectos."

Some footnote numbers are skipped. To avoid confusion with references to the footnotes, none of the footnotes were re-numbered. In particular,

## Book I does not have footnote 24; Book VI does not have footnote 9; Book

VIII does not have footnote 9, 10 or 18; Book IX does not have footnote 24; Book XI does not have footnote 3.

Inserted missing anchor for footnote 1 on page v.

Changed "Albertham" to "Abertham" on page vii: "the God's Gift mine at Abertham."

Changed "honored" to "honoured" on page xi: "most honoured citizens."

Treated the explanatory text on page xxiv as a footnote (number 1) and created its anchor on page xxi.

Changed "license" to "licence" in the note on page xxiv: "only poets have licence."

Changed "Bibliotheque" to "Bibliotheque" in the footnote on page xxix: "the Bibliotheque Nationale."

Changed "Theosebeia" to "Theosebia" and inserted closing double quotation mark after "written to Theosebia, etc....'" on page xxx.

Left "loadstone" on page 2 although it's spelled "lodestone" everywhere else, because it's in a quote.

Changed "silver-mines" to "silver mines" on page 5: "the silver mines at Freiberg."

Removed the extra comma after "ll." in footnote 20 on page 11: "Odes, I., 35, ll. 17-20;" and in footnote 21 on page 15: "Satires, II., 3, ll. 99-102."

Changed "realised" to "realized" on page 25: "his hopes are not realized."

Removed extra double quotation mark from before "probable that the work" on page 28.

Changed "Hipprocrene" to "Hippocrene" in footnote 19 on page 37: "named Hippocrene after that horse."

Changed "Joachimstal" to "Joachimsthal" on page 42.

Adjusted the formats of the captions to the illustrations on page 45, 55, 56 and 60 to be consistent with other captions.

Removed extra double quotation mark after "not a metal" in the footnote from page 51.

Changed "foot walls and hanging walls" to "footwalls and hangingwalls" on page 65.

Changed "hanging-wall" to "hangingwall" in footnote 5 on page 80: "into the hangingwall."

Changed "Phaenippis" to "Phaenippus" in the footnote on page 83: "the other against Phaenippus."

Inserted double quotation mark after "Droit Francais et Etranger" in the footnote on page 84.

Changed "Inama-Strenegg" to "Inama-Sternegg" in the footnote on page 84.

Changed "Himmelich" to "Himmelisch" on page 92: "Himmelisch Hoez." "Himmelsch hoz" was retained as a variant elsewhere.

Changed "shovelers" to "shovellers" on page 100: "miners, shovellers, windlass men."

The table in the note on page 109 refers to note 7 on p. 573. It would make more sense to refer to note 8, but was left as is.

Changed "chrusos" to "chrysos" in the footnote on page 110: "(chrysos, gold and kolla, solder)."

The footnote on page 110 contains the reference "(see note xx., p. x)." Rather than Roman numerals, this appears to be a placeholder to a reference that was not filled in. Perhaps it should be "(see note 8, p. 560)," but it was left as is.

Changed "tinstone" to "tin-stone" in the footnote on page 110.

Changed "De La Pirotechnica" to "De La Pirotechnia" in the footnote on page 112.

Changed "Mansfeld" to "Mannsfeld" in the footnote on page 113: "Mannsfeld copper schists."

Changed "CoAsA" to "CoAsS" in the footnote on page 113: "Cobaltite (CoAsS)."

Changed "Phoenecians" to "Phoenicians" on page 119: "Phoenicians must have possessed."

Changed "hanging wall" to "hangingwall" on page 124: "the hangingwall and the footwall."

Changed "venae dilatatae" (ae-ligature) to "venae dilatatae" on page 127: "mine venae dilatatae lying down."

Changed "venae cumulatae" (ae-ligature) to "venae cumulatae" on page 128: "as to venae cumulatae."

Changed "Watts's" to "Watt's" in footnote 1 on page 149: "Watt's improvements."

Changed "locks" to "blocks" on page 151: "blocks, and plates."

Something is wrong with the sentence on page 153 that ends with the reference to footnote 3. One metreta is larger than one-sixth of a congius. Perhaps "metreta" and "congius" should be swapped in this sentence, but it was left as is.

Changed "bail" to "bale" on page 153: "iron semi-circular bale."

Changed "Fosilium" to "Fossilium" twice in the footnote on page 155: "De Natura Fossilium."

Changed "decends" to "descends" on page 166: "descends into an underground chamber," and again on page 190: "the plank descends."

Changed "Pig-skin" to "Pigskin" in the caption to the illustration on page 168: "Pigskin sacks."

Left "vapor" as is in footnote 20 on page 210 although it's spelled "vapour" everywhere else, because it's in a quote.

Changed "de hydrated" to "dehydrated" in the footnote on page 221: "Probably dehydrated alum."

Changed "Na_{2}Co_{3}" to "Na_{2}CO_{3}" in the footnote on page 222.

Changed "fore-part" to "forepart" on page 226: "the forepart lies."

Changed "four-fold" to "fourfold" on page 226: "with fourfold curves."

Changed "or" to "of" on page 230: "an ore of copper."

Changed "factictius" to "facticius" in the footnote on page 233: "Sal facticius."

Changed "Interpretaltio" to "Interpretatio" in footnote 13 on page 234: "Interpretatio, die heffe."

Changed "Loehneys" to "Lohneys" in footnote 21 on page 237.

"Cramner" in footnote 21 on page 237 may be a typo for "Cramer," but it was left as is.

Changed "neutralized" to "neutralised" in footnote 21 on page 237: "neutralised by the nitre."

Changed "notes" to "note" in footnote 33 on page 248: "note 10."

Changed "liquified" to "liquefied" on page 250: "has become sufficiently liquefied."

Changed "touchneedles" to "touch-needles" in footnote 37 on page 253: "detailed account of touch-needles."

The reference to page 259 in footnote 39 on page 253 does not seem to make sense, but was not changed. Perhaps the reference should be to footnote 27 on page 242.

In the table on page 257, the entries for the 20th and 21st needles do not add up, because the entry for the number of sextulae of copper belongs in the 21st needle, not the 20th. This was corrected. However, there are other errors in this table, which are not so obvious and were not corrected. In particular, the entries for the 22nd, 28th and 31st needles do not add correctly.

In the table on page 258, the number for the siliquae of copper was sometimes in the sextulae column. These were corrected. The affected lines were the ones for needles 13, 22 and 24. There is some other error (uncorrected) for the 17th needle; probably it should have another sextula of silver.

Filled in the missing "4" in the line for the 8th needle in the table on page 260.

Changed "52" to "25" in the line for the 3rd weight in the table for the "greater" weights on page 261.

Changed "stele" to "stelae" on page 279: "Certain stelae."

Changed "hanging-wall" to "hangingwall" on page 279: "the hangingwall rock;" and on page 292: "from the hangingwall."

Changed "lead" to "led" in the footnote on page 281: "led through a series."

Changed "Humpfrey" to "Humphrey" in the footnote on page 283: "William Humphrey."

Changed "Erbisdroff" to "Erbisdorff" on page 304: "tin-stuff of Schlackenwald and Erbisdorff."

Changed "colleced" to "collected" on page 328: "concentrates are collected."

Changed "civilisation" to "civilization" in footnote 17 on page 330: "glimmer of civilization."

Changed "