CHAPTER II

.

OF THE CHEMICAL KNOWLEDGE POSSESSED BY THE ANCIENTS.

Notwithstanding the assertions of Olaus Borrichius, and various other writers who followed him on the same side, nothing is more certain than that the ancients have left no chemical writings behind them, and that no evidence whatever exists to prove that the science of chemistry was known to them. Scientific chemistry, on the contrary, took its origin from the collection and comparison of the chemical facts, made known by the practice and improvement of those branches of manufactures which can only be conducted by chemical processes. Thus the smelting of ores, and the reduction of the metals which they contain, is a chemical process; because it requires, for its success, the separation of certain bodies which exist in the ore chemically combined with the metals; and it cannot be done, except by the application or mixture of a new substance, having an affinity for these substances, and capable, in consequence, of separating them from the metal, and thus reducing the metal to a state of purity. The manufacture of glass, of soap, of leather, are all chemical, because they consist of processes, by means of which bodies, having an affinity for each other, are made to unite in chemical combination. Now I shall in this chapter point out the principal chemical manufactures that were known to the ancients, that we may see how much they contributed towards laying the foundation of the science. The chief sources of our information on this subject are the writings of the Greeks and Romans. Unfortunately the arts and manufactures stood in a very different degree of estimation among the ancients from what they do among the moderns. Their artists and manufacturers were chiefly slaves. The citizens of Greece and Rome devoted themselves to politics or war. Such of them as turned their attention to learning confined themselves to _oratory_, which was the most fashionable and the most important study, or to history, or poetry. The only scientific pursuits which ever engaged their attention, were politics, ethics, and mathematics. For, unless Archimedes is to be considered as an exception, scarcely any of the numerous branches of physics and mechanical philosophy, which constitute so great a portion of modern science, even attracted the attention of the ancients.

In consequence of the contemptible light in which all mechanical employments were viewed by the ancients, we look in vain in any of their writings for accurate details respecting the processes which they followed. The only exception to this general neglect and contempt for all the arts and trades, is Pliny the Elder, whose object, in his natural history, was to collect into one focus, every thing that was known at the period when he lived. His work displays prodigious reading, and a vast fund of erudition. It is to him that we are chiefly indebted for the knowledge of the chemical arts which were practised by the ancients. But the low estimation in which these arts were held, appears evident from the wonderful want of information which Pliny so frequently displays, and the erroneous statements which he has recorded respecting these processes. Still a great deal may be drawn from the information which has been collected and transmitted to us by this indefatigable natural historian.

I.--The ancients were acquainted with SEVEN METALS; namely, gold, silver, mercury, copper, iron, tin, and lead. They knew and employed various preparations of zinc, and antimony, and arsenic; though we have no evidence that these bodies were known to them in the metallic state.

1. Gold is spoken of in the second chapter of Genesis as existing and familiarly known before the flood.

“The name of the first is Pison; that is it which encompasseth the whole land of Havilah, where there is gold. And the gold of that land is good: there is bdellium and the onyx-stone.” The Hebrew word for gold, בהז (_zahav_) signifies to be clear, to shine; alluding, doubtless, to the brilliancy of that metal. The term _gold_ occurs frequently in the writings of Moses, and the metal must have been in common use among the Egyptians, when that legislator led the children of Israel out of Egypt.[28] Gold is found in the earth almost always in a native state. There can be no doubt that it was much more abundant on the surface of the earth, and in the beds of rivers in the early periods of society, than it is at present: indeed this is obvious, from the account which Pliny gives of the numerous places in Asia and Greece, and other European countries, where gold was found in his time.

[28] Exodus xi. 2--xxv. 11, 12, 13, 17, 18, 24, 25, 26--xxviii. 8--xxxii. 2, &c.

Gold, therefore, could hardly fail to attract the attention of the very first inhabitants of the globe; its beauty, its malleability, its indestructibility, would give it value: accident would soon discover the possibility of melting it by heat, and thus of reducing the grains or small pieces of it found on the surface of the earth into one large mass. It would be speedily made into ornaments and utensils of various kinds, and thus gradually would come into common use. This we find to have occurred in America, when it was discovered by Columbus. The inhabitants of the tropical parts of that vast continent were familiarly acquainted with gold; and in Mexico and Peru it existed in great abundance; indeed the natives of these countries seem to have been acquainted with no other metal, or at least no other metal was brought into such general use, except silver, which in Peru was, it is true, still more common than gold.

Gold, then, was probably the first metal with which man became acquainted; and that knowledge must have preceded the commencement of history, since it is mentioned as a common and familiar substance in the Book of Genesis, the oldest book in existence, of the authenticity of which we possess sufficient evidence. The period of leading the children of Israel out of Egypt by Moses, is generally fixed to have been one thousand six hundred and forty-eight years before the commencement of the Christian era. So early, then, we are certain, that not only gold, but the other six malleable metals known to the ancients, were familiar to the inhabitants of Egypt. The Greeks ascribe the discovery of gold to the earliest of their heroes. According to Pliny, it was discovered on Mount Pangæus by Cadmus, the Phœnician: but Cadmus’s voyage into Greece was nearly coeval with the exit of the Israelites out of Egypt, at which time we learn from Moses that gold was in common use in Egypt. All that can be meant, then, is, that Cadmus first discovered gold in Greece; not that he made mankind first acquainted with it. Others say that Thoas and Eaclis, or Sol, the son of Oceanus, first found gold in Panchaia. Thoas was a contemporary of the heroes of the Trojan war, or at least was posterior to the Argonautic expedition, and consequently long posterior to Moses and the departure of the children of Israel from Egypt.

2. Silver also was not only familiarly known to the Egyptians in the time of Moses, but, as we learn from Genesis, was coined into money before Joseph was set over the land of Egypt by Pharaoh, which happened one thousand eight hundred and seventy-two years before the commencement of the Christian era, and consequently two hundred and twenty-four years before the departure of the children of Israel out of Egypt.

“And Joseph gathered up all the money that was found in the land of Egypt, and in the land of Canaan, for the corn which they bought; and Joseph brought the money into Pharaoh’s house.”[29] The Hebrew word ףםכ (_keseph_), translated _money_, signifies silver, and was so called from its pale colour. Silver occurs in many other passages of the writings of Moses.[30] The Greeks inform us, that Erichthonius the Athenian, or Ceacus, were the discoverers of silver; but both of these individuals were long posterior to the time of Joseph.

[29] Genesis xlvii. 14.

[30] For example, Exodus xi. 2--xxvi. 19, 21--xxvii. 10, 11, 17, &c.

Silver, like gold, occurs very frequently in the metallic state. This, no doubt, was a still more frequent occurrence in the early ages of the world; it would therefore attract the attention of mankind as early as gold, and for the same reason. It is very ductile, very beautiful, and much more easily fused than gold: it would be therefore more easily reduced into masses, and formed into different utensils and ornaments than even gold itself. The ores of it which occur in the earth are heavy, and would therefore draw the attention of even rude men to them: they have, most of them at least, the appearance of being metallic, and the most common of them may be reduced to the state of metallic silver, simply by keeping them a sufficient time in fusion. Accordingly we find that the Peruvians, before they were overrun by the Spaniards, had made themselves acquainted with the mode of digging out and smelting the ores of silver which occur in their country, and that many of their most common utensils were made of that metal.

Silver and gold approached each other nearer in value among the ancients than at present: an ounce of fine gold was worth from ten to twelve ounces of fine silver, the variation depending upon the accidental relation of the supply of both metals. But after the discovery of America, the quantity of silver found in that continent, especially in Mexico, was so great, compared with that of the gold found, that silver became considerably cheaper; so that an ounce of fine gold came to be equivalent to about fourteen ounces and a half of fine silver. Of course these relative values have fluctuated a little according to the abundance of the supply of silver. Though the revolution in the Spanish American colonies has considerably diminished the supply of silver from the mines, that deficiency seems to have been supplied by other ways, and thus the relative proportion between the value of gold and silver has continued nearly unaltered.

3. That copper must have been known in the earliest ages of society, is sufficiently evident. It occurs frequently native, and could not fail to attract the attention of mankind, from its colour, weight, and malleability. It would not be difficult to fuse it even in the rudest ages: and when melted into masses, as it is malleable and ductile, it would not require much skill to convert it into useful and ornamental utensils. The Hebrew word תשחנ (_nechooshat_) translated _brass_, obviously means _copper_. We have the authority of the Book of Genesis to satisfy us that copper was known before the flood, and probably as early as either silver or gold.

“And Zillah, she also bore Tubal-cain, an instructor of every artificer in brass (_copper_) and iron.”[31]

[31] Genesis iv. 22.

The word _copper_ occurs in many other passages of the writings of Moses.[32] That the Hebrew word translated _brass_ must have meant copper is obvious, from the following passage: “Out of whose hills thou mayest dig brass.”[33] Brass does not exist in the earth, nor any ore of it, it is always made artificially; it must therefore have been copper, or an ore of copper, that was alluded to by Moses.

[32] For example, Exodus xxvii. 2, 3, 4, 6, 10, 11, 17, 18, 19--xxx. 18, &c. Numbers xxi. 9.

[33] Deut. viii. 9.

Copper must have been discovered and brought into common use long before iron or steel; for Homer represents his heroes of the Trojan war as armed with swords, &c. of copper. Copper itself is too soft to be made into cutting instruments; but the addition of a little tin gives it the requisite hardness. Now we learn from the analyses of Klaproth, that the copper swords of the ancients were actually hardened by the addition of tin.[34]

[34] Beitrage, vi. 81.

Copper was the metal in common use in the early part of the Roman commonwealth. Romulus coined copper money alone. Numa established a college of workers in copper (_ærariorum fabrum_).[35]

[35] Plinii Hist. Nat. xxxiv. 1.

The Latin word _æs_ sometimes signifies copper, and sometimes brass. It is plain from what Pliny says on the subject, that he did not know the difference between copper and brass; he says, that an ore of _æs_ occurs in Cyprus, called _chalcitis_, where _æs_ was first discovered. Here _æs_ obviously means copper. In another place he says, that _æs_ is obtained from a mineral called _cadmia_. Now from the account of cadmia by Pliny and Dioscorides, there cannot be a doubt that it is the ore to which the moderns have given the name of _calamine_, by means of which brass is made. It is sometimes a silicate and sometimes a carbonate of zinc; for both of these ores are confounded together under the name of cadmia, and both are employed in the manufacture of brass.

Solinus says, that _æs_ was first made at Chalcis, a town in Eubœa. Hence the Greek name, χαλκος (_chalkos_), by which copper was distinguished.

The proper name for brass, by which is meant an alloy of copper and zinc, was _aurichalcum_, or golden, or yellow copper. Pliny says, that long before his time, the ore of aurichalcum was exhausted, so that no more of that beautiful alloy was made. Are we to conclude from this, that there once existed an ore consisting of calamine and ore of copper, mixed or united together? After the exhaustion of the aurichalcum mine, the _salustianum_ became the most famous; but it soon gave place to the _livianum_, a copper-mine in Gaul, named after Livia, the wife of Augustus. Both these mines were exhausted in the time of Pliny. The _æs marianum_, or copper of Cordova, was the most celebrated in his time. This last _æs_, he says, absorbs most cadmia, and acquires the greatest resemblance to aurichalcum. We see from this, that in Pliny’s time brass was made artificially, and by a process similar to that still followed by the moderns.

The most celebrated alloy of copper among the ancients, was the _æs corinthium_, or Corinthian copper, formed accidentally, as Pliny informs us, during the burning of Corinth by Mummius in the year 608, after the building of Rome, or one hundred and forty-five years before the commencement of the Christian era. There were four kinds of it, of which Pliny gives the following description; not, however, very intelligible:

1. White. It resembled silver much in its lustre, and contained an excess of that metal.

2. Red. In this kind there is an excess of gold.

3. In the third kind, gold, silver, and copper are mixed in equal proportions.

4. The fourth kind is called _hepatizon_, from its having a liver colour. It is this colour which gives it its value.[36]

[36] Plinii Hist. Nat. xxxiv. 2.

Copper was put by the ancients to almost all the uses to which it is put by the moderns. One of the great sources of consumption was bronze statues, which were first introduced into Rome after the conquest of Asia Minor. Before that time, the statues of the Romans were made of wood or stoneware. Pliny gives various formulas for making bronze for statues. Of these it may be worth while to put down the most material.

1. To new copper add a third part of old copper. To every hundred pounds of this mixture, twelve pounds and a half of tin[37] are added, and the whole melted together.

[37] Pliny’s phrase is _plumbum argentorium_. But that the addition was tin, and consequently that plumbum argentorium meant tin, we have the evidence of Klaproth, who analyzed several of these bronze statues, and found them composed of copper, lead, and tin.

2. Another kind of bronze for statues was formed, by melting together

100lbs. copper, 10lbs. lead, 5lbs. tin.

3. Their copper-pots for boiling consisted of 100lbs. of copper, melted with three or four pounds of tin.

The four celebrated statues of horses which, during the reign of Theodosius II. were transported from Chio to Constantinople; and, when Constantinople was taken and plundered by the Crusaders and Venetians in 1204, were sent by Martin Zeno and set up by the doge, Peter Ziani, in the portal of St. Mark; were in 1798, transported by the French to Paris; and finally, after the overthrow of Buonaparte, and the restoration of the Bourbons in 1815, returned to Venice and placed upon their ancient pedestals. The metal of which these horses had been made was examined by Klaproth, and found by him composed of

Copper, 993 Tin, 7 ---- 1000[38]

[38] Beitrage, vi. 89.

Klaproth also analyzed an ancient bronze statue in one of the German cabinets, and found it composed of

Copper, 916 Tin, 75 Lead, 9 ---- 1000[39]

[39] Beitrage, vi. 118. The statue in question was known by the name of “The Statue of Püstrichs,” at Sondershausen.

Several other old brass and bronze pieces of metal, very ancient, but found in Germany, were also analyzed by Klaproth. The result of his analyses was as follows:

The metal of which the altar of Krodo was made consisted of

Copper, 69 Zinc, 18 Lead, 13 ---- 100[40]

[40] Ibid., p. 127.

The emperor’s chair, which had in the eleventh century been transported from Harzburg to Goslar, where it still remains, was found to be composed of

Copper, 92·5 Tin, 5 Lead, 2·5 ---- 100[41]

[41] Ibid., p. 132.

Another piece of metal, which enclosed the high altar in a church in Germany, was composed of

Copper, 75 Tin, 12·5 Lead, 12·5 ---- 100[42]

[42] Ibid., p. 134.

These analyses, though none of them corresponds exactly with the proportions given by Pliny, confirms sufficiently his general statement, that the bronze of the ancients employed for statues was copper, alloyed with lead and tin.

Some of the bronze statues cast by the ancients were of enormous dimensions, and show decisively the great progress which had been made by them in the art of working and casting metals. The addition of the lead and tin would not only add greatly to the hardness of the alloy, but would at the same time render it more easily fusible. The bronze statue of Apollo, placed in the capitol at the time of Pliny, was forty-five feet high, and cost 500 talents, equivalent to about £50,000 of our money. It was brought from Apollonia, in Pontus, by Lucullus. The famous statue of the sun at Rhodes was the work of Chares, a disciple of Lysippus; it was ninety feet high, was twelve years in making, and cost 300 talents (about £30,000). It was made out of the engines of war left by Demetrius when he raised the siege of Rhodes. After standing fifty-six years, it was overthrown by an earthquake. It lay on the ground 900 years, and was sold by Mauvia, king of the Saracens, to a merchant, who loaded 900 camels with the fragments of it.

Copper was introduced into medicine at rather an early period of society, and various medicinal preparations of it are described by Dioscorides and Pliny. It remains for us to notice the most remarkable of these. Pliny mentions an institution, to which he gives the name of _Seplasia_; the object of which was, to prepare medicines for the use of medical men. It seems, therefore, to have been similar to our apothecaries’ shops of the present day. Pliny reprobates the conduct of the persons who had the charge of these Seplasiæ in his time. They were in the habit of adulterating medicines to such a degree, that nothing good or genuine could be procured from them.[43]

[43] Plinii Hist. Nat. xxxiv. 11.

Both the oxides of copper were known to the ancients, though they were not very accurately distinguished from each other: they were known by the names _flos æris_ and _scoria æris_, or _squama æris_. They were obtained by heating bars of copper red-hot and letting them cool, exposed to the air. What fell off during the cooling was the _flos_, what was driven off by blows of a hammer was the _squama_ or _scoria æris_. It is obvious, that all these substances were nearly of the same nature, and that they were in reality mixtures of the black and red oxides of copper.

_Stomoma_ seems also to have been an oxide of copper, which was gradually formed upon the surface of the metal, when it was kept in a state of fusion.

These oxides of copper were used as external applications in cases of polypi of the nose, diseases of the anus, ear, mouth, &c., seemingly as escharotics.

_Ærugo_, verdigris, was a subacetate of copper, doubtless often mixed with subacetate of zinc, as not only copper but brass also was used for preparing it. The mode of preparing this substance was similar to the process still followed. Whether verdigris was employed as a paint by the ancients does not appear; for Pliny takes no notice of any such use of it.

_Chalcantum_, called also _atramentum sutorium_, was probably a mixture of sulphate of copper and sulphate of iron. Pliny’s account of the mode of procuring it is too imperfect to enable us to form precise ideas concerning it; but it was crystallized on strings, which were extended for the purpose in the solution: its colour was blue, and it was transparent like glass. This description might apply to sulphate of copper; but as the substance was used for blackening leather, and on that account was called _atramentum sutorium_, it is obvious that it must have contained also _sulphate of iron_.

_Chalcitis_ was the name for an ore of copper. The account given of it by Pliny agrees best with copper pyrites, which is now known to be a _sulphur salt_, composed of one atom of sulphide of copper (the acid) united to one atom of sulphide of iron (the base). Pliny informs us, that it is a mixture of _copper_, _misy_, and _sory_: its colour is that of honey. By age, he says, it changes into sory. I think it most probable that native sory, of which Pliny speaks, was sulphuret of copper, and artificial sory sulphate of copper. The native sory is said to constitute black veins in chalcitis. Pliny’s description of misy (μισυ) best agrees with copper pyrites. Dioscorides describes it as hard, as having the colour of gold, and as shining like a star.[44] All this agrees pretty well with copper pyrites.

[44] Lib. v. c. 117.

_Scoleca_ (so called because it assumed the shape of a worm) was formed by triturating alumen, carbonate of soda, and white vinegar, till the matter became green. It was probably a mixture of sulphate of soda, acetate of soda, acetate of alumina, and acetate of copper, probably with more or less oxide of copper, &c., depending upon the proportions of the respective constituents employed.

Such are the preparations of copper, employed by the ancients. They were only used as external applications, partly as escharotics, and

## partly to induce ulcers to put on a healthy appearance. It does not

appear that copper was ever used by the ancients as an internal remedy.

4. Though _zinc_ in the metallic state was unknown to the ancients, yet as they knew some of its ores, and employed preparations of it in medicine, and were in the habit of alloying copper with it, and converting it into brass, it will be proper to state here what was known to them concerning it.

Pliny nowhere makes us acquainted with the process by which copper was converted into brass, nor does he seem to have been acquainted with it; but from several facts incidentally mentioned by him, it is obvious that their process was similar to that which is followed at present by modern brass-makers. The copper in grains is mixed with a certain quantity of calamine (cadmia) and charcoal, and exposed for some time to a moderate heat in a covered crucible. The calamine is reduced to the metallic state, and imbibed by the copper grains. When the copper is thus converted into brass, the temperature is raised sufficiently high to melt the whole: it is then poured out and cast into a slab or ingot.

The cadmia employed by the ancients in medicine was not calamine, but oxide of zinc, which sublimed during the fusion of brass in an open vessel. It was distinguished by a variety of names, according to the state in which it was obtained: the lighter portion was called _capnitis_. _Botryitis_ was the name of the portion in the interior of the chimney: the name was derived from some resemblance which it was supposed to have to a bunch of grapes. It had two colours, ash and red. The red variety was reckoned best. This red colour it might derive from some copper mixed with it, but more probably from iron; for a small quantity of oxide of iron is sufficient to give oxide of zinc a rather beautiful red colour. The portion collected on the sides of the furnace was called _placitis_: it constituted a crust, and was distinguished by different names, according to its colour; _onychitis_ when it was blue externally, but spotted internally: _ostracitis_, when it was black and dirty-looking. This last variety was considered as an excellent application to wounds. The best cadmia in Pliny’s time was furnished by the furnaces of the Isle of Cyprus: it was used as an external application in ulcers, inflammations, eruptions, &c., so that its use in medicine was pretty much the same as at present. Sulphate and acetate of zinc were unknown to the ancients. No attempt seems to have been made by them to introduce any preparations of zinc as internal medicines.

_Pompholyx_ was the name given to oxide of zinc, sublimed by the combustion of the zinc which exists in brass. _Spodos_ seems to have been a mixture of oxides of zinc and copper. There were different varieties of it distinguished by various names.[45]

[45] See Plinii Hist. Nat. xxxiv. 13.

5. Iron exists very rarely in the earth in a metallic state, but most commonly in the state of an oxide; and the processes necessary to extract metallic iron from these ores are much more complicated, and require much greater skill, than the reduction of gold, silver, or copper from their respective ores. This would lead us to expect that iron would have been much longer in being discovered than the three metals whose names have been just given. But we learn from the Book of Genesis that iron, like copper and gold, was known before the flood, Tubal-cain being represented as an artificer in copper and iron.[46] The Hebrew word for iron, לזרב (_barzel_), is said to be derived from רב (_bar_), bright, לזנ (_nazal_), to melt; and would lead one to the suspicion, that it referred to _cast_ iron rather than _malleable_ iron. It is possible that in these early times native iron may have existed as well as native gold, silver, and copper; and in this way Tubal-cain may have become acquainted with the existence and properties of this metal. In the time of Moses, who was learned in all the wisdom of the Egyptians, iron must have been in common use in Egypt: for he mentions furnaces for working iron;[47] ores from which it was extracted;[48] and tells us that swords,[49] knives,[50] axes,[51] and tools for cutting stones,[52] were then made of that metal. Now iron in its pure metallic state is too soft to be applied to these uses: it is obvious, therefore, that in Moses’s time, not only iron but steel also must have been in common use in Egypt. From this we see how much further advanced the Egyptians were than the Greeks in the knowledge of the manufacture of this most important metal: for during the Trojan war, which was several centuries after the time of Moses, Homer represents his heroes as armed with swords of copper, hardened by tin, and as never using any weapons of iron whatever. Nay, in such estimation was it held, that Achilles, when he celebrated games in honour of Patrocles, proposes a ball of iron as one of his most valuable prizes.[53]

[46] Genesis iv. 22.

[47] Deut. iv. 20.

[48] Deut. viii. 9.

[49] Numbers xxxv. 16.

[50] Levit. i. 17.

[51] Deut. xviii. 5.

[52] Deut. xxvii. 5.

[53] Iliad, lib. xxiii. l. 826.

“Then hurl’d the hero, thundering on the ground, A mass of iron (an enormous round), Whose weight and size the circling Greeks admire, Rude from the furnace and but shaped by fire. This mighty quoit Ætion wont to rear, And from his whirling arm dismiss’d in air; The giant by Achilles slain, he stow’d Among his spoils this memorable load. For this he bids those nervous artists vie That teach the disk to sound along the sky. Let him whose might can hurl this bowl, arise; Who farthest hurls it, takes it as his prize: If he be one enrich’d with large domain Of downs for flocks and arable for grain, Small stock of iron needs that man provide, His hinds and swains whole years shall be supplied From hence: nor ask the neighbouring city’s aid For ploughshares, wheels, and all the rural trade.”

The mass of iron was large enough to supply a shepherd or a ploughman with iron for five years. This circumstance is a sufficient proof of the high estimation in which iron was held during the time of Homer. Were a modern poet to represent his hero as holding out a large lump of iron as a prize, and were he to represent this prize as eagerly contended for by kings and princes, it would appear to us perfectly ridiculous.

Hesiod informs us, that the knowledge of iron was brought over from Phrygia to Greece by the Dactyli, who settled in Crete during the reign of Minos I., about 1431 years before the commencement of the Christian era, and consequently about sixty years before the departure of the children of Israel from Egypt: and it does not appear, that in Homer’s time, which was about five hundred years later, the art of smelting iron had been so much improved, as to enable men to apply it to the common purposes of life, as had long before been done by the Egyptians. The general opinion of the ancients was, that the method of smelting iron ore had been brought to perfection by the Chalybes, a small nation situated near the Black Sea,[54] and that the name _chalybs_, occasionally used for steel, was derived from that people.

[54] Xenophon’s Anabasis, v. 5.

Pliny informs us, that the ores of iron are scattered very profusely almost every where: that they exist in Elba; that there was a mountain in Cantabria composed entirely of iron ore; and that the earth in Cappadocia, when watered from a certain river, is converted into iron.[55] He gives no account of the mode of smelting iron ores; nor does he appear to have been acquainted with the processes; for he says that iron is reduced from its ore precisely in the same way as copper is. Now we know, that the processes for smelting copper and iron are quite different, and founded upon different principles. He says, that in his time many different kinds of iron existed, and they were _stricturæ_, in Latin _a stringenda acie_.

[55] Plinii Hist. Nat. xxxiv. 14.

That steel was well known and in common use when Pliny wrote is obvious from many considerations; but he seems to have had no notion of what constituted the difference between iron and steel, or of the method employed to convert iron into steel. In his opinion it depended upon the nature of the water, and consisted in heating iron red-hot, and plunging it, while in that state, into certain waters. The waters at Bilbilis and Turiasso, in Spain, and at Comum, in Italy, possessed this extraordinary virtue. The best steel in Pliny’s time came from China; the next best, in point of quality, was manufactured in Parthia.

It would appear, that at Noricum steel was manufactured directly from the ore of iron. This process was perfectly practicable, and it is said still to be practised in certain cases.

The ancients were acquainted with the method of rendering iron, or rather steel, magnetic; as appears from a passage in the fourteenth chapter of the thirty-fourth book of Pliny. Magnetic iron was distinguished by the name of _ferrum vivum_.

When iron is dabbed over with alumen and vinegar it becomes like copper, according to Pliny. Cerussa, gypsum, and liquid pitch, keep it from rusting. Pliny was of opinion that a method of preventing iron from rusting had been once known, but had been lost before his time. The iron chains of an old bridge over the Euphrates had not rusted in Pliny’s time; but a few new links, which had been added to supply the place of some that had decayed, were become rusty.

It would appear from Pliny, that the ancients made use of something very like _tractors_; for he says that pain in the side is relieved by holding near it the point of a dagger that has wounded a man. Water in which red-hot iron had been plunged was recommended as a cure for the dysentery; and the actual cautery with red-hot iron, Pliny informs us, prevents hydrophobia, when a person has been bitten by a mad dog.

Rust of iron and scales of iron were used by the ancients as astringent medicines.

6. Tin, also, must have been in common use in the time of Moses; for it is mentioned without any observation as one of the common metals.[56] And from the way in which it is spoken of by Isaiah and Ezekiel, it is obvious that it was considered as of far inferior value to silver and gold. Now tin, though the ores of it where it does occur are usually abundant, is rather a scarce metal: that is to say, there are but few spots on the face of the earth where it is known to exist. Cornwall, Spain, in the mountains of Gallicia, and the mountains which separate Saxony and Bohemia, are the only countries in Europe where tin occurs abundantly. The last of these localities has not been known for five centuries. It was from Spain and from Britain that the ancients were supplied with tin; for no mines of tin exist, or have ever been known to exist, in Africa or Asia, except in the East Indies. The Phœnicians were the first nation which carried on a great trade by sea. There is evidence that at a very early period they traded with Spain and with Britain, and that from these countries they drew their supplies of tin. It was doubtless the Phœnicians that supplied the Egyptians with this metal. They had imbibed strongly a spirit of monopoly; and to secure the whole trade of tin they carefully concealed the source from which they drew that metal. Hence, doubtless, the reason why the Grecian geographers, who derived their information from the Phœnicians, represented the Insulæ Cassiterides, or tin islands, as a set of islands lying off the north coast of Spain. We know that in fact the Scilly islands, in these early ages, yielded tin, though doubtless the great supply was drawn from the neighbouring province of Cornwall. It was probably from these islands that the Greek name for _tin_ was derived (κασσιτερος). Even Pliny informs us, that in his time tin was obtained from the Cassiterides, and from Lusitania and Gallicia. It occurs, he says, in grains in alluvial soil, from which it is obtained by washing. It is in black grains, the metallic nature of which is only recognisable by the great weight. This is a pretty accurate description of _stream tin_, which we know formerly constituted the only ore of that metal wrought in Cornwall. He says that the ore occurs also along with grains of gold; that it is separated from the soil by washing along with the grains of gold, and afterwards smelted separately.

[56] Numbers xxxi. 22.

Pliny gives no particulars about the mode of reducing the ore of tin to the metallic state; nor is it at all likely that he was acquainted with the process.

The Latin term for tin was _plumbum album_. _Stannum_ is also used by Pliny; but it is impossible to understand the account which he gives of it. There is, he says, an ore consisting of lead, united to silver. When this ore is smelted, the first metal that flows out is _stannum_. What flows next is _silver_. What remains in the furnace is _galena_. This being smelted, yields _lead_.

Were we to admit the existence of an ore composed of lead and silver, it is obvious that no such products could be obtained by simply smelting it.

Cassiteros, or tin, is mentioned by Homer; and, from the way in which the metal is said by him to have been used, it is obvious that in his time it bore a much higher price, and, consequently, was more valued than at present. In his description of the breastplate of Agamemnon, he says that it contained ten bands of steel, twelve of gold, and twenty of tin (κασσιτεροιο).[57] And in the twenty-third book of the Iliad (line 561), Achilles describes a copper breastplate surrounded with shining tin (φαεινου κασσιτεροιο). Pliny informs us, that in his time tin was adulterated by adding to it about one-third of white copper. A pound of tin, when Pliny lived, cost ten denarii. Now, if we reckon a denarius at 7¾_d._, with Dr. Arbuthnot, this would make a Roman pound of tin to cost 6_s._ 5½_d._ But, as the Roman pound was only equal to three-fourths of our avoirdupois pound, it is plain that in the time of Pliny an avoirdupois pound of tin was worth 8_s._ 7¼_d._, which is almost seven times the price of tin in the present day.

[57] Iliad xi. 25.

Tin, in the time of Pliny, was used for covering the inside of copper vessels, as it is at this day. And, no doubt, the process still followed is of the same nature as the process used by the ancients for tinning copper. Pliny remarks, with surprise, that copper thus tinned does not increase in weight. Now Bayen ascertained that a copper pan, nine inches in diameter, and three inches three lines in depth, when tinned, only acquired an additional weight of twenty-one grains. These measures and weights are French. When we convert them into English, we have a copper pan 9·59 inches in diameter, and 3·46 inches deep, which, when tinned, increased in weight 17·23 troy grains. Now the surface of the copper pan, thus tinned, was 176·468 square inches. Hence it follows, that a square inch of copper, when tinned, increases in weight only 0·097 grains. This increase is so small, that we may excuse Pliny, who probably had never seen the increase of weight determined, except by means of a rude Roman statera, for concluding that there was no increase of weight whatever.

Tin was employed by the ancients for mirrors: but mirrors of silver were gradually substituted; and these in Pliny’s time had become so common, that they were even employed by female servants or slaves.

That Pliny’s knowledge of the properties of tin was very limited, and far from accurate, is obvious from his assertion that _tin_ is less fusible than silver.[58] It is true that the ancients had no measure to determine the different degrees of heat; but as tin melts at a heat under redness, while silver requires a bright red heat to bring it into fusion, a single comparative trial would have shown him which was most fusible. This trial, it is obvious, had never been made by him.

[58] Lib. xxxiv. c. 17.

The ancients seem to have been ignorant of the method of tinning iron. At least, no reference to _tin plate_ is made by Pliny, or by any other ancient author, that I have had an opportunity of consulting.

It would appear from Pliny, that both copper and brass were tinned by the Gauls at an early period. Tinned brass was called _æra coctilia_, and was so beautiful that it almost passed for silver. _Plating_ (or covering the metal with plates of silver), was gradually substituted for tinning; and finally _gilding_ took the place of plating. The trappings of horses, chariots, &c., were thus ornamented. Pliny nowhere gives a description of the process of plating; but there can be little doubt that it was similar to that at present practised. Gilding was accomplished by laying an amalgam of gold on the copper or brass, as at present.

7. Lead appears also to have been in common use among the Egyptians, at the time of Moses.[59] It was distinguished among the Romans by the name of _plumbum nigrum_. In Pliny’s time the lead-mines existed chiefly in Spain and Britain. In Britain lead was so abundant, that it was prohibited to extract above a certain quantity in a year. The mines lay on the surface of the earth. Derbyshire was the county in which lead ores were chiefly wrought by the Romans. The rich mines in the north of England seem to have been unknown to them.

[59] Numbers xxxi. 22.

Pliny was of opinion that if a lead-mine, after being exhausted, be shut up for some time, the ore will be again renewed.

In the time of Pliny leaden pipes were commonly used for conveying water. The vulgar notion that the ancients did not know that water will always rise in pipes as high as the source from which it proceeds, and that it was this ignorance which led to the formation of aqueducts, is quite unfounded. Nobody can read Pliny without seeing that this important fact was well known in his time.

Sheet lead was also used in the time of Pliny, and applied to the same purposes as at present. But lead was much higher priced among the ancients than it is at present. Pliny informs us that its price was to that of tin as 7 to 10. Hence it must have sold at the rate of 6_s._ 0¼_d._ per pound. The present price of lead does not much exceed three halfpence the pound. It is therefore only 1-48th part of the price which it bore in the time of Pliny. This difference must be chiefly owing to the improvements made by the moderns in working the mines and smelting the ores of lead.

Tin, in Pliny’s time, was used as a solder for lead. For this purpose it is well adapted, as it is so much easier smelted than lead. But when he says that lead is used also as a solder for tin, his meaning is not so clear. Probably he means an alloy of lead and tin, which, fusing at a lower point than tin, may be used to solder that metal. The addition of some bismuth reduces the fusing point materially; but that metal was unknown to the ancients.

_Argentarium_ is an alloy of equal parts of lead and tin. _Tertiarium_, of two parts lead and one part tin. It was used as a solder.

Some preparations of lead were used by the ancients in medicine, as we know from the description of them given us by Dioscorides and Pliny. These preparations consisted chiefly of protoxide of lead and lead reduced to powder, and partially oxidized by triturating it with water in a mortar. They were applied to ulcers, and employed externally as astringents.

_Molybdena_ was also employed in medicine. Pliny says it was the same as galena. From his description it is obvious that it was _litharge_; for it was in scales, and was more valued the nearer its colour approached to that of gold. It was employed, as it still is, for making plasters. Pliny gives us the process for making the plaster employed by the Roman surgeons. It was made by heating together

3 lbs. molybdena or litharge, 1 lb. wax, 3 heminæ, or 1½ pint, of olive oil.

This process is very nearly the same as the one at present followed by apothecaries for making adhesive plaster.

_Psimmythium_, or _cerussa_, was the same as our _white lead_. It was made by exposing lead in sheets to the fumes of vinegar. It would seem probable from Pliny’s account, though it is confused and inaccurate, that the ancients were in the habit of dissolving cerussa in vinegar, and thus making an impure acetate of lead.

Cerussa was used in medicine. It constituted also a common white paint. At one time, Pliny says, it was found native; but in his time all that was used was prepared artificially.

_Cerussa usta_ seems to have been nearly the same as our _red lead_. It was formed accidentally from cerussa during the burning of the Pyræus. The colour was purple. It was imitated at Rome by burning _silis_ _marmarosus_, which was probably a variety of some of our ochres.

8. Besides the metals above enumerated, the ancients were also acquainted with quicksilver. Nothing is known about the first discovery of this metal; though it obviously precedes the commencement of history. I am not aware that the term occurs in the writings of Moses. We have therefore no evidence that it was known to the Egyptians at that early period; nor do I find any allusion to it in the works of Herodotus. But this is not surprising, as that author confines himself chiefly to subjects connected with history. Dioscorides and Pliny both mention it as common in their time. Dioscorides gives a method of obtaining it by sublimation from cinnabar. It is remarkable, because it constitutes the first example of a process which ultimately led to distillation.[60]

[60] Dioscorides, lib. v. c. 110.

Cinnabar is also described by Theophrastus. The term _minium_ was applied to it also, till in consequence of the adulteration of cinnabar with _red lead_, the term minium came at last to be restricted to that preparation of lead. Theophrastus describes an artificial cinnabar, which came from the country above Ephesus. It was a shining red-coloured sand, which was collected and reduced to a fine powder by pounding it in vessels of stone. We do not know what it was. The native cinnabar was found in Spain, and was used chiefly as a paint. Dioscorides employs _minium_ as the name for what we at present call cinnabar, or bisulphuret of mercury. His cinnabar was a red paint from Africa, produced in such small quantity that painters could scarcely procure enough of it to answer their purposes.

Mercury is described by Pliny as existing native in the mines of Spain, and Dioscorides gives the process for extracting it from cinnabar. It was employed in gilding precisely as it is by the moderns. Pliny was aware of its great specific gravity, and of the readiness with which it dissolves gold. The amalgam was squeezed through leather, which separated most of the quicksilver. When the solid amalgam remaining was heated, the mercury was driven off and pure gold remained.

It is obvious from what Dioscorides says, that the properties of mercury were very imperfectly known to him. He says that it may be kept in vessels of glass, or of lead, or of tin, or of silver.[61] Now it is well known that it dissolves lead, tin, and silver with so much rapidity, that vessels of these metals, were mercury put into them, would be speedily destroyed. Pliny’s account of quicksilver is rather obscure. It seems doubtful whether he was aware that native _argentum vivum_ and the _hydrargyrum_ extracted from cinnabar were the same.

[61] Lib. v. c. 110.

Cinnabar was occasionally used as an external medicine; but Pliny disapproves of it, assuring his readers that quicksilver and all its preparations are virulent poisons. No other mercurial preparations except cinnabar and the amalgam of mercury seem to have been known to the ancients.[62]

[62] The ancients were in the habit of extracting mercury from cinnabar, by a kind of imperfect distillation. The native mercury they called _argentum vivum_, that from cinnabar _hydrargyrus_. See Plinii Hist. Nat. xxxiii. 8.

9. The ancients were unacquainted with the metal to which we at present give the name of _antimony_; but several of the ores of that metal, and of the products of these ores were not altogether unknown to them. From the account of stimmi and stibium, by Dioscorides[63] and Pliny,[64] there can be little doubt that these names were applied to the mineral now called _sulphuret of antimony_ or crude antimony. It is found most commonly, Pliny says, among the ores of silver, and consists of two kinds, the male and the female; the latter of which is most valued.

[63] Lib. v. c. 99.

[64] Lib. xxxiii. c. 6.

This pigment was known at a very early period, and employed by the Asiatic ladies in painting their eyelashes, or rather the insides of their eyelashes, black. Thus it is said of Jezebel, that when Jehu came to Jezreel she painted her face. The original is, _she put her eyes in sulphuret of antimony_.[65] A similar expression occurs in Ezekiel, “For whom thou didst wash thyself, paintedst thy eyes”--literally, put thy eyes in sulphuret of antimony.[66] This custom of painting the eyes black with antimony was transferred from Asia to Greece, and while the Moors occupied Spain it was employed by the Spanish ladies also. It is curious that the term _alcohol_, at present confined to _spirit of wine_, was originally applied to the powder of sulphuret of antimony.[67] The ancients were in the habit of roasting sulphuret of antimony, and thus converting it into an impure oxide. This preparation was also called stimmi and stibium. It was employed in medicine as an external application, and was conceived to act chiefly as an astringent; Dioscorides describes the method of preparing it. We see, from Pliny’s account of stibium, that he did not distinguish between sulphuret of antimony and oxide of antimony.[68]

[65] 2 Kings ix. 30.

[66] Chap. 23. v. 40, the Vulgate has it εστιβιζω τους οφθαλμους σουo.

[67] Hartmanni Praxis Chemiatrica, p. 598.

[68] Plinii Hist. Nat. xxxiii. 6.

9. Some of the compounds of arsenic were also known to the ancients; though they were neither acquainted with this substance in the metallic state, nor with its oxide; the nature of which is so violent that had it been known to them it could not have been omitted by Dioscorides and Pliny.

The word σανδαραχη (_sandarache_) occurs in Aristotle, and the term αρῥενιχον (_arrhenichon_) in Theophrastus.[69] Dioscorides uses likewise the same name with Aristotle. It was applied to a scarlet-coloured mineral, which occurs native, and is now known by the name of _realgar_. It is a compound of arsenic and sulphur. It was employed in medicine both externally and internally, and is recommended by Dioscorides, as an excellent remedy for an inveterate cough.

[69] Περι των λιθων, c. 71.

_Auripigmentum_ and _arsenicum_ were names given to the native yellow sulphuret of arsenic. It was used in the same way, and considered by Dioscorides and Pliny as of the same nature with realgar. But there is no reason for supposing that the ancients were acquainted with the compositions of either of these bodies; far less that they had any suspicion of the existence of the metal to which we at present give the name of arsenic.

Such is a sketch of the facts known to the ancients respecting metals. They knew the six malleable metals which are still in common use, and applied them to most of the purposes to which the moderns apply them. Scarcely any information has been left us of the methods employed by them to reduce these metals from their ores. But unless the ores were of a much simpler nature than the modern ores of these metals, of which we have no evidence, the smelting processes with which the ancients were familiar, could scarcely have been contrived without a knowledge of the substances united with the different metals in their ores, and of the means by which these foreign bodies could be separated, and the metals isolated from all impurities. This doubtless implied a certain quantity of chemical knowledge, which having been handed down to the moderns, served as a foundation upon which the modern science of chemistry was gradually reared: at the same time it will be admitted that this foundation was very slender, and would of itself have led to little. Most of the oxides, sulphurets, &c., and almost all the salts into which these metallic bodies enter, were unknown to the ancients.

Besides the working in metals there were some other branches of industry practised by the ancients, so intimately connected with chemical science, that it would be improper to pass them over in silence. The most important of these are the following:

II.--COLOURS USED BY PAINTERS.

It is well known that the ancient Grecian artists carried the art of painting to the highest degree of perfection, and that their paintings were admired and sought after by the most eminent and accomplished men of antiquity; and Pliny gives us a catalogue of a great number of first-rate pictures, and a historical account of a vast many celebrated painters of antiquity. In his own time, he says, the art of painting had lost its importance, statues and tablets having came in place of pictures.

Two kinds of colours were employed by the ancients; namely, the florid and the austere. The florid colours, as enumerated by Pliny, were _minium_, _armenium_, _cinnaberis_, _chrysocolla_, _purpurissum_, and _indicum purpurissum_.

The word _minium_ as used by Pliny means _red lead_; though Dioscorides employs it for bisulphuret of mercury or cinnabar.

_Armenium_ was obviously an ochre, probably of a yellow or orange colour.

_Cinnaberis_ was bisulphuret of mercury, which is known to have a scarlet colour. Dioscorides employs it to denote a vegetable red colour, probably similar to the resin at present called _dragon’s blood_.

_Chrysocolla_ was a green-coloured paint, and from Pliny’s description of it, could have been nothing else than carbonate of copper or malachite.

_Purpurissum_ was a _lake_, as is obvious from the account of its formation given by Pliny. The colouring matter is not specified, but from the term used there can be little doubt that it was the liquor from the shellfish that yielded the celebrated purple dye of the Tyrians.

_Indicum purpurissum_ was probably _indigo_. This might be implied from the account of it given by Pliny.

The austere colours used by the ancient painters were of two kinds, native and artificial. The native were _sinopis_, _rubrica_, _parætonium_, _melinum_, _eretria_, _auripigmentum_. The artificial were, _ochra_, _cerussa usta_, _sandaracha_, _sandyx_, _syricum_, _atramentum_.

_Sinopis_ is the red substance now known by the name of reddle, and used for marking. On that account it is sometimes called _red chalk_. It was found in Pontus, in the Balearian islands, and in Egypt. The price was three denarii, or 1_s._ 11¼_d._ the pound weight. The most famous variety of _sinopis_ was from the isle of Lemnos; it was sold sealed and stamped: hence it was called _sphragis_. It was employed to adulterate minium. In medicine it was used to appease inflammation, and as an antidote to poison.

_Ochre_ is merely sinopis heated in a covered vessel. The higher the temperature to which it has been exposed the better it is.

_Leucophorum_ is a compound of

6 lbs. sinopis of Pontus, 10 lbs. siris, 2 lbs. melinum,

triturated together for thirty days. It was used to make gold adhere to wood.

_Rubrica_ from the name, was probably a red ochre.

_Parætonium_ was a white colour, so called from a place in Egypt, where it was found. It was obtained also in the island of Crete, and in Cyrene. It was said to be a combination of the froth of the sea consolidated with mud. It consisted probably of carbonate of lime. Six pounds of it cost only one denarius.

_Melinum_ was also a white-coloured powder found in Melos and Samos in veins. It was most probably a carbonate of lime.

_Eretria_ was named from the place where it was found. Pliny gives its medical properties, but does not inform us of its colour. It is impossible to say what it was.

_Auripigmentum_ was yellow sulphuret of arsenic. It was probably but little used as a pigment by the ancient painters.

_Cerussa usta_ was red lead.

_Sandaracha_ was red sulphuret of arsenic. The pound of sandaracha cost 5 as.: it was imitated by red lead. Both it and _ochra_ were found in the island Topazos in the Red Sea.

_Sandyx_ was made by torrefying equal parts of true sandaracha and sinopis. It cost half the price of sandaracha. Virgil mistook this pigment for a plant, as is obvious from the following line:

Sponte sua sandix, pascentes vestiet agnos.[70]

[70] Bucol. iv. 1. 45.

_Siricum_ is made by mixing sinopis and sandyx.

_Atramentum_ was obviously from Pliny’s account of it _lamp-black_. He mentions ivory-black as an invention of Apelles: it was called _elephantinum_. There was a native atramentum, which had the colour of sulphur, and got a black colour artificially. It is not unlikely that it contained sulphate of iron, and that it got its black colour from the admixture of some astringent substance.

The ink of the ancients was lamp-black mixed with water, containing gum or glue dissolved in it. _Atramentum indicum_ was the same as our _China ink_.

The _purpurissum_ was a high-priced pigment. It was made by putting _creta argentaria_ (a species of white clay) into the caldrons containing the ingredients for dying purple. The creta imbibed the purple colour and became _purpurissum_. The first portion of _creta_ put in constituted the finest and highest-priced pigment. The portions put in afterwards became successively worse, and were, of consequence lower priced. We see, from this description, that it was a lake similar to our modern cochineal lakes.[71]

[71] Plinii Hist. Nat. xxxv. 6.

That the purpurissum indicum was indigo is obvious from the statement of Pliny, that when thrown upon hot coals it gives out a beautiful purple flame. This constitutes the character of indigo. Its price in Pliny’s time was ten denarii, or six shillings and five-pence halfpenny the Roman pound; which is equivalent to 8_s._ 7⅓_d._ the avoirdupois.

Though few or none of the ancient pictures have been preserved, yet several specimens of the colours used by them still remain in Rome and in the ruins of Herculaneum. Among others the fresco paintings, in the baths of Titus, still remain; and as these were made for a Roman emperor, we might expect to find the most beautiful and costly colours employed in them. These paints, and some others, were examined by Sir Humphrey Davy, in 1813, while he was in Rome. From his researches we derive some pretty accurate information respecting the colours employed by the painters of Greece and Rome.

1. _Red paints._ Three different kinds of red were found in a chamber opened in 1811, in the baths of Titus, namely, a bright orange red, a dull red, and a brown red. The bright orange red was _minium_, or _red lead_; the other two were merely two varieties of iron ochres. Another still brighter red was observed on the walls; it proved, on examination, to be _vermilion_ or _cinnabar_.

2. _Yellow paints._ All the _yellows_ examined by Davy proved to be _iron ochres_, sometimes mixed with a little _red lead_. Orpiment was undoubtedly employed, as is obvious from what Pliny says on the subject: but Davy found no traces of it among the yellow colours which he examined. A very deep yellow, approaching orange, which covered a piece of stucco in the ruins near the monument of Caius Cestius, proved to be protoxide of lead, or massicot, mixed with some red lead. The yellows in the Aldobrandini pictures were all ochres, and so were those in the pictures on the walls of the houses at Pompeii.

3. _Blue paints._ Different shades of blues are used in the different apartments of the baths of Titus, which are darker or lighter, as they contain more or less carbonate of lime with which the blue pigment had been mixed by the painter. This blue pigment turned out, on examination, to be a frit composed of alkali and silica, fused together with a certain quantity of oxide of copper. This was the colour called χυανος (_kyanos_) by the Greeks, and _cæruleum_ by the Romans. Vitruvius gives the method of preparing it by heating strongly together sand, carbonate of soda, and filings of copper. Davy found that fifteen parts by weight of anhydrous carbonate of soda, twenty parts of powdered opaque flints, and three parts of copper filings, strongly heated together for two hours, gave a substance exactly similar to the blue pigment of the ancients, and which, when powdered, produced a fine deep blue colour. This cæruleum has the advantage of remaining unaltered even when the painting is exposed to the actions of the air and sun.

There is reason to suspect, from what Vitruvius and Pliny say, that glass rendered blue by means of cobalt constituted the basis of some of the blue pigments of the ancients; but all those examined by Davy consisted of glass tinged blue by copper, without any trace of cobalt whatever.

4. _Green paints._ All the green paints examined by Davy proved to be carbonates of copper, more or less mixed with carbonate of lime. I have already mentioned that verdigris was known to the ancients. It was no doubt employed by them as a pigment, though it is not probable that the acetic acid would be able to withstand the action of the atmosphere for a couple of thousand years.

5. _Purple paints._ Davy ascertained that the colouring matter of the ancient purple was combustible. It did not give out the smell of ammonia, at least perceptibly. There is little doubt that it was the _purpurissum_ of the ancients, or a clay coloured by means of the purple of the buccinum employed by the Syrians in the celebrated purple dye.

6. _Black and brown paints._ The black paints were lamp-black: the browns were some of them ochres and some of them oxides of manganese.

7. _White paints._ All the ancient white paints examined by Davy were carbonates of lime.[72] We know from Pliny that white lead was employed by the ancients as a pigment; but it might probably become altered in its nature by long-continued exposure to the weather.

[72] Phil. Trans. 1814, p. 97.

III.--GLASS.

It is admitted by some that the word which in our English Bible is translated crystal, means glass, in the following passage of Job: “The gold and the crystal cannot equal it.”[73] Now although the exact time when Job was written is not known, it is admitted on all hands to be one of the oldest of the books contained in the Old Testament. There are strong reasons for believing that it existed before the time of Moses; and some go so far as to affirm that there are several allusions to it in the writings of Moses. If therefore glass were known when the Book of Job was written, it is obvious that the discovery of it preceded the commencement of history. But even though the word used in Job should not refer to glass, there can be no doubt that it was known at a very early period; for glass beads are frequently found on the Egyptian mummies, and they are known to have been embalmed at a very remote period. The first Greek author who uses the word glass (ὑαλος, _hyalos_) is Aristophanes. In his comedy of The Clouds, act ii.

## scene 1, in the ridiculous dialogue between Socrates and Strepsiades,

the latter announces a method which had occurred to him to pay his debts. “You know,” says he, “the beautiful transparent stone used for kindling fire.” “Do you mean glass (τον ὕαλον, _ton hyalon_)?” replied Socrates. “I do,” was the answer. He then describes how he would destroy the writings by means of it, and thus defraud his creditors. Now this comedy was acted about four hundred and twenty-three years before the beginning of the Christian era. The story related by Pliny, respecting the discovery of this beautiful and important substance, is well known. Some Phœnician merchants, in a ship loaded with carbonate of soda from Egypt, stopped, and went ashore on the banks of the river Belus: having nothing to support their kettles while they were dressing their food, they employed lumps of carbonate of soda for that purpose. The fire was strong enough to fuse some of this soda, and to unite it with the fine sand of the river Belus: the consequence of this was the formation of glass.[74] Whether this story be entitled to credit or not, it is clear that the discovery must have originated in some such accident. Pliny’s account of the manufacture of glass, like his account of every other manufacture, is very imperfect: but we see from it that in his time they were in the habit of making coloured glasses; that colourless glasses were most highly prized, and that glass was rendered colourless then as it is at present, by the addition of a certain quantity of oxide of manganese. Colourless glass was very high priced in Pliny’s time. He relates, that for two moderate-sized colourless drinking-glasses the Emperor Nero paid 6000 sistertii, which is equivalent to 25_l._ of our money.

[73] Job xxviii. 17.

[74] Plinii Hist. Nat. xxxvi. 26.

Pliny relates the story of the man who brought a vessel of malleable glass to the Emperor Tiberius, and who, after dimpling it by dashing it against the floor, restored it to its original shape and beauty by means of a hammer; Tiberius, as a reward for this important discovery, ordered the artist to be executed, in order, as he alleged, to prevent gold and silver from becoming useless. But though Pliny relates this story, it is evident that he does not give credit to it; nor does it deserve credit. We can assign no reason why malleable substances may not be transparent; but all of them hitherto known are opaque. Chloride of silver, chloride of lead and iron constitute no exception, for they are not malleable, though by peculiar contrivances they may be extended; and their transparency is very imperfect.

Many specimens of the coloured glasses made by the ancients still remain, particularly the beads employed as ornaments to the Egyptian mummies. Of these ancient glasses several have been examined chemically by Klaproth, Hatchett, and some other individuals, in order to ascertain the substances employed to give colour to the glass. The following are the facts that have been ascertained:

1. _Red glass._ This glass was opaque, and of a lively copper-red colour. It was probably the kind of red glass to which Pliny gave the name of hæmatinon. Klaproth analyzed it, and obtained from 100 grains of it the following constituents:

Silica 71 Oxide of lead 10 Oxide of copper 7·5 Oxide of iron 1 Alumina 2·5 Lime 1·5 ----- 93·5[75]

[75] Beitrage, vi. 140.

No doubt the deficiency was owing to the presence of an alkali. From this analysis we see that the colouring matter of this glass was _red oxide of copper_.

2. _Green glass._ The colour was light verdigris-green, and the glass, like the preceding, was opaque. The constituents from 100 grains were,

Silica 65 Black oxide of copper 10 Oxide of lead 7·5 Oxide of iron 3·5 Lime 6·5 Alumina 5·5 ----- 98·0[76]

[76] Ibid., p. 142.

Thus it appears that both the red and green glass are composed of the same ingredients, though in different proportions. Both owe their colour to copper. The red glass is coloured by the red oxide of that metal; the green by the black oxide, which forms green-coloured compounds, with various acids, particularly with carbonic acid and with silica.

3. _Blue glass._ The variety analyzed by Klaproth had a sapphire-blue colour, and was only translucent on the edges. The constituents from 100 grains of it were,

Silica 81·5 Oxide of iron 9·5 Alumina 1·5 Oxide of copper 0·5 Lime 0·25 ----- 93·25[77]

[77] Beitrage, p. 144.

From this analysis it appears that the colouring matter of this glass was oxide of iron: it was therefore analogous to the lapis lazuli, or ultramarine, in its nature.

Davy, as has been formerly noticed, found another blue glass, or frit, coloured by means of copper; and he showed that the blue paint of the ancients was often made from this glass, simply by grinding it to powder.

Klaproth could find no cobalt in the blue glass which he examined; but Davy found the transparent blue glass vessels, which are along with the vases, in the tombs of Magna Græcia, tinged with cobalt; and he found cobalt in all the transparent ancient blue glasses with which Mr. Millingen supplied him. The mere fusion of these glasses with alkali, and subsequent digestion of the product with muriatic acid, was sufficient to produce a sympathetic ink from them.[78] The transparent blue beads which occasionally adorn the Egyptian mummies have also been examined, and found coloured by cobalt. The opaque glass beads are all tinged by means of oxide of copper. It is probable from this that all the transparent blue glasses of the ancients were coloured by cobalt; yet we find no allusion to cobalt in any of the ancient authors. Theophrastus says that copper (χαλκος, _chalcos_) was used to give glass a fine colour. Is it not likely that the impure oxide of cobalt, in the state in which they used it, was confounded by them with χαλκος (_chalcos_)?

[78] Phil. Trans. 1815, p. 108.

IV.--VASA MURRHINA.

The Romans obtained from the east, and particularly from Egypt, a set of vessels which they distinguished by the name of _vasa murrhina_, and which were held by them in very high estimation. They were never larger than to be capable of containing from about thirty-six to forty cubic inches. One of the largest size cost, in the time of Pliny, about 7000_l._ Nero actually gave for one 3000_l._ They began to be known in Rome about the latter days of the republic. The first six ever seen in Rome were sent by Pompey from the treasures of Mithridates. They were deposited in the temple of Jupiter in the capitol. Augustus, after the battle of Actium, brought one of these vessels from Egypt, and dedicated it also to the gods. In Nero’s time they began to be used by private persons; and were so much coveted that Petronius, the favourite of that tyrant, being ordered for execution, and conceiving that his death was owing to a wish of Nero to get possession of a vessel of this kind which he had, broke the vessel in pieces in order to prevent Nero from gaining his object.

There appear to have been two kinds of these vasa murrhina; those that came from Asia, and those that were made in Egypt. The latter were much more common, and much lower priced than the former, as appears from various passages in Martial and Propertius.

Many attempts have been made, and much learning displayed by the moderns to determine the nature of these celebrated vessels; but in general these attempts were made by individuals too little acquainted with chemistry and with natural history in general to qualify them for researches of so difficult a nature. Some will have it that they consisted of a kind of gum; others that they were made of glass; others, of a particular kind of shell. Cardan and Scaliger assure us that they were _porcelain_ vessels; and this opinion was adopted likewise by Whitaker, who supported it with his usual violence and arrogance. Many conceive them to have been made of some precious stone, some that they were of _obsidian_; Count de Veltheim thinks that they were made of the Chinese _agalmatolite_, or _figure stone_; and Dr. Hager conceives that they were made from the Chinese stone _yu_. Bruckmann was of opinion that these vessels were made of sardonyx, and the Abbé Winckelmann joins him in the same conclusion.

Pliny informs us that these vasa murrhina were formed from a species of stone dug out of the earth in Parthia, and especially in Carimania, and also in other places but little known.[79] They must have been very abundant at Rome in the time of Nero; for Pliny informs us that a man of consular rank, famous for his collection of vasa murrhina, having died, Nero forcibly deprived his children of these vessels, and they were so numerous that they filled the whole inside of a theatre, which Nero hoped to have seen filled with Romans when he came to it to sing in public.

[79] Plinii Hist. Nat. xxxvii. 2.

It is clear that the value of these vessels depended on their size. Small vessels bore but a small price, while that of large vessels was very high; this shows us that it must have been difficult to procure a block of the stone out of which they were cut, of a size sufficiently great to make a large vessel.

These vessels were so soft that an impression might be made upon them with the teeth; for Pliny relates the story of a man of consular rank, who drank out of one, and was so enamoured with it that he bit pieces out of the lip of the cup: “Potavit ex eo ante hos annos consularis, ob amorem abraso ejus margine.” And what is singular, the value of the cup, so far from being injured by this abrasure, was augmented: “ut tamen injuria ilia pretium augeret; neque est hodie murrhini alterius præstantior indicatura.”[80] It is clear from this that the matter of these vessels was neither rock crystal, agate, nor any precious stone whatever, all of which are too hard to admit of an impression from the teeth of a man.

[80] Plinii Hist. Nat. xxxvii. 2.

The lustre was vitreous to such a degree that the name _vitrum murrhinum_ was given to the artificial fabric, in Egypt.

The splendour was not very great, for Pliny observes, “Splendor his sine viribus nitorque verius quam splendor.”

The colours, from their depth and richness, were what gave these vessels their value and excited admiration. The principal colours were purple and white, disposed in undulating bands, and usually separated by a third band, in which the two colours being mixed, assumed the tint of flame: “Sed in pretio varietas colorum, subinde circumagentibus se maculis in purpuram candoremque, et tertium ex utroque ignescentem, velut per transitum coloris, purpura rubescente, aut lacte candescente.”

Perfect transparency was considered as a defect, they were merely translucent; this we learn not merely from Pliny, but from the following epigram of Martial:

Nos bibimus vitro, tu murra, Pontice: quare? Prodat perspicuus ne duo vina calix.

Some specimens, and they were the most valued, exhibited a play of colour like the rainbow: Pliny says they were very commonly spotted with “sales, verrucæque non eminentes, sed ut in corpore etiam plerumque sessiles.” This, no doubt, refers to foreign bodies, such as grains of pyrites, antimony, galena, &c., which were often scattered through the substances of which the vessels were made.

Such are all the facts respecting the vasa murrhina to be found in the writings of the ancients; they all apply to fluor spar, and to nothing else; but to it they apply so accurately as to leave little doubt that they were in reality vessels of fluor spar, similar to those at present made in Derbyshire.[81]

[81] This opinion was first formed by Baron Born, and stated in his Catalogue of Minerals in M. E. Raab’s collection, i. 356. But the evidences in favour of it have been brought forward with great clearness and force by M. Roziere. See Jour. de Min. xxxvi. 193.

The artificial vasa murrhina made at Thebes, in Egypt, were doubtless of glass, coloured to imitate fluor spar as much as possible, and having the semi-transparency which distinguishes that mineral. The imitations being imperfect, these factitious vessels were not much prized nor sought after by the Romans, they were rather distributed among the Arabians and Ethiopians, who were supplied with glass from Egypt.

Rock crystal is compared by Pliny with the stone from which the vasa murrhina were made; the former, in his opinion, had been coagulated by cold, the latter by heat. Though the ancients, as we have seen, were acquainted with the method of colouring glass, yet they prized colourless glass highest on account of its resemblance to rock crystal; cups of it, in Pliny’s time, had supplanted those of silver and gold; Nero gave for a crystal cup 150,000 sistertii, or 625_l._

V.--DYEING AND CALICO-PRINTING.

Very little has been handed down by the ancients respecting the processes of dyeing. It is evident, from Pliny, that they were acquainted with madder, and that preparations of iron were used in the black dyes. The most celebrated dye of all, the _purple_, was discovered by the Tyrians about fifteen centuries before the Christian era. This colour was given by various kinds of shellfish which inhabit the Mediterranean. Pliny divides them into two genera; the first, comprehending the smaller species, he called _buccinum_, from their resemblance to a hunting-horn; the second, included those called _purpura_: Fabius Columna thinks that these were distinguished also by the name of _murex_.

These shellfish yielded liquor of different shades of colour; they were often mixed in various proportions to produce particular shades of colour. One, or at most two drops of this liquor were obtained from each fish, by extracting and opening a little reservoir placed in the throat. To avoid this trouble, the smaller species were generally bruised whole, in a mortar; this was also frequently done with the large, though the other liquids of the fish must have in some degree injured the colour. The liquor, when extracted, was mixed with a considerable quantity of salt to keep it from putrifying; it was then diluted with five or six times as much water, and kept moderately hot in leaden or tin vessels, for eight or ten days, during which the liquor was often skimmed to separate all the impurities. After this, the wool to be dyed, being first well washed, was immersed and kept therein for five hours; then taken out, cooled, and again immersed, and continued in the liquor till all the colour was exhausted.[82]

[82] Plinii Hist. Nat. ix. 38.

To produce particular shades of colour, carbonate of soda, urine, and a marine plant called _fucus_, were occasionally added: one of these colours was a very dark reddish violet--“Nigrantis rosæ colore sublucens.”[83] But the most esteemed, and that in which the Tyrians

## particularly excelled, resembled coagulated blood--“laus ei summa

in colore sanguinis concreti, nigricans aspectu, idemque suspectu refulgens.”[84]

[83] Ibid., ix. 36.

[84] Plinii Hist. Nat. ix. c. 38.

Pliny says that the Tyrians first dyed their wool in the liquor of the purpura, and afterwards in that of the buccinum; and it is obvious from Moses that this purple was known to the Egyptians in his time.[85] Wool which had received this double Tyrian dye (_dia bapha_) was so very costly that, in the reign of Augustus, it sold for about 36_l._ the pound. But lest this should not be sufficient to exclude all from the use of it but those invested with the very highest dignities of the state, laws were made inflicting severe penalties, and even death, upon all who should presume to wear it under the dignity of an emperor. The art of dyeing this colour came at length to be practised by a few individuals only, appointed by the emperors, and having been interrupted about the beginning of the twelfth century all knowledge of it died away, and during several ages this celebrated dye was considered and lamented as an irrecoverable loss.[86] How it was afterwards recovered and made known by Mr. Cole, of Bristol, M. Jussieu, M. Reaumur, and M. Duhamel, would lead us too far from our present object, were we to relate it: those who are interested in the subject will find an historical detail in Bancroft’s work on Permanent Colours, just referred to.

[85] Exodus xxv. 4.

[86] See Bancroft on Permanent Colours, i. 79.

There is reason to suspect that the Hebrew word translated _fine linen_ in the Old Testament, and so celebrated as a production of Egypt, was in reality _cotton_, and not linen. From a curious passage in Pliny, there is reason to believe that the Egyptians in his time, and probably long before, were acquainted with the method of calico-printing, such as is still practised in India and the east. The following is a literal translation of the passage in question:

“There exists in Egypt a wonderful method of dyeing. The white cloth is stained in various places, not with dye stuffs, but with substances which have the property of absorbing (_fixing_) colours, these applications are not visible upon the cloth; but when they are dipped into a hot caldron of the dye they are drawn out an instant after dyed. The remarkable circumstance is, that though there be only one dye in the vat, yet different colours appear upon the cloth; nor can the colour be afterwards removed.”[87]

[87] Plinii Hist. Nat. xxxv. 11.

It is evident enough that these substances applied were different mordants which served to fix the dye upon the cloth; the nature of these mordants cannot be discovered, as nothing specific seems to have been known to Pliny. The modern mordants are solutions of alumina; of the oxide of tin, oxide of iron, oxide of lead, &c.: and doubtless these, or something equivalent to these, were the substances employed by the ancients. The purple dye required no mordant, it fixed itself to the cloth in consequence of the chemical affinity which existed between them. Whether indigo was used by the ancients as a dye does not appear, but there can be no doubt, at least, that its use was known to the Indians at a very remote period.

From these facts, few as they are, there can be little doubt that dyeing, and even calico-printing, had made considerable progress among the ancients; and this could not have taken place without a considerable knowledge of colouring matters, and of the mordants by which these colouring matters were fixed. These facts, however, were probably but imperfectly understood, and could not be the means of furnishing the ancients with any accurate chemical knowledge.

VI.--SOAP.

Soap, which constitutes so important and indispensable an article in the domestic economy of the moderns, was quite unknown to the ancient inhabitants of Asia, and even of Greece. No allusion to it occurs in the Old Testament. In Homer, we find Nausicaa, the daughter of the King of the Phæacians, using nothing but water to wash her nuptial garments:

They seek the cisterns where Phæacian dames Wash their fair garments in the limped streams; Where gathering into depth from falling rills, The lucid wave a spacious bason fills. The mules unharness’d range beside the main, Or crop the verdant herbage of the plain. Then emulous the royal robes they lave, And plunge the vestures in the cleansing wave. _Odyssey_, vi. 1. 99.

We find, in some of the comic poets, that the Greeks were in the habit of adding wood-ashes to water to make it a better detergent. Wood-ashes contain a certain portion of carbonate of potash, which of course would answer as a detergent; though, from its caustic qualities, it would be injurious to the hands of the washerwomen. There is no evidence that carbonate of soda, the _nitrum_ of the ancients, was ever used as a detergent; this is the more surprising, because we know from Pliny that it was employed in dyeing, and one cannot see how a solution of it could be employed by the dyers in their processes without discovering that it acted powerfully as a detergent.

The word _soap_ (_sapo_) occurs first in Pliny. He informs us that it was an invention of the Gauls, who employed it to render their hair shining; that it was a compound of wood-ashes and tallow, that there were two kinds of it, _hard_ and _soft_ (_spissus et liquidus_); and that the best kind was made of the ashes of the beech and the fat of goats. Among the Germans it was more employed by the men than the women.[88] It is curious that no allusion whatever is made by Pliny to the use of soap as a detergent; shall we conclude from this that the most important of all the uses of soap was unknown to the ancients?

[88] Plinii Hist. Nat. xxviii. 12. The passage of Pliny is as follows: “Prodest et sapo; Gallorum hoc inventum rutilandis capillis ex sevo et cinere. Optimus fagino et caprino, duobus modis, spissus et liquidus: uterque apud Germanos majore in usu viris quam feminis.”

It was employed by the ancients as a pomatum; and, during the early part of the government of the emperors, it was imported into Rome from Germany, as a pomatum for the young Roman beaus. Beckmann is of opinion that the Latin word _sapo_ is derived from the old German word _sepe_, a word still employed by the common people of Scotland.[89]

[89] Hist. of Inventions, iii. 239.

It is well known that the state of soap depends upon the alkali employed in making it. _Soda_ constitutes a _hard_ soap, and _potash_ a _soft_ soap. The ancients being ignorant of the difference between the two alkalies, and using wood-ashes in the preparation of it, doubtless formed soft soap. The addition of some common salt, during the boiling of the soap, would convert the soft into hard soap. As Pliny informs us that the ancients were acquainted both with hard and soft soap, it is clear that they must have followed some such process.

VII.--STARCH.

The manufacture of starch was known to the ancients. Pliny informs us that it was made from wheat and from _siligo_, which was probably a variety or sub-species of wheat. The invention of starch is ascribed by Pliny to the inhabitants of the island of Chio, where in his time the best starch was still made. Pliny’s description of the method employed by the ancients of making starch is tolerably exact. Next to the China starch that of Crete was most celebrated; and next to it was the Egyptian. The qualities of starch were judged of by the weight; the lightest being always reckoned the best.

VIII.--BEER.

That the ancients were acquainted with wine is universally known. This knowledge must have been nearly coeval with the origin of society; for we are informed in Genesis that Noah, after the flood, planted a vineyard, and made wine, and got intoxicated by drinking the liquid which he had manufactured.[90] Beer also is a very old manufacture. It was in common use among the Egyptians in the time of Herodotus, who informs us that they made use of a kind of wine made from barley, because no vines grew in their country.[91] Tacitus informs us, that in his time it was the drink of the Germans.[92] Pliny informs us that it was made by the Gauls, and by other nations. He gives it the name of _cerevisia_ or _cervisia_; the name obviously alluding to the grain from which it was made.

[90] Genesis ix. 20.

[91] “Oinô d’ ek kritheôn pepoiêmenô diachreontai; ou gar sphi eisi en tê chôrê ampeloi.” Euterpe chap. 77.

[92] De Moribus Germanorum, c. 23. “Potui humor ex hordeo aut frumento in quandam similitudinem vini corruptus.”

But though the ancients seem acquainted with both wine and beer, there is no evidence of their having ever subjected these liquids to distillation, and of having collected the products. This would have furnished them with ardent spirits or alcohol, of which there is every reason to believe they were entirely ignorant. Indeed, the method employed by Dioscorides to obtain mercury from cinnabar, is a sufficient proof that the true process of distillation was unknown to them. He mixed cinnabar with iron filings, put the mixture into a pot, to the top of which a cover of stoneware was luted. Heat was applied to the pot, and when the process was at an end, the mercury was found adhering to the inside of the cover. Had they been aware of the method of distilling the quicksilver ore into a receiver, this imperfect mode of collecting only a small portion of the quicksilver, separated from the cinnabar, would never have been practised. Besides, there is not the smallest allusion to ardent spirits, either in the writings of the poets, historians, naturalists, or medical men of ancient Greece; a circumstance not to be accounted for had ardent spirits been known, and applied even to one-tenth of the uses to which they are put by the moderns.

IX.--STONEWARE.

The manufacture of stoneware vessels was known at a very early period of society. Frequent allusions to the potter’s wheel occur in the Old Testament, showing that the manufacture must have been familiar to the Jewish nation. The porcelain of the Chinese boasts of a very high antiquity indeed. We cannot doubt that the processes of the ancients were similar to those of the moderns, though I am not aware of any tolerably accurate account of them in any ancient author whatever.

Moulds of plaster of Paris were used by the ancients to take casts precisely as at present.[93]

[93] Plinii Hist. Nat. xxxv. 12.

The sand of Puzzoli was used by the Romans, as it is by the moderns, to form a mortar capable of hardening under water.

Pliny gives us some idea of the Roman bricks, which are known to have been of an excellent quality. There were three sizes of bricks used by the Romans.

1. Lydian, which were 1½ foot long and 1 foot broad.

2. Tetradoron, which was a square of 16 inches each side.

3. Pentadoron, which was a square, each side of which was 20 inches long.

Doron signifies the palm of the hand: of course it was equivalent to 4 inches.

X.--PRECIOUS STONES AND MINERALS.

Pliny has given a pretty detailed description of the precious stones of the ancients; but it is not very easy to determine the specific minerals to which he alludes.

1. The description of the diamond is tolerably precise. It was found in Ethiopia, India, Arabia, and Macedonia. But the Macedonian diamond, as well as the adamas cyprius and siderites, were obviously not diamonds, but soft stones.

2. The _emerald_ of the ancients (_smaragdus_) must have varied in its nature. It was a green, transparent, hard stone; and, as colour was the criterion by which the ancients distinguished minerals and divided them into species, it is obvious that very different minerals must have been confounded together, under the name of emerald. Sapphire, beryl, doubtless fluor spar when green, and probably even serpentine, nephrite, and some ores of copper, seem to have occasionally got the same name. There is no reason to believe that the _emerald_ of the moderns was known before the discovery of America. At least it has been only found in modern times in America. Some of the emeralds described by Pliny as losing their colour by exposure to the sun, must have been fluor spars. There is a remarkably deep and beautiful green fluor spar, met with some years ago in the county of Durham, in one of the Weredale mines that possesses this property. The emeralds of the ancients were of such a size (13½ feet, large enough to be cut into a pillar), that we can consider them in no other light than as a species of rock.

3. Topaz of the ancients had a green colour, which is never the case with the modern topaz. It was found in the island Topazios, in the Red Sea.[94] It is generally supposed to have been the _chrysolite_ of the moderns. But Pliny mentions a statue of it six feet long. Now chrysolite never occurs in such large masses. Bruce mentions a green substance in an emerald island in the Red Sea, not harder than glass. Might not this be the emerald of the ancients?

[94] The word topazo is said by Pliny to signify, in the language of the Troglodytes, _to seek_.

4. _Calais_, from the locality and colour was probably the Persian turquoise, as it is generally supposed to be.

5. Whether the _prasius_ and _chrysoprasius_ of Pliny were the modern stones to which these names are given, we have no means of determining. It is generally supposed that they are, and we have no evidence to the contrary.

6. The _chrysolite_ of Pliny is supposed to be our _topaz_: but we have no other evidence of this than the opinion of M. Du Tems.

7. _Asteria_ of Pliny is supposed by Saussure to be our sapphire. The lustre described by Pliny agrees with this opinion. The stone is said to have been very hard and colourless.

8. _Opalus_ seems to have been our _opal_. It is called, Pliny says, _pæderos_ by many, on account of its beauty. The Indians called it _sangenon_.

9. _Obsidian_ was the same as the mineral to which we give that name. It was so called because a Roman named Obsidianus first brought it from Egypt. I have a piece of obsidian, which the late Mr. Salt brought from the locality specified by Pliny, and which possesses all the characters of that mineral in its purest state.

10. _Sarda_ was the name of _carnelian_, so called because it was first found near Sardis. The _sardonyx_ was also another name for _carnelian_.

11. Onyx was a name sometimes given to a rock, _gypsum_; sometimes it was a light-coloured _chalcedony_. The Latin name for chalcedony was _carchedonius_, so called because Carthage was the place where this mineral was exposed to sale. The Greek name for Carthage was Καρχηδων (_carchedon_).

12. _Carbunculus_ was the garnet; and _anthrax_ was a name for another variety of the same mineral.

13. The _oriental amethyst_ of Pliny was probably a sapphire. The fourth species of amethyst described by Pliny, seems to have been our amethyst. Pliny derives the name from α (_a_) and μυθη (_mythe_), _wine_, because it has not quite the colour of wine. But the common derivation is from α and μυθυω, _to intoxicate_, because it was used as an amulet to prevent intoxication.

14. The _sapphire_ is described by Pliny as always opaque, and as unfit for engraving on. We do not know what it was.

15. The _hyacinth_ of Pliny is equally unknown. From its name it was obviously of a blue colour. Our hyacinth has a reddish-brown colour, and a great deal of hardness and lustre.

16. The _cyanus_ of Pliny may have been our _cyanite_.

17. _Astrios_ agrees very well, as far as the description of Pliny goes, with the variety of felspar called _adularia_.

18. _Belioculus_ seems to have been our _catseye_.

19. _Lychnites_ was a violet-coloured stone, which became electric by heat. Unless it was a _blue tourmalin_, I do not know what it could be.

20. The _jasper_ of the ancients was probably the same as ours.

21. _Molochites_ may have been our _malachite_. The name comes from the Greek word μολοχη, _mallow_, or _marshmallow_.

22. Pliny considers _amber_ as the juice of a tree concreted into a solid form. The largest piece of it that he had ever seen weighed 13 lbs. Roman weight, which is nearly equivalent to 9¾ lbs. avoirdupois. _Indian amber_, of which he speaks, was probably _copal_, or some transparent resin. It may be dyed, he says, by means of _anchusa_ and the _fat of kids_.

23. _Lapis specularis_ was foliated sulphate of lime, or selenite.

24. _Pyrites_ had the same meaning among the ancients that it has among the moderns; at least as far as iron pyrites or bisulphuret of iron is concerned. Pliny describes two kind of pyrites; namely, the _white_ (_arsenical pyrites_), and the _yellow_ (iron pyrites). It was used for striking fire with steel, in order to kindle tinder. Hence the name _pyrites_ or _firestone_.

25. _Gagates_, from the account given of it by Pliny, was obviously pit-coal or jet.

26. _Marble_ had the same meaning among the ancients that it has among the moderns. It was sawed by the ancients into slabs, and the action of the saw was facilitated by a sand brought for the purpose from Ethiopia and the isle of Naxos. It is obvious that this sand was powdered corundum, or emery.

27. _Creta_ was a name applied by the ancients not only to chalk, but to _white clay_.

28. _Melinum_ was an _oxide of iron_. Pliny gives a list of one hundred and fifty-one species of stones in the order of the alphabet. Very few of the minerals contained in this list can be made out. He gives also a list of fifty-two species of stones, whose names are derived from a fancied resemblance which the stones are supposed to bear to certain parts of animals. Of these, also, very few can be made out.

XI.--MISCELLANEOUS OBSERVATIONS.

The ancients seem to have been ignorant of the nature and properties of air, and of all gaseous bodies. Pliny’s account of air consists of a single sentence: “Aër densatur nubibus; furit procellis.” “Air is condensed in clouds, it rages in storms.” Nor is his description of water much more complete, since it consists only of the following phrases: “Aquæ subeunt in imbres, rigescunt in grandines, tumescunt in fluctus, præcipitantur in torrentes.”[95] “Water falls in showers, congeals in hail, swells in waves, and rushes down in torrents.” In the thirty-eighth chapter of the second book, indeed, he professes to treat of _air_; but the chapter contains merely an enumeration of meteorological phenomena, without once touching upon the nature and properties of air.

[95] Plinii Hist. Nat. ii. 63.

Pliny, with all the philosophers of antiquity, admitted the existence of the four elements, fire, air, water, and earth; but though he enumerates these in the fifth chapter of his first book, he never attempts to explain their nature or properties. Earth, among the ancients, had two meanings, namely, the planet on which we live, and the soil upon which vegetables grow. These two meanings still exist in common language. The meaning afterwards given to the _term_, earth, by the chemists, did not exist in the days of Pliny, or, at least, was unknown to him; a sufficient proof that chemistry, in his time, had made no progress as a science; for some notions respecting the properties and constituents of those supposed four elements must have constituted the very foundation of scientific chemistry.

The ancients were acquainted with none of the acids which at present constitute so numerous a tribe, except _vinegar_, or _acetic acid_; and even this acid was not known to them in a state of purity. They knew none of the saline bases, except lime, soda, and potash, and these very imperfectly. Of course the whole tribe of salts was unknown to them, except a very few, which they found ready formed in the earth, or which they succeeded in forming by the action of vinegar on lead and copper. Hence all that extensive and most important branch of chemistry, consisting of the combinations of the acids and bases, on which scientific chemistry mainly depends, must have been unknown to them.

Sulphur occurring native in large quantities, and being remarkable for its easy combustibility, and its disagreeable smell when burning, was known in the very earliest ages. Pliny describes four kinds of sulphur, differing from each other, probably, merely in their purity. These were

1. Sulphur vivum, or apyron. It was dug out of the earth solid, and was doubtless pure, or nearly so. It alone was used in medicine.

2. Gleba--used only by fullers.

3. Egula--used also by fullers.

Pliny says, it renders woollen stuffs white and soft. It is obvious from this, that the ancients knew the method of bleaching flannel by the fumes of sulphur, as practised by the moderns.

4. The fourth kind was used only for sulphuring matches.

Sulphur, in Pliny’s time, was found native in the Æolian islands, and in Campania. It is curious that he never mentions Sicily, whence the great supply is drawn for modern manufacture.

In medicine, it seems to have been only used externally by the ancients. It was considered as excellent for removing eruptions. It was used also for fumigating.

The word _alumen_, which we translate _alum_, occurs often in Pliny; and is the same substance which the Greeks distinguished by the name of στυπτηρια (_stypteria_). It is described pretty minutely by Dioscorides, and also by Pliny. It was obviously a natural production, dug out of the earth, and consequently quite different from our alum, with which the ancients were unacquainted. Dioscorides says that it was found abundantly in Egypt; that it was of various kinds, but that the slaty variety was the best. He mentions also many other localities. He says that, for medical purposes, the most valued of all the varieties of alumen were the _slaty_, the _round_, and the _liquid_. The slaty alumen is very white, has an exceedingly astringent taste, a strong smell, is free from stony concretions, and gradually cracks and emits long capillary crystals from these rifts; on which account it is sometimes called _trichites_. This description obviously applies to a kind of slate-clay, which probably contained pyrites mixed with it of the decomposing kind. The capillary crystals were probably similar to those crystals at present called _hair-salt_ by mineralogists, which exude pretty abundantly from the shale of the coal-beds, when it has been long exposed to the air. _Hair-salt_ differs very much in its nature. Klaproth ascertained by analysis, that the _hair-salt_ from the quicksilver-mines in Idria is sulphate of magnesia, mixed with a small quantity of sulphate of iron.[96] The _hair-salt_ from the abandoned coal-pits in the neighbourhood of Glasgow is a double salt, composed of sulphate of alumina, and sulphate of iron, in definite proportions; the composition being

[96] Beitrage, iii. 104.

1 atom protosulphate of iron, 1½ atom sulphate of alumina, 15 atoms water.

I suspect strongly that the capillary crystals from the schistose alumen of Dioscorides were nearly of the same nature.

From Pliny’s account of the uses to which alumen was applied, it is quite obvious that it must have varied very much in its nature. _Alumen nigrum_ was used to strike a black colour, and must therefore have contained iron. It was doubtless an impure native sulphate of iron, similar to many native productions of the same nature still met with in various parts of the world, but not employed; their use having been superseded by various artificial salts, more definite in their nature, and consequently more certain in their application, and at the same time cheaper and more abundant than the native.

The alumen employed as a mordant by the dyers, must have been a sulphate of alumina more or less pure; at least it must have been free from all sulphate of iron, which would have affected the colour of the cloth, and prevented the dyer from accomplishing his object.[97]

[97] “Quoniam inficiendis claro colore lanis candidum liquidumque utilissimum est, contraque fuscis et obscuris nigrum.”--_Plinii_, xxxv. 15.

What the _alumen rotundum_ was, is not easily conjectured. Dioscorides says, that it was sometimes made artificially; but that the artificial alumen rotundum was not much valued. The best, he says, was full of air-bubbles, nearly white, and of a very astringent taste. It had a slaty appearance, and was found in Egypt or the Island of Melos.

The _liquid alumen_ was limpid, milky, of an equal colour, free from hard concretions, and having a fiery shade of colour.[98] In its nature, it was similar to the alumen candidum; it must therefore have consisted chiefly, at least, of sulphate of alumina.

[98] See Dioscorides, lib. v. c. 123. Plinii Hist. Nat. xxxv. 18.

Bitumen and naphtha were known to the ancients, and used by them to give light instead of oil; they were employed also as external applications in cases of disease, and were considered as having the same virtues as sulphur. It is said, that the word translated _salt_ in the New Testament--“Ye are the salt of the earth: but if the salt have lost his savour, wherewith shall it be salted? It is henceforth good for nothing, but to be cast out, and to be trodden under foot of men”[99]--it is said, that the word salt in this passage refers to asphalt, or bitumen, which was used by the Jews in their sacrifices, and called _salt_ by them. But I have not been able to find satisfactory evidence of the truth of this opinion. It is obvious from the context, that the word translated _salt_ could not have had that meaning among the Jews; because salt never can be supposed to lose its savour. Bitumen, while liquid, has a strong taste and smell, which it loses gradually by exposure to the air, as it approaches more and more to a solid form.

[99] Matthew v. 13.--“Ὑμεις εστε το ἁλας της γης· εαν δε το ἁλας μωρανθη, εν τινι ἁλισθησεται· εις ουδεν ισχωει ετι ει μη βληθηναι εξω, και καταπατεισθαι ὑπο των ανθρωπων.”

Asphalt was one of the great constituents of the Greek fire. A great bed of it still existing in Albania, supplied the Greeks with this substance. Concerning the nature of the Greek fire, it is clear that many exaggerated and even fabulous statements have been published. The obvious intention of the Greeks being, probably, to make their invention as much dreaded as possible by their enemies. Nitre was undoubtedly one of the most important of its constituents; though no allusion whatever is ever made. We do not know when _nitrate of potash_, the nitre of the moderns, became known in Europe. It was discovered in the east; and was undoubtedly known in China and India before the commencement of the Christian era. The property of nitre, as a supporter of combustion, could not have remained long unknown after the discovery of the salt. The first person who threw a piece of it upon a red-hot coal would observe it. Accordingly we find that its use in fireworks was known very early in China and India; though its prodigious expansive power, by which it propels bullets with so great and destructive velocity, is a European invention, posterior to the time of Roger Bacon.

The word _nitre_ (רתנ) had been applied by the ancients to _carbonate of soda_, a production of Egypt, where it is still formed from sea-water, by some unknown process of nature in the marshes near Alexandria. This is evident, not merely from the account given of it by Dioscorides and Pliny; for the following passage, from the Old Testament, shows that it had the same meaning among the Jews: “As he that taketh away a garment in cold weather, is as vinegar upon nitre: so is he that singeth songs to a heavy heart.”[100] Vinegar poured upon saltpetre produces no sensible effect whatever, but when poured upon carbonate of soda, it occasions an _effervescence_. When saltpetre came to be imported to Europe, it was natural to give it the same name as that applied to carbonate of soda, to which both in taste and appearance it bore some faint resemblance. Saltpetre possessing much more striking properties than carbonate of soda much more attention was drawn to it, and it gradually fixed upon itself the term _nitre_, at first applied to a different salt. When this change of nomenclature took place does not appear; but it was completed before the time of Roger Bacon, who always applies the term _nitrum_ to our nitrate of potash and never to carbonate of soda.

[100] Proverbs xxv. 20.

In the preceding history of the chemical facts known to the ancients, I have taken no notice of a well-known story related of Cleopatra. This magnificent and profligate queen boasted to Antony that she would herself consume a million of sistertii at a supper. Antony smiled at the proposal, and doubted the possibility of her performing it. Next evening a magnificent entertainment was provided, at which Antony, as usual, was present, and expressed his opinion that the cost of the feast, magnificent as it was, fell far short of the sum specified by the queen. She requested him to defer computing till the dessert was finished. A vessel filled with vinegar was placed before her, in which she threw two pearls, the finest in the world, and which were valued at ten millions of sistertii; these pearls were dissolved by the vinegar,[101] and the liquid was immediately drunk by the queen. Thus she made good her boast, and destroyed the two finest pearls in the world.[102] This story, supposing it true, shows that Cleopatra was aware that vinegar has the property of dissolving pearls. But not that she knew the nature of these beautiful productions of nature. We now know that pearls consist essentially of carbonate of lime, and that the beauty is owing to the thin concentric laminæ, of which they are composed.

[101] “Cujus asperitas visque in tabem margeritas resolvit.”

[102] Plinii Hist. Nat. ix. 35.

Nor have I taken any notice of lime with which the ancients were well acquainted, and which they applied to most of the uses to which the moderns put it. Thus it constituted the base of the Roman mortar, which is known to have been excellent. They employed it also as a manure for the fields, as the moderns do. It was known to have a corrosive nature when taken internally; but was much employed by the ancients externally, and in various ways as an application to ulcers. Whether they knew its solubility in water does not appear; though, from the circumstance of its being used for making mortar, this fact could hardly escape them. These facts, though of great importance, could scarcely be applied to the rearing of a chemical structure, as the ancients could have no notion of the action of acids upon lime, or of the numerous salts which it is capable of forming. Phenomena which must have remained unknown till the discovery of the acids enabled experimenters to try their effects upon limestone and quicklime. Not even a conjecture appears in any ancient writer that I have looked into, about the difference between quicklime and limestone. This difference is so great that it must have been remarked by them, yet nobody seems ever to have thought of attempting to account for it. Even the method of burning or calcining lime is not described by Pliny; though there can be no doubt that the ancients were acquainted with it.

Nor have I taken any notice of leather or the method of tanning it. There are so many allusions to leather and its uses by the ancient poets and historians, that the acquaintance of the ancients with it is put out of doubt. But so far as I know, there is no description of the process of tanning in any ancient author whatever.

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