Practical blowpipe assaying

„ - . UNWERSnTg/mlFORNIA 1 COLLEGE o/- MINING DEPARTMENTAL LIBRARY BEQUEST OF SAMUELBENEDICTCHRISTY PROFESSOR OF MINING AND METALLURGY 1885-1914 BLOWPIPE ASSAYING LONDON: 1'HINTED BY SPOTTISWOOUK AND CO., XEW-STUKKT SQUAUK AND PABMAJIEXT STBKKT S. B. CHRISTY, PEACTICAL / BLOWPIPE ASSAYING BY GEORGE ATTWOOD \\ . S., ASSOC. INST. C.E., F.C.S., MEM. AM. INST. M.E., ETC, NEW YORK D. VAN NOSTRAND 23 MURRAY STREET 1881 /9s PREFACE. IN publishing this small volume of Practical Blowpipe Assaying it is the wish of the Author to record the methods of assaying adopted by himself during eighteen years of foreign travel, in hopes that they will assist others who have to make examinations where complete assay offices and laboratories are not to be found. Plattner's instruments and apparatus have been used as much as possible ; but, as the methods here adopted have in so many instances differed materially from those of Plattner and other authorities on this subject, different apparatus has been devised to suit the requirements. The general system of assaying adopted is a simple and a direct one. Sixty-four elements are mentioned in this work, and the assayer may be asked to de- termine the presence of one or all. The system being a direct one, directions are laid down for the separate determination of each. Practice will, however, soon en- able the assayer to determine from one assay piece or sample the presence of several elements instead of one, and thereby save time and labour. For assaying, the Author has always adopted the system of checking his assays by synthetic assays, or, in other words, preparing an assay with a weighed quantity of the chemically pure metal or element to be determined, and mixing it with 30371 fi vi PKEFACE. materials resembling as nearly as possible those of the ore, alloy, or compound to be assayed, and then, after the completion of the assay, adding to the direct assay the loss found to have been incurred in the synthetic. In the assay of gold and silver alloys a check assay is necessary. In silver assays it is absolutely necessary, and by using the same most accurate results can be obtained. Silver and gold coins, bars, and ingots can be valued or stamped for market, and found to be correctly assayed, by following the methods hereafter described. , Whilst this little book has been going through the press, my old friend, Professor John Morris, has, with his usual kindness to all friends of science, assisted most materially in the correction of the proof sheets and in the revision of the work, and to him the Author now returns his best thanks. The following list of books has been used in the preparation of this work, and in some cases material has been drawn from them. 4, UPPER GLOUCESTER PLACE, N.W. BOOKS CONSULTED IN THE PREPARATION OF THIS WORK. 'A Manual of Practical Assaying.' By John Mitchell, F.C.S. Edited by William Crookes, F.R.S. London, 1873. ' Plattner's Manual of Qualitative and Quantitative Analysis with the Blowpipe.' By Professor Th. Richter. Translated by H. B. Cornwall, A.M. , E.M. New York, 1873. ' A Manual of Metallurgy.' By George Hogarth Makins, M.R.C.S. , F.C.S. London, 1873. 'Chemical and Pharmaceutical Manipulations.' By Professor Campbell Morfit and Clarence Morfit. Philadelphia, 1857. ' A Text-Book of Mineralogy. ' By Edward Salisbury Dana. New York, 1877. ' Manual of Determinative Mineralogy. ' With an Introduction on 'Blowpipe Analysis.' By Professor George J. Brush. New York, 1878. 'Elements of Metallurgy.' By J. Arthur Phillips, M. Inst. C.E., F.G.S., F.C.S., &c. London, 1874. 1 Determination of Minerals by the Blowpipe.' By Dr. C. W. C. Fuchs. Translated and edited by F. W. Danby, M.A., F.G.S. London. 'The Metallurgy of Silver and Lead.' By Robert H. Lamborn, Ph.D. London, 1878. ' The Blowpipe : a Guide to its Use in the Determination of Salts and Minerals.' By Professor George W. Plympton, C.E., &c. New York, 1874. ' A System of Instruction in Quantitative Chemical Analysis.' By Dr. C. Remigius Fresenius. London, 1860. ' Manual of Qualitative Chemical Analysis.' By Dr. C. Remigius Fresenius. New York, 1864. ' Handbook of Chemistry.' By Professors F. A. Abel and C. L. Bloxam. ' Chemical News.' David Forbes. Nos. 380, 384, 392, 396, 398, and 412. ' Journal Chemical Society.' May 1879. Geo. Attwood on the Assay of the Ores and Compounds of Mercury by the Blowpipe. CONTENTS. INTRODUCTION PAGE xiii PAET I. DESCRIPTION OF THE MOUTH BLOWPIPE AND APPARATUS. BLOWPIPE . . . . HOW TO USE THE BLOWPIPE BLOWPIPE FUEL . . . LAMPS „ FLAMES . . . SUPPORTS . „ WEIGHING IN- STRUMENTS . PAGE 3 7 10 12 17 BLOWPIPE TOOLS, SMALL IM- PLEMENTS AND APPARATUS . 22 BATEA . . . 29 „ REAGENTS, DRY AND WET . 32 „ TEST OR PROOF METALS 34 PART II. Q UA LIT A TIVE DETERMINA TION. COLOURS OF SUBLIMATES ON CHARCOAL POTASSIUM . . . . SODIUM C.ESIUM RUBIDIUM . BARIUM STRONTIUM . CALCIUM . . . 49 43 MAGNESIUM . . 50 45 ALUMINIUM . . 52 46 MANGANESE . . 52 47 TIN .... . . 55 47 ANTIMONY . . 55 47 SILVER 5G 48 GOLD r,o CONTEXTS. PAGE I)AOK CHROMIUM . . 57 BORON 83 IRON . 57 SILICIUM .... 83 COBALT . . 61 GLUCINUM . . . . 84 NICKEL . . 62 LANTHANUM 85 ZINC . 63 YTTRIUM C(\ CADMIUM . 65 TERBIUM .... oO 86 COPPER . . 66 TANTALUM . . . . 86 LEAD . 66 URANIUM .... 87 INDIUM . . 68 TUNGSTEN . . . . 87 BISMUTH . 68 VANADIUM .... 88 TITANIUM . . . 69 PALLADIUM . . . . 88 MERCURY . 71 RUTHENIUM 89 PLATINUM . . 71 CERIUM ... . . 89 LITHIUM . 72 DIDYMIUM .... 90 OXYGEN . . . 73 ERBIUM 91 HYDROGEN . . 73 NIOBIUM, or COLUMBIUM 91 NITROGEN . . 74 THORIUM ' 92 FLUORINE . 75 THALLIUM .... 92 CHLORINE . . 75 MOLYBDENUM , . . . 92 BROMINE . 76 RHODIUM .... 93 IODINE . . 77 IRIDIUM 93 SULPHUR . . . 77 OSMIUM 93 PHOSPHORUS . . . 78 SELENIUM . . . . 93 ARSENIC . 80 TELLURIUM .... 94 CARBON 82 94 PAET III. ASSAY OF SILVER . 97 ASSAY OF IRON . . . 159 „ GOLD . . 125 „ NICKEL 163 „ MERCURY . 135 „ COBALT . . . 164 „ COPPER . . . 145 „ NICKEL AND CO- „ LEAD . . 150 BALT 165 „ BISMUTH . . . 153 „ COAL . . . 171 TIN . 156 CONTENTS. XI PAET IV. PAGE TABLE OF THE ENGLISH MINT VALUE OF GOLD ACCORDING TO ITS FINE- NESS 179 VALUE OF GOLD COINS IN THE UNITED STATES OF AMERICA . .191 PAGK EXPLANATION OF AMERICAN GOLD TABLE . . . 192 TABLE OF THE AMERICAN MINT VALUE OF GOLD ACCORDING TO ITS FINE- NESS . .195 INDEX INTEODUGTION INTRODUCTION. XV IN searching for and determining the different elements mentioned in the following tables, the method adopted is a direct examination for each separate element. The beginner will find, by following the methods here de- scribed, that his task will be simplified, and when practice has made him proficient he can then look for several elements out of one sample. Table of ' Metallic ' Elements of Commercial Value. Names of the Elements Symbols Atomic Weight Names of the Elements Symbols Atomic Weight Potassium . K 39-1 Chromium Cr 26-7 Sodium Na 23 Iron . Fe 28 Csesium « Cs 133 Cobalt Co 29-5 Rubidium . Rb 85-4 Nickel Ni 29-5 Barium Ba 68-5 Zinc . Zn 32-6 Strontium . Sr 43-8 Cadmium Cd 56 Calcium Ca 20 Copper Cu 31-7 Magnesium Mg 12 Lead Pb 103-5 Aluminium Al 13-5 Indium In Manganese Mn 27'5 Bismuth Bi 210 Tin . Sn 59 Titanium Ti 25 Antimony . Sb 122 Mercury Hg 100 Silver Ag 108 Platinum Pt 987 Gold. Au 197 Lithium Li 7 Table of ' Non-Metallic ' Elements of Commercial Value. Names of the Elements Symbols Atomic Weight Names of the Elements Symbols 1 Atomic Weight Oxygen 0 8 Sulphur . s 16 Hydrogen H 1 Phosphorus p 31 Nitrogen N 14 Arsenic As 75 Fluorine Fl 19 Carbon C 6 Chlorine Cl 35-5 Boron B 11 Bromine Br 80 Silicium . Si 14 Iodine I 127 XVI INTRODUCTION. Table of ' Metallic ' Elements of No Commercial Value. Names of the Elements Symbols Atomic Weight Names of the Elements Symbols Atomic Weight Glucinum . Be 4-7 Cerium Ce 46 Lanthanum La 46 Didymium Di 48 Yttrium Y — Erbium Er — Terbium . Tr — Niobium . Nb — Tantalum . Ta 37-6 Thorium . Th 59-5 Uranium . U 60 Thallium . Tl 203 Tungsten . W 92 Molybdenum Mo 48 Vanadium V 68-6 Rhodium . Rh 52-2 Palladium , Pd 53-3 Iridium Ir 99 Ruthenium Ru 52-2 Osmium . Os 99-6 Table of ' Non-Metallic ' Elements of No Commercial Value. Names of the Elements Symbols Atomic Weight Names of the Elements Symbols Atomic Weight Selenium . Tellurium . Se Te 39-7 64°5 Zirconium . Zi 44-8 EXPLANATION OF THE TEEMS USED IN THE TABLE OF THE ELEMENTS. Element. — One of the ultimate indecomposable constituents of any kind of matter, as oxygen and hydrogen, which are the elements of water. Atomic Weight is the weight of the atom of an element as com- pounded with that of the atom of another element, ascertained from the proportions by weight in which they combine ; or, leaving out of view the hypothetical idea of an atom, it is the number expressing the proportions by weight in which the elements combine, one of the elements, either hydrogen or oxygen, being assumed as the unit for comparison with the others. Oxygen and hydrogen combine to form water in the ratio of 1 of hydrogen to 8 of oxygen ; and 1 and 8 are therefore the combining proportions of hydrogen and oxygen — also called, to avoid hypothesis, their * combining equivalents. ' Symbol. — An abbreviation of the name of one of the elements. Some of the abbreviations are taken from the Latin meaning of one of the words, such as silver, Ag, from argentum. xviii INTRODUCTION. The following- elements are nearly always found combined with oxygen, and they are spoken of as oxides in the qualitative determi- nation. For instance, in the case of Potassium (page 45) the expres- sion, * The presence of potash is detected by the blowpipe in two ways,' is used. Potassium .... Potash. Sodium ..... Soda. Calcium Lime. Magnesium .... Magnesia. Aluminium .... Alumina. Titanium ..... Titanic acid. Lithium Lithia. Phosphorus .... Phosphoric acid. Silicium ..... Silicic acid. Glucinum Glucina. Tantalum ..... Tantalic acid. Tungsten Tungstic acid. Vanadium ..... Vanadic acid. Niobium Niobic acid. Thorium Thoria. Molybdenum .... Molybdic acid. Zirconium Zirconia. The new earths announced as occurring in gadolinite and sa- marsldte — as mosandrin, philippin, decipin, scandin, holrnin, thulin, samarin, ytterbin — are not alluded to in this work, as the characters of some of them are still a subject of enquiry. (See Delafontaine Conipt Eend. 1880. x. c. 221). PART I. DESCRIPTION OF THE MOUTH BLOWPIPE AND APPARATUS, BLOWPIPE. HOW TO USE THE BLOWPIPE. BLOWPIPE FUEL. LAMPS. FLAMES. SUPPORTS. WEIGHING INSTRUMENTS. TOOLS, SMALL IMPLEMENTS, AND APPARATUS. REAGENTS, WET AND DRY. TEST OR PROOF METALS. BLOWPIPE. THE mouth blowpipe is a small and convenient instrument by which a blast of air may be forced through the flame produced by the combustion of a candle or lamp fed with oil or alcohol, so as to intensify the heat of the blast to such an extent as to render it a substitute on a small scale for the furnaces used in smelting ores as well as in assaying. It furnishes what may be termed a miniature blast furnace, which is so perfectly under control that the tem- perature can be made intense or mild at the will of the operator; therefore the many advantages it affords the mining explorer, the chemist, and metallurgist are great. It is so portable that the little instrument with all the necessary apparatus and reagents, both wet and dry, re- quired for qualitative determinations as well as for assays, can be packed up in a box twelve inches square. For a rapid determination of ores and minerals it has no qual and it possesses in careful hands most accurate means of estimating the actual percentage of metals in most of the commercial ores. In the assay of gold and silver alloys the blowpipe affords the operator very correct results, and also in the examination of mineral coals it is invaluable. Makins states that he has seen a skilful operator fuse a farthing (a considerable weight of copper) by the blast afforded by the lungs alone, and without fatigue. B 2 BLOWPIPE AND APPARATUS. PART I. Blowpipes are made in many forms, but that devised by Gahn and recommended by Berzelius may be con- sidered to best fulfil all the requirements for general use. It consists of a slightly taper- ing tube, fitting into a cylindri- cal chamber one inch long and half an inch in diameter. The chamber serves to collect any moisture which may form in the tube during blowing. Into the side of this chamber a much smaller tube in diameter, about one inch in length, is inserted at a right angle. The end of this tube is covered with a platinum tip (fig. 2) having a fine aper- ture. Although silver and brass tips answer very well it is always best, when they can be procured, to employ platinum tips, as they are easily cleaned from soot, &c., by heating over the spirit lamp. The assayer should be provided wdth three or four tips, the finest being used for qualitative work, having an aperture of 0*4 milli- metre in diameter. Those required for reductions should have a larger aperture. The blowpipe should be provided with a trumpet-shaped mouth- piece, which is best made of horn or ivory turned in the lathe. The use of this mouthpiece very much diminishes the PART I. BLOWPIPE. 5 fatigue of the muscles of the lips in long-continued blow- ing, and the difficulty at first felt in preventing the escape of air at the corners of the mouth is easily overcome by practice. The mouthpiece is shown in the drawing (fig. 1). The length of the blowpipe must be adjusted to the sight of the operator, so that the test object may be held at such a distance as to be distinctly visible. HOW TO USE THE BLOWPIPE. The blowpipe is held firmly in the right hand (see fig. 3), and in such a manner as to facilitate a direction of the flame upon the substance under pro- FIG. 3. cess. The assay is held upon a support by the left hand, care being taken to retain the arms in their fixed position, for unsteadiness will prevent an uninter- rupted action of the blast on the assay. The mouth furnishes the blast, which derives its force from the muscles of the cheek. To prevent fatigue of the respiratory organs, communication between the mouth and chest must be closed during the blowing, and breath- ing maintained through the nostrils. A few days' practice removes all the difficulty at first experienced in producing a continuous steady current, and it is by this means only that proficiency can be acquired. The operation is com- menced by filling the mouth with air, expanding the cheeks, and then, keeping up a steady forcible pressure with the muscles, respiration being allowed to go on as usual through the nose. The blowing is not unhealthy, and with a little perse- verance is soon acquired, and assays made for several hours in succession without fatiguing even the muscles of the cheeks. 6 BLOWPIPE AND APPARATUS. PART I. Beginners are apt to imagine that they must blow with considerable force, and also if they stop blowing for a moment, that the assay will be spoiled. In both these cases a little practice convinces them of their error, and they soon find that although the operator appears to be trying to burst his cheeks in his efforts to fuse an assay, he is quietly using his cheeks as a miniature air-bellows, and not tiring himself in the least. A practised operator, directly he lays down his blowpipe, even after a continuous blow of fifteen minutes or more, will speak to a com- panion with ease, without a single gasp, proving that the blowing has not exhausted his breath. BLOWPIPE FUEL. Pure olive oil is the best fuel for reductions and quan- titative fusions. Alcohol makes a good fuel for qualitative work, and is especially useful for the scorification and cupellation of silver and gold alloys, as well as for heating glass tubes and matrasses, and is employed in the assay for mercury. By adding about one-seventh part of turpentine to alcohol the reducing strength is increased. Kefined rapeseed oil answers very well as a blowpipe fuel. The ordinary illuminating gas makes a good fuel, but it is much better for oxidation than for reduction. The flame of a wax candle, or even the flame of an ordinary candle, answers the purpose when nothing better can be found. Although assays can be made from the flame supplied by candles, yet such assays are generally attended with considerable difficulty, owing to the small volume of the flame. Paraffin melted and poured into a lamp having an open top and a broad wick attached to one end answers PART I. BLOWPIPE FUEL AND LAMPS. 7 nearly all the purposes required for blowpipe fuel. The great objection is that soot accumulates on the glass tubes or porcelain vessels when heated over the flame. In some countries — the interior of South America, for instance — alcohol cannot be procured except at a great cost ; but as crude spirits made from sugar-cane, &c., are generally plentiful in such places, they afford the explorer a good substitute for alcohol as well as oil, owing to the presence of more carbon than pure alcohol contains. The spirits, however, contain some water ; and after the fuel is about one-half consumed it is best to empty the lamp and fill again with fresh spirits. BLOWPIPE LAMPS. The form of blowpipe lamp generally used is the one proposed by Berzelius and used by Plattner (see fig. 4). The cistern is made either of sheet brass or tinned sheet iron, about 4^ inches long, and slightly tapering from 1£ inch in width to 1 inch at the end nearest the ope- rator, and it is usually coated with a dark lacquer. It is made to slide on a Grerman silver or brass rod, and can be adjusted to the required height by a screw. At one end of the lamp is an opening for introducing oil, and at the other is the wick-holder. Roth of these openings are closed by screw caps, with the thread cut on the inside. The escape of oil is prevented by washers cemented to the caps with shell-lac and wax. The wick-holder has its greatest breadth at right angles to the axis of the lamp, and must be cut off obliquely, to allow the flame to be directed downwards. Cylindrical woven wicks, such as are made for the Argand*burners, are best adapted for this lamp, and they are pressed flat and folded lengthwise, so as to be introduced fourfold. 8 BLOWPIPE AND APPARATUS. PART I. The wicks must not fit too tightly, and should be free from lime, which is sometimes used in the bleaching of them. On the blowpipe stand an arm is attached, which has a metal ring on the top, about If inch in diameter. FIG. 4. The arm is movable, and, like the cistern, it can be moved up and down, and it is kept in position by a small thumb screw. The ring is covered with either a network of iron or platinum wire, and is used for holding substances which require to be heated. PART I. BLOWPIPE LAMPS. The lamp just described is best adapted for burning oils, but alcohol can be used .if required. A small glass lamp for burning alcohol is used in the mercury assay also for heating substances in the glass matrasses, &c. (fig. 5). Flet- Jm. 6. FIG. 6. , „ ' . x ' -, . (Half size.) (Half size.) cher (of Warrmgton) has in- vented a most useful blow- pipe lamp, which possesses the great advantage of being clean and portable, and it can be easily refilled by melting solid paraffin and pouring it into the reservoir. The lamp is constructed of either tin or German silver (fig. 6). The paraffin reservoir is about 1 J inch in length, and 1 J inch in width at its widest part, and tapers to \ inch at the wick end, the depth being about 1 inch. The wick is about \ inch in width and about -f^ of an inch thick, and is held in its place by being run through a wick-holder at- tached to the narrow end of the reservoir. The reservoir is held by a flat-bottomed hollow cup of a similar form, but made larger, so that when the lamp has been used the reservoir can be reversed and packed away without injuring the wick (fig. 7). The reservoir is made to slide up and down on a strip of metal soldered to the Top View of FIG. cup, and by means of a thumb screw it can Lam?'ze be inclined to any angle necessary. For all ordinary blowpipe work this lamp answers every purpose, and it is one of the most convenient and cleanly lamps that are in use at the present time. The 10 BLOWPIPE AND APPAKATUS. PART I. FIG. 8. (Half size.) lamp required for using the ordinary illumination gas is of the simplest description. Brush recommends the following : — ' A blowpipe gas lamp may be readily made by selecting an iron or brass tube, 8 inches in length and f of an inch in bore, bending it at a right angle at the middle, and passing it through a block properly cut, or placing it in a mould, which is then filled writh melted lead. The top of the tube is then flattened, and the proper inclina- tion given to the orifice by filing ' (see fig. 8). FLAMES OBTAINED BY MEANS OF THE BLOWPIPE BLAST. The assayer produces, when using the blowpipe, two distinct flames. They are called the oxidising and re- ducing flames. Practical knowledge of the way to create and use these flames is essential, and until such know- ledge has been acquired the operator cannot proceed in his manipulations with safety. The production of the flames can be acquired in one hour's lesson, or from studying and carrying out the fol- lowing instructions. Dr. Lamborn describes the blow- pipe flames as follows : — ' When we examine the flame of a common candle, we discover that it is composed of four parts. PART I. BLOWPIPE FLAMES 11 (Half size.) ' At the base a small crescent (fig. 9) a 6, with a clear blue colour ; higher up, and in the centre of the flame, the dark conical portion c ; surrounding this is FIG. 9. the luminous portion d\ and exterior to the last is the scarcely perceptible mantle / e. The student has to remark the nature of two of these divisions : the exterior non-luminous part / e, which is composed of gases already saturated with oxygen, that under certain circumstances goes over to bodies with which the flame is brought in contact, and hence constitutes the oxidising flame ; and secondly, the luminous portion d, which consists of gases not yet saturated with oxygen, and therefore capable of extracting that element from easily reducible oxides, and hence called the reducing flame. ' When the point of the blowpipe is held one-third of FIG. 10. (Half size.) FIG. 11. (Half size.) oi the wick in the lamp /** flame, as in ' - - '* figure 10, a flame is pro- duced by blowing that is long, slender, and blue, which is hottest at the outer- most point a, and is an oxidising flame. This action, however, is strongest slightly beyond a, about cZ, in the stream of heated gas. ' If now the point of the blowpipe be held as in fig. 11, somewhat higher than before, and not quite within the flame, a larger and more luminous cone of burning gases may be driven in 'the direction b c ; within the bright portion of the flame at a the above-mentioned chemical 12 BLOWPIPE AND APPARATUS. PART I. action on oxides takes place, which causes this to be called the reducing flame.'' The most important matter is to produce optionally oxidation or reduction. Oxidation is very easily performed, whilst reduction requires more practice. Berzelius recommends the ope- rator to take a small grain of tin, place it on charcoal, then direct the blowpipe upon it ; it will soon fuse, and if the operator has not produced a good reducing flame it will become covered with a coat of oxide. The nature of the flame must be altered until, by observation, the proper kind is produced at will. The longer the button of tin is kept bright the better and more expert the operator. BLOWPIPE SUPPORTS. When a substance has to be examined by the blow- pipe it must be held by some means firmly. The article used is called a support. A suitable support should be one that will not fuse at a high heat, combine chemically with the fused body, or prevent its complete heating by rapid conduction. The best supports are charcoal and platinum wire or foil. Charcoal makes an excellent support, as it is infusible; it has great reducing power, and it is also porous, allowing alkalies and fluxes to pass into it, whilst metals and substances that are less fusible remain behind. Soft pine wood makes the best charcoal for blow- pipe work. It should be well charred, and that which snaps or smokes in the fire should be rejected. ' Hard woods' generally contain a large percentage of ash, which contains traces of iron and manganese, and in some quali- PART!. BLOWPIPE SUPPORTS. 13 tative determinations the results are liable to be incorrect by these metals being absorbed by the fluxes. Straight pieces free from knots should be selected, and sawed in the direction of the fibre into oblong supports, about 6 inches in length and 2 inches broad. For qualitative determinations small pieces of charcoal answer every purpose ; and if the pieces used are too small to be held by the hand, they can be supported on a strip of tin or thin sheet iron and the assay proceeded with. The saw for cutting the charcoal should be a ' cross- cut ' saw with fine teeth, and a blade of 5 inches in length, f of an inch in breadth, and -^ of an inch in thickness. Cavities, deep or shallow, according to the substance to be examined, are made by a borer, or by the point of a knife in the charcoal, and the assay placed in the same for treatment. Oxidation, reduction, and fusion are sometimes so rapidly performed on charcoal that the operator is not certain of the result obtained. In such cases platinum in the form of foil or wire is used. Platinum foil is best used in a narrow strip about 3 inches long and 1 inch broad, and it is useful for oxida- tion. The substance which is to be oxidised is placed on it, near one end, and heat is applied by the blowpipe flame upon its under side. The conducting power of platinum is so inconsiderable that the other end may be held between the fingers without inconvenience. For reduction platinum cannot be generally used, as it forms fusible alloys with some of the metals ; nor should sulphides, arsenides, or chlorides be heated in contact with it. Platinum wire should be about 2£ inches long, mode- rately thin, and bent into a hook at one end, which serves 14 BLOWPIPE AND APPARATUS. PAUT 1. as the assay support. The wire may be held in the hand, either with or without a holder, but the latter is more convenient. It is best made out of a piece of hard wood or iron turned ; and, to prevent injury to the wires, FIG. 12. (Half size.) holders are used, in which the wire is inserted into the middle of two slits crossing each other at right angles ; the latter are then shut tight by a band which is thrust over them and arranged to screw up and thus hold the wire (see fig. 12). The large end of the holder unscrews, and five or six of the wires can be kept in a small hole bored in the handle. The form used resembles a crotchet- holder in nearly every respect. After the wires have been in use they can be cleaned by warming the ends in a test tube with hydrochloric acid, or by fusing a bead of soda upon it, and then dissolving it in water. To use platinum wire, either heat the hook for a moment over the lamp and then dip it into the flux to be used, or moisten it and dip in the flux. Melt the flux over the lamp, and when a good transparent bead has been obtained add the portion to be assayed to it whilst it is still hot ; or if that is not practicable moisten the flux bead slightly and let the assay adhere to it. Fuse the assay over the lamp, and the appearance of the bead in reference to opacity, colour, and other charac- teristics can be distinctly seen from all sides, and in this way are colorations of the bead by metallic oxides parti- cularly to be distinguished. Some fluxes are so thin that they fall through the loop or hook, but by turning the assay a few times the flux will generally remain on the wire. PART I. BLOWPIPE SUPPOKTS. 15 Platinum wire cannot be used when reduction to the metallic state is required. All oxidation and reduction experiments in which the results are to be known by the colour of the fluxes should be effected upon platinum wire. FIG. 13. (Half size.) FIG. 14. (Half size.) Platinum spoons are useful for heating substances with bisulphate of potash and saltpetre. Two sizes are convenient, made similar to figs. 13 and 14. Crucibles and capsules of fire clay are made by kneading into a thick paste some fine FIG. 15. (Half size.) elutriated fire clay and moulding them as follows : — The crucible mould is made of brass, and consists of three parts — a plug, a box divided into two parts, and a stout ring to keep the box together (figs. 15 and 16). Knead with the fingers some of the elutriated fire clay and make it into small balls, each one a little larger than is necessary to form the crucible re- quired; oil the inside of the box and . the end of the plug ; place the clay B ball in the box, and after pressing the plug on the clay give the plug a couple Box. of sharp blows with a mallet. The box in the meantime must rest on a piece of 16 BLOWPIPE AND APPAEATUS. PART I. (Half size.) hard wood, or upon an anvil (upon which has been pre- viously placed a piece of old cloth or flannel). The plug is then removed, and after that the ring; the box is then separated easily, and the crucible is ready to be dried. They should be dried very slowly at first, and then baked in an oven, muffle, or crucible. Capsules, or roasting dishes, or cups, are made in a hard-wood mould (boxwood being generally used) by pressing the clay with a pestle of the same. The clay is FIG. 17. prepared in a similar manner as it is for moulding the crucibles (fig. 17). Oil both the mould and the end of the pestle, place over the mould a thin piece of paper, take a small ball of the elutriated clay, place it on the paper, and then press and turn the pestle round until the capsule is of an equal thickness. Kemove the pestle, take the paper by two ends, and lift the capsule out and place it to dry, the paper soon falls off, then bake as in the case of the crucibles. Open glass tubes, closed tubes, and bulb tubes, made of hard glass free from lead, are used for the ignition of bodies and minerals which be- come volatile at a high temperature and deposit a subli- mate on the glass tube. Open glass tubes are useful when a substance has to FIG. 18. (Half size.) be ignited in an excess of air. They are made from 4 to 6 inches in length, and from ^ to J of an inch in PART I. BLOWPIPE SUPPOETS. 17 /Half' diameter (fig. 18), of hard glass, and are easily bent to the required angle by heating them over the spirit or oil lamp. Closed and bulb tubes (fig. 19) are employed when substances require heat- ing to the exclusion of air as much as possible. The bulb tube is especially serviceable when ores and rocks have to be examined to see if they contain water. WEIGHING INSTRUMENTS. A fine, delicate, as well as portable assay balance is required for blowpipe assays. Mr. L. Oertling -has con- structed a balance under the author's directions which fulfils all the requirements. The balance is constructed to carry 30 grains in each pan, and to turn distinctly with j^- ^ of a grain- " size of the case is only eight inches square by two inches, deep. To prepare the balance for use, the front cover, which is attached to the case by hinges, is folded back under the case, where it is held by two brass buckles, one on each side of the case. A stand is thus formed. After the two sockets which receive the adjusting screws have been turned outwards, place in them the two screws (which will be found in the drawers), also the third screw, which fits in the back of the lid. By means of the three screws, assisted by the two levels attached to the stand inside, the balance can be placed in a horizontal position. Now hang to the ends of the beam the two stirrup pans, which will be found fixed against the back of the case in notches, from which they can be removed by turning on one side a small latch which moves on a pin. c -6C>0{ ^0- 6> 18 BLOWPIPE AND APPARATUS. PART I. The small milled head button at the top of the stand may be removed, and the fork piece which holds the beam firmly to the stand (without allowing the steel knife-edge to come into contact with the agate planes) taken away. The handle may now be put in its place, and the balance is ready for use. A glass sliding front is included in the balance, which prevents dust and currents of air gaining admission ; also FIG. 20. If two small drawers, in which are carried the adjusting screws, the handle, the set of weights and riders ; also a small pair of brass tweezers to handle the latter. The weights are as follows : — 10 grains I/O grain 010 grain 1 grain 0-5 0-3 0-2 o-i 0-05 0-03 0-02 0-01 PART I. WEIGHING INSTEUMENTS. 19 The riders are made of fine gold wire, and weigh 0-10 grain. They are used to increase the fine weighing capacity of the balance by placing them on the top of the beam (which is graduated) and sliding them from one division to another. At each end of the beam a small steel pointer is fixed, at the back of which are ivory graduated scales. These steel pointers help to indicate the weight of a substance much finer than the weights can be conveniently made. A pair of small metal pans and another pair made of horn complete the balance. The horn pans are used in weighing ores and minerals, also in weighing the globules obtained in the mercury The metal pans are used for weighing alloys and beads of gold, silver, copper, &c. For blowpipe assay purposes another balance is required, which will weigh upwards of 30 ounces, and at the same time must be sensitive and portable. The author, after experimenting for several years, has at last succeeded in constructing an instrument that answers the purpose in all respects. This balance (fig. 21) resembles in some of its features a steelyard. A brass bar a, lOf inches in length, f of an inch in depth, and T\ of an inch in thickness, represents the beam. The beam is finely polished and graduated. On the right-hand side the graduations represent pounds (Ibs.) and ounces ; on the left-hand side the graduations repre- sent fractions of ounces and grains. On the right-hand side there is a large movable weight 6, which can be clamped at will by means of a small set screw c at the top. On the left-hand side there is a light weight d, which slides smoothly along the beam. By sliding the large weight to ^, 1, H, and 2 Ibs. respect- c 2 PART I. WEIGHING INSTRUMENTS. 21 ively, it shows the pounds as marked on the side of the beam, whilst each mark represents 1 ounce. The minor scale to the left represents 1 ounce in its whole graduated length, whilst its subdivisions represent each 10 grains, and by sliding the weight to one-half or one- quarter of these divisions, 5 or 2J- grains may be weighed by estimation. On the left-hand end of the beam there is a weight attached (e) by means of a screw ; it serves as a counterpoise, also as a stop to the light weight. On the right-hand end of the beam there is also a stop (/) to prevent the heavy weight sliding off. The beam is provided with an indicating steel needle g and with a fixed steel knife-edge, which works in rings of hardened steel which are let into the brass part /t, called the beam support. The part h has fixed to it a small arc, graduated into ten divisions, by means of which the balance can be made to weigh much closer by using the sliding weights. It has also a steel hook, which enables the assayer to suspend the instrument by means of a string or wire when he wishes to weigh any substance with great care. The pan (fig. 22) is made of brass or copper, and it is about 3 inches in diameter and 1 inch deep at the centre. The pan is sustained by a steel hook (fig. 21, i), which is connected with the short end of the beam. At the upper end of the hook attachment two hard steel rings are let in, upon which a knife-edge (which is fixed to the beam) works. The hook is sharpened at the point, so that the assayer can weigh small sample bags of ore or minerals without using the pan. The balance weighs 13^ ounces, and with the pan 14^ ounces ; it is very portable, and not liable to get out of repair. To show the capabilities of the balance, the author has 22 BLOWPIPE AND APPARATUS. PART I. recorded the following experiments which he has made with it : — Loaded with 32 ounces = 15,360 grains in the pan, it turns dis- tinctly on the addition of 10 grains. Loaded with 8 ounces = 3,840 grains in the pan, it turns distinctly on the addition of 3 grains. Loaded with 4 ounces = 1,920 grains in the pan, it turns distinctly on the addition of 1 grain. Loaded with ] ounce = 480 grains in the pan, it turns distinctly on the addition of 0'5 grain. Loaded with £ ounce = 240 grains in the pan, it turns distinctly on the addition of 0'2 grain. Loaded with £ ounce = 120 grains in the pan, it turns distinctly on the addition of O'l grain. When the large and small sliding weights both point to zero the instrument is balanced. The readings are always taken from the inner ends of the sliding weights.1 TOOLS, SMALL IMPLEMENTS, AND APPARATUS. One hammer for chipping and breaking rocks and minerals, for making cupels, and for striking the pestle in the steel mortar. Total length of the hammer, about 10 inches; length of hammer head, 2 J inches, having a face about f of an FIG. 23. (One-quarter size.) inch square at one end and coming to a sharp point at the other. It must be made of hard steel (fig. 23). 1 This ba^nce is made only by L. Casella, 147 Holborn Bars, E.G. PART I. TOOLS, SMALL IMPLEMENTS, AND APPARATUS. 23 A small hammer (fig. 24) is required for flattening metallic buttons, and it should be made of highly tem- pered Steel and brightly FIG. 24. (One-quarter size.) polished. A small steel anvil, highly polished, about 1-J- by 1^ inch and ^ inch thick, is useful to flatten metallic beads upon, and to re- move slags from buttons obtained in fusing assays. To prevent the buttons flying off and being lost, always wrap them up in a piece of paper before using the hammer. One of the most necessary implements used in pre- paring ores and minerals for assay is a steel mortar. The mortar consists of three separate pieces, each of which is smoothly turned and made of hard steel (fig. 25). A is the pestle, B is FIG. 25. (Half size.) a cylinder in which the pestle fits tightly, and C is the mortar into which both A and B fit. In using, place the cylinder in the mortar, then add the mineral or rock, place the pestle in the cylinder, and with the hammer strike a few hard blows. (It is best to place the mortar on some firm base before using the ham- mer.) The mineral will soon be reduced fine enough to be removed to an agate mortar for its final grinding. An agate mortar and pestle are used to grind to the finest powder the ores for assay, also to crush up slags for further examination (fig. 26). A mortar about 2 inches in diameter in the clear on 24 BLOWPIPE AND APPARATUS. PART I. the top, and 2J inches on the outside, and -J of an FIG. 26. inch in depth at the bot- tom, answers the pur- pose. A small selection of files is most useful. Flat, round, triangular shapes are best, and they should not be more than 6 inches long. A small knife and a pair of scissors are constantly needed, and should be included with the other tools. A steel magnet, 4 inches long, sharp at the end, like a chisel, is used in the detection of iron, nickel, &c. A horn spoon, made from a bullock's horn, cut, and finely scraped in the inside, so that it is perfectly smooth, is a most useful addenda to the assayer's outfit. The horn is generally hardened by soaking it for some hours in a weak solution of sulphate of iron or copper, after it has been scraped. It is used for vanning or washing ores of all kinds, also to wash slags after they have been powdered, FIG. 27. (Quarter size.) to S66 if the Operation has been carried on suc- cessfully (see fig. 27). Charcoal borers are made of different sizes and shapes. Fig. 28 represents a borer used for boring holes large FIG. 28. (Half size.) enough to make the charcoal furnace, which holds crucibles, mercury retorts, and roasting cups. PART I. TOOLS, SMALL IMPLEMENTS, AND APPAEATUS. 25 Fig. 29 represents the borer mostly used in mak- ing assays of silver and gold FlG- 29« (Half size.) ores. Fig. 30 is a long bore, the small end of which is used for boring holes through the coal cover and sides of the charcoal furnace. The flat end is used for FIG. 30. (Half size.) boring holes on char- coal for qualitative de- terminations. Forceps with platinum tips are used to hold sub- FIG. 31. (| nat. size.) stances directly in the blowpipe flame when testing for fusibility (fig. 31). Brass forceps with very fine points are used to hold small objects, such as the small silver beads obtained in cupellation (fig. 32). FIG. 32. (Half size.) Iron forceps, very strong, are useful in rough work, such as holding a button of metal whilst it is hammered on the anvil, or raising and cleaning the lamp wick (fig. 33). FIG. 33. (Half size.) Cutting shears are used to clip pieces of assay silver, gold, and all kinds of metals after they have been beaten BLOWPIPE AND APPARATUS. PART I. or rolled out. They should be made of good steel, and the blades kept sharp (fig. 34). FIG. 34. (Half size.) FIG. 35. (Half size.) Steel pliers having fine points, with jaws slightly roughed on the inside, are used to remove buttons and beads from slags and cupels, also in sepa- rating a button from slag by gently press- ing the substance after placing it near the inner part of the jaw, or to clean a cupel bead the same way. Good pliers are often strained by placing the substance to be pressed too near the point of the pliers (fig. 35). A magnifying glass composed of two convex lenses is the best, and it answers all the purposes required in blow- pipe work. Two small mixing capsules, one of polished brass, the other of horn, are used to mix the powdered mineral with the flux, and then to pour the charge conveniently into FIG. 36. (Full size.) assay crucible, roasting cup, or paper cornet in the assays (fig. 36). the PART I. TOOLS, SMALL IMPLEMENTS, AND APPARATUS. 27 A small ivory spoon is used to remove fluxes from the bottles, and minerals from the mortar. After a little prac- tice it is not necessary to weigh many of the fluxes, as, the weight once ascertained, the operator can judge by measure (fig. 37). FIG. 37. (Full size.) Two small wire sieves, one having 1,400 holes to the square inch (wire sieving), the other 2,000 holes to the square inch. Punched screens will do, but it is difficult to get them as fine as the sieving. A stand is necessary to hold cupels and cupel moulds for the cupellation of gold and silver. Fig. 38 represents a useful form. The top is made of iron, and is set in a wooden stand to F og prevent the heat affecting the fingers during (Half size.) the operation. (For cupels, see p. 29 ; for moulds, see p. 29.) A small cylinder of hard wood, turned, is used to prepare the soda paper cornets for assays (fig. 39). A small quantity of fine iron and platinum wire is used for holding the small crucibles in the furnace, and the pieces can be cut and bent to suit (fig. 40). The charcoal-holder and furnace is de- scribed fully in the mercury assay. Evaporating dishes and small cups, also watch-glasses, are necessary when acids are used. It is best to have FIG. 39. (Half size.) 28 BLOWPIPE AND APPARATUS. PART I. half a dozen different sizes. FIG. 40. (Full size.) FIG. 41. (Half size.) Figs. 41 and 42 are con- venient sizes. Test tubes for sepa- rating gold from silver are useful (fig. 43). A few small pipe- clay annealing cups to collect the finely-pow- dered gold that has been separated in the test tube from silver by means of acids are useful, as FIG. 43. (Half size.) c D the gold can be dried and annealed in them, and after- wards removed for weighing in one lump. Beaker glasses, a few small funnels, and a stand to match are required (fig. 44). FIG. 44. FIG. 45. A small glass wash bottle is used for washing preci- pitates, &c. (fig. 45). PART I. TOOLS, SMALL IMPLEMENTS, AND APPAEATUS. 29 A small drop bottle to hold acids is useful (fig. 46). A small cupel mould is used to FIG. 46. make cupels for the assay of gold and silver alloys, which are called the 'previously prepared cupels' (fig. 47). To make the above cupels, finely crushed bone ashes that have been previously burnt, so that they contain no animal matter, are moistened, and the mould filled to the top, FIG. 47. (Half size.) the mould resting on a solid substance, such as a piece of hard wood. The pestle is placed on the top, and a few sharp blows are struck with a mallet or heavy piece of wood. The cupel is removed and carefully dried. When perfectly dry, it should be smooth at the top and show no flaws or cracks. A package of best Swedish filtering paper is re- quired in some of the assays. Blotting or some soft paper, soaked in a strong solution of carbonate of soda, then dried and cut into slips about 1J inch long by 1 inch wide, is used in the assay of silver and gold ores, and a supply should always be kept on hand. The batea is one of the most useful parts of the mining explorer and assayer's outfit, and it enables the operator to make preliminary examinations of gold, silver, copper, mercury, lead, tin, ores, &c. It is also used in the assay of gold and tin ores. Melville Attwood describes it as follows : * Batea is the name given to the gold-washer's bowl or vanning 30 BLOWPIPE AND APPARATUS. PART I. dish, used in the placers and gold mines of Brazil — a small implement which affords the most simple method of separating on a limited scale the grains of gold from the dirt, sand, pyritic matter, magnetic iron, &c. The form of the batea in common use in Brazil is a circular shallow wooden dish or bowl, rudely fashioned with an adze and chisel, varying considerably in depth and size, but never- theless in practical hands giving remarkable results.' The best form of batea is represented in fig. 48, and John Eoach, of San Francisco, describes it as c a disk of FIG. 48. (j_ size.) 17 inches diameter, being turned conical 12 degrees, will have a depth of 1J inch from centre to surface. The thickness may be J of an inch. The outer edge, perpen- dicular to axis, will require wood 2^ inches thick for its construction — the best wood, Honduras mahogany.' The author has used them for more than twenty years, and finds that by taking a hot iron and blackening the wood from the centre about H inch all round the pecu- liarities of the separated gold, or material, are shown more distinctly than with the batea in its normal condi- tion as it comes from the lathe. PART I. TOOLS, SMALL IMPLEMENTS, AND APPARATUS. 31 To use the batea requires practice, and to describe the modus operandi is difficult. Prof. Warington Smyth states as follows : c A quantity of the material to be operated on having been mingled and well stirred by hand with water in the bowl, it is shaken from side to side and circularly with a variety of movements suited to the form and the nature of the ore, only to be acquired by long practice. The separation of the gold is partly assisted by striking one side of the bowl occasionally, so as to arrest the course of the particles for the moment ; and, finally, several different layers or lines of mineral matter may be distinguished from one another, the gold occupying the lower position, then the magnetic iron, then the pyrites, and lastly other wastes.' Henry Hanks also gives a very good description of the way to use a batea. He states — 6 The manner of using the batea may be described as follows : — 4 A quantity of water will be required. This may be contained in a tank or large tub, or at a convenient place near the bank of a stream or lake. 6 The pulverised ore — several pounds at a time — is placed in the batea, which is gradually sunk in the water. Several times it is broken down with, the fingers, while the batea floats on the water. When the ore is thoroughly wet and formed into mud, the batea is taken by-the-bye with both hands and again sunk in the water. A circular motion is then imparted to it (soon learned by practice). The lighter particles will continuously flow over the edge and sink, while the heavier ones collect at the centre. 4 When only a small portion remains the batea may be lifted, and the water held in the depression caused to sweep round the centre, while one edge is slightly de- pressed. 32 BLOWPIPE AND APPARATUS. PART I. ' This motion will gradually remove the heavier par- ticles toward the depressed part. If there is any gold, platinum, galena, cinnabar, or other unusually heavy sub- stance, its gravity will resist the power of the water, while comparatively light particles move slowly forward. ' The form of the vessel is such that the heaviest matter forms a point, and can be closely observed. If there is a particle of cinnabar present it will be found at the point of the prospect, clearly distinct from all other substances. The value of the batea to the prospector cannot be too highly estimated, and it should come into more general use.' Bateas can be made over two feet in diameter, or only a few inches. A portable and useful size is about 1 7 TO 18 inches in diameter. By seeing the batea once used, and then taking time to wash the first few samples, the operator very soon be- comes an expert at the management of the batea ; and when he has once learned its use he will seldom examine strange ores without it. REAGENTS REQUIRED FOR BLOWPIPE ASSAYING. All reagents which are employed in blowpipe investi- gations should be chemically pure. Dry. 1. Carbonate of soda. 2. Neutral oxalate of potassa. 3. Cyanide of potassium. 4. Borax (biborate of soda). 5. Salt of phosphorus, or microcosmic salt (phosphate of soda and ammonia). PART I. REAGENTS REQUIRED FOR BLOWPIPE ASSAYING. 33 6. Nitre (nitrate of potash or saltpetre). 7. Bisulphate of potassa. 8. Vitrified boracic acid. 9. Protosulphate of iron. 10. Arsenic (metallic). 11. Argol (bitartrate of potash). 12. Ked and blue litmus paper. 13. Common salt (chloride of sodium). 14. Fluor spar. 15. Quartz (silicic acid). 16. Graphite (soft lead- pencil scrapings answer every purpose). 17. Sulphate of copper. 18. Magnesium wire (in testing for phosphorus). 19. Caustic potash. 20. Oxide of copper. 21. Oxychloride of lead. 22. Litharge (absolutely free from silver). 23. Finely crushed burnt-bone ash. 24. A small stick of roll sulphur. 25. Carbonate of ammonia. 26. Carbonate of potash. 27. Oxalate of nickel. 28. Chloride of ammonia. Wet. 1. Nitric acid. 2. Nitrous acid. 3. Sulphuric acid. 4. Hydrochloric acid. 5. Ammonia. 6. Nitrate of cobalt. 7. Sulphide of ammonium. The assayer can purchase all the above reagents from i) 34 BLOWPIPE AND APPARATUS. PART I. the chemist ; therefore it is not necessary to give any in- structions in regard to their preparation. To obtain pure metals for test or proof purposes to prove the assays is frequently a difficult matter ; therefore the author has added the methods adopted by himself to obtain pur« silver, gold, lead, copper, tin, bismuth, mer- cury, and iron. TEST OB PROOF METALS. Silver. . The silver used for both qualitative and quantitative examinations by the blowpipe must be chemically pure to enable the operator to make accurate and reliable assays of either gold or silver. For convenience it is best to have the silver in two forms, one in the shape of an ingot — say, about 1J inch long and ^ inch square — the other should be in thin foil, which latter will be found most useful in the gold assay. If chemically pure silver cannot be procured from a reliable source, such as a mint, a first-class laboratory, or assay office, it can be prepared as follows : — Dissolve the purest silver that can be obtained in weak nitric acid, dilute with water, allow the solution to settle for several hours, after which decant carefully and reserve for use only the portions that are perfectly clear, to which add a solution of chloride of sodium (common salt) until the white flocculent clouds of chloride of silver cease to appear. The precipitation is then complete. Filter and wash the precipitate repeatedly in warm distilled water, then dry and fuse (in a new and perfectly clean crucible) with its own weight of crystallised carbonate of soda and about J of its weight of pure nitre. The heat should be applied gently at first, and finally raised to the fusing PART I, TEST OR PROOF METALS. 35 point of silver, and when cold the crucible should be broken and the button of silver carefully washed. The silver must be again dissolved in nitric acid, water added, the solution allowed to settle, and great care taken in decanting as before. The silver is precipitated as before, and the precipitate repeatedly washed for twenty-four hours with ivarm distilled water. Dry, and again fuse with carbonate of soda. If this process is carefully carried out the silver obtained will be found to be chemically pure. Gold. Grold for blowpipe examinations should be pure, especi- ally for assays of nickel and copper. The most convenient form will be found to be that of a thin foil. If not procurable it can be prepared as follows : — Take a piece of gold coin and fuse it with three times its weight of silver, and when in the state of fusion pour into a vessel containing cold water. Collect the granulations thus formed, and dissolve in a flask or beaker glass with dilute nitric acid. After boiling for fifteen or twenty minutes decant carefully, and wash the gold residue with distil' ed water; then attack the gold with strong nitric acid (of 1-30 specific gravity) for twenty to thirty minutes. Decant and wash repeatedly with warm water, then add nitro-hydrochloric acid and boil until the gold is completely dissolved. Dilute with water, warm slightly, allow the solution to settle for about twenty-four hours, then decant and add oxalic acid slightly in excess. The mixture of trichloride and acid to be heated gently. The precipitation is slow, but is greatly assisted by heat. When finished, decant and wash on a filter ; afterwards heat over a gas or lamp flame in an evaporating dish or capsule. The gold is easily reduced by this means to a metallic state. Then fuse with an addition of bisulphate of potash and cast into D 2 36 BLOWPIPE AND APPARATUS. PART I. an ingot or any other desirable shape. The gold can be beaten or rolled into thin foil, and it is then ready for use. The author recommends the addition of bisulphate of potash as an extra precaution in case that a slight trace of silver should still remain with the gold before the fusion. Lead. Lead is difficult to procure entirely free from silver, and has generally to be prepared by the operator. It can easily be done by dissolving acetate of lead in distilled water and then precipitating the lead by pieces of metallic zinc, always rejecting the first portions of lead thrown down. The second portion should be washed repeatedly in warm distilled water, to remove any acid still remaining, and afterwards dried carefully between pieces of thick filter paper. The lead thus obtained should be melted on charcoal (in a hole bored for the purpose) by the blowpipe, and for convenience in use some of it should be rolled or beaten out into thin foil and the rest fused into the form of a small ingot. The foil is used to wrap up the pieces of gold or silver alloys preparatory to cupellation. The ingot shape will be found most suitable for the following plan, which the author has found very successful in the assays of silver and gold ores: i.e. instead of using granulations, as generally recommended, take the ingot, and by means of a small fine flat file reduce the lead to the finest possible powder. By care and rejecting any large filings that may have been formed, a 6 lead powder,' nearly as fine as ground litharge, will be obtained, which can be intimately mixed with the ore about to be assayed. The lead filings so prepared can then be kept in a small PART I. TEST OR PROOF METALS. 37 glass bottle, well corked, and will be ready for immediate use. The files must be kept in a small case by themselves, and never used on any other metal but the pure lead, else inaccurate results are likely to be obtained. Copper. The copper of commerce is seldom sufficiently pure for proof purposes. The following is the most convenient mode of prepar- ing pure copper : — Dissolve crystallised sulphate of copper in distilled water, and precipitate the metal by a clean ircn plate ; free the precipitated copper from the iron by boiling with hydrochloric acid, dilute with water, allow to settle, then decant and remove the precipitate to a filter, wash repeatedly with warm water, then dry and fuse in a clean crucible. When cold, break the crucible, wash, then dry and beat or roll into a thin sheet or foil. N.B. Pure copper rolls easily, but it must be repeat- edly annealed to obtain thin sheets. Pure copper, especially when in the form of a thin sheet, should be cut into narrow strips and kept free from the atmosphere in a tightly corked bottle. Tin. The best qualities of commercial tin generally contain 3 per cent, of impurities. Pure tin can be prepared as follows : — Dissolve good commercial tin in hydrochloric acid : thus hydrogen will be evolved and the metals all converted into chlorides, with the exception of antimony and arsenic. If either of these be present, it will combine with hydrogen and be evolved as a gas, viz. as anti- moniuretted or arsensiuretted hydrogen, and some of the 38 BLOWPIPE AND APPAKATUS. PAST I. antimony may also remain as an insoluble black residue. Any residue having been separated by nitration, the liquid is to be evaporated to a small bulk and then treated with nitric acid. This will convert the tin into insoluble metastannic acid, a crystalline white body. The whole is now evaporated to dryness, and then washed with a little hydrochloric acid, after which it is to be thrown upon a filter, thoroughly washed and dried, and subsequently reduced by mixing it with charcoal, and heated strongly in a crucible, when a button of pure tin will be the result. The button of tin can now be rolled or beaten out into sheets or foil, and is ready for use. Bismuth. The chief impurities of commercial bismuth are sulphur, traces of arsenic, lead, and iron. The best method of purification is the following:— Dissolve the crude metal in nitric acid, and then concen- trate the solution by evaporation. Next pour the clear solution into a large bulk of distilled water. It will be thus decomposed, and a white sparkling soluble powder falls, which is a basic nitrate. This is to be removed and digested for a time in a little caustic potash, whereby any arsenious or arsenic acids present will be dissolved. Next the basic nitrate is to be well washed, dried, and heated with about one-tenth its weight of charcoal in an earthen crucible ; thus the salt is reduced, and the bismuth sub- sides in the pot in a state of purity. The bismuth thus obtained can be broken into small pieces and placed in a bottle for use. Mercury. The mercury of commerce is often adulterated with lead, tin, zinc, bismuth, gold, &c. PART I. TEST OR PROOF METALS. 39 Pure mercury can be obtained by the following method : — Take about half a pound of mercury, place it in a bottle of one-quarter of its capacity, and add about one ounce of powdered white sugar ; shake vigorously for a few moments, then pour the portion of mercury that is still in moderate-sized globules into another bottle, add more finely powdered sugar, and again shake for several minutes ; then filter the mercury by pouring it into a small cone of blotting paper having its apex pierced with a small pin. The filter retains the oxides of foreign metals, also a portion of the mercury that is in a very fine state of division. The mercury filters slowly ; but when complete remove it to a small glass retort, distil at a low temperature very slowly, and only (Mow about two- thirds of the whole to go over in vapour. Collect the condensed mercury and keep it for use in a bottle with a glass stopper. N.B. Mercury that has been used in amalgamation works, even after having been distilled, invariably contains traces of gold and silver, besides lead, &c. (often owing to the rapid manner in which it is volatilised during the dis- tillation of amalgams) ; and in selecting mercury for purification it is always advisable to procure some that has not been employed for such purposes. Proof mercury should be tested for gold by dissolving it in nitric acid, and if any insoluble residue remains the mercury is impure and must be again distilled until found to be pure. Iron. Chemically pure iron is very difficult to prepare. The method used by Berzelius gives iron of sufficient purity for blowpipe investigations, and is the one generally adopted. 40 BLOWPIPE AND APPARATUS. PART I. Clean ordinary iron filings are taken and mixed with about one-fifth their weight of fine oxide of iron. The mixture is placed into a refractory crucible and covered with a layer of green bottle glass, such being used that is free from oxide of lead. The whole is luted up, and heated for an hour to whiteness. In this way traces of carbon and silicon are oxidised by the oxygen of the iron scale, and, such foreign matters being removed by the glass flux, a button of pure iron subsides in the pot. The button thus obtained, after being cleaned carefully, ean be used as a proof, but it must be kept sealed up from the air to prevent oxidation. Piano wire of different sizes will be found not only of sufficient purity, but also a most convenient form to use in the assay of lead. PART II. QUALITATIVE DETERMINATION. COLOUR OF SUBLIMATES ON CHARCOAL. THE colour of the sublimates found on the surface of a piece of charcoal after a mineral has been heated in either the O.F. or R.F. frequently affords the assayer a very good idea of the nature of the mineral to be assayed. Charcoal ashes vary in colour, and care must be taken not to confound the colour of the ash with that of the sublimate. For instance, the ash which is formed on some of the hard-wood charcoal by the blowpipe blast is generally of a bluish white colour, whilst the ash obtained from burning soft-wood or pine charcoal shows a dullish or darkish white colour, and after cooling scarcely any colour can be observed. The colour of the hard-wood ash, however, remains unaltered when cold. Before heating a mineral on charcoal apply a strong R.F. to a piece of the charcoal about to be used. Note the colour of the ash, and then heat the mineral on it. The sublimate derived from the mineral is generally found some distance from the charcoal ash, and it can then be examined with comparative certainty. The following table on the colours of sublimates on charcoal, prepared by D. Forbes, will be found of use : — 44 QUALITATIVE DETERMINATION. PART II. Colours of Sublimates or Coatings on Charcoal before the Blowpipe in Oxidising Flame. Reducing Flame. White . . A 1 Greyish white. Bluish white . Reddish white ; Yellowish white Faint yellow . Yellow . Sulphur yellow Lemon yellow Dark lemon yellow Dark yellow . Orange yellow Dark orange yellow ^ Brown yellow . [ Brown . Reddish brown (Red . Dark red. 1 Copper red Carmine red . V Whitish red . - Faint violet . Te, As, Sb, Zn, Sn, PbS, BiS, NaCl, NH4C1, KC1, CdCl,J PbCl, BiCl, NaBr, KBr, Nal, KI, 11 LiCl, As Sb, Bi, Pb, CuCl . (Ag+Sb) Sn . Sn, Mo ... Zn, PbOS03 . Pb . Bi . Pb . Te, CuCl, Cd, In . Bi, Cd . Pb, Bi . CuCl CuCl Cd . Te Ag Mo (Sb + Ag+Pb) (Ag+Sb) Se , Pb, Sn, Zn, Mo3, Te, As, Sb, NaS, PbS, BiS, KC1, NaCl, NH4C1, HgCl, SbCl, ZnCl, CdCl, PbCl, BiCl, SnCl, KBr, NaBr, KI, Nal LiS, LiCl, As CuCl, Sb, Bi, Pb Sn Sn, Mo3 Zn Pb Bi Pb Te, Cd, CuCl Cd Bi CuCl CuCl Cd Se 3 [ Blue Mo3 Iridescent Sa* j Dark grey t$ (Steel grey . Cd . . . . Cd . Se, As, CuCl . . Se, As, CuCl . Se, As . . . Se, As The following give no sublimate or incrustation in either flame. BaO, SrO, MgO, A12O3, Zr203, YO, ThO, EO, Si02, Ce2O3, Cr2O3, Di, Fe, Au Ir, Co, Cu, Zn, Mn, Ni, Os, Pd, Co, Pt, Ru, Ta, Ti, Ur, Vd, Wo. PART II. COLOUK OF SUBLIMATES ON CHARCOAL. 45 The abbreviation of O.F. for the oxidising flame and of R.F. for the reducing flame will in future be used. POTASSIUM. The presence of potash is detected by the blowpipe in two ways. 1st. By the more or less intense violet colour imparted to the outer flame when a substance containing it is heated in the point of the blue flame. 2nd. By the property which potash has of producing a blue glass when fused into a borax bead containing protoxide of nickel. In the first instance it is simply necessary to expose a small quantity of the substance (held in the loop of a platinum wire) to the point of the blue flame, when, upon fusion, the outer flame immediately beyond the substance should show the characteristic violet colour. This reaction, however characteristic in the case of tolerably pure potash salts, as the carbonate, nitrate, sulphate, chloride, bromide, iodide, and cyanide, is very easily interfered with. Phosphates and borates of potash do not give it, and even a small percentage of soda renders it invisible in the overpowering yellow reaction. When lithia is present it is .easily obscured by the more intense red flame due to that alkali. In very few- silicates is this reaction of value, as most of them contain more or less soda ; and even when they are quite free from soda the reaction is generally too indistinct, and particu- larly so in the more infusible ones. In employing the second method the loop of a platinum wire is filled up with a fused globule of borax glass, to which a small quantity of boracic acid has been added. Sufficient protoxide of nickel (oxalate of nickel is the QUALITATIVE DETEKMINATION". PART IT. best salt to use) is now dissolved in it, so as to make the glass bead, when cold, appear of a brownish colour. This globule is now melted in the oxidising flame along with the sub- stance supposed to contain potash, and when perfectly cold is examined to see if it has changed its original brown colour to a more or less blue tint. If no potash is present, or too little of the substance has been dissolved in the glass, the colour will be unchanged ; but if sufficient of the substance has been employed, and it was not too poor in potash, then the glass bead will be found to possess a blue tint, not unlike that of a weak solution of oxide of nickel in ammonia. As the colour of the glass is unchanged when smaller quantities of potash are present, this method is of little use in the examination of most silicates, and the deter- mination must be left to spectroscopic examination or to a chemical analysis. SODIUM. When soda is fused in the point of the blue flame, the outer flame is coloured strongly yellow, or rather reddish yellow. This property affords an excellent test for detecting the presence of soda in its compounds, as it is only necessary to heat a splinter (in the platinum forceps, or in the loop of a perfectly clean platinum wire) in the point of the blue flame, when, if soda is present, the outer flame will be seen to enlarge itself and be coloured reddish yellow. This test is extremely sensitive. It is applicable to silicates and the more infusible compounds, and it is not interfered with by the presence of considerable quantities of potash or lithia. When potash is present in much greater quantity than PART II. SODIUM, CESIUM, RUBIDIUM, AND BARIUM. 47 the soda, provided no phosphoric or boracic acid is present, the outer flame nearest the assay is tinged more or less violet, but farther off shows only the soda yellow. If lithia is present the flame will be of a more or less reddish yellow, or yellowish red colour, in proportion to the greater or less amount of lithia contained in the substance under examination. CJESIUM. Cassia is a rare alkali ; and although its volatile salts communicate a violet colour to the flame, its determination cannot be effected with certainty by the blowpipe, and it must be examined by the spectroscope. The spectrum of caesium characterises the element with certainty, its pale blue lines being very brilliant as well as distinct. RUBIDIUM. Rubidia, like csesia, is a rare alkali, found generally in mineral waters. It gives a violet colour to the flame, but the definite determination must be referred to the spectro- scope. Its splendid indigo blue lines, as shown by the above instrument, are most prominent as well as charac- teristic. BARIUM. Baryta and its compounds, when fused in the point of the blue flame, communicate more or less an intense yellowish green colour to the outer flame. When mois- tened with a very weak solution of nitrate of cobalt and fused in the O.F., it gives a light brown bead. With a strong solution it gives a brown or brick red bead, which loses its colour on cooling, and on exposure to air breaks up to a faint grey-coloured powder. 48 QUALITATIVE DETERMINATION. PART II. On charcoal alone the hydrate fuses, boils, swells up, and is absorbed by the charcoal. With soda on charcoal baryta fuses and is absorbed. ( )n charcoal alone the carbonate of baryta fuses easily to a clear glass, which becomes enamel white on cooling, and if longer heated become caustic, boils up, and is absorbed. With borax on platinum wire baryta dissolves to a clear glass, which, if sufficiently saturated, can be flamed to a white enamel. If supersaturated the glass becomes of itself enamel white on cooling. With salt of phosphorus the reactions are the same as with borax. In silicates, either natural or artificial, the blowpipe is altogether inefficient to detect the presence of baryta without the assistance of humid analysis. STRONTIUM. The compounds of strontium, when heated in the point of the blue flame, colour the outer flame purple red. When much baryta is present this coloration is obscured by the yellow green due to baryta. When a soluble strontia salt is dissolved in strong alcohol and the solution burnt alone, or on a small piece of cotton wool attached to a platinum wire, the purple red coloration of the flame is seen. In some cases a few drops of hydrochloric acid are previously added, which forms a chloride and colours the flame more intensely. But if it is a sulphate of strontia subject it to a K.F. on charcoal (forming a sulphide) ; then treat it with acid and alcohol, which will give an intense red flame. The hydrate, when heated on charcoal, boils up in its water of crystallisation, solidifies, and again fuses with violence, and is absorbed by the charcoal. ' The carbonate only fuses at its edges and effloresces at the same, and it is reduced to strontia, giving a strong light and colouring TART II. STRONTIUM AND CALCIUM. 49 the reducing flame red, and on cooling reacts alkaline for test papers. The red coloration of strontia is so much stronger than that produced by lime, that a small quantity of strontia can be detected in aragonite (carbon dioxide 44 and lime 56 = 100). The mineral must be previously decrepitated, then heated in the blue flame (it does not fuse). It will soon be observed that the flame is coloured more red than it would be by an equally large piece of calc spar. When testing the carbonate or sulphate, the flame is often noted to be first yellowish, but afterwards purple red is seen. CALCIUM. Lime, when heated in the point of the blue flame, communicates to the outer flame a weak red colour, much fainter than that produced by strontia. In its compounds this colour is more or less mixed with yellow. In the case of carbonates it is at first yellow, and later on, as the carbonic acid is driven off, it becomes red. The sulphate, chloride, and fluoride all give this reaction. The presence of barytes or soda in any quantity obscures this test, which is also not visible in the com- pounds of lime with phosphoric, arsenic, boracic, titanic, and tungstic acids ; and amongst silicates (wollastonite, silica 51*7, lime 48*3 = 100) stands alone in producing a faint reddish flame before the blowpipe, due to the pre- sence of lime. Before the blowpipe lime is unchanged ; the carbonate becomes caustic, and at the same time it appears strongly illuminated by the flame, and, if in pieces, slacks and falls to powder when moistened, and reacts alkaline. With E 50 QUALITATIVE DETERMINATION. PART II. borax it dissolves easily to a clear glass, which becomes opaque on flaming. When the glass is saturated it crystallises on cooling, and loses its round form, but in no case does it become as white as the glass from baryta or strontia. With soda on charcoal it is not affected ; the soda, being absorbed by the charcoal, leaves the lime behind. With nitrate of cobalt it is infusible and acquires a greyish colour. When lime is associated with baryta or strontia, as sometimes in heavy spar, strontianite, baryta, &c., the powdered substance, when treated with soda on charcoal, leaves the lime and oxides of iron on the charcoal surface, whilst the other substances sink into the charcoal. In silicates little dependence can be placed on re- actions for lime, but in general the presence of lime may be suspected by the following tests : — 1st. The swelling or frothing up in testing for fusibi- lity. 2nd. Keactions with borax and salt of phosphorus prove that silicates containing lime dissolve easily, and with salt of phosphorus alone the silica is separated, and the glass on cooling is in most cases opalescent. 3rd. With a small quantity of soda it fuses to a glo- bule, but with more soda it gives a slaggy mass. It is best, however, to employ the humid process. MAGNESIUM. Before the blowpipe magnesia does not give any sen- sible colorations to the flame, and it remains unchanged. The carbonate is decomposed by the heat and becomes more luminous and reacts alkaline to test papers. FALT II. MAGNESIUM. 51 With borax magnesia is easily soluble to a clear bead, which can be flamed opaque, and after saturation gives on cooling a crystalline glass, but less so than lime. It is easily soluble in salt of phosphorus, forming a clear glass, rendered opaque by flaming, and if fully satu- rated the glass becomes milk white on cooling. With soda on charcoal the soda sinks into the charcoal, leaving the magnesia unchanged. With nitrate of cobalt it acquires a flesh-red colour, which is best seen when entirely cold. The phosphates of magnesia melt and give a violet red colour on similar treat- ment. Native magnesia (periclase or magnesium oxide), the hydrate (brucite, magnesia 69, water 31 = 100), the car- bonate (magnesite, carbon dioxide 52*4, magnesia 47*6 = 100), and hydromagnesite (carbon dioxide 36*3, mag- nesia 43*9, wTater 19*8 = 100), and in Epsom salts (epsomite, sulphur trioxide 32*5, magnesia 16'3, water f51'2 = 100), the above reactions are sufficiently charac- teristic to decide the presence of magnesia if the mine- rals in question are free from other colouring metallic oxides ; but in nearly all the other metallic compounds the wet way must be resorted to, except in cases where the physical properties or chemical reactions of the other constituent of the mineral in question .give a clue to its identity. Zehmen gives the following method for distinguishing ordinary limestones from dolomite or magnesian limestone (which is often a question of interest). A quantity of the finest possible powder is placed in a small depression on pla- tinum foil, or a platinum spoon, and heated several minutes strongly to a thorough red heat. Ordinary limestone on cooling sinters together slightly, and can be turned out of the platinum without breaking up if handled carefully, E 2 52 QUALITATIVE DETERMINATION. PART II. and it often shows a tendency to adhere to the platinum, and therefore it requires a little assistance to detach it. Dolomite (calcium carbonate 54*35, magnesium car- bonate 45*65 = 100), on the contrary, does not sinter after heating, but falls to pieces, forming a still more porous and light powder, and many dolomites even on heating swell up from the fact that the gas frequently carries off traces of the powder with the flame. ALUMINIUM. Alumina in both the oxidising and reducing flames remains unchanged. With borax it dissolves slowly, form- ing a clear glass, which is not rendered turbid on flaming, nor does it become so on cooling. If a large quantity is added to the glass in the state of the finest powder it is rendered opaque, and on cooling the surface becomes crystalline and is almost infusible. With phosphate salt it is dissolved to a clear glass, which remains so. A very large quantity renders the glass semitransparent. With soda on charcoal it swells up a little and gives an infusible product, whilst the excess of soda is absorbed by the charcoal. With nitrate of cobalt and a high tem- perature it gives a fine blue compound, the colour of which is most intense when cold. In minerals which contain no colouring metallic oxide the blue furnished by the action of nitrate of cobalt gives a very good test for alumina. MANGANESE. The oxides are infusible both in the O.F. and R.F., and they leave on the charcoal the red oxide, which has a reddish brown colour. PART II. MANGANESE. 53 With borax the oxide is dissolved in the O.F., forming a glass which is of an amethyst violet colour when hot, and when cold a reddish violet. If too much mineral is treated the glass may appear quite black, as the above colour is very intense, and even opaque, unless pressed flat or drawn out by the forceps. In the E.F. this co- loured glass becomes colourless, and if very dark it is best reduced on charcoal by the addition of a little tin. With phosphate glass in the O.F., if much manganese is dissolved, the glass, when hot, is brownish violet, and when cold it is reddish violet, but it never becomes opaque. If the glass contains but little oxide and in nearly colourless, the addition of a little nitre will bring out the colour. On charcoal with soda in E.F. the oxide is not reduced, and remains behind whilst the soda is absorbed by the charcoal. In O.F. on platinum wire or foil wTith soda, when too much oxide is not used, a transparent green mass is formed (manganite of soda), which on cooling becomes bluish green and opaque. In substances which do not contain metals giving coloured beads with borate and phosphate salts in O.F. and K.F. manganese is very easily detected by its be- haviour with the above reagents, the former of which gives a much more intense colour. If other colour- ing metals are present in small quantities they do not have much influence on the amethyst colour seen in the O.F. bead, but in the reduction bead show their colours (for example, iron oxides) distinctly, as the manganese colour has disappeared. If much iron oxide is present the bead will appear in the O.F. blood red, and after the R.F. action yellow. In case the manganese present is so small that it does not colour the phosphate beads, a small crystal of nitre is 54 QUALITATIVE DETERMINATION. PART II. placed in a porcelain capsule, and the phosphate bead, having been made to take up as much as possible of the substance under examination in the O.F., is, whilst fused, quickly brought into contact with the crystal of nitre, which causes the glass to swell up, and it is seen at the point of contact to tint the froth an amethyst or rose- red colour the instant after cooling, an effect due to the formation of manganite of potash at the point. If a substance is mixed with other volatile oxides, but contains above 0*1 per cent, of oxide of manganese, it should be brought to the finest powder and mixed with two or three times its bulk of soda, then melted in O.F. on platinum foil ; the soda forms manganate of soda, having a transparent green colour, more so when hot, but a bluish green on cooling. Even with less than 0*1 per cent., by using two parts soda and one part nitre instead of soda alone, the manganese is more completely oxidised and tints the mass bluish green when cold. If chrome was present the yellow chromate of soda would give a yellow tint ; this, however, would not destroy the tjst, which may even be used for finding a trace of manganese in oxide of chromium ; the colour is, however, when cold, yellowish green instead of bluish green. To employ these tests with metallic alloys they must first be oxidised by roasting, action of acids, or deflagration with nitre. In case of sulphides and arseniates they must first be roasted on charcoal. If the ore contains at the same time both silica and oxide of cobalt, this test would give a blue colour on treat- ing it in this way, from the cobalt present; therefore the test for manganese is destroyed and the mineral must be determined by the humid way. PART II. TIN AND ANTIMONY. 55 TIN. Heat any compound supposed to contain tin with a flux made of equal parts of borax and cyanide of potassium. A malleable globule of tin will be obtained. Sulphides of tin must be first roasted on charcoal, then treated in E.F. with soda and borax. A metallic button of tin will be obtained, which can always be detected by removing the slag from it, and again placing it on charcoal and applying the R.F. The globule cannot be kept bright, and becomes covered with a crust of oxide, which can only be removed with difficulty by adding borax. For further particulars on tin, see Tin Assay. ANTIMONY. Antimony fuses easily on charcoal, and coats the char- coal in R.F. or O.F. with oxide of antimony (nearer the assay than the oxide of arsenic) in a thin layer of bluish white, and it can be driven about the charcoal by a gentle O.F. without colouring the flame, but if a R.F. be used the flame will be coloured a faint greenish blue. As the sublimate of antimony is less volatile than that of arsenic it may be easily distinguished from the last. When metallic antimony is fused* on charcoal and heated to redness, and the blowing stopped, the fused metal keeps itself a long time liquid and evolves a dense white smoke, which deposits on the charcoal and at last coats the globule itself with white pearly crystals of oxide of antimony. This phenomenon is due to the absorption of oxygen by the metal and the heat eliminated in the combination. Antimony with lead and bismuth may be detected by dissolving the above metals in boracic acid, provided the 56 QUALITATIVE DETERMINATION. PART II. fused mass is kept covered with the blue flame. A coating of fine oxide of antimony is formed, if the heat is not applied too strong. Antimony and zinc both give a white sublimate on charcoal near the assay. The zinc oxide is not volatilised in the outer flame, whilst the oxide of antimony can be driven from place to place or almost entirely volatilised. If antimony is combined with tin or copper, the assay is treated on charcoal in E.F. with soda and borax ; by this means small metallic globules are formed. The globules are separated by triturating and washing in the horn spoon. The globules are then fused on charcoal in the R.F. with 3 to 5 times their volume of lead and a little boracic acid. If the glass only is exposed to the E.F. the antimony is volatilised, and it coats the coal distinctly with its oxide. In alloys of copper, silver, lead, and iron, a small piece of the alloy should be dissolved in nitric acid, and the antimony will be found in an insoluble white powder (anti- monic acid), and it should be then dried and treated on charcoal for the antimonial sublimate. SILVER. Silver can be detected with the greatest accuracy, and the percentage estimated by following the instructions in Silver Assay. GOLD. Gold can be detected with great certainty, and the percentage estimated, by following the rules laid out in the Gold Assay. PART II. CHROMIUM AND IKOX. 5 7 CHROMIUM. The oxides of chromium afford a distinct reaction before the blowpipe when they are tested in the O.F. with borax or salt of phosphorus, the beads appearing yellowish green when quite cool ; and the bead (if free from the oxides of lead or copper) in the R.F. becomes a beautiful eme- rald green. If the above metals are present the beads become when cool opaque, red, or grey. IRON. The sesquioxide of iron is unchanged by the O.F., but in the R.F. it loses part of its oxygen, and then be- comes black and is attracted by the magnet. In O.F. it dissolves in borax, and if a small quantity is present the glass is, whilst hot, yellow, and, when cold, colourless. If in a larger amount it is, when hot, red, and, when cold, yellow ; and if fully saturated is, when hot, dark red, and, on cooling, dark yellow. In R.F. the glass formed as above becomes bottle green, and if treated on charcoal with a little metallic tin it becomes first a bottle -green colour, and on continued reducing copperas green. With phosphate salt in O.F. the glass formed is, when hot, yellowish 'red, and, in the course of cooling, it loses colour, becoming yellow, then greenish, and lastly co- lourless when cold. When saturated it is, when hot, dark red, and, in cooling, successively brown red, dirty green, and then brownish red when cold. The latter colours show themselves much quicker during cooling than when, borax is used. In the R.F. the phosphate glass, if it does not contain much iron, is unchanged, but if more saturated with iron 58 QUALITATIVE DETERMINATION. PART II. it becomes, when red hot, and, in cooling, successively yellow, greenish, and at last reddish when cold. Treated with glass on charcoal, this glass becomes, on cooling, green, and when cold colourless. In detecting the presence of iron in its numerous compounds the reactions of borax and salt of phosphorus will in most cases be sufficiently characteristic. In metallic alloys which are not easily fusible it is only necessary to treat them with borax on charcoal in an O.F. until the glass has taken up sufficient of the oxide formed to give it a distinct colour. If the alloy is very fusible, from containing lead, tin, bismuth, antimony, or zinc, the R.F. should be used by directing it on the glass, which causes it to absorb as little as possible of these metals. In either case the glass is, whilst still fused, separated by the forceps and treated on clean charcoal with the R.F., which separates the readily reducible metals, especially copper, nickel, arsenic, bismuth, antimony, and zinc (which are to a great part volatilised and sublimed on the charcoal around), and leaves the glass coloured bottle green, due to iron. If the alloy contained tin the assay may be of a copperas green colour ; if not it becomes so by treat- ing with E.F. on charcoal with metallic tin (should, how- ever cobalt have been present the glass will turn out blue). The bead (free from any adherent reduced metallic matter) should now be treated on platinum wire in a good O.F. until all iron is fully oxidised (if the colour is too in- tense for inspection a part of it only need to be taken and fused with fresh borax, so as to dilute it), when, accord- ing to the proportion of iron present, the colour will be more or less yellow, or even brown red. If a little cobalt is present the glass, while warm, is a dark green, and when cold green forms the admixture of colours. When, on the contrary, but little iron is present along with much cobalt PART II, IRON. 59 it will appear, when hot, green, but on cooling pure blue. Compounds of iron with arsenic and sulphur may be examined by several methods. (a) In most cases it is best to fuse the substance with borax on charcoal, using the K.F., and when the whole is in fusion the flame should be directed on the glass alone, so that the air may have access to the metallic globules. As soon as the glass begins to be coloured by the absorbed metallic oxide it is removed by the forceps, and can be examined for iron in both flames and with tin. (6) The sulphide or arsenide may be calcined on charcoal, and a little of the oxide thus produced is taken up by a borate globule upon platinum wire in O.F., until the glass is coloured. Frequently when no metals having strong co^ louring properties are present this test suffices at once to determine the presence or absence of iron. If not, the glass can be treated on charcoal in E.F., which separates copper, nickel, or any other easily reducible metals (some- times to effect the separation of such metals a small piece of gold or silver may be added to them, as it en- ables the metals to separate much quicker by so alloying) ; then the bead is left with the iron reactions visible and it can be examined as before. (c) According to Plattner the powdered substance can be fused with borax and some lead on charcoal, covering the whole with a good E.F. When the borax has united and formed a pearl the flame is directed on to this alone, so that air has access to the fluid metallic globule. When the borate is coloured by the absorbed metallic oxides it should be removed quickly with the forceps, and treated on fresh charcoal in E.F. to reduce any oxide of lead in the glass, after which it may be examined for iron reactions as usual. 60 QUALITATIVE DETERMINATION. PART II. In oxides, when no copper, nickel, chromium, or uranium is present, the iron is recognised without difficulty. In case of uranium a humid analysis is necessary, as this metal gives the same coloration as iron. With nickel the colour is more or less brownish yellow or yellowish brown. In case of both nickel and copper they may (as before mentioned) be reduced out of the glass, when the colour of iron is then distinctly seen. With cobalt the colour of the glass has already been noted, but if very little iron is present the wet way must be used. If manganese is present the colour in O.F. will be violet red, or if very much is present dark red when hot, and, on cooling, red with a violet tinge. On treating such a glass in R.F. on charcoal with tin the manganese colour disappears and the copperas green is at once seen. If very little manganese is present merely treat it in R.F., which will be sufficient to reduce the manganese and bring forward the bottle-green colour due to iron. When a great deal of manganese is present the phos- phate test shows the iron at once, as the manganese colour of this glass is not very intense in the O.F., and in E.F. it becomes colourless, whilst the iron colour after treatment with K.F. remains generally reddish. When iron is in combination with chromium the blow- pipe test does not give a sufficiently decided result, owing to the colours produced by the chromium., If, however, the substance be melted in the platinum spoon with 3 parts nitre and 1 part soda, and the result washed well with water, the residual oxide will at once react for iron as usual. If tungsten or titanium is present the O.F. will, with borax or phosphorus salt, give the iron reaction, as the above metals give too feeble a yellow colour to interfere with PART II. IRON AND COBALT. 61 it, also with borax in R.F., but with phosphate in R.F. both of these become darkened to brown red. The compounds of iron with carbonic acid, sulphuric acid, phosphoric acid, arsenic acid, tantalic acid, silicic acid, and alumina are in general easily shown to contain iron by the reactions with borate and phosphate salts. It is also the case with most slags and other products of the arts. In such metallurgical products as pig iron, steel, brass, black copper, copper, tin, or lead (containing iron), speiss, regulus, &c., the iron can easily be showrn by the treatment given for alloys or compounds of sulphur and arsenic. COBALT. Before the blowpipe in O.F. the oxide is unchanged. In R.F. it does not fuse, shrinks a little, and is reduced to a metallic powder, which receives lustre by friction and is attracted by the magnet. In both O.F. and R.F. the oxide is dissolved by borax, and gives, both when hot and cold, a pure blue glass, which is seen, especially on cooling, to be less intense than with borax glass, from equal saturation. On platinum in O.F. with soda the oxide, if in very small quantity, dissolves to a clear bright red mass, which becomes grey on cooling. The examination for cobalt is generally easy, and especially so when no other strongly colouring metal is present. This being the case, the sub- stance, when treated with borax in O.F., will indicate the presence of cobalt by the blue colour of the glass. If iron is present the glass, when warm, may appear green, from the admixture of colours, but on cooling (if the iron be not in very large amount) the blue is seen above the peculiar colour arising from the mixture of bottle green and blue. When the glass is treated in the R.F. it is not easily mis- taken for any other reaction ; also the action of the R.F. 62 QUALITATIVE DETEBMINATICXN7. PART II. renders a manganese glass colourless. This substance if present, is no obstacle in the way of recognising the blue of the cobalt, as it is when using the O.F. with iron and cobalt. Plattner detects cobalt in metallic alloys of nickel by converting the metal into an arsenide before testing it for cobalt by mixing it in thin scales or filings with a little metallic arsenic, fusing them together in a small cavity on charcoal with the R.F., and treating the fused button a short time with borax directly with the tip of the blue flame ; if any cobalt is present the glass becomes blue, and if the amount is not too small the cleansed button will impart a blue colour to a fresh portion of borax also. NICKEL. The protoxide in the O.F. is unchanged. In the R.F. it is reduced to an infusible metallic powder, which is magnetic. With borax in the O.F. on platinum wire a little of the oxide colours the hot glass violet, but when cold a pale reddish brown ; with more oxide the colours are darker. In R.F. with borax the glass becomes grey and cloudy or quite opaque, owing to finely divided metallic nickel. On continuing the blast the reduced metallic particles collect together without fusing, and the glass becomes colourless. With phosphate salt on platinum wire in O.F. it dissolves to a reddish glass, yellow on cooling. In R.F. on platinum wire it is unchanged. On charcoal with tin it becomes at first opaque and grey, but after long blowing all the nickel is reduced and the glass becomes colourless. With soda it is insoluble in O.F., but in R.F. on char- coal it is easily reduced to white metallic particles, which, after washing, follow the magnet. PART II. NICKEL AND ZINC. 63 Plattner detects a small quantity of nickel in oxides of cobalt, manganese, and iron by dissolving a small quantity in borax on platinum wire in O.F. — the dark or opaque bead is shaken off, and two or three such beads prepared. These are treated in a cavity on coal,, or in a coal crucible, with a small pure gold button in a strong, active K.F. until it is certain that all the nickel is reduced from the bead and collected in the gold button, which has been brought into contact with every portion of the fluid glass by carefully turning the coal. When the button has solidified, it is lifted from the glass and freed from any adherent glass between paper on the anvil. If the borax glass was not supersaturated with oxides, so that none of the cobalt could be reduced, the gold button treated for some time in the O.F. on coal with phosphate will impart to this only the nickel colour, reddish to brownish red whilst hot, and yellow to red- dish yellow after cooling, according to the amount dissolved. If, however, cobalt has been reduced it will oxidise sooner than the nickel, and either produce a blue cobalt bead or a bead which will be dark violet when hot and dirty green on cooling, if some nickel had been oxidised. In either case the button, freed from glass, is treated with fresh phosphate in O.F. until the hot glass seems coloured, when, if the original borax beads had not been too highly supersaturated, the glass will show only the nickel coloration ; if the metallic oxides were, however, free from nickel the glass will be colourless (Plattner's 'Manual,' p. 245). ZINC. If the substance contains much zinc, or when it is free from other metals which form a sublimate on charcoal, the presence of this metal is easily detected. When a small amount of zinc is combined with much lead, bismuth, or 64 QUALITATIVE DETERMINATION. PART II. antimony it is quite impossible to prove its presence with certainty, and frequently the presence of tin prevents its detection. The examination for zinc is in all cases based upon the reduction of the metal or the formation of sublimate (white when cold and yellow when hot) on the charcoal. This sublimate, being further tested by reheating with a solution of nitrate of cobalt, produces the characteristic yellowish green colour. Large quantities of oxide of lead or bismuth in the sublimate may obscure this reaction ; but in some cases the lead and bismuth oxides may be driven farther off, so as to leave the zinc reaction tolerably clear. If the quantity of zinc present is extremely small, and only produces a very faint coating of sublimate, which might be easily lost mechanically, it is in such cases better to moisten the charcoal first with a drop of nitrate of cobalt before blowing. It must, however, be observed, if much antimony or tin is present, a greenish colour is also produced with nitrate of cobalt from combinations with the oxide of cobalt which are not volatile in the O.F. (the colour with tin a bluish green), and in such cases dependence cannot be placed on this reaction. When much zinc is present a zinc flame is observed in K.F., and the charcoal is covered with a strong sublimate, closer to the assay than that of lead oxide. Substances containing zinc in combination with sulphur can be treated alone on charcoal in K.F. Those containing zinc as oxide with but little sulphur are treated with soda on charcoal in the E.F. Those containing other metallic oxides and earths require borax in addition. A mixture of 2 parts soda with 1 to 1 1 borax glass on charcoal in E.F. (especially when in combination with alumina) soon frees the zinc, and the usual sublimate is readily formed. PART II. CADMIUM. 65 CADMIUM. Metallic cadmium fuses readily and volatilises, covering the charcoal with a reddish brown (in thin films), dark yellow, or orange-coloured sublimate of the oxide, which still farther off on the charcoal gives an iridescent play of colours. The oxide treated on platinum is unchanged in O.F. On charcoal in K.F. it is reduced, and covers the charcoal with a red brown to dark yellow sublimate (colour best seen when cold), as in the case of metallic cadmium. In borax glass in O.F. the oxide readily dissolves, and gives a transparent yellow glass when hot ; on cool- ing it is almost colourless ; on larger saturation the glass can be flamed to a milky enamel, and when still more saturated it becomes enamel white on cooling. On charcoal in K.F. che phosphatic glass is slowly and but partially reduced, giving but a very faint sublimate of a dark yellow colour ; the true colour is only seen well on cooling. An addition of tin hastens the reduction. With soda in O.F. the oxide remains unchanged, but in K.F. it is reduced, with the production of the charac- teristic sublimates before described. It does not give any characteristic reaction with nitrate of cobalt. In searching for this mineral the means of detecting the cadmium depends entirely upon the reduction and the subsequent volatilisation of the metal, giving rise to the characteristic sublimate of the metal. Substances containing much cadmium give the above reaction if powdered finely and heated quickly in the K.F. If the mineral contains as little as 1 per cent, of cadmium it is better to mix the powder with soda and heat for a very short time in a K.F., when the sublimate will be seen. F 66 QUALITATIVE DETERMINATION. PART II. As zinc is frequently present with cadmium, the heat, if continued too long, will also drive off the less volatile zinc, the white sublimate of which may more or less obscure the cadmium reaction. COPPER. The oxides of copper, when heated on charcoal in K.F. with soda, yield a metallic button of copper. When heated in the O.F. on platinum wire with borax, they colour the glass strongly ; a little oxide causes a green glass when hot and a blue when cold, and with more it is dark green to opaque when hot, but greenish blue on cooling. With borax in the K.F. on platinum wire, if saturated to a certain degree, the glass soon becomes colourless, but on cooling it becomes red and opaque. On charcoal the copper is reduced to metal, and the cold glass is quite colourless. The sulphides of copper are roasted on charcoal with the O.F. and E.F. alternately, and on the completion of the roasting soda is added, a E.F. applied, and a globule of metallic copper produced. Silicates and other salts of copper dissolve in O.F. in the glass fluxes to green beads, which should be blue on cooling. For full details of copper assay see p. 146. LEAD. Metallic lead fuses easily, tinging the flame light blue, and in both K.F. and O.F. volatilises, covering the char- coal around it with a sublimate of pure oxide of lead, dark orange yellow when hot and sulphur yellow when cold, on the outskirts of which is generally seen a thin bluish-white sublimate of carbonate of lead. The flame PART II. LEAD. 67 of the blowpipe chases these sublimates from place to place on the charcoal, which, when red hot, reduces the oxides, volatilising the metal to a greater distance when it is redeposited as a sublimate of oxide, at the same time colouring the flame light blue. The protoxide of lead heated in O.F. on platinum alone becomes darker in colour and fuses to a yellow glass. The red oxide becomes almost black, and at a low red heat is converted into protoxide, and it behaves as before stated under similar circumstances. On charcoal in both O.F. and E.F. all the oxides are reduced to metallic lead with effervescence, which on con- tinued blowing is volatile and is deposited as a sublimate of oxide, which can be reduced again to metallic lead by the K.F., which is thus tinged light blue. With borax glass in O.F. the oxides dissolve readily, forming a clear yellow glass, colourless on cooling. With greater saturation this glass can be flamed opaque, and upon full saturation on cooling it becomes of itself a yellow opaque enamel. In R.F. this borax globule upon charcoal spreads out with effervescence, and the lead may be reduced to its metallic state by continued blowing, leaving a clear borax globule. With phosphate salt in O.F. the oxide (the same as with the borate) requires more saturation before the globule shows any yellow colour when hot. In R.F. the phosphate salt globule on charcoal becomes greyish and opaque, and when the globule is saturated the charcoal around is covered by a yellow sublimate of oxide. The addition of tin to the globule makes it more opaque and darker grey in colour, but it never becomes quite opaque. With soda on platinum wire it dissolves in O.F. to a clear glass, becoming yellowish and opaque on cooling. o8 QUALITATIVE DETERMINATION. PART II. With soda on charcoal it is reduced to metallic lead in E.F., which on continued blowing covers the charcoal with oxide. INDIUM. In O.F. the oxide becomes of a dark yellow colour, does not fuse, and on cooling recovers its lighter colour. On charcoal in E.F. it is slowly reduced and volatilised, and the oxide sublimed on to the charcoal. During the reduction the outer flame is coloured very distinctly violet. With borax in O.F. it dissolves to a clear glass, feebly yellowish whilst hot, but colourless on cooling. A more saturated globule becomes opaque. With borax in R.F. the glass does not change, but on charcoal it commences to reduce and to give a sublimate on the charcoal ; at the same time the violet colouring of the outer flame is seen, and is not concealed by the soda coloration. With phosphate salt the reactions are the same as with borate, but if tin be added to the glass in the R.F. the glass on cooling becomes grey and opaque. With soda in O.F. it is not dissolved, but on charcoal in R.F. is reduced, and part of the metal volatilises and forms a sublimate of oxide on the charcoal, whilst some nearly silver white globules of indium are seen in the soda. BISMUTH. Bismuth fuses very easily, and gives a coat of oxide, which is dark orange yellow when hot, and lemon yellow when cold, being yellowish white in thin layers. The yellow coat is pure oxide, and the yellowish white one (which is at the greatest distance) is carbonate with PART II. BISMUTH AND TITANIUM. 69 some oxide of bismuth. It can be driven about on the glowing coal like lead, but does not colour the R.F. during the operation. Bismuth combined with sulphur gives on charcoal a white coat of sulphate of bismuth beyond the yellow coat, but it is prevented by a small addition of soda. When much lead or antimony is present, roast care- fully on charcoal, then fuse with 3 times its volume of bisulphate of potash in the platinum spoon, then treat the mass with water in a small porcelain dish until every- thing is detached from the spoon. Sulphate of potash and other soluble sulphates are dissolved, leaving neutral sulphate of lead and basic sulphate of bismuth. Antimony, if present, remains behind as acid. After decanting the clear solution the residue is boiled in distilled water, to wThich a few drops of sulphuric acid and some nitric acid are added, when the sulphate of bismuth dissolves, leaving a residue of sulphate of lead with any oxide of antimony present. After nitration the bismuth is thrown down from the warm nitrate by means of salt of phosphorus as a white precipitate, which is collected on a filter and tested with phosphate salt. The phosphate bead on platinum wire is colourless, or faintly yellow, but on coal with tin in E.F. becomes dark grey on cooling, behaving there like oxide of bismuth. Oxides of bismuth, if treated either alone or with soda on charcoal, give the usual bismuth coating. TITANIUM. Titanic acid both in E.F. and O.F. on charcoal assumes a yellow colour, but it is white again on cooling. With borax on platinum wire in O.F. it dissolves easily to a clear glass ; if much is present it appears 70 QUALITATIVE DETERMINATION. PART II. yellow whilst hot and colourless on cooling, and becomes opaque by flaming. In R.F. a small addition yields a yellow glass ; more oxide yields a dark yellow to brown glass. A saturated glass becomes emanel blue by flaming. With phosphate salt on platinum wire in O.F. it dis- solves easily to a clear glass, yellow while hot. In R.F. the glass becomes yellow while hot, but reddens on cool- ing and assumes a fine violet colour. If the acid contains iron the glass becomes brownish yellow to brownish red on cooling. With soda in O.F. on charcoal it dissolves with effer- vescence to a dark yellow glass, which crystallises on cool- ing a,nd thereby evolves so much heat that the globule glows strongly again. When perfectly cold the glass is greyish white to white. With cobalt solution in the O.F. it assumes a yellowish green colour, similar to oxide of zinc, but not so fine. Plattner recommends the following plan to detect small amounts of titanium : — In complex substances which give no decisive reaction for titanium with the fluxes the finely powdered substance is fused in a platinum spoon at a moderate red heat with 6 to 8 times its weight of bisulphate of potash, the mixture being melted in small portions at a time. The mass is then dissolved in just sufficient water in a porcelain dish over the lamp, and the insoluble parts allowed to settle. The solution, if concentrated, may be heated to boiling. The clear solution is then poured into a larger dish, mixed with a few drops of nitric acid diluted with at least 6 times as much water, and then boiled. If the substance contains titanium the latter is dis- solved by the fusion with bisulphate of potash and treat- ment with water, and it is precipitated from the acid solution by continued boiling as white titanic acid. PART II. TITANIUM, MEECUEY, AND PLATINUM. 71 If the solution is not acidified with nitric acid before boiling, a yellow ferruginous titanic acid is obtained when the substance contains iron. The precipitated titanic acid is collected upon a small filter, washed with water con- taining nitric acid, and tested with phosphate salt either on platinum wire or charcoal. If the amount of titanic acid is so small that in R.F. it does not impart to the phosphate salt the violet colour of the sesquioxide of titanium, add a little sesquioxide of iron when the assay is upon a wire, or a small piece of iron wire when on charcoal, and fuse the glass a short time with the R.F. ; it then appears yellowish while hot and brownish red when cool (' Manual,' 1873, p. 323). MERCURY. The assay for mercury is treated fully on p. 135. PLATINUM. Platinum, when treated with borax or phosphate salt, does not fuse, and is neither oxidised nor dissolved. Platinum is found native, and forms alloys with other metals — iron, copper, rhodium, iridium, ruthenium, osmium, gold, and silver. To examine an alloy for plati- num dissolve a small piece in aqua regia (3 parts hydro- chloric acid and 1 part nitric acid). If there is any black, fine, metallic insoluble powder in the bottom of the flask it is iridium. Separate it by decanting carefully, then evaporate the blood-red solution almost to dryness ; the acid fluid is then diluted with water ; a few drops of a solution of potassa is added. A yellow precipitate is formed, which consists chiefly of platinchloride of potas- sium. 72 QUALITATiV^ DETERMINATION. PART II. LITHIUM. Lithia, when heated in the point of the blue flame, communicates a fine purple-red colour to the outer flame. According to Plattner, when lithia is fused upon platinum foil it causes the platinum in contact with it to acquire a yellow tarnish, which is removed by water, but upon drying or heating leaves the platinum surface without lustre, as if acted upon. To detect lithia in its compounds it is only necessary to heat them on a platinum wire or in the platinum forceps and in the point of the blue flame. Observe the purple-red colour communicated to the outer flame. This reaction serves also for silicates. Those which contain very little lithia require to be tested according to Turner's method, by mixing I part of the impalpable powder with 2 parts fluor spar and three parts bisulphate of potash, and by addition of a little water rendering the mixture plastic enough to stick to the loop of a platinum wire. This is now subjected to the blue flame. If no lithia is present, only the violet colour due to the potash employed will be seen, but if the contrary is the case the lithia red will be seen even more or less overpowering the violet. The presence of soda in the mineral may render this reaction indistinct ; but if boracic acid is contained in the substance the green colour due to this body will be first seen, but it subsequently gives place to the lithia reaction. In testing for lithia it must be remembered that strontia and lime also produce a red coloration of the flame. When soda is present along with lithia the red coloration may be overpowered by the intense soda yellow, especially if the heat employed be high. By employing the outer flame and less heat the lithia reaction is frequently seen when otherwise invisible. Stein states that 1 part lithia in 2,580 parts soda gives PART II. LITHIUM, OXYGEN, AND HYDROGEN. 73 a red coloration, if the substance be heated so as to soften and render it porous by quenching it in tallow and then heating it in the flame of a candle. Potash interferes less with the lithia reaction, but communicates a stronger or weaker violet tinge in propor- tion to the amount present. When both potash and soda are associated with an excess of lithia the outer flame will be reddish violet nearest and reddish yellow farther away from the assay. If soda is present in excess both potash and lithia reactions disappear, but sometimes the lithia can be observed by using less heat, as before men- tioned. If a lithia mineral containing phosphoric acid (but no soda) be treated in the blue flame, two distinct colours are seen in the outer flame, which do not mix with one an- other, being the lithia red and a bluish green due to phos- phoric acid. OXY GEN. According to Fuchs, this element is only detected in substances which can readily be made to part with it in a free state. In substances that give up their oxygen when heated in a glass tube, the gas is recognised by its rekind- ling a glowing match. This reaction is often inconclusive, owing to the small size of the fragment under examination. However, another test presents itself at once for these small quantities. The assay is heated in a test tube with a fragment of chloride of sodium and a few drops of sulphuric acid. Chlorine is now evolved in place of oxygen, and it may be recognised by its characteristic odour, or by its bleaching effect on a piece of moist litmus paper. HYDROGEN. To detect hydrogen in water, place a small piece of metallic zinc in a small porcelain cup, and add a few drops 74 QUALITATIVE DETERMINATION. PART II. of sulphuric acid. Hydrogen gas is given off, which is easily recognised by its sickly odour. The examination for hydrogen does not come within the scope of a blowpipe investigation, and it must be de- termined by chemical analysis. NITROGEN. Substances containing nitrates detonate when heated on charcoal. Heated in a tube with a little sulphuric acid, they give off red fumes of nitric peroxide. A small amount of a nitrate present in another salt or substance can be readily detected by heating it with rather more than its volume of bisulphate of potassa in a closed tube or matrass. The tube becomes filled with gaseous nitrous acid, the yellow colour of which may be seen by looking down through the tube. Should there be so little nitrate present that this colour cannot be plainly seen, the minutest quantities may, according to Stein, be detected by heating the assay with litharge, which at first absorbs the nitric acid, but yields it up at a higher temperature. A slip of paper which has been immersed in a solution of protosul- phate of iron, free from sesquioxide and acidulated with some sulphuric acid, is inserted into the neck of the tube, and if nitrous acid is present it will assume a yellowish to brown colour. In this way the nitric acid in a mixture of 1 part of nitre with 1,000 parts of sulphate of soda con- taining only 0-0005 nitric acid can be distinctly shown. The paper quickly loses its colour if too strongly heated, and therefore the tube or matrass should be rather long. Nitre, soda nitre, and nitrocalcite are immediately re- cognised as nitrates by the above tests, and their bases may be distinguished by the colour they impart to the flame. PART II. FLUORINE AND CHLORINE. 75 FLUORINE. Fluorides, when treated in a closed tube, give off fumes of hydrofluoric acid, which react acid with test papers and sometimes etch the glass. If no acid reaction has taken place, first heat with a little sulphuric acid in the closed tube, and if that still does not evolve fumes of hydrofluoric acid heat in a closed tube with a small quantity of bisulphate of potash. In case no characteristic reaction has taken place Berzelius recommends the following test : — The finely powdered substance is mixed with phos- phate salt (previously fused on charcoal), and the mixture heated in the open tube, so that the flame can be carried inside the tube by the current of air. Under the solvent action of the phosphate upon minerals free from silica, hydrofluoric acid is formed, which passes through the tube ; and it can be recognised both by its peculiar pungent odour and by its effects on the glass, which it- attacks and renders dull, especially where any moisture has collected. The escaping air will also turn Brazil-wood paper yellow. CHLORINE. According to Berzelius, ' chlorine may be detected in its compounds by dissolving oxide of copper in salt of phos- phorus or platinum wire in O.F. until the glass is opaque, and then causing the substance under examination to adhere to the soft bead, which is then treated with the tip of the blue flame.' 4 If chlorine is present the bead will be surrounded with an intense azure blue flame of chloride of copper, which volatilises as long as chlorine remains. A fresh addition of the substance will reproduce this reaction. Bromine is the only other body occuring in minerals which produces 76 QUALITATIVE DETERMINATION. PART II. a similar flame.' As the above frequently occur together the result is not satisfactory without a still further in- vestigation. When a substance gives the azure blue re- action in salt of phosphorus, fuse another portion of the compound in phosphate glass with copper oxide. As soon as the fusion is complete stop blowing, let the glass cool, then crush into the finest powder on the agate mortar and attack it in a tube or matrass with a small quantity of nitric acid. Add water, allow the assay to settle for a few moments, then add a solution of nitrate of silver. If chlorine alone is present the precipitate will be a milky white. If the compound contains as much as J per cent, of bromine the precipitate will have a beautiful light lemon yellow tinge. If the compound contains a large per- centage of chlorine to a very small percentage of bromine the colour will only be observed at the moment of precipita- tion ; but if a large amount of bromine is in the compound the yellow colour is permanent, and will of ten be seen en- tirely separate from the pure milky white precipitate which is thrown down by chlorine. The colours, however, cannot be correctly discerned after the test tube has been shaken up. In mineral waters and aqueous salts the slightest traces of chlorine can be detected (if very dilute, evaporate down) by adding a few drops of nitrate of silver. A milky cloud will be observed immediately after the above addition if any chlorine is present. BROMINE. Bromides behave in a similar manner to chlorine, and with phosphorus salt and oxide of copper the same reaction takes place as with silver. The flame, however, has not a pure azure blue colour, but inclines to green, especially at the edges. PART II. BROMINE, IODINE, AND SULPHUR. 77 When all the bromine has been eliminated the green flame of the oxide of copper alone remains. To distinguish bromides from chlorides Berzelius has proposed to fuse them in a matrass with bisulphate of potash, when bromine and sulphurous acid are liberated, and the matrass is filled with reddish yellow vapours of bromine, which can be recognised by their similarity to that of chlorine notwithstanding the sulphurous acid. Bromide of silver forms an exception, as it yields very little bromine, but it may be distinguished from chloride of silver by the asparagus green colour which it assumes when exposed to the sunlight after fusion with the bi- sulphate of potash. IODINE. Iodides, if fused with oxide of copper in a phosphate bead, produce an intense green flame. When iodides are fused in the matrass with bisul- phate of potash, the iodine is sublimed and partly fills the matrass with violet vapours, while sulphurous acid is simultaneously evolved. The test is so delicate that small quantities of iodine may be detected in salts, &c. SULPHUR. Sulphur fuses in the matrass ; sublimes, leaving a fine yellow sublimate when cool. If ignited on charcoal it burns with a bluish flame, evolving sulphurous acid, which is easily recognised by its characteristic pungent odour. By roasting a finely powdered mineral in an open tube sulphurous acid will be evolved, and if the odour is not perceptible the presence of sulphur will be ascertained by inserting a small strip of moistened litmus paper. 78 QUALITATIVE DETERMINATION. PART II. According to Plattner, in some cases even a very little sulphur may be detected by fusing the powdered substance with 2 parts of soda and 1 part of borax on charcoal in E.F., provided no selenium is present. In the case of easily fusible metals which contain only finely disseminated sulphides and cannot be pulverised — e.g. raw lead, black copper, &c. — a fragment of the size of the mustard seed or small peppercorn is used. In case of metals that fuse with difficulty, as raw iron, the amount may be obtained by filing. When the powdered substance is fused with soda and borax in K.F. on charcoal, sulphide of sodium is formed, which leaves a sulphur reaction when the fused mass is removed from the charcoal, pulverised, and placed on a bright sheet of silver (a silver coin will do), and moistened with water. Sulphuretted hydrogen is evolved, which colours the silver black with sulphide of silver if a notable amount of sulphur is present, but if less is present only dark brown or yellow. A minute trace of sulphur can be detected in water made acid (by a small addition of nitric acid) and then adding a little nitrate of baryta in a test tube. If sulphur is present a fine white precipitate of baryta is thrown down. The precipitation is greatly facilitated by slightly warming over the spirit lamp. PHOSPHORUS. Phosphoric acid imparts a green colour to the flame, especially after having been moistened with sul- phuric acid. This test is, however, not always conclu- sive. Crush up and then ignite the assay to expel any mois- ture ; place in a tube with a little magnesium wire, close PART II. PHOSPHORUS. 79 the tube entirely, heat strongly. Magnesium phosphide is the result. When the fused mass is treated with water and broken up the characteristic odour of phosphoretted hydrogen is evolved. Pig iron may be examined for phosphorus by dissolving a fragment in nitric acid ; then evaporating to dryness in a porcelain dish, heat it strongly, and then test for phosphoric acid as directed above. Substances consisting of earths, metallic oxides, iron ore, &c., are tested by intimately mixing (after they have been ground to a fine powder) with 5 parts by volume of a previously prepared mixture (4 parts by weight of soda and 1 of silica) in the agate mortar, and transferring it to a soda-paper cornet and fusing it in O.F. to a clear bead. (In case of iron ores it is best to take 4 assays of about 0*5 grain each and afterwards treat as one globule.) The bead is pulverised in the steel mortar, and the powder boiled in a small porcelain dish with water. Phosphate of soda, also the excess of soda, are dissolved. The clear liquid is either filtered or carefully decanted from the insoluble matter and removed into a small porce- lain dish. If much silica has been dissolved and remains in the clear liquid, add a little carbonate of ammonia, boil, and the silica will be separated in a gelatinous form. Filter, and to the filtrate add an excess of acetic acid, then some acetate of lead, stir, and if the phosphoric acid amounts to several per cent, a white precipitate of phos- phate of lead is at once formed, which is collected on a filter, dried, and fused in a shallow cavity on charcoal. If the precipitate has been well washed a white or yellowish globule with a crystalline surface is obtained. When the precipitate formed by acetate of lead is so trifling that it cannot be removed without partially de- 80 QUALITATIVE DETERMINATION. PA«T II. stroying the filter, a drop of dilute sulphuric acid must be added, which produces a mixture of sulphate and phos- phate of lead in such quantity that it may readily be transferred from the filter to charcoal. When this is fused by the blowpipe the sulphate is reduced partly to sulphide of lead, which soon volatilises, and partly to metallic lead, which gradually volatilises, leaving small globules of phosphate of lead that can be recognised with the aid of the magnifying glass by reason of its characteristic qualities. ARSENIC. Arsenic on charcoal evolves an unmistakable smell of garlic. A slight grey incrustation is formed some distance from the assay, which in K.F. disappears, assuming a faint blue tinge. Metallic arsenides, if heated on charcoal with E.F., yield part of their arsenic, which volatilises, forming a coat of arsenious acid. If a large amount of arsenic is present greyish white fumes are evolved, and the odour of garlic is recognised without stopping the blast. If the latter is not recognised the glowing assay must be held directly under the nose, so that the smallest quantity of escaping arsenic may be recognised. In cases of nickel and cobalt ores when arsenic is separated with difficulty, fuse the compound with lead in O.F. on charcoal, and the presence of the volatilising arsenic will be ascertained by its odour. Provided the quantity of arsenic is very small in a metallic compound the following process must be resorted to: brittle metals are pulverised to powder ; malleable ones are reduced by filing : — Mix 1 grain with 6 volumes of nitre and ignite in the PART II. AKSENIC. 81 platinum spoon with the blowpipe flame until no metallic particles are visible. Arsenic acid is formed, which com- bines with the potassa. The other metals are oxidised and nitrous acid is liberated. The mass in the spoon is now digested with water in a beaker glass over the spirit lamp, until everything is removed from the spoon. The clear solution is poured off from the oxides into a small porcelain vessel, acidified with hydrochloric acid, about 0*7 grain sulphate of magnesia dissolved in it by heating slightly, an excess of ammonia added, and the whole heated to boiling. Arseniate of ammonia and magnesia separate and settle quickly when the vessel is removed from the flame. The clear fluid is decanted from the precipitate, which is washed in strong water of ammonia, again allowed to settle, and freed by decantation from the fluid, after which it is dried in the vessel. The dry salt is mixed with 6 volumes of a mixture of cyanide of potassium and soda in equal parts, then treated (1) on charcoal or (2) in a matrass with a narrow neck. In the former case it is fused in R.F., and the volatilised arsenic detected by the odour. In the latter case it is first warmed over the spirit lamp in the matrass, to expel any traces of moisture (which are collected by an inserted roll of blotting paper), after F 49 which the mixture is heated to fusion. The arsenic acid is reduced, and forms a sublimate of metallic arsenic in the neck of the matrass a (fig. 49). If the amount of the arsenic is too small to produce a distinct mirror, cut off the neck above the sublimate with a file, then hold the portion of the matrass containing the sublimate in the flame. If the sublimate consists of arsenic it will volatilise and yield the arsenic odour. G 82 QUALITATIVE DETERMINATION. PART II. Oxide of antimony (antimonious acid), containing less than -poVo part of arsenic when heated to redness in a nar- row-necked matrass with 3 volumes of neutral oxalate of potash and 1 volume of charcoal dust, will afford a very distinct mirror, which on further treatment in the spirit flame is volatilised with an unmistakable odour. CARBON. Pure carbon (diamond) in a fine state of division glows like coal and burns slowly if placed on a piece of platinum foil and the flame directed down on it. It is consumed, the product of combustion being carbonic acid. Coal, anthracite, graphite, asphaltum, amber, &c., and all such compounds of carbon volatilise when heated in the platinum spoon, first with a mild O.F. and then with a strong K.F., leaving nothing but silica, lime, and other non-volatile elements. Minerals containing carbonic acid are easily tested, and with great certainty, by crushing them up finely and adding a little dilute nitric acid to them in a glass vessel and observing whether any effer- vescence ensues. The glass should be slightly heated if no gas is evolved. If carbonic acid exists in a large amount the effervescence is most violent. In raw iron, steel, and brass, the carbon (no matter how combined) is easily found by digesting a small frag- ment in a porcelain dish with about 6 times its weight of fused chloride of silver and some water acidulated with a few drops of hydrochloric acid, leaving the whole covered with a watch glass until all the iron is dissolved. The iron is converted into protochloride, the carbon remains behind, and a corresponding amount of silver is reduced. As the carbon compounds may contain earthy matter, they must be dried, mixed with 3 parts of antimoniate of PART II. CARBON, BORON, AND SILICIUM. 83 potash, then heated to redness in a matrass over the spirit lamp. The carbon is oxidised at the expense of the anti- monic acid, forming carbonic acid, which combines with the liberated potassa. When cold, fill the matrass nearly to the neck with water, which is gradually heated to boiling. The carbonate and sulphate of potash dissolve with part of the undecomposed antimoniate of potash, whilst most of the latter remains with the earths and metallic oxides. To the warm solution a few drops of nitric acid are added, which causes effervescence, more or less lively, according to the amount of carbonic acid present. Not a bubble ascends if the substance contains no carbonic acid, but several will be seen when the most trifling amount is present. BORON Is a substance found in nature combined with water, soda, ammonia, and metallic oxides, and never native. Turner has proposed a test for boracic acid in salts and minerals as follows : — The fine powder is mixed to a paste with a little water and 1 part of a flux (it is better to employ 3 parts to obtain a reliable test), consisting of 4^ parts bisulphate of potash and 1 part of finely powdered fluor spar perfectly free from boracic acid. It is then fused on a platinum wire within the blue flame, and as soon as the water is expelled fluoboracis acid is found, which is volatilised and imparts a yellowish green tinge to the flame. This colour is very transient, however, and must be looked for with great attention if little boracic acid is present. SILICIUM. Silicic acid, in the forms commonly known as quartz, flint, &c., is infusible before the blowpipe. It dissolves (when powdered finely) slowly in borax to a clear, diffi- cultly fusible glass, which while hot is frequently co- G 2 84 QUALITATIVE DETERMINATION. PART II. loured by the metallic oxides present. It is scarcely at- tacked by phosphate salt ; with soda it fuses to a clear glass with effervescence. Both naturaland artificial silicates can be tested by fusing a bead of phosphate salt on a platinum wire, then adding a splinter of the silicate and treating it in 0 F. The bases dissolve, leaving a silica skeleton, which floats in the hot, clear bead. Quartz rocks and all such directly infusible and insoluble compounds of silica should be treated in the following manner : — One part, very finely powdered, is fused with four times its weight of carbonate of soda in the platinum spoon. When fused, remove to a small beaker glass and add about 20 times its volume of water, then add hydrochloric acid, enough to make the solution a weak one. Warm the beaker over the spirit lamp until the solution has been effected and the carbonic acid gas expelled ; remove to a porcelain dish and evaporate to dryness. When cold, moisten with hydro- chloric acid, allow it to stand a short time, then dilute with hot water, stir, allow to deposit, then decant the fluid, and again treat the residue with warm water, after which filter and dry. Kemove the fine white precipitate, which is pure silicic acid. The silicium in raw iron, steel, brass, &c., is easily se- parated by dissolving a fragment in nitric acid, which holds in solution the metallic oxides formed and leaves the silica in a fine white powder, which should be tested by fusing with soda on coal. If the powder contains silica, it will be dissolved in the soda with effervescence. GLUCINIUM. Glucina alone is unchanged before the blowpipe. In PART II. GLUCINIUM AND LANTHANUM. 85 borax it dissolves in considerable quantity, forming a clear glass, which by flaming becomes milk white, as it does on cooling when fully saturated. In phosphate salt it dis- solves with the same reactions as borax. With soda on charcoal it is unchanged. With nitrate of cobalt it shows a faint bluish grey colour. The blowpipe characters of glucina are not sufficiently prominent to admit of its being recognised in such minerals as contain it ; therefore it must be detected by the humid analysis. To detect glucina the finely powdered mineral must be dissolved in hydrochloric acid, then evaporated to dryness, the residue moistened with hydrochloric acid, dis- solved in boiling water, and the silica filtered out. The acid solution is made slightly anmoniacal, when glucina and any traces of sesquioxide of iron are thrown down. They are collected on a filter, washed thoroughly, and heated while moist with a solution of potassa, until the glucina is redissolved and the iron remains behind. After diluting the solution with water, filtering it, and making it slightly acid with hydrochloric acid the glucina can be again thrown down with ammonia, and may then be tested for alumina. Filter, thoroughly wash, and shake in a test tube with an excess of carbonate of ammonia solution, which dissolves the glucina, leaving the alumina. On boiling the am- moniacal solution the glucina goes down as a carbonate, and this can be converted into pure glucina by ignition in the platinum capsule. LANTHANUM. The oxide alone on charcoal is not changed. With borax in O.F. it dissolves to a transparent colour- less glass, which, if dissolved in a sufficient quantity, can be flamed enamel white. If saturated, the glass of itself, on cooling, becomes enamel white. 86 QUALITATIVE DETERMINATION. PART II. In E.F. with borax it reacts the same as in O.F. With phosphate it acts the same as with borax. With soda on charcoal the soda is absorbed, and the oxide remains with a greyish colour behind. As lanthanum is generally found combined with cerium and didymium the exact determination of it must be referred to the laboratory. For humid assay see Cerium, p. 89. YTTRIUM Before the blowpipe is unchanged. On borax it dissolves to a clear glass bead, which by flaming becomes milk white as well as on cooling if fully saturated. With phosphate salt it presents the same reactions as with borax. With soda on charcoal it is unchanged. Yttrium is but rarely met with, and then nearly always in common with erbium in various combinations. The wet way must be employed to correctly distinguish this element. TERBIUM. The oxide is unchanged before the blowpipe. In borax it dissolves to a transparent glass, rendered milk white on naming or on cooling, when sufficiently saturated. In phosphate glass it presents the same reactions as in borax. With soda on charcoal it does not change. It must be determined by the wet way. TANTALUM. Tantalic acid in O.F. alone on charcoal becomes PART II. TANTALUM, URANIUM, AND TUNGSTEN. 87 slightly yellow, but is white again when cold. In E.F. the same. With borax on platinum wire it dissolves easily to a clear glass, which with a certain amount appears yellowish while hot, colourless on cooling, and can be made opaque by naming. With still more the glass becomes enamel white on cooling. In E.F. the same as in O.F. With phosphate salt in O.F. it dissolves largely to a clear glass, which with a very large amount is yellowish while hot, but colourless on cooling. In E.F. the above glass undergoes no alteration. With soda in O.F. with a little more than its volume of soda it fuses on charcoal with effervescence and soon spreads out, and with more soda it sinks into the coal. In the E.F. the same reaction takes place and it cannot be reduced to metal. The wet way must be employed for its compounds. URANIUM. The sesquioxide of uranium, when heated in O.F. with phosphate salt, yields a yellow glass, which becomes yellow- ish green on cooling and pure green in E.F. This test is a very good one ; but when oxides of iron, and probably titanic acid, are present the phosphate bead becomes red on cooling, and the uranium colour can only be perceived by treating the glass in O.F., when it assumes, on cooling, a green colour mixed with much yellow. Any further examination must be made by the wet way. TUNGSTEN. Tungstite, according to Von Kobell, acts before the blowpipe as follows : — On charcoal in E.F. it becomes black. In phosphate salt in O.F. it dissolves to a colourless 88 QUALITATIVE DETERMINATION. PART II. or yellowish glass, which in E.F. becomes fine blue when cold. Tungstic acid can be easily recognised by its examina- tion with phosphate salt. The bead in E.F. becomes blue when cold, or in the presence of iron more or less red. The presence of tungstic acid in tin slags may be recognised by the deep indigo blue solution which is formed when the pulverised slag is warmed in a test tube with hydrochloric acid. VANADIUM. Vanadic acid alone on charcoal fuses, is reduced, and goes partly into the coal ; the remainder assumes the colour and lustre of graphite and is protoxide of vanadium. With borax on platinum wire in O.F. it dissolves to a clear, colourless glass, but with more it gives a yellow glass, yellowish green on cooling. In E.F. the above glass changes, appearing brownish when hot and fine chrome green on cooling. With phosphate salt on platinum wire in O.F. it dissolves to a clear glass ; if not in too small a quantity, dark yellow while hot, and light yellow on cooling. In E.F. the same as with borax. Vanadium is a very rare metal, and has only been found as an acid in a very few minerals. The further examination must be made by means of a humid analysis. PALLADIUM. Protoxide of palladium is reduced at a red heat, but the metallic particles are infusible. In O.F. and E.F. on charcoal with borax the metallic oxides are reduced without dissolving, and a metallic button cannot be obtained. PART II. PALLADIUM, RUTHENIUM, AND CERIUM. 89 With phosphate salt the same as with borax. With soda on charcoal the soda sinks into the coal, leaving the palladium as an infusible powder. Palladium reduced from its oxides behaves, according to Berzelius, as follows : — 6 Carefully heated on platinum foil to low redness, it acquires upon the surface a blue colour, which, however, disappears at full redness. 4 On charcoal alone it is infusible and unchangeable. With sulphur in K.F. it fuses, but in O.F. the sulphur burns off, leaving the palladium behind. When fused with bisulphate of potash in a sufficiently large matrass it is dissolved with evolution of sulphurous acid. The salt appears yellow when cool.' RUTHENIUM. This metal is only found in small quantities in native platinum, and is grey white, brittle, and very infusible. It is not attacked by fusing with bisulphate of potash, and is scarcely acted upon by aqua regia. No characteristic blowpipe reactions can be obtained from this metal. CERIUM. Before the blowpipe on charcoal the protoxide is changed by O.F. into the sesquioxide, which remains unchanged even in R.F. In borax with O.F. it is soluble to a dark yellow or red glass (similar to the sesquioxide of iron glass), but in cool- ing it is yellow. If sufficiently saturated the glass can be flamed opalescent, and if fully saturated it becomes so of itself on cooling. In R.F. the yellow glass becomes colourless, and a 90 QUALITATIVE DETERMINATION, PART II. strongly saturated glass on cooling becomes enamel white and crystalline. In O.F. with phosphate glass it reacts the same as with borax, but the colour disappears entirely on cooling. In E.F. no saturation prevents the glass being transparent. It is colourless both w^hilst hot and cold (which distinguishes oxide of cerium from oxide of iron). With soda on charcoal the soda is absorbed, and the oxide is reduced to protoxide, which remains behind, of a light grey colour. As cerium, lanthanum, and didymium are generally combined together, the following simple method is given to enable the assay er to determine all three : — The mixed oxides, after having been ignited, are first treated with weak, then with concentrated nitric acid, which extracts the lanthanum and didymium. Upon evaporating this solution, igniting the salt, and again treating the oxides with very dilute nitric acid, any oxide of cerium which has been dissolved now remains undissolved. From the solution of lanthanum and didymium the oxide^ are thrown down with ammonia and dissolved in sulphuric acid. The dry salt being then dissolved to saturation in water at 43° to 45° Fahr., and the solution then warmed to 100°, sulphate of lanthanum separates, leaving the didymium salt in the solution, from which it can be precipitated by potassa. The oxides may be obtained still purer by repeating the process. DIDYMIUM. The oxide on charcoal in O.F. is unchanged, but in E.F. with a strong heat it loses its brown colour and becomes grey. In borax with O.F. it dissolves to a clear glass of a dark amethyst colour. PART II. DIDYMIUM, ERBIUM, AND NIOBIUM. 91 In phosphate salt it behaves the same as with borax. With soda on charcoal it is insoluble ; the soda is absorbed and the oxide remains of a grey colour. For a minute examination see assay of cerium, p. 90. ERBIUM. The yellow oxide in R.F. becomes lighter in colour and translucent in appearance. In borax it dissolves with difficulty to a colourless glass, which by naming, and also when saturated, is milk white. With phosphate salt the same reactions as with borax. With soda on charcoal it is unaltered. The humid method must be employed for any further examinations of erbium. NIOBIUM, or COLUMBIUM. Niobic acid, before the blowpipe on charcoal in O.F., becomes yellowish, but is white again on cooling. In R.F. the same. With borax in O.F. on platinum wire it dissolves easily to a clear, colourless glass, becoming opaque by flam- ing with a moderate addition, and with more becomes opaque when cool. In R.F. yields a glass which, after treatment in O.F., becomes opaque of itself, and on cooling remains unaltered. With phosphate salt on platinum wire in O.F. it dis- solves largely to a clear glass, yellow while hot, but colour- less on cooling. In R.F. with a very large addition the glass becomes brown. The addition of sulphate of iron causes a blood red bead. With soda in O.F. fuses with an equal volume of soda, 92 QUALITATIVE DETERMINATION. PAET II. with effervescence, but with more soda goes into the coal. In E.F. the same, and it cannot be reduced to metal. The wet way must be employed for an accurate deter- mination. THORIUM. Thoria alone before the blowpipe remains unaltered. With borax on platinum wire it dissolves in small quantity to a clear glass, milk white on cooling, if saturated, but if it appears clear on cooling it cannot be made opaque by flaming. With phosphate salt, same as with borax. With soda on charcoal it is insoluble. Thorium is a rare element, seldom met with, and as it gives no characteristic blowpipe reaction the humid analysis must be employed. THALLIUM. Thallium melts very easily on charcoal, and when touched with the point of the blue flame the metal is surrounded by a green flame. When being fused on charcoal a moderate amount of white coat of oxide is formed at some distance from the assay, which is driven off when E.F. is applied. Its salts also give an intense green flame. With the spectroscope it can be readily determined. MOLYBDENUM. When molybdic acid is heated on charcoal in O.F. it volatilises ; at the same time the support acquires a yellow coating, often crystalline, which becomes white on cooling. In R.F. metallic molybdenum is formed, which may be obtained as a grey powder by washing PART II. MOLYBDENUM, ETC. 93 the pulverised charcoal. Sulphide of molybdenum, when heated in O.F., yields sulphurous acid gas and a sub- limate of molybdic acid. In order to find a small amount of molybdenum in its compounds it is necessary to have recourse to the wet way. RHODIUM. Rhodium gives no characteristic reactions with the blowpipe. IRIDIUM. Iridium before the blowpipe cannot be determined. It can be separated from platinum, gold, silver, copper, &c., by following the method laid out in the gold assay (Class B, /), and the percentage estimated. OSMIUM. Osmium generally occurs with platinum and iridium, &c., and forms, with iridium, iridosmine. The metal as well as the protoxide and binoxide change easily, when heated in the air, to osmic acid, which is volatile and recognisable by its highly characteristic, penetrating, and disagreeable odour, resembling that of chlorine and bromine. If osmium be placed on a strip of platinum and brought into the outer flame at half its height, the flame becomes intensely luminous. For minute portions the wet method must be employed. SELENIUM. Selenium, even when combined with other elements, is easily determined by heating on charcoal, when it evolves a strong odour of bad horse-radish. When heated in a glass tube selenium forms a red sublimate. 94 QUALITATIVE DETERMINATION. PART II. Selenium, when fused within the blue flame on coal, volatilises with an intense azure blue flame. The salts of selenium (selenates and selenites) are re- duced in E.F. on coal, either alone or with addition of soda, to selenides, which emit a distinct horse-radish odour. TELLURIUM. Tellurium is very rare, and is found alloyed with other elements and as tellurous acid in tellurite. It is a white, brittle, and easily fusible metal. It sublimes in a glass tube over the lamp. Heated on charcoal, it burns with a greenish blue flame, with production of dense white vapours of tellurous acid. ZIRCONIUM. Zirconia is infusible and unchanged by either E.F. or O.F. If prepared from the sulphate and heated by a blow- pipe it becomes so brilliant that it dazzles the eye, and in this property it exceeds any other substance. In borax it dissolves to a transparent glass, which becomes on flaming, or if saturated on cooling, milk white. In phosphate glass it dissolves slower than in borax, and gives quickly an opaque glass. With soda on charcoal it is unchanged. With nitrate of cobalt in O.F. it receives a dirty violet colour. PAET III. ASSAY OF SILVER. GOLD. MERCURY. COPPER. LEAD. BISMUTH. TIN. IRON. NICKEL. COBALT. NICKEL AND COBALT. COAL. SILVER. ONLY a small proportion of the large amount of silver which is at the present time produced for commercial purposes is found native, and then not pure, as it is gene- rally alloyed with a little copper, gold, platinum, mercury, arsenic, iron, lead, bismuth, or antimony. Native silver occurs in masses or in arborescent and filiform shapes in veins traversing gneiss, schists, porphyry, and other rocks ; it also occurs disseminated in native copper and galena, but usually invisible to the naked eye, therefore requiring the aid of a good microscope to deter- mine its presence. Silver, when pure, has a metallic lustre. Colour and streak, silver white. Ductile. Hardness, 2-5- 3. Specific gravity when pure, 1O5. Minerals containing silver are found in veins of nearly all descriptions, and even in sea water minute traces have been found by a careful ana- lysis. The principal minerals containing silver are as follows : — Argentite : silver glance, containing 87 per cent, silver, with sulphur. Stephanite : brittle silver ore, containing 68 per cent, silver, with sulphur and antimony. Proustite: light red silver ore, containing 65'4 per cent, silver, with sulphur and arsenic. Pyrargyrite: dark red silver ore, containing 59 per cent, silver, with sulphur and antimony. H 98 ASSAY OF SILVER, GOLD, MERCUKY, ETC. PART III. Argentiferous grey copper ore (fahlerz), containing from 5-7 to 18-31*8 per cent, silver, with antimony and sulphur. Argentiferous sulphide of copper, containing 53 per cent, silver, with sulphur and copper. Polybasite, containing 72-94 per cent, silver, with copper, sulphur, arsenic, and antimony. Chilenite, containing 86*2 per cent, silver, with bismuth 13*8 per cent. Bromyrite, containing 57*4 per cent, silver, with bro- mine 42*6 per cent. Cerargyrite (horn or chloride), containing 7 5 '3 per cent, silver, with chlorine 24-7 per cent. Embolite, containing 60-72 per cent, silver, with bromine and chlorine. Sternbergite, containing 33*2 per cent, silver, with iron 36 per cent, and sulphur 30 per cent. lodyrite, containing 46 per cent, silver, with iodine 54 per cent. Selenic silver, containing 11*6— 42*8— 65*5 per cent. silver, with selenium, copper, and lead. Hessite, containing 62 '8 per cent, silver, with tellurium 37-2 per cent. Silver is a metal extensively used in the arts and manufactories, and many of their products contain it in more or less proportions. Silver will be found in the products as well as in the refuse from nearly all lead and copper smelting works, if carefully looked for, and a very small amount can be determined with great accuracy. Any mineral, alloy, or product containing what is termed 6 a trace of silver,' about ^ ounce to the ton of 2,000 pounds, can be assayed, and the metal extracted and determined with accuracy by the following methods. PART III. SILVER. 99 Assay of Silver. In order to separate silver from its ores and compounds by the blowpipe the previous metal must be formed into an alloy with lead ; then the silver lead concentrated by a process known as scorification, by which the bulk of the lead, copper, &c., is oxidised ; then the concentrated silver lead is subjected to the process of cupellation, whereby all the lead and other base metals are oxidised and the silver left in the form of a metallic button. Commercial ores, especially very rich ones, frequently differ in richness ; it is therefore advisable in all cases of importance to make two or three assays of each sample, and if the results do not agree to make one or two more, and then to take the mean or average of the whole, and to that add the loss of silver proved by the synthetical assay. In assays of alloys, proof and synthetical assays are absolutely necessary to prove the work. Silver Assay. The assay of silver is divided into three classes, A, B, and C. A. When the silver is principally in combination with non-metallic bodies. (a) Containing volatile matters, as sulphur and arsenic, and so combined as to be decomposed by fusion with borax and lead on charcoal. (6) Containing sulphides not decomposed by borax and lead alone (argentiferous sulphides of molyb- denum). (c) Containing chlorine, bromine, and iodine, with little or no other volatile matters. (d) Consisting of metallic oxides, easily reduced on charcoal (litharge, &c.) (e) General method adapted to the assay of a, 6, c ; either to one or all. u 2 100 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III. B. Metallic alloys ready for cicpellation after the necessary addition of lead, (a) Bar and ingot silver, standard silver, coins, native silver, alloys of silver, gold, and copper. (7. Metallic alloys requiring either distillation, or fusion with fluxes before they are ready for cupellation. (a) Containing mercury in the form of amalgam. (6) Test and precipitated silver. Eetorted silver amalgam. (c) Containing copper or nickel with more or less sul- phur, arsenic, zinc, black copper, brass, and German silver. (d) Containing tin — argentiferous tin, bronze, bell metal, gun metal, and bronze coinage. (e) Containing antimony, tellurium, or zinc. (/) Iron bears from smelting furnaces and silver-steel, &c. (g) Containing alloys of lead or bismuth with silver, in which the proportions of the former predominate. (h) Containing copper in the form of coins, ingot, sheet, or wire ; cement and copper nickel alloys con- taining silver. A. (a) Consists of most commercial ores which con- tain iron, copper, and arsenical pyrites, antimonial glance, blende, selenides, silver glance, sulphide of silver, ruby silver, sulphide of silver and copper, miargyrite, &c. ; also copper ores, as copper glance, purple copper, fahlerz, &c.; also lead ores, as galena, selenide of lead, &c. ; also copper and lead mattes, lead sublimate, and cobalt speiss. Reduction to Silver Lead. The ore is reduced to powder and passed through a. sieve of 2,000 holes to the linear inch; it is then tho- PART 111. SILVEE. 101 roughly mixed and 1*5 grain weighed out. The ore is fluxed with borax and lead. The amount of borax required is dependent on the fusibility and amount of matter to be slagged. Ores containing much gangue, iron, cobalt, or tin require 1J grain borax glass. When ores contain little gangue and much metallic sulphides 0*8 to 1*2 grain borax glass is quite sufficient. Should the assay during the fusion show itself refractory, a little more borax may be added to it. The amount of lead required depends on the other metals present in the ore. A substance containing 7 per cent, copper or 10 per cent, nickel requires five times its weight of lead (7 -5 grains), but when it contains more than this amount the proportion must be dependent on the amount of copper, &c., present. When this is not known it is in all cases better to use too much than too little lead, as in the last case the separation of the silver from the copper is not effected, and a lead alloy rich in nickel can- not be cupelled. The following table will show the relative proportions to be employed :— Copper glance, containing about 80 per cent, copper, requires 15 times its weight of lead. Covellite, containing about 65-66 per cent, copper, requires 12 times its weight of lead. Purple copper, containing about 55-60 per cent, copper, requires 11 times its weight of lead. Tennantite, containing about 48-50 per cent, copper, requires 10 times its weight of lead. Kupferblende, containing about 41-40 per cent, copper, requires 10 times its weight of lead. Fahlerz, containing about 30-40 per cent, copper, requires 10 times its weight of lead. Cupreous bismuth ore, containing about 34-35 per cent, copper, requires 10 times its weight of lead. Copper pyrites, containing about 30-34 per cent, copper, requires 10 times its weight of lead . 102 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III. Sulphide of copper and silver, containing about 30-31 per cent. copper, requires 10 times its weight of lead. Tin pyrites, containing about 29-30 per cent, copper, requires 7 times its weight of lead. Eukairite, containing about 23-25 per cent, copper, requires 7 times its weight of lead. Bournonite, containing about 12-13 per cent, copper, requires 7 times its weight of lead. Copper regulus, containing up to 45 per cent, copper, requires 10 times its weight of lead. Copper regulus, containing up to 50-60 per cent, copper, re- quires 10 times its weight of lead. Lead speiss, containing up to 10-40 per cent, copper, requires 10 times its weight of lead. Cobalt speiss, containing up to 40-50 per cent, copper, requires 10 times its weight of lead. The assay having been prepared, is poured with care into a soda-paper cornet, placed in a charcoal bore of about T4^ FIG 50 (Full size ) of an inch in diameter at the bottom, and from T% to -^ at the top. The cavity is bored wider at the top, to allow the flame to reach down to the bottom of the bore. The top of the cornet is then closed up with a pair of pliers and pressed firmly down (see fig. 50). The assay is now in- clined towards the flame, and a re- duction flame, at first moderately strong, is employed to cover nearly all the top of the assay. The paper, is not consumed until the par- ticles below it have entered into fusion and prevented mechanical loss. The whole assay is now submitted to a strong but pure R.F. at an angle of 30° to 35° degrees. By the action of this flame a part of the sulphur, arsenic, antimony, zinc, &c., is volatilised, but the greater PART III. SILVER. 103 part, along with the metallic bases, unite with the lead to a globule, whilst the gangue, the difficultly reducible metals, and a smaller part of the easily oxidisable but non-volatile metals (which have, been oxidised by the first action of the heat) combine with the borax to form the slag. With re- fractory ores it often appears as if the slag were quite free from lead globules; but this is not to be trusted to, as often, under the surface of the well-fused slag, unacted-upon par- ticles of the ore may be concealed, which is only to be obviated by moving frequently the charcoal, so as to change the portion of the assay ; this must be done also with easily fusible assays, as by this means the lower part of the assay and the carbonised soda paper is exposed to the flame. As the paper is hardly acted upon in a good R.F., it is necessary to direct the flame on to the slag, so as to cover it but leave the paper on one side with access to the air, by wilich it is consumed, while the slag is not affected. When consumed, the whole slag is again covered by the R.F., to reduce any litharge that may have been formed, and which by this means is united to the main globule. If the slag, after being treated thus in the R.F. and moved about several times, forms a globule itself, and shows no lead globules, and is perfectly fluid, it may be considered free from silver. Whilst the slag is covered with the E.F. the metallic globule is only touched by the side of the flame, to keep it perfectly fluid and ready to take up any straggling lead globule (fig. 51). The assay is allowed to cool, and then removed with the pliers and placed between two thick pieces of paper on the steel anvil and broken up with the hammer; the lead button carefully picked up with the pliers and brushed, is then ready for the next process. The finely crushed slag is washed in water and then 104 ASSAY OF SILVER, .GOLD, MERCURY, ETC. PART III. examined with the magnifying glass, to see if any small globules of lead, &c., remain, and if such are found the safest plan to secure a perfect assay is to repeat the operation. In assays of no commercial importance the FIG. 51. (f nat. size.) fine globules can be separated from the slag by vanning in water and then adding them to the main globule. Scorification and Concentration of the Silver Lead. If the lead button is malleable the scorification can be proceeded with direct ; but if, on the contrary, it is brittle, FIG. 52. (Full size.) from one to three grains of proof lead and 0'3 grain borax glass is added to it on the scorifier, and the ope- ration carried on as before. The scorification is best carried on in a small scori- fier made of good fine clay, about T%- of an inch in diameter, £ of an inch thick in its deepest place, and 1 of an inch deep in the centre (see fig. 52). It is used in a holder made of fire clay, which is partially covered with thick, smooth paper about 2J inches long and with a hollow place in PART III. SILVER. 105 the top, in which the scorifier fits (see fig. 53). A piece of charcoal will also make a good holder, and can be readily cut to the required shape. FIG. 53. (Full size.) The scorifier is warmed, and when at a red heat the globule of silver lead is added and brought into a state of fusion by the use of the K.F. Then the O.F. is used and the heat applied gently. The fluid litharge soon forms, and portions of which adhere and glaze the sides of the cup. The formation of the litharge is greatly assisted by slowly turning the assay round and round and from side to side at a gentle inclination, and at the same time keeping the flame at the edge of the bead. When the litharge has once formed, it accumulates rapidly, and from five to ten minutes completes the operation. If the ore is poor in silver the scorification can be carried on until what is termed the 6 eye ' appears, i.e. the small button of lead is nearly covered with litharge and only just visible. The operator can, after a few experi- ments, decide when the operation should be discontinued. When the lead is rich in silver it oxidises very slowly and assumes a spherical form. The assay is allowed to cool, and then the scorifier is broken on the steel anvil and the button carefully brushed. It is then ready for cupellation. N.B. Plattner and David Forbes advise scorification to be partially carried on, on charcoal, after the reduction of the assay, and then finished on a cupel of coarse bone ash. The author has found a loss of silver, as well as an occasional spirting, &c., by the prolongation of the assay on 1 06 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III. charcoal after the complete reduction of the assay has been effected, and for accuracy and despatch he recommends the above method, as it has been used for some j/ears with success by himself. Cupellation. When an alloy of lead, silver, gold, copper, &c., is fused in a cupel in a current of air, the lead is readily oxi- dised and forms a very fusible oxide. The lead parts with portions of its oxygen to the copper and other base metals. The oxides thus produced are dissolved and carried down into the porous cupel in a liquid state by the vitrified oxide of lead, leaving the silver and gold in the form of a small globule on the surface of the cupel. The cupellation is conducted as follows : — Any lead FIG. 54. (Full size.) alloy over 5 grains in weight is best cupelled in one of the previously prepared cupels placed in the cupel-holder (see fig. 54). If the weight is under 5 grains a small cupel is sufficient, which can be rapidly prepared by moistening some of the finely powdered bone ash with enough water to form a dryish paste. The paste is placed in the steel cupel mould (see fig. 55), the bottom of which must either rest on the steel anvil or some hard solid substance, and a cupel formed by placing the bolt (fig. 56) on the top of the mould and applying a few light strokes. The mould (fig. 57) containing the cupel is now dried slowly over the lamp, and finally heated to redness, and if no cracks or flaws appear, and the cupel presents a smooth and regular surface, the alloy can now be added (it is never advisable to proceed with the cupellation unless the cupel is found to be perfect), and a mild K.F. applied until the assay is PART III. SILVER. 107 in a state of fusion ; directly it is so the O.F. must be applied, and the same continued at the outer edge of the globule, and without touching the assay. A strong enough heat must be imparted to the bone ash, to keep the assay .in oxidation without allowing it to become FIG. 55. (Full size.) (Full size.) chilled or quiet. The cupel can also be moved slightly from side to side, which gives the lead a fresh surface of clean bone ash to act upon and facilitate the completion of the operation. It is best to finish the assay about the centre of the cupel, but at the same time it is FIG. 56. not absolutely necessary for the accuracy of the assay. With a little practice the operator can tell when the oxidation is nearly finished by the surfaces of the bead being covered with iridescent colours (resembling rainbow co- lours),which only last but amoment,when the globule rotates and brightens. Directly the colours disappear the heat should be slightly raised, to free the bead from the last traces of lead, and then the assay is cooled down slowly. In assays very poor in silver the latter precau- tion is scarcely necessary. In the case of rich ores, alloys, &c., much care must be exercised in cooling the bead gradually, else a violent spurting takes place and small particles of the silver are thrown out from the bead, and the assay cannot be relied upon, and it should be repeated. When cool the bead is removed with the steel pliers from the cupel and 108 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III. FIG. 57. (Full size.) cleaned from any adherent bone ash, and if too small to be weighed it must be very carefully detached by a needle or some other sharp instrument, and so as not to injure its form. It is then measured or weighed, according to its size, but when the bead weighs more than O'Ol grain it is more correctly estimated by the balance than if measured. In case the ore is very poor, and the button found to be very minute (on scale below No. 16, or 0*11 per cent.), it is best to make a duplicate assay and add the first button to the silver lead on the cupel of the second assay, and when finished measure or weigh both together. The loss of silver by reduction., scorification, and cupellation can be corrected by comparing the results ob- tained from the ore or alloy with those obtained by operat- ing on a carefully weighed piece of proof silver., which is added to an artificial compound, prepared by the operator to resemble as nearly as possible the composition of the ore or alloy which has been assayed. The synthetical assay, so prepared, must be free from silver, with the exception of the amount weighed and added ; and it should be fused, scorified, and cupelled in a similar manner to the native ore or alloy, and with the same quantity of lead and fluxes. The difference in weight of the proof silver before assaying, and what is found afterwards, will represent the loss of silver, and it should be added to the assay weight of the ore or alloy which has been assayed, and it may be considered as the correct loss which has taken place. Ores and alloys very poor in silver, and so poor that their weight cannot be readily ascertained by the balance, do not require any compensation to be made for the loss of silver in cupellation, &c., as the loss on very small beads is so PART III. SILVER. 109 minute that it can scarcely be estimated with accuracy, and even if it could it would be too little to be of any commercial importance. Most accurate results will be obtained by making synthetical assays and following the methods here de- scribed, and the student will find that by adopting the same he can easily make his assays, check them himself , and have perfect confidence in the results he obtains. Synthetical assays entail more labour and time than that of using tables which have been compiled by authorities on the subject; but it ensures great accuracy, owing in a great measure to the different ways in which different operators use the blowpipe, also to the degrees of heat, apparatus, quality of material, and the fuel, &c., employed. The following tables, with full instructions for their use, have been compiled by David Forbes, and will be found of great service to the assay er.1 ' Determination of the Weight of the Silver Globule ob- tained on Cupellation. — As the amount of lead which can, by the method before described, be conveniently cupelled before the blowpipe is necessarily limited, the silver globule which remains upon the bone-ash surface of the cupel at the end of the operation is, when substances poor in silver have been examined, frequently so very minute that its weight could not be determined with correctness by the most delicate balances in general use.' The blowpipe balance employed by the author turns readily with y^Vo °^ a gram? but could not be used for • determining weights below that amount. Grlobules of silver of far less weight than 1 0iQO are distinctly visible to the naked eye — a circumstance which induced Harkort to invent a volumetrical scale based upon the measurement of the diameters of the glo- 1 See Mitchell's Manual of Practical Assaying, pp. 676-681 ; also D. Forbes, Chemical News, Nos. 380, 384, 392, 396, 398, and 412. ICQ— r 98' 96- 94' 92- 90- ASSAY OF SILVER, GOLD, ETC. PART III. bules, which scale in practice has been found of very great utility in the blowpipe assay of silver. The scale for this purpose which is em- ployed by the author is shown in full size in the annexed woodcut. This figure (5 8) represents a small strip of highly polished ivory about 6^ inches long, f inch broad, and |- inch in thickness, on which are drawn, by an extremely fine point, two very fine and distinct lines emanating from the lower or zero point, and diverging upwards until, at the distance of exactly 6 English standard inches, they are precisely To~o Parts °f an inch apart. This dis- tance (6 inches) is, as shown in wood- cut, divided into 100 equal parts by cross lines numbered in accordance from zero up- wards. It is now evident, if a small globule of silver be placed in the space between these two lines, using a magnifying glass to assist the eye in moving it up or down until the diameter of globule is exactly con- tained within the lines themselves, that we have at once a means of estimating the dia- meter of the globule itself, and therefrom are enabled to calculate its weight. As the silver globules which cool upon the surface of the bone-ash cupel are not true spheres, but are considerably flattened on the lower surface, where they touch and rest upon the cupel, it follows that the weight of globules corresponding in diameter to the extent of divergence at the different degrees of the scale cannot be calculated directly PART III. SILVER. 1 1 1 from their diameters as spheres, but require to have their actual weight experimentally determined in the same manner as employed by Plattner. The table appended on next page has been calculated by the author, and in one column shows the diameter in English inches corresponding to each number or degree of the scale itself, and in the two next columns the respective weights of the flattened spheres which correspond to each degree or diameter ; for convenience these weights are given in the different columns in decimals, both of English grains and of French grammes. These weights are calculated from the following data, found as the average result of several very careful and closely approximating assays, which showed that globules of silver exactly corresponding to No. 95 on this scale, or O038 inch in diameter, possessed a weight of 0*0475573 grain, or 0*003079 gramme. From this the respective weights of all the other numbers or degrees on this scale were calculated, on the principle that solids were to one another in the ratio of the cubes of their diameters. This mode of calculation is not, however, absolutely correct in principle, for the amount of flattening of the under sur- face of the globule diminishes in reality with the decreasing volume of the globule. In actual practice, however, this difference may be assumed to be so small that it may be neglected without injury to the correctness of the results. The smaller the diameter of the globule, the less will be the difference or variation in weight in descending the degrees of this scale, since the globules themselves vary in weight with the cubes of their diameters ; for this reason, also, all such globules as come within the scope of the balance employed should be weighed in preference to being measured, and this scale should be regarded as more specially applicable to the smaller globules beyond the reach of the balance. J 1 2 ASSAY OF SILVER, GOLD, MERCUEY, ETC. PART III. No. on Scale Greatest Diame- ter in Inches Weight of Globule in Grains Weight of Globule in Grammes 1 0-0004 0-00000005 0-000000003 2 0-0008 0-00000044 0-000000028 3 0-0012 0-00000149 0-000000090 4 o-ooio 0-00000355 0-000000229 5 0-0020 0-0000009 0-00000044 6 0-0024 0-0000119 0-00000077 7 0-0028 0-0000190 0-00000120 8 0-0032 0-0000284 0-00000184 9 0-0030 0-0000403 0-00000202 10 0-0040 0-0000554 0-00000359 11 0-0044 0-0000730 0-00000478 12 0-0048 0-0000958 0-00000020 13 0-0052 0-0001218 0-00000789 14 0-0050 0-0003522 0-00000985 15 o-ooeo 0-0001872 0-00001203 10 0-0004 0-0002272 0-00001471 17 0-0008 0-0002725 0-00001704 18 0-0072 0-0003234 0-00002094 19 0-0070 0-0003804 0-00002403 20 0-0080 0-0004437 0-00002872 21 0-0084 0-0005137 0-00003327 22 0-0088 0-0005900 0-00003823 23 0-0092 0-0000748 0-00004307 24 0-0090 0-0007008 0-00004904 25 o-oioo 0-0008007 0-00005011 20 0-0104 0-0009749 0-00000311 27 0-0108 0-0010918 0-00007008 28 0-0112 0-0012170 0-00007883 29 o-oiio 0-0013528 0-00008758 30 0-0120 0-0014970 0-00009090 31 0-0124 0-0010524 0-00010098 32 0-0128 0-0018170 0-00011077 33 0-0132 0-0019934 0-00012817 34 0-0130 0-0021801 0-00014114 35 0-0140 0-0023780 0-00015397 30 0-0144 0-0025879 0-00010755 37 0-0148 0-0028097 0-00018190 38 0-0152 0-0030437 0-00019705 39 0-0150 0-0032903 0-00021302 40 o-oioo 0-0035550 0-00022983 41 0-0104 0-0038230 0-00024751 42 0-0108 0-0041090 0-00020000 43 0-0172 0-0044111 0-00028553 44 0-0170 0-0047250 0-00030589 PART III. SILVER, 113 No. on Scale Greatest Diameter in Inches Weight of Globule in Grains Weight of Globule in Grammes 45 0-0180 0-0050546 0-00032725 46 0-0184 0-0053991 0-00034955 47 0-0188 0-0057590 0-00037285 48 0-0192 0-0061344 0-00039716 49 0-0196 0-0065258 0-00042250 50 0-0200 0-0069335 0-00044890 51 0-0204 0-0073581 0-00047638 52 0-0208 0-0077799 0-00050495 53 0-0212 0-0082580 0-00053464 54 0-0216 0-00873438 0-00056549 55 0-0220 0-00922854 0-00059748 56 0-0224 0-0097412 0-00063067 57 0-0228 0-0102725 0-00066506 58 0-0232 0-0108228 0-00070021 59 0-0236 0-0113922 0-00073753 60 0-0240 0-0119815 0-00077570 61 0-0244 0-0125901 0-00081513 62 0-0248 0-0132119 0-00085588 63 0-0252 0-0138901 0-00089797 64 0-0256 0-0145440 0-00094141 65 0-0260 0-0152311 0-00098623 66 0-0264 0-0159472 0-00103245 67 0-0268 0-0166828 0-00108010 68 0-0272 0-0174414 0-00112918 69 0-0276 0-0182220 0-00117974 70 0-0280 0-0190256 0-00123177 71 0-0284 0-0198529 0-00128535 72 0-0288 0-0207035 0-00134041 73 0-0292 0-0215782 0-00139704 74 0-0296 0-0224469 0-00145525 75 0-0300 0-0234010 0-00151504 76 0-0304 0-0243496 ' 0-00157645 77 0-0308 0-0253224 0-00163950 78 0-0312 0-0263228 0-00170422 79 0-0316 0-0273484 0-00177060 80 0-0320 0-0284000 0-00183869 81 0-0324 0-0294789 0-00190852 82 0-0328 0-0305838 0-00198008 83 0-0332 0-0317162 0-00205340 84 0-0336 0-0328768 0-00212851 85 0-0340 0-0340649 0-00220549 86 0-0344 0-0349739 0-00228400 87 0-0348 0-0364422 0-00235938 88 0-0352 0-0378008 0-00244730 114 ASSAY OF SILVEE, GOLD, MERCUKY, ETC. PART III. No. on Scale Greatest Diameter in Inches Weight of G-lobule in Grains Weight of Globule in Grammes 89 0-0356 0-0390138 0-00253168 90 0-0360 0-0404368 0-00261797 91 0-0364 0-0417943 0-00270790 92 0-0368 0-0431930 0-00279642 93 0-0372 0-0446162 0-00288860 94 0-0376 0-0460718 0-00298279 95 0-0380 0-0475573 0-00307900 96 0-0384 0-0465239 0-00317728 97 0-0388 0-0506249 0-00327759 98 0-0392 0-0522069 0-00338020 99 0-0396 0-0538215 0-00348452 100 0-0400 0-0554688 0-00359138 Silver Assay. Cupellation Loss. — This term is ap- plied to indicate a minute loss of silver, unavoidably sustained in the process of cupellation, which arises from a small portion of that metal being mechanically carried along with the litharge into the body of the cupel. The amount of this loss increases with the quantity of lead present in the assay (whether contained originally in the assay or added subsequently for the purpose of slagging off the copper, &c.); it is relatively greater, as the silver globule is larger, but represents a larger percentage of the silver actually contained in the assay, in proportion as the silver globule obtained diminishes in size. It has, however, been experimentally proved that in assays of like richness in silver, this loss remains constant when the same temperature has been employed, and similar weights of lead been oxidised in the operation. In the blowpipe assay this loss is not confined to the ultimate operation of cupellation, but occurs, though in a less degree, in the concentration of the silver lead, and in the previous scorification of the assay, had such operation preceded the concentration. The total loss in the blow- pipe assay is found, however, to be less than in the ordinary PART III. SILVER. 115 muffle assay, since in the latter case the whole of the oxidised lead is directly absorbed by the cupel. In mercantile assays of ore it is not customary to pay attention to the cupellation loss, and the results are usually stated in the weight of silver actually obtained. Where, however, great accuracy is required, especially when the substances are very rich in silver, the cupellation loss is added to the weight of the silver globule obtained, in order to arrive at the true percentage. The amount to be added for this purpose is shown in the annexed table, which is slightly modified from Platt- ner s : — Actual Per- centage of Silver found by Assay Cupellation Loss, or Percentage of Silver to be added to the actual per- centage found by assay in order to show the true percentage of silver contained in same, the entire amount of lead in or added to the assay being the following multiples of the original weight of assay :— 1 2 3 4 5 6 8 11 13 16 99-75, 99-5 / 0-25 0-32 0-39 0-45 0-50 — — — — — 90 0-22 0-29 0-36 0-42 0-47 0-69 0-83 — — — 80 0-20 0-26 0-33 0-3^ 0-44 0-64 0-75 — — — 70 0-18 0-23 0-29 0-35 0-40 0-58 0-68 0-82 — — 60 0-16 0-20 0-26 0-30 0-36 052 0-61 0-74 — — 50 0'14 0-17 0-23 0-26 0-32 0-46 0-54 0-65 — — 40 0-12 0-15 020 0-22 0-27 0-39 0-46 0-55 0-62 — 35 0-11 0-13 0-18 0-18 0-25 0-36 0-42 0-50 0-57 — 30 o-io 012 0-16 016 0-22 0-32 0-38 0-45 0-51 — 25 0-09 o-io 0-14 0-14 0-20 0-29 0-34 0-40 0-45 — 20 0-08 0-09 0-12 012 0'17 0-25 0-29 0-35 0-39 0-45 15 0-07 0-08 o-io O'll 0-15 0-20 0-23 0-28 0-32 0-37 112 0-06 0-07 0-09 o-io 0-13 0-17 0-19 0-23 0-26 0-32 10 0-05 0-06 0-08 0-09 0-11 0-15 0-17 0-20 0-23 0-27 ! 9 0-04 0-05 0-07 0-08 o-io 0-14 0-16 0-18 0-21 0-25 ! 8 0-03 0-04 0-06 0-07 0-09 0-13 0-15 0-16 0-18 0-22 ! 7 0-02 0-03 0-05 0-06 0-08 0-12 0-13 0'14 0-16 0-20 6 o-oi 0-02 0-04 0-05 0-07 o-io O'l] 0-12 014 0-17 5 o-oi 0-03 0-04 0-06 0-09 o-io O'll 0-12 0-14 4 — 0-02 0'03 0-05 0-07 0-08 0-09 o-io 0-11 3 — o-oi 0-02 0-04 0-05 0-06 0-07 0-08 0-09 2 o-oi 0-03 0-04 0-04 0-05 0-06 0-07 1 — — — — o-oi 0-03 0-03 0-04 0-04 005 116 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III. The use of the above table is best explained by an example, as the following : — An assay to which there had been added, in all, five times its weight of assay lead, gave a globule of silver equivalent to 6 per cent. Upon refer- ring to the table, it will be seen that the cupellation loss for this would be 0'07 ; consequently the true percentage of silver contained in the assay would be 6*07. This table is only extended to whole numbers, but fractional parts can easily be calculated from the same. To enable the operator to sum up the result of his assays the author has compiled the following tables for estimating the amount of gold or silver in one ton of ore, also the per- centage found in the 'assay sample' of 1 j grain. They are arranged for both the ' long ' and ' short ' ton, and have been calculated from the following data : — Avoirdupois. 4 Long ton' . =20cwt. = 2,240 Ibs. =1015 '649 kilogrammes. < Short ton' . . .=2,000,, = 906'8296 „ Hundredweight . . = 112 „ = 50 '78245 ,, Quarter . . . .= 28,, = 12 -6956144 kilogrms. Pound . .=16oz. =7,000 grains = 433'4148 grammes. Ounce . . =16 drams = 437 '5 ,, = 28 '3375 „ Dram . . . .= 27 '344 = 1 "77108 gramme. Troy (Precious Metals}. Pound . .=12oz. =5,760 grains = 373 '096 grammes. Ounce . . =20dwt. = 480 „ = 31 '0913 „ Pennyweight . .. .= 24 ,, = 1 '55457 gramme. Grain . . . . . . 0'064773 ,, Owing to the great fluctuation which has of late years taken place in the value of silver no permanent standard can be made for its value per ounce, and the assayer should re- port only the ounces or percentage found, and give the market value to date of same. After the weight of the silver has been determined the but- ton must always be examined to see if it contains any gold (by dissolving it in nitric acid), and if such is found the weight of same must be ascertained and deducted from that of the button, and the percentage of silver estimated accordingly. PART III. SILVER. 117 Gold and Silver Tables for calculating the amount of gold or silver in 1 ton of 2,240 Ibs., or 35,840 ounces, or 15,680,000 grains, using 1^ grain for the assay sample. Weight of Ore or Alloy. Grains Gave Fine Metal. Grains Equivalent per Ton to Ounces Dec. Equivalent to per Cent. 1-5 1-000000 23893-33 66-666 1-5 0-900000 21503-99 59-999 1-5 0-800000 19114-66 53-333 1-5 O'TOOOOO 16725-33 46-666 1-5 0-600000 14335-99 39-999 1-5 0-500000 11946-66 33-333 1-5 0-400000 9557-33 26-666 1-5 0-300000 7167-99 19-999 1-5 0-200000 4778-66 13-333 1-5 o-iooooo 2389-33 06-666 1-5 0-090000 2150-39 - 05-999 1-5 0-080000 1911-46 05-333 1-5 0-070000 1672-53 04-666 1-5 0-060000 1433-59 03-999 1-5 0-050000 1194-66 03-333 1-5 0-040000 955-73 02-666 1-5 0-030000 716-79 01 -999 1-5 0-020000 477-86 01-333 1-5 o-oioooo 238-93 00-6666 1-5 0-009000 215-03 00-5999 1-5 0-008000 191-14 00-5333 1-5 0-007000 167-25 00-4666 1-5 0-006000 143-35 00-3999 1-5 0-005000 119-46 00-3333 1-5 0-004000 95-57 00-2666 1-5 0-003000 71-67 00-1999 1-5 0-002000 47-78 00-1333 1-5 o-ooiooo 23-89 00-06666 1-5 0-000900 21-50 00-05999 1-5 0-000800 19-11 00-05333 1-5 0-000700 16-72 00-04666 1-5 0-000600 14-33 00-03999 1-5 0-000500 11-94 00-03333 - 1-5 0-000400 9-55 00-02666 1-5 0-000300 7-16 00-01999 1-5 0-000200 . 4-77 00-01333 1-5' o-oooioo 2-38 00-006666 1-5 0-000090 2-15 00-005999 1-5 0-000080 1-91 00-005333 118 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III. Gold and Silver Tables — continued. Weight of Ore or Alloy. Grains Gave Fine Metal. Grains Equivalent per Ton to Ounces Dec. Equivalent to per Cent. 1-5 0-000070 1-67 00-004666 1-5 0-000060 1-43 00-003999 1-5 0-000050 1-19 00-003333 1-5 0-000040 0-95 00-002666 1-5 0-000030 0-71 00-001999 1-5 0-000020 0-47 00-001333 1-5 o-ooooio 0-23 00-0006666 1-5 0-000009 0-215 00-0005999 1-5 0-000008 0-191 00-0005333 1-5 0-000007 0-167 00-0004666 1-5 0-000006 0-143 00-0003999 1-5 0-000005 0-119 00-0003333 1-5 0-000004 0-095 00-0002666 1-5 0-000003 0-071 00-0001999 1-5 0-000002 0-047 00-0001333 1-5 o-oooooi 0-023 00-00006666 Gold and Silver Tables for calculating the amount of gold or silver in 1 ton of 2,000 Ibs., or 32,000 ounces, or 14,000,000 grains, using 1^ grain for the assay sample. Weight of Ore or Alloy. Grains Gave Fine Metal. Grains Equivalent per Ton to Ounces Dec. Equivalent to per Cent. 1.5 i-oooooo 21333-33 66-666 1-5 0-900000 19200-00 59-999 1-5 0-800000 17066-66 53-333 1-5 0-700000 14933-22 46-666 15 0-600000 12799-99 39-999 1-5 0-500000 10666-66 33-333 1-5 0-400000 8533-33 26-666 1-5 0-300000 6399-99 19-999 1-5 0-200000 4266-66 13-333 1-5 o-iooooo 2133-33 06-666 1-5 0-090000 . 1920-00 05-999 1-5 0-080000 1706-66 05-333 1-5 0-070000 1493-32 04-666 1-5 0-060000 1279-99 03-999 1-5 0-050000 1066-66 03-333 1-5 0-040000 853-33 02-666 PART III. SILVER. Gold and Silver Tables — continued. 119 Weight of Ore or Alloy. Grains Gave Pine Metal. Grains Equivalent per Ton to Ounces Dec. Equivalent to per Cent. 1-5 0-030000 639-99 01-999 1*6 0-020000 426-66 01-333 1-5 o-oioooo 213-33 00-6666 1-5 0-009000 192-00 00-5999 1-5 0-008000 170-66 00-5333 1-5 0-007000 149-33 00-4666 1-5 0-006000 127-99 00-3999 1-5 0-005000 106-66 00-3333 1-5 0-004000 85-33 00-2666 1-5 0-003000 63-99 00-1999 1*6 0-002000 42-66 00-1333 1-5 o-ooiooo 21-33 00-06666 1-5 0-000900 19-20 00-05999 1-5 0-000800 17-06 00-05333 1-5 0-000700 14-93 00-04666 1-5 0-000600 12-79 00-03999 1-5 0-000500 10-66 00-03333 I'd 0-000400 8-53 00-02666 1-5 0-000300 6-39 00-01999 1-5 0-000200 4-26 00-01333 1-5 o-oooioo 2-13 00-006666 1*5 0-000090 1-92 00-005999 1-5 0-000080 1-70 00-005333 1-5 0-000070 1-49 00-004666 1-5 0-000060 1-27 00-003999 1-5 0-000050 1-06 00-003333 1-5 0-000040 0-85 00-002666 1-5 0-000030 0-63 00-001999 1-5 0-000020 0-42 00-001333 1-5 o-ooooio 0-21 00-0006666 1-5 0-000009 0-192 00-0005999 1-5 0-000008 0-170 000005333 1-5 0-000007 0-149 00-0004666 1-5 0-000006 0-127 00-0003999 1-5 0-000005 0-106 00-0003333 1-5 0-000004 0-085 00-0002666 1-5 0-000003 0-063 00-0001999 1*6 0-000002 0-042 00-0001333 1-5 o-oooooi 0-021 00-00006666 Class A (b). — This class consists only of argentiferous mo- lybdenite, and decomposes very readily when soda is used. 120 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III. The ore is finely powdered, and 1-5 grain is fluxed with 7 '5 grains proof lead, 2-3 soda, and 2 -3 borax glass in a soda-paper cornet (which has been previously placed in a charcoal bore), and is heated with a strong E.F. When the assay is thoroughly fused incline it gently and allow the lead globules to come out from under the slag. Treat it with the O.F. for several minutes, until all the molybdenum is volatilised ; then allow it to cool, and scorify and cupel as before. Class A (c). — To this class belong bromyrite, cerar- gyrite, embolite, iodyrite, all ores and furnace products calcined with salt, amalgamation residues, old test and cupels, all argentiferous slags, and silver sweeps and polishings. Finely powdered ore . . . 1'5 grain. Borax glass ' . - . . . . I'O ,, Proof lead t *. . . 7 '5 grains. The above, after being mixed, is placed in a soda- paper cornet on charcoal, and fused by a R.F. until all the silver is combined with the lead, and the slag shows itself as a perfectly fluid globule. If copper is present- in the ore the quantity of assay lead must be added in proportion to the percentage of copper, as stated under A (a). Taking all the precautions noted under reduction of Glass A (a), the assay is soon finished, as the chlorine, bromine, and iodine unite and form chlorides, bromides, and iodides of lead, which volatilise, whilst the silver unites with the lead. The reduced lead is scorified and cupelled, as described in Class A (a). Class A (d). — The most important substance of this class is litharge (lead oxide), which is readily reduced on charcoal, but generally very poor in silver ; so it is neces- PART III. SILVER, 121 sary to take a larger amount for assay than is ordinarily used. Five times the weight of the usual assay sample — 7'5 grains — is mixed with 1 grain borax glass and 1 grain soda in a soda-paper cornet, and treated with R.F. until all the oxide is reduced and the fluid slag shows no lead globules. Towards the end of the operation the flame is directed principally on to the slag ; otherwise the metal may become too much agitated and cause a loss. The silver lead thus obtained is then ready for scorification and cupellation, and it can be proceeded with as described in Class A (a). N.E. It is often found necessary to make several assays of substances of the above class, on account of the very small amount of silver they contain. Class A (e). — General method adapted to the assay of a, by c, either to one or all (d, being composed of litharge, does not come under the head of this assay). Take finely powdered ore 1/5 grain, and add to it from five to ten times its FIQ 59 (Fullsize0 weight in finely powdered litharge (which must be free from silver). The excess of litharge is neces- sary only when the ore con- tains a large amount of metallic sulphides ; for ordinary ores 5 times the weight will be found ample. Add soda 0-7 grain and finely powdered charcoal 0-5 grain. Mix intimately and then remove to a small fire-clay crucible (see fig. 59). A piece of platinum wire is now bent into the required form to act as a holder and support to the crucible whilst it is in the charcoal furnace (see fig. 60). FIG. 60. (Full size.) .122 ASSAY OF SILVER, GOLD, MERCUEY, ETC. PART III. The charcoal furnace (fig. 61) is made out of two sound pieces of charcoal, and the inside bored out by the large borer (see fig. 28, appara- tus), and the blast hole and escape way made by the small borer (see fig. 30, apparatus). For furnace holder see Mer- cury Assay. The crucible, already charged, is placed in the fur- nace and held in its place by the platinum wire. The fur- nace is then held securely by the holder; the flame is applied through the blast hole — at first a gentle flame, then a strong E.F. Flames will soon be seen to issue from the top hole, and by looking into the same the operator can see whether the assay is fused or not. If it is found to be fused, give it a strong blast for about one minute, and then allow it to cool. The crucible, when cool, is broken and the lead button cleaned. The slag must be examined, and if a per- fect fusion has not taken place the assay must be repeated. The assay will be finished as described in a. Class B (a) consists of alloys ready for cupellation after an addition of lead. The following table will guide the operator in regard to the quantity of lead required. The sample to be assayed is either hammered or rolled out, and from 1 to 2 grains weighed for assay. A preliminary assay should first be made and an ex- cess of lead added. After cupelling and ascertaining the approximate fineness, the assay can be prepared according to the following scale, and the synthetical also. PART III. SILVER. 123 Table of the Amount of Test Lead to be added to Alloys of Copper and Silver for their Cupellation by the Blowpipe. FiiienesH of Silver Parts of Lead t ineness of Slver Parts of Lead 1000 2 750 11 975 4 700 12 950 5 650 13 925 6 600 14 900 7 550 15 875 8 500 16 850 9 100 17 800 10 Take from 1 to 2 grains of the alloy, and, after adding the amount of lead necessary, place it on a pre- viously prepared cupel and proceed according to method described in p. 106 under the head of ' Cupellation.' The synthetical assay is conducted in the same manner, and its loss of silver should be added to what is found in the assay of the alloy, which will give the actual loss ex- perienced in the manipulation. The button obtained from the alloy must, after weighing, be always tested for gold by dissolving it in nitric acid, and if gold is present the weight of the same is deducted from that of the silver. In assaying silver bars that are over 950 fine it is advisable not to take more than 1 grain for assay, and in all cases where the operator has not had much practice it is best to only take 1 grain. Class C (a), consisting of amalgams, is treated first according to assay of mercury and Class (7, p. 137. The retorted residue is now assayed according to 6. (6) Two grains of the precipitated, or retorted, silver are fused on charcoal with 0*7 grain of borax, and the button thus cleaned is cupelled as an alloy. See Class B (a). (c) Consisting of brass, black copper. Take of alloy 1 grain and mix with 15 times its weight 124 ASSAY OF SILYEE, GOLD, MEECUEY, ETC. PART III. of lead and 1 grain of borax glass ; melt with a strong R.F. until a complete fusion has taken place and the silver lead button has a bright appearance. Then scorify and cupel according to Class A (a). (c£) Tin and gun metal. Fuse 1 grain of the alloy with 12 parts assay lead and 0-5 grain dry carbonate of soda and 0'5 grain borax glass. Place in a soda cornet and fuse in charcoal. First apply a strong E.F. As soon as the assay is melted, change the flame to an oxidising one, and continue until all the tin has become absorbed in the flux. If any tin is suspected to be still in the alloy, remove the button and again scorify with a little borax on char- coal, as tin cannot be cupelled. The button should now be treated as Class A (a). (e) Antimony, tellurium, and zinc. One grain of the alloy is mixed with 5 grains lead and O5 grain borax glass, and melted on a soda cornet on charcoal. A strong R.F. is first applied, then an O.F., until the lead button appears clear and white. If the latter does not occur in a few minutes allow the assay to cool, and repeat the fusion with more lead and borax until it does. Then finish as in A (a). (/) Silver-steel and iron not uniting with lead, the alloy must be first converted into a sulphide of iron by fusion with sulphur. The alloy must be broken into fragments, the largest not to weigh over 0'5 grain. Take 1 '5 grain alloy fragments. , , 12'0 grains lead. ,, 1*0 grain borax glass. ,, 0'8 ,, sulphur. Fuse in a soda-paper cornet on charcoal with the R.F. until a good fluid globule is formed, then add 1-5 grain TAUT III. SILVER. 125 more borax glass to complete the slagging of the iron. Treat with a strong O.F. until the lead is clear and has a bright surface. Then cool, clean, and treat as in A (a). ((/) Alloys of lead or bismuth. Take 10 grains and melt with a little borax on char- coal. Then clean the button, and if it is found brittle (from an excess of bismuth) add a small quantity of lead and then scorify and cupel. See A (a). (Ji) Copper coins, wire, and cement, containing some- times nickel. Take 1*5 grain of the alloy and fuse with 10 grains lead and 0'7 grain of borax glass on charcoal. When the assay has been fused apply the O.F., to slag as much as possible of the copper. Clean the button when the borax and litharge are fully charged with the copper oxide. Then scorify with 20 grains of lead and 0'5 grain of borax, as in A (a), and finish the assay as usual. GOLD. Grold is nearly ajways found in the metallic state, but 4 never pure.' A good crystal is considered a rarity. The octahedron and dodecahedron are the most common forms. Crystals sometimes acicular, through elongation of octa- hedral or other forms ; also passing into filiform, reticulated, and arborescent shapes, and occasionally spongiform from an aggregation of filaments ; edges of crystals often salient. Cleavage none. Twins : twinning plane octahedral. Also massive and in thin laminae. The above forms usually occur in veins or lodes. In alluvial soils, streams, rivers, and gravel beds gold is generally found in flattened grains or scales and in rolled masses. Hardness = 2-5 — 3. Spec, gravity =15-6 — 19*5; 19'30 — 19*34 when quite pure (Gr. Kose). 126 ASSAY OF SILVER, GOLD, MERCURY, ETC. PAKT III. Gold is generally alloyed with silver in various propor- tions, arid pieces from California, Idaho, and Nevada, U.S.A., have been assayed by the author and found to con- tain as much as 50 per cent, silver ; whilst the purest native gold from the same sources that he has examined have assayed 97 per cent, pure gold and nearly 3 per cent, silver. Gold is also found combined with copper, iron, bismuth, palladium, rhodium, and tellurium. Grold combines with mercury in what is generally termed gold amalgam. Gold is also found associated (or as an incidental ingre- dient) with certain ores containing iron and copper pyrites, mispickel, blende, and galena. In metallurgical works the proportions of mercury to gold in amalgam vary greatly, owing to the size as well as the purity of the particles of gold which have been brought into contact with the mercury. The author has found in reduction works in California that the percentage of mercury in the gold amalgam there obtained varied from 36 to 85 per cent. Nearly all metallurgical products from lead, silver, and copper smelting works contain gold, and especially those obtained from the smelting of argentiferous lead ores ; but as a general rule the quantity is too small to pay for extrac- tion, as in many instances ' a slight trace ' can only be found by the most careful analysis. Gold Assay. The assay for gold, although apparently easy, is de- cidedly the reverse, and accurate results depend greatly upon the judgment of the operator in first selecting the sample and then employing the correct method of assaying the same. Gold is separated from its matrix by fusion with lead, and the button so obtained is scorified in the same manner PART III. GOLD. 127 as the ores described in the silver assay. Gold alloys are fused with lead; three times the weight of pure silver is added, then the assay is cupelled and the button boiled in nitric acid, which dissolves the silver, leaving the gold in a fine powder, which is heated to redness and weighed. In assaying gold ores it is necessary to take a large quantity for assay, and as such cannot be fused by the blowpipe the author has adopted the following methods : — The assay of gold is divided into three classes — A, B, C. A. Ores, minerals, furnace slags, mint, and jewellers sweeps. B. Gold alloys. C. Gold amalgams. A (a). Ordinary gold ores, from which the metal is extracted by raw amalgamation. Wash 5 Ibs. (80 oz.) in a batea ; then collect the sulphides, &c. (from which the lighter portions have been separated by the vanning), remove them to a flask, and boil in nitric acid; then filter, and burn the filter paper and insoluble residue in a small evaporating dish, add twice its weight of lead and its own weight of borax. (The filtrate can now be tested for silver, adding a few drops of hydrochloric acid, and if silver be present it will be thrown down in a white flocculent cloud as a chloride of silver. The same should be collected on a filter, and can be weighed after drying care- fully and then gently fusing in a small porcelain cup that has been previously weighed, silver, 75*28; chlorine, 24'72.) Place in a soda-paper cornet and then fuse in the deep bore on charcoal as in the Silver Assay. Clean the lead button so obtained, then scorify, and afterwards cupel. Weigh the button found after cupellation and fuse it on charcoal with three times its weight of silver ; boil it in a small flask with nitric acid, and after all action has ceased pour off the liquor and wash the fine dark powder with distilled 128 ASSAY OF SILVEE, GOLD, MEECUEY, ETC. PART III. water, add more acid, boil again, wash again, and then re- move to a small porcelain cup and allow it *to dry slowly over the lamp ; when it is quite dry heat the cup to a bright red colour, and then remove the gold (now pure) to the balance and weigh. (6) Gold ores consisting of nearly pure pyrites, also quartz mill concentrations, cannot be washed with safety. After the mineral has been finely pulverised take from 100 to 1,000 grains, according to the amount of silica in the ore, and roast it on an ordinary piece of sheet iron, turned up at the edges (an old worn-out miner's shovel has often been used by the author), which has been previously coated with a little moist fire clay ; heat the sheet iron over a charcoal or coal fire, keeping it at a dull red heat, and stir continually until the smell of sulphurous acid is no longer perceptible ; then boil the roasted ore in nitric acid until all soluble matter in dissolved, and proceed as in a. Assays of the above class are generally of great com- mercial importance, and in such cases make three assays and take the mean for the report. (c) Grold sands, such as are found in the rivers and streams of California and British Columbia, and also on the sea beach in Oregon, U.S.A., contain a large amount of specular and titanic iron, and is called ' black sand ' by the miners. The gold is generally very fine and in the form of thin laminae. Platinum and iridium are often found in the same sand. The above sand cannot be washed for assay. Take 100 to 1,000 grains, according to the amount of black sand in the ore, and attack with aqua regia in a flask ; boil for about 30 minutes or more, dilute with water, and filter. If gold is present it will now be held in solution in the filtrate; remove the filter and evaporate the filtrate to dryness ; then add a little hydrochloric acid and redissolve the dry salt in PART III. GOLD. 129 warm water ; add to the solution so formed protosulphate of iron, which will throw down the gold in the form of a fine dark precipitate. The precipitate is seldom pure, being mixed with oxides of iron, and must now be dried in the filter paper and both burned over the lamp in a porcelain dish. Then mix the dried precipitate with three times its weight of lead, and its own weight of borax, and one-half its volume of soda ; fuse, scorify, and cupel as directed in a. In case platinum, iridium, &c., are found associated with the gold an extra amount of pure silver should be added before cupellation, and the gold button will be found pure. (d) Grold from alluvial deposits, ancient and modern river-beds, and placer washings. The greater part of the gold obtained from such sources is usually found to consist of coarse grains, nuggets, &c., making it a difficult matter to take a sample for assay. A large quantity (20 tons or more) should be washed through the ordinary gold sluice-box (which has rifles or stops charged with a small quantity of mercury) and the gold collected ; then a careful sample should be taken of the tailings or residues and three to five different assays made. Weigh out 5 Ibs. (80 oz.) of the tailings and wash carefully in a batea. The concentrated mineral must be dried, and fused in small portions (about 2 grains at a time) with twice its weight in lead, and its own weight in borax, and half its volume of soda, and the assay carried on as in a. The coarse gold first obtained should now be weighed and a sample taken for assay. The assay must be conducted as described on p. 130 under the head of < Gold Alloys.' The assay of the tailings or residues must be added to that of the gold alloy first obtained, and the value per ton of the whole will be ascertained. 130 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III. (e) Furnace slags generally contain a very small per- centage of gold, which at the same time is so minutely distributed through the slag that a direct fusion is the only safe method to employ. Take 2 grains slag. ,,6 „ lead. ,, 1 grain borax. „ £ „ soda. After a complete fusion in charcoal reduce the lead by scorification and cupel. The assay is now finished as di- rected in a. (/) Mint and jewellers ' sweeps ' are composed of such various metals and compounds that it is difficult to select an average sample for blowpipe assay ; therefore Take 1 00 grains of the sweeps and boil them in a flask with nitric acid until all the soluble matter is held in solution. Dry the insoluble matter and the filter, and burn the latter. After so doing fuse with lead according to directions in e, and finish as directed in a. \g) Direct and universal method for assaying gold ores and minerals, such as telluride of gold, mixed sulphides with which gold is associated — for instance, sul- phides of arsenic, copper, zinc, bismuth, iron, lead, &c.&c. Take 1*5 grain of ore, mix with 5 to 10 times its weight of pure litharge, and assay in precisely the same way and with the same apparatus as used and described in the Silver Assay, A (e\ and purify the gold as directed in p. 127. B (a). Fine gold, bar and ingot gold, coins and na- tive gold, without any adhering matrix or foreign sub- stances. All the above are capable of direct cupellation after an addition of lead. The lead must be added in the following proportions : — PART III. GOLD. 131 Fineness of Gold in Alloy Parts of Lead necessary to remove the Copper by Cupellation Fineness of Gold in Alloy Parts of Lead necessary to remove the Copper by Cupellation 1000 5 700 27 975 7 650 30 950 9 .000 33 925 11 550 35 900 13 500 36 875 15 400 36 850 17 300 36 825 19 200 36 800 21 100 36 750 24 The gold coin of France is 900 gold to 1 00 copper, and that of the U.S. of America the same. The British standard is gold 916*66 and the remainder copper. Weigh out 1 grain of alloy and 3 grains of pure silver, and wrap up in a small piece of rolled assay lead which has been weighed, and cupel on a previously pre- pared cupel (see fig. 54, Silver Assay). The heat required is greater than that which is employed in the Silver Assay, as the alloys of gold, copper, and silver require a high temperature for cupellation. Grold suffers but a slight loss by volatilisation. When the cupellation is complete remove the button with the pliers and clean the lower surface with a small brush ; then beat the button on the steel anvil until a thin sheet has been obtained. The last operation can be facilitated by placing the assay on a piece of charcoal and heating it to redness and then beating it out. When thin enough anneal again and twist the small sheet of alloy into the form of a coil, and boil in a small flask or test tube with about -J oz. of nitric acid (of 1'3 specific gravity) for 5 to 10 minutes; then add a little pure water and pour off the nitrate of silver ; again add J oz. of nitric acid (of 1'3 specific gravity) and boil until all action has ceased. Then pour off the acid, add an ounce K 2 132 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III. of pure water, and boil for a minute. Pour off the hot water and fill the tube with cold water, and remove the gold into a small pipe-clay crucible by first placing the crucible on the mouth of the flask or test tube (see FIG. 61. FIG. 62. fig. 61), then inverting- them both (Half size.) (Halfsize.) ^ fig'_ ^ The ~« ^ (eyen if in a fine powder) soon settle to the bottom of the cup, and it can be quickly done if the operator will slightly tap the sides of the tube with his finger nail, remove the tube from the crucible, and carefully pour off the water, and then allow to dry slowly, and when dry heat the cruci- ble to a bright redness over the spirit lamp, and then remove the gold to the balance and weigh as pure. If the alloy is only about 800 (or under) fine take 0*7 gr. for as- say, and cupel first with the neces- sary quantity of lead, and add the charge of silver with 2 grains of lead when the cupel- lation is nearly complete. Chemically pure gold, even when boiled 3 times in nitric acid, still retains a trace of silver, and 1,000 parts of pure gold, after being carefully cupelled and parted, will weigh 1000*2. The amount is, however, so small that it is only deducted in the Mint and Gold Assay Office reports. (6) Gold nuggets and fine gold dust. Take 1 grain, and fuse on charcoal with 1 grain borax and ^ grain nitre, and after the bead is thoroughly cleaned by the fusion proceed as in B (a). In assaying nuggets cut them in two, and get an average sample if possible. PART III. , GOLD. 133 The outside is generally deceptive, and frequently coated with foreign substances, such as silicates, iron oxides, &c. (c) Worn-out copper plates that have been used in gold amalgamation works, copper coins, wire, and cement. Weigh out 10 grains, and attack with dilute nitric acid ; after a thorough boiling and decantation, dry the fine dark residue, add to it pure silver and lead, cupel, and then finish the assay as in B (a). (d) Gold containing palladium and not more than 10 per cent, of platinum. Cupel 1 grain of alloy with 4 grains of silver and the proper quantity of lead (see table, p. 131). Attack with nitric acid three times, and the gold residue will be found pure. (e) Gold containing more than 10 per cent, of platinum. Dissolve 1 grain of the alloy in nitro-hydrochloric acid (3 parts hydrochloric and 1 part nitric acid). Whilst the solution is still warm add chloride of ammonium to it, and evaporate the whole to dryness at a moderate temperature. The dried salt is then washed on a filter with alcohol of 70° to 80° until a fresh addition of it is no longer coloured yellow. The gold is by this means dissolved out. Add water to the alcoholic solution, remove the alcohol by evaporation, and then precipitate the gold with protosul- phate of iron according to the methods described in A (c). (/) Gold containing iridium. Dissolve 1 grain in aqua regia. The iridium remains behind in the form of a black powder, which can be washed and dried and the percentage of iridium estimated. The gold can be esti- mated as in A (c). If the alloy contains copper it must be first cupelled with about 5 parts of lead, and the last trace of lead removed by fusing it on charcoal with boracic acid. (#) Gold with platinum and silver. 134 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III. Plattner recommends the following plan : — When the silver has to be determined, it must be extracted by sul- phuric acid. To do this with proper accuracy the alloy should contain for 1 part of gold and platinum not less than 1£ nor more than 2 parts of silver, because some platinum seems to dissolve with more silver. When silver is lacking, an accurate quantity of pure silver must be added, and if gold is lacking the alloy must be molted with pure gold, to secure the necessary proportions of the metals. One grain of the alloy being weighed out and brought to the proper proportions by fusing it with gold or silver and borax glass on coal, the button is beaten as thin as pos- sible, heated to redness, and rolled up. After being weighed, to see that no mechanical loss has occurred, it is covered with concentrated sulphuric acid in a porcelain vessel and boiled for 10 minutes. After cooling, the acid solution containing sulphate of silver is decanted, and the porous metallic residue boiled five minutes longer with fresh acid to complete the separa- tion of the silver. The remaining roll is boiled with distilled water, dried, ignited, and weighed ; the difference gives the weight of silver. The gold and platinum are then separated according to B (d). (h) Grold containing rhodium. Weigh 1 grain of alloy, dissolve in aqua regia, and precipitate the gold with protosulphate of iron, as in A (c). The rhodium remains in solution. (i) Gold with lead, bismuth, gun metal, antimony, zinc, brass, &c., is assayed according to Class B in Silver Assay. If much antimony or zinc is present the alloy should be fused on charcoal with borax before cupellation. (j) A rapid method of making an approximate assay of gold coins, nuggets, gold dust, or bullion. PART III. GOLD AND MERCURY. 135 Take 1 grain of the alloy, melt it with 4 grains of silver, 1 grain borax, 0*5 grain nitre, on charcoal. After a thorough fusion beat it out and dissolve as usual in nitric acid. The assay can be made in a few minutes, and will be within 5 to 10 thousandth of the true standard. C (a). Gold amalgams are first retorted according to Class C in assay of mercury. Then the alloy is fused with a small quantity of borax and nitre on charcoal. One grain of the fused metal is weighed out and treated as in B (a). MERCURY. Mercury occurs in small fluid globules scattered through its gangue. Specific gravity =13*5 6. Lustre metallic. Colour tin white. Becomes solid at 39° Fahr. below zero, and crystallises in octahedrons. Volatilises at 64° Fahr. and entirely so at 662° Fahr. The rocks affording the metal and its ores are mostly clay shales or schists of different geological ages. Cinnabar, or sulphide of mercury. Contains sulphur 13*8 per cent., mercury 86*2 per cent. Cinnabar is of a bright red or reddish brown colour, and is sometimes impure from clay, oxide of iron, and bitumen. Tiemannite, or selenide of mercury. Contains selenium 28*4 per cent., mercury 71*6 per cent. Calomel, or flour mercury. Contains chlorine 15-1 percent., mercury 84*9 per cent. Mercury is also found combined in various proportions with sulphides of zinc, and also with iodine. 136 ASSAY OF SILVEE, GOLD, MERCURY, ETC. PART III. Amalgams. Mercury with gold, silver, and copper in the form of amalgam has been frequently found in nature, but the proportions vary greatly in different localities, and no correct formula has yet been arrived at. In metallurgical products mercury is obtained in combination with many metals, the principal of which are gold, silver, copper, lead, bismuth, zinc, iron, tin, &c., and under certain conditions it combines with sodium and potassium. Amalgams of silver, bismuth, &c., are extensively used by dentists. In the practice of medicine mercury is largely used, the general forms being metallic, subchloride, chloride, and oxide. Mercury is nearly always determined by distillation, but before making an assay of its ores the operator should examine with great care the ore in question with regard to metallic globules of mercury, and if such are found to exist (which is frequently the case, especially in the ores from Californian mines) several ounces of the ore should be weighed, and then crushed up and vanned carefully in a horn spoon, or porcelain bowl, and the metallic mercury collected on blotting or filter paper, which, when dry, weigh, and add the percentage so found to what is afterwards obtained by assay from the remainder. The residue both of water and crushed ore must be all carefully saved, the water evaporated, and when dry mix and take a sample for assay. Assay for Mercury. The compounds to be examined are divided into three classes, and will be called A, B, C. PART III. MERCUKY. 137 Class A, Consisting of metallic mercury. ,, cinnabar (artificial slate forms what is called vermillion). , , tiemaimite. ,, sub-oxide. ,, protoxide. ,, mixed sulphides, &c. Class B. Consisting of calomel (sub-chloride). „ chloride of mercury (corrosive sublimate). ,, iodide of mercury. Class C. Consisting of amalgams of gold, silver, copper, lead, zinc, tin, &c. &c. Class A. — The assay is conducted as follows : — Keduce the ore to a fine powder, so that the sample to be assayed will all pass through a sieve of 2,000 holes to the linear inch. Weigh out from 10 to 20 grains of ore, according to its richness; intimately mix with 5 to 10 times its weight of finely powdered litharge, and distil in a small glass retort over the spirit lamp. Eetorts of the following size and shape (see fig. 63) have been found to give very accurate results, and can be made by the operator from hard flint glass tubing by closing one end over the lamp and then bending it, when heated, to the required angle. The retort a, or cup, is made f inch in length, and neck b of same f inch, and J inch in diameter. The neck is fitted into a good tight cork, and placed firmly in the top of a glass tube c of about 2 J inches in length and T%- of an inch in diameter, tapering at the bottom to J of an inch. The tube is also bent slightly, to facilitate the collection of mercurial vapour in the receiver d. The end of the tube is kept immersed during the heating of the assay in a small cup or capsule containing water, and, as the operation occupies 138 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III. only a few minutes, the retort and condensing tube can be held with a small pair of wooden tongs without any inconvenience. FIG. 63. (Full size.) Before the retort is used expel all the moisture by a thorough drying. The above-shaped retorts are easily charged by pouring in the ore and litharge from a small mixing spoon, and then connecting it by means of the cork 'with the condensing tube. The retort is heated very gradually at first over the spirit lamp, and finally the heat is raised until the assay is fused, and the glass softens and nearly melts. The greater portion of the mercury will be found in the receiving cup, but small particles will generally be found in the condens- ing tube. Heat the tube slightly, which has the effect of bringing the minute globules of mercury together ; then remove them carefully with a feather and add them to the globules in the cup. The retort and its fused contents should now be broken up in a horn spoon or porcelain dish, in which a small quantity of water has been previously added, and after vanning examine carefully with a magnify- PART III. MERCURY. 139 ing glass, to see if any globules can be found. If they are the assay should be repeated. Slightly heat the receiving cup over the lamp, taking care to have it half full of a FIG. 64. (§ size.) water. The fine globules of mercury will then unite into one globule. Pour off the water and dry the mercury with blotting paper, and re- move to a small weighing cup and ascertain its weight on the balance. The mer- cury so obtained can be con- sidered pure. Class B. — Cannot be re- duced by litharge alone, and a different reducing agent as well as shaped retort must be employed. Take of the finely powdered ore or product 10 grains, and mix it with about 3 times its volume of neutral potassium oxalate and 1 volume of potassium cyanide, and distil in a retort of the following description (see fig. 64) : — A small bulb-shaped retort a, constructed of thick, hard flint glass, about ^ inch in diameter at its widest part and j inch in depth ; length of neck b about J inch ; diameter of the latter about } inch. The neck is fitted with a good cork and placed firmly on the top of a glass tube about 2 J inches in length, and -fa of an inch in diameter at the top, tapering at the bottom to J of an inch. The mixture having been placed on the retort, the heat is applied very slowly and with great care at first, to avoid the rapid reaction which would otherwise take place. The distillation only occupies a few minutes, and the assay should be completed and the mercury collected and weighed with all the precautions mentioned in Class A. 140 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III. Class G. — Native and artificial amalgams, as well as dentists' products, are often so hard and compact, as well as mixed with lead, bismuth, zinc, copper, &c., that a correct determination cannot be arrived at by direct distillation, owing to the swelling, spitting, and spurting that take place soon after the application of heat. An approximative test should be made on charcoal or in a small crucible or glass tube, and if the spurting is found to be so violent that the amalgam cannot be distilled without loss, it should be crushed up in the agate mortar and then placed in the retort for distillation. In many cases the latter plan is most difficult, and in some im- possible without losing a large, portion of the sample. In such a case weigh out one equal part of pure mercury, mix it with the assay sample, and then crush it in the agate mortar. The amalgam will then be found to be in a semi-fluid condition, in which state remove it to the iron retort, and the mercury can be evaporated and collected without danger of loss in spitting, and the weight of the mercury added deducted from the total found. In assaying amalgams make two assays. 1st. Distil the amalgam, then condense and collect the mercury, and weigh. 2nd. Subject the amalgam to the blowpipe flame either in an open cup or dish, and take the loss of weight to be mercury. The heat never to be sufficient to fuse the retorted metal, else a loss will arise from the volatilisation of lead, zinc, silver, &c., all of which are frequently found combined with mercury. The last method will be found to be very accurate when the amalgams consist of nearly pure silver or gold combined with the mercury, but if other metals exist with them the results are very uncertain. It serves, however, not only as an approximate assay, but as a check on the distillation assay. PART III. MERCUEY. 141 The retorts used for the determination of the amount of mercury contained in amalgams must be differently constructed to those which are used for Classes A and 5, and are best made of cast steel, which is afterwards turned in the lathe to the required form. FIG. 65. (f size.) The retort is made 1 inch in height, which includes the cup and cap ; the neck about 2 inches in length, having a gentle taper towards the end, w^hich is made to fit into a good cork which has been previously placed in the glass condenser. (See fig. 65, cross section of the steel re- tort with glass condenser.) Fig. 66, view of the cup and distillation pipe of the amalgam retort. Fig. 67, view of the FlG- 66- (Ful1 size-) receiving cup of the amalgam retort. Fig. 6 8, view of the glass condenser. Ten to 30 grains of the amalgam to be examined is weighed, wrapped up in a small piece of tissue paper, and (the weight of ash, contained in a similar piece of the same paper, must always be determined in a quantitative assay) placed 142 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III. in the receiving cup (fig. 67). The cap is now placed ,^•^7- firmly on. The joint being perfectly air-tight, no luting is necessary. The condenser (fig. 68) is attached, and the retort placed in the charcoal furnace, which has now to be held firmly by the holder. See fig. 69, a side view of the holder and charcoal furnace, showing end of retort. FIG. 68. (Full size.) Fig. 70, a top view of the charcoal furnace and holder. The furnace is now brought near the blowpipe lamp FIG. G9. (Half size.) and the end of the condenser kept immersed in water con- tained in a small porcelain crucible. The heat is applied very quietly at first, but in a few minutes a strong R.F. may be applied through the hole PART III. MERCURY. 143 in the lower part of the furnace. Flames will soon be seen coming out of the top hole of the furnace, and the retort will be found to be red hot. Keep it so for about two minutes, then cease blowing and allow the retort to cool. See fig. 71, sectional view of blowpipe stand and lamp, with flame playing on the amalgam retort, which has been placed in the charcoal furnace ; also a view showing the position of the condenser and receiver of the mercurial vapour. FIG. 70. (Half size.) The whole operation does not take ten minutes, and although the retort may appear large, the operator will find no difficulty even in obtaining a white heat if necessary ; and in a few minutes the assay is completed. The mercury is collected and weighed according to the methods laid down in Class A* Most accurate results will be obtained by following the above instructions. In Plattner's * Manual of Qualitative and Quantitative Analysis with the Blowpipe,' by Prof. T. Kichter, and translated by Henry B. Cornwall, and published 1873, 144 ASSAY OF SILVER, GOLD, MERCURY, ETC. PABT III. on p. 509 will be found the following under the head of ' Assay for Mercury : ' — ' This assay, essentially the same as that proposed by Domeyko and described in the " Berg- und Hiittenm.- Zeitung," 1845, No. 20, is very simple and exact/ A glass tube, about 3 lines in diameter and 7 to 8 inches long, of not too thin glass, is bent as shown FIG. 71.1 (I size.) in fig. 72, and closed at one end, leaving the shorter arm a 1J to 2 inches long. The tube is thoroughly dried, and then from 500 to 3,000 milligrammes of finely powdered ore, according to its richness, intimately mixed with 5 to 10 grammes litharge, 1 The three different retorts, also charcoal holder, all originally de- signed by the author, were made by L. Cassella, 147 Holborn Bars, E.G., where similar ones can now be procured. PART III. MERCURY. 145 being introduced into it, the lower end is gradually heated over the spirit lamp until the whole mass is fused and the glass begins to soften. The moisture that may be present condenses in the middle of the tube, while the mercury will settle as a thin film, sometimes1 scarcely perceptible, on the sides of the glass (see fig. 72). When all of the mercury has been sublimed the tube is carefully heated, so as to concentrate the mercury as much as possible to a ring at 6 ; the tube is allowed to cool, cut off with a file close to the ring, and the mercury then brushed together to one drop and transferred to a weighed capsule. FIG. 72. (Half size.) In this way 0*05 per cent, of mercury can be very readily determined, and the nature of the gangue has no influence upon the result. The excess of litharge serves not only to oxidise the sulphur and selenium, but also to remove the arsenic, antimony, and bitumen so frequently found in ores of mercury, and the resulting metal is so pure that it can be very easily and perfectly united in one drop. COPPER. Copper is a metal having a metallic lustre and of a copper-red colour. It has a streak, metallic shining, and is ductile and malleable with a hackly fracture. Hardness, 2*5 to 3. Specific gravity, 8*838 when native. 146 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III. The principal ores of copper are — 'Copper glance . containing 797 per cent, copper. Chalcopyrite . ,, 34 '4 ,, Bornite . ,< . . „ 557 Bournonite . . ,, 13 '0 ,, iFahlerz . . . ,, 30 to 48 Covelline . . . - . „ 667 I Wolfsbergite , ,, 24 '9 ,, IDomeykite (copper arsenide),, 71 '6 ,, - Copper regulus, copper speiss, &c. ^ f Red copper .. . containing 887 „ || I Malachite ',. ! ., „ 57 '3 §i1 Azurite . . „ 55'1 „ •^ ^ Cyanosite. . ,^ ,, 25 '3 „ .| g | Phosphate of copper ,, 30 to 56 ,, •"I | JArseniate. . , . ,, 25 ,, 50 „ ^ ^ Chromate, vanadate, and silicate ^ of copper, slags, &c. Assay. The assay for copper is divided into three classes, called A, B, and C. Class A . Consists of ores and products in which the copper is com- bined with volatile substances, such as sulphur, arsenic, and selenium. Clans B. Consists of ores and products in which the copper exists as an oxide or is combined with chlorine. Class C. Consists of alloys containing copper. Copper is separated by the blowpipe from its matrix or compounds by first freeing it from its combinations with PART III. COPPEK. 147 sulphur, &c., by roasting the finely crushed substance with powdered charcoal or graphite. The oxidised mineral is then fused with soda, borax glass, and a small quantity of test lead. The soda reduces the copper oxides to metal, and the lead assists in the collection of the copper in the shape of a globule. The alloy of lead and copper is then fused on charcoal with boracic acid, which dissolves the lead and leaves a copper button. The fire assay of copper is of great use to the smelter and miner. By observing the behaviour of the small assay sample under treatment, and by examining the copper prill or button obtained by the assay, a conclusion can be arrived at in regard to the quantity as well as the quality of the copper which will be produced from similar ores or products treated on a large scale in smelting works. The fire assay always yields a smaller percentage of copper than that which is found by analysis or by assays made by the volumetric methods. With a little practice and care the following methods of assaying have been found to give equally as good results as the German fire assay. The latter is considered more accurate than the English fire assay : — Class A. — Take 1J grain of the finely powdered ore and mix in the agate mortar with 3 to 4 FIG. 73. times its volume of dry charcoal powder, or with | grain graphite powder (N.B. the graphite used in an ordinary lead pencil answers very well) ; place the assay in a small clay capsule. The clay capsule should be painted with reddle before using (see fig. 73). The assay is now ready for roasting. Place the roasting cup on the holder above the lamp flame (see fig. 74). L 2 148 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III (The best fuel to use is common methylated spirit, as oil is apt to cover the cup with lampblack.) Place over the roasting cup a small hollow cone made of thin sheet iron, which confines the heat and makes a mild form of a furnace. The roasting is nearly complete in 10 minutes. Kemove the assay again to the agate mortar, and mix it with 3 times FIG. 74. (Half nat. size), its volume of dry powdered charcoal, or J a grain of graphite powder, and place it over the lamp as before, and conti- nue the heat until no fumes of sulphur or arsenic are observed after stirring with a small piece of iron wire. For the success of the assay it is neces- sary that all the sulphur should be eli- minated ; therefore, to be certain of the assay, remove the cone, turn the support partly to one side and a little below or on a level with the lamp wick, and apply to the bottom of the cup a strong O.F. for a few moments. The copper is now in the state of oxide mixed with various other metallic oxides and earthy matters, and the assay will be finished according to the plan adopted in Class B. Class B. — The roasted ore, product, or mineral, having been reduced to the state of a fine powder, is mixed in the following proportions with a reducing flux : — Ore1 .... 1 '5 grain. Soda . . . 3'0 grains. Borax glass . . 0'5 grain. Test lead . . . 0'5 „ 1 Ore belonging to Class A that has been weighed once need not be so again. PART III. COPPER. 149 The assay is then removed to a small soda-paper cornet, previously placed in a deep bore on a piece of char- coal. A mild R.F. is first applied, and then finally a strong flame to unite all the metallic globules. This having been accomplished, the assay is allowed to cool, and the button is separated from the slag by enclosing it, in a piece of thick paper and gently hitting it on the steel anvil with the hammer, after which it is treated as Class C. Class C. — (a) Alloy of copper and lead. The button obtained from Class B is now ready for refining, and will be assayed in a similar manner to a copper and lead alloy, viz. a small hole is made in a piece of sound charcoal, and boracic acid, equal in weight to the crude button containing copper, is melted on the charcoal. When the boracic acid is in a state of fusion the copper button is added. The E.F. is applied until the button and flux are dissolved ; then an O.F. is applied, and continued until the lead has absorbed oxygen and has been taken into combination with the borax, and the remaining copper assumes a greenish colour. The copper button is allowed to cool, and is separated from its surrounding impurities by folding it in a thick piece of paper and striking it gently on the steel anvil with a hammer. The slag should be examined, to see if it has a reddish colour ; if it has, it must be remelted with a strong R.F. on charcoal, and any globule of copper so obtained added to the larger button. A pure button of copper should be malleable. If the copper ore or compound contains either gold or silver, they will be found alloyed with the button so obtained. To test for the above the button is cupelled and treated according to directions given in the Silver Assay. 150 ASSAY OF SILVER, GOLD, MKRCURY, ETC. PART III. (6) Alloy of copper and antimony. Weigh out 1J grain of the alloy and fuse in a small bore on charcoal. The O.F. alone is used after the assay melts, and it is continued until the antimony is burnt away. The button obtained is then beaten on the anvil, and it should be malleable and not fracture if hammered out from two to three times its diameter. The button should also be tested for gold and silver. N.B. Alloys of copper and tin, consisting of bronze, bell and gun metal, &c., also alloys consisting of copper with iron, nickel, cobalt, zinc, and bismuth, and sometimes containing lead, antimony, and arsenic, have afforded Platt- ner results not sufficiently satisfactory for a quantitative assay. The author has also experienced similar trouble in the quantitative separation of copper from the above alloys, and at present he cannot recommend any method to be used by the blowpipe beyond a qualitative determi- nation. LEAD. Lead has occasionally been found native, but only in small quantities in the form of thin plates and small globules. It has a hardness of 1*5 and a specific gravity of 11*44 when pure, with a metallic lustre and a lead- grey colour, and is both malleable and ductile. The ores of lead are numerous ; the principal one, called galena, contains, when pure, lead 86'55 per cent, and sul- phur 13-45 per cent. For the purposes of assaying the ores of lead by the blowpipe the method adopted has been divided into two classes, according to the composition of the ore to he ex- amined, and will be called A and B. PART III. LEAD. 1,51 Class A. — Comprises galena and all leader es contain- ing either arsenic, phosphorus, or sulphur. Class B. — Comprises all ores of lead and plumbi- ferous substances which are free from sulphur and arsenic, or contain only traces of the latter. Litharge, carbonate of lead and minium, are the chief substances which come under this class. Assay. Lead is extracted from its matrix by fusing the finely powdered mineral with metallic iron and a fluxing and reducing agent in a small crucible placed in the charcoal melting furnace. The earthy matters and non-reducible oxides and sulphides are slagged off, and a button of metallic lead will be found on the bottom of the crucible. The assay of lead by fire is always attended with a heavy loss, as lead volatilises readily when strongly heated, and portions are also liable to be carried off in the slag. Fire assays of lead ores, when compared with the re- sults obtained by humid analysis, generally show a loss varying from 5 to 12 per cent. The fire assay, however, represents what is produced by smelting lead ores on a large scale, and it is therefore of great commercial use. Class A. — Take of the finely crushed ore 2 grains, and mix with 3 grains dry carbonate of soda, O5 grain borax glass, 0*5 grain powdered charcoal, and 1 grain cyanide of potassium. In the small crucible (similar to what is used in the Silver Assay, p. 121) place two small pieces of wrought iron about the thickness and length of a small steel pen, and then pour in the assay; cover the assay with about 4 grains of common salt, but allow the ends of the iron pieces to project above the assay charge ; put on the cover of the charcoal furnace, and screw the tightening pin ; apply a K.F. through the opening made in the fur- 152 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III. nace, but apply it at first in a downward direction, so that the flame does not attack the bottom of the crucible. After a few minutes' blowing the assay commences to boil, and the furnace will be found to be at a good red heat. Do not increase the heat until, by a glance through the hole in the top of the furnace, the assay is found to be thoroughly fused ; then increase the heat, and with a pair of iron pliers extract the pieces of iron one by one whilst the assay is in a thorough state of fusion. After the iron has been taken away allow the assay to cool slowly. When cool, break the crucible between two pieces of paper on the steel anvil, and clean the lead button and weigh ; examine the slag with a lens, and if any globules of lead are found add them to the larger button. If numerous small globules are found in the slag the assay should be repeated. This assay only takes about 8 minutes, and if carefully made it will agree closely with fire assays made on a large scale. The lead button frequently contains a large amount of copper. This can be ascertained by dissolving the lead with boracic acid in a deep bore on charcoal (see Copper Assay) and deducting the weight of the copper found from that already considered to be lead. Lead nearly always contains silver, also gold ; therefore the button should be cupelled and treated as silver lead (see Silver Assay). It should also be tested for gold (see Gold Assay). Class B. — Mix the finely powdered material with 4 grains of carbonate of soda, and 1 grain of argol, and 0*5 grain borax glass Place the mixture in a small crucible, and after covering with from 3 to 4 grains of common salt fuse and treat in a similar manner to Class A. PART III. BISMUTH. 1 53 BISMUTH. Bismuth native has a metallic lustre, the streak, and colour, silver white, with a reddish hue. It tarnishes readily. It has a hardness of 2—2*5 and specific gravity = 9-72. Native bismuth occurs in veins in gneiss and other crystalline rocks and in clay slate accompanying various ores of silver, cobalt, lead, and zinc. The principal ores of bismuth are — Sulphide', contains bismuth 81*3 per cent., sulphur 18*7 per cent. Bismuth blende : contains oxide of bismuth 58*8 per cent., and is mixed with silica, arsenic, and small proportions of copper, iron, and cobalt. Acicular bismuth : contains from 34 to 37 per cent, bismuth, combined with sulphur, copper, and lead. Carbonate of bismuth : contains about 89*75 per cent, oxide of bismuth, combined with carbon dioxide and water. Bismuth has also been found combined with tellurium, and exists in about the following proportions : bismuth 52 per cent., and tellurium 48 per cent. The carbonates and oxides of bismuth, when mixed with their gangue, resemble in appearance some lead ores ; and, as the assay is conducted in a similar manner, it often happens that until the button is examined for malleability, the difference is not discovered. Bismuth forms a brittle and coarsely crystalline button, having a bright fracture, which will not bear hammering on the anvil without breaking up into fragments, whilst lead is ductile and malleable. The button, if pure, possesses, when fractured, a fine reddish colour. If arsenic is present the button appears of a white colour. 154 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III. Copper does not alloy with bismuth, but its presence can be detected by using a magnifying glass. When copper is present it will be found to be mixed and not alloyed. Antimony gives the button a dull appearance, and the crystals are much finer. Sulphur blackens bismuth. Lead, when present, does not prevent bismuth from forming large crystals, but it is detected by the large crystals being studded all over with fine crystals Before making a determinative assay it is best to make a qualitative examination by taking about 1 ^ grain of the crushed ore or product and roasting at a gentle heat with powdered charcoal in a similar manner to the copper assay (see p. 147). Then mix with 1^ grain soda, 1^ grain carbonate of potash, Oo grain borax glass, and a very small quantity of powdered charcoal. Place in the crucible two small pieces of metallic iron, add the assay charge, and cover with a thin layer of salt, and fuse according to directions given in the Lead Assay (p. 151). The difficulty in making the bismuth assay by this method is to obtain all the small shots of metal in one globule. It is seldom done, but the button or buttons which are formed can be separated from the flux and examined by hammering on the anvil, when the appearance of the fracture will, as described above, indicate the pre- sence of other metals. To collect bismuth in one button an addition of some other metal is necessary. Pure silver is considered the best and is generally employed. The ores and products of bismuth are assayed in the following way : — Take 1J grain of the finely powdered mineral and PART III. BISMUTH. 155 roast on a small clay capsule in a similar manner to the copper assay. The heat required is not so great as that necessary in roasting copper ores, as bismuth is readily fusible and sinters if the heat applied is too great. After roasting, mix the assay with 2 grains of finely pre- cipitated pure silver, with 1^ grain soda, 1^ grain car- bonate of potash, 0-5 grain borax glass, a small quantity of powdered charcoal, and place in the small crucible, in which two or three small pieces of iron have been pre- viously placed ; cover with a thin layer of salt and fuse as before directed. The button obtained consists of an alloy of silver and bismuth, but it is seldom clean enough to weigh without further treatment. The button should be fused for a few moments on charcoal with a little borax glass. The flame employed must be a very mild K.F., as bismuth volatilises at a low temperature. When the surface of the assay becomes bright, stop blowing, allow it to cool, and then clean the button by brushing it. Weigh, and deduct the weight of the silver previously added from the total found ; the remainder should be bismuth. Bismuth ores and products are generally associated with silver, and to ensure the assay being correct the author always makes a separate assay for silver by fusing 1 J grain of the mineral (see Silver Assay), and if any silver is present its weight -is deducted from the button of bismuth silver found in the bismuth assay. No fire assay of bismuth ores or products gives analytic- ally accurate results. The blowpipe assay is made in less than half an hour, and is sufficiently accurate to guide the explorer or metallurgist in his practical estimation or treatment of the ores or products. 156 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III. TIN. Tin in a metallic state is probably only an artificial pro- duct. J. A. Phillips states that tin has more than almost any other metal a characteristic mode of occurrence, being in- variably found in the older crystalline and metamorphic rocks. This opinion is confirmed by Dana and others, and the author has observed the same peculiarity in the dis- tribution of tin ores. Metallic tin is a white metal with a lustre closely approaching that of silver and with a specific gravity of 7*29. It is easily distinguished from any other metal by the peculiar ' tin odour ' which it gives to the hand or finger after it has been rubbed for a few moments. The principal ore of tin is cassiterite, containing 78*62 tin and oxygen 21*38. Tin has been found combined with sulphides of copper, iron, and zinc in Cornwall, in stannite, but the tin obtained was only 26 per cent. The pure oxides of tin are readily assayed by a gentle fusion with a reducing flux in a small crucible before the blowpipe, when a pure metallic button is obtained ; but, as many tin ores are combined with an excess of silica as well as some sulphur, arsenic, and tungsten, it is necessary to subject them to a preparatory treatment before fusing them in a crucible with a reducing flux. Assay. The tin assay is divided into four classes — Class A. Pure oxides of tin. Class B. Tin ores containing silica, also tin slags. PART III. TIN. 157 Class C. Tin ores containing arsenic, sulphur, and tungsten. Class D. Ores containing under 5 per cent, of tin. Class A. — Weigh out 1J grain of the oxide, and in- timately mix with 10 grains of cyanide of potassium and 1 grain of soda. Place the mixture in a crucible in the bottom of which has been previously placed and pressed down a small quantity of cyanide of potassium. Eemove the crucible to the charcoal furnace and fuse with a gentle heat. The time required to finish the assay is seldom more than 6 to 7 minutes. The assay can be watched, and the completion of the fusion ascertained by looking through the hole in the top of the furnace. When cold, break the crucible. The button should be of a silvery white colour. Dissolve the flux in warm water, and look carefully for any small shots of tin that may be present. If any are found they should be cleaned and then weighed with the large button. The cyanide of potassium used for blowpipe assaying being pure, soda is added to secure the perfect fusion of any small quantities of silica or other impurities which generally accompany tin oxides. The button of tin obtained should be rolled or hammered out, and then tested to see if it contains any lead or copper. The above-described method, if carefully followed, affords accurate results. Class B. — Silica being injurious to the extraction of tin by fusion, the ore to be examined should be first crushed up fine. Take from 1 to 20 oz. of the crushed ore, according to its richness, and van carefully in the batea. Tin oxides have a specific gravity of about 7, and silica only a specific gravity of about 2 -7 ; therefore 158 ASSAY OF SILVER, GOLD, MERCURY, ETC. PAIIT III. the operator, by careful washing, can with safety separate the silica from the tin ore, or tin stone, as it is generally termed. Eemove the concentrated ore from the batea to a small porcelain dish and carefully dry ; then weigh ; after weigh- ing grind in the agate mortar and thoroughly mix. Then weigh out 1 ^ grain of the concentrated ore and proceed to melt, and determine as in Class A. The percentage of tin in the original sample treated is ascertained by first noting the quantity weighed out for vanning, then noting the quantity of concentrated ore obtained, and then the amount of pure metallic tin ex- tracted from 1 1 grain of the concentrated ore. Sometimes the tin ores cannot be washed down closely without a loss of tin ; in such a case concentrate the ore as much as possible by washing, then dry and weigh. Take 1^ grain of the concentrations and boil with hydrochloric acid in a platinum dish or porcelain capsule over the spirit lamp. The assay being finely powdered, the silica is dissolved. Tin oxide is insoluble in hydro- chloric acid. The dissolved silica is decanted off; the tin oxide is washed with a small quantity of water, then dried, and fused as in Class A. Class C. — The removal of sulphur, arsenic, and tungsten from tin is necessary before tin can be extracted in a pure state from its ores by the blowpipe. Take from 3 to 10 grains, according to the quality, of the finely powdered ore, and place it in a small flask ; add a small quantity of nitro-hydrochloric acid (made up of 3 parts of hydrochloric to 1 part of nitric acid). Boil until the greater part of the mixed acids has evapo- rated. Allow the flask to cool, add water, settle, and decant, and so on until the water is free from acid. The PART III. TIN. 159 insoluble residue consists of tin oxide, tungsten, and a little silica. Add a small quantity of caustic ammonia solution to the residue, and allow it to boil in the flask for about an hour ; then decant and van the residue to remove the silica. Dry the tin oxide and proceed to finish the assay accord- ing to the method adopted in Class A. Class D. — Many ores of tin contain less than 5 per cent, of metallic tin. To arrive at a correct assay of such ores it is necessary to treat a large quantity. Take about 5 Ibs. in weight of the finely crushed ore and van carefully in the batea, and afterwards treat according to the directions given in Classes A, B, and C. IRON. Native iron is rare. It has a hardness 4-5 and specific gravity= 7*3-7*8, with a metallic lustre and an iron-grey colour, also a streak shining. It is malleable, but has a hackly fracture and is strongly attracted by the magnet. Native iron must be considered only as a mineralogical curiosity, as it has rarely been found. Nearly all inorganic as well as organic substances that exist in nature con- tain more or less iron. The principal ores from which iron is manufactured are those in which the iron is combined with oxygen and carbon, as oxides and carbonates. Sulphides of iron are disseminated all over the globe, but they are rarely converted into metallic iron. Magnetic iron ore contains about 72*41 per cent, iron ; the re- mainder is oxygen. Specular and red hematite ore contain about 70 per cent, iron and 30 per cent, oxygen. Brown iron ore, or brown hematite, contains about 59*90 per cent, iron, and the rest consists of oxygen and water. 160 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III. Carbonate of iron, or spathic iron, contains 48'22 per cent, iron, and the remainder carbon and oxygen. Menaccanite (ilmenite), a titanic iron ore, varies in its composition ; it contains about 36 per cent, of iron on the average. Franklinite contains about 45*16 per cent, of iron, and the remainder is made up of zinc, manganese, and oxygen. The assay of iron ores scarcely comes under the head of the blowpipe fire assay, as the most accurate as well as expeditious method of ascertaining the percentage of iron in a sample of ore is nearly all done by the humid process. The reagents and apparatus required for the iron quantitative determination are necessary adjuncts to the blowpipe outfit; therefore, instead of using a tedious and a very unreliable method of extracting metallic iron by fire from its ores, the following plan has been adopted, as it affords correct results. Assay. Crush the iron ore in the steel mortar, and then grind to the finest possible powder in the agate mortar. Weigh out 1J grain of the finely powdered ore, and place the same in a small test tube ; add a little hydrochloric acid. If the assay effervesces the ore is a carbonate, and the acid must be added little by little to avoid the loss of a portion of the assay ; but if effervescence does not take place the acid can be poured over the assay at once. Heat the assay contained in the test tube over the spirit lamp until everything is in solution that the hydrochloric acid will take up. Then add a few drops of nitric acid and again boil the assay over the spirit lamp. PART III. IRON. 161 The assay having been thoroughly boiled, is allowed to cool, and the solution is diluted with distilled water. If, on dilution, any sediment is found, it must be sepa- rated by nitration, and the filter must be examined with great care in regard to colour. If white, the sediment contains no iron. If red, yellowish, or grey, it contains undissolved iron, and it must be treated by carefully drying it on a procelain dish over the lamp. When dry, mix it with 3 times its volume of soda and an equal part of borax glass ; wrap the mixture in a soda-paper cornet, and fuse it on charcoal in a deep bore with an O.F. until the mass is thoroughly fused and transparent. When the fused mass is cold, remove it to the steel mortar and crush. After crushing, boil with HC1 in a small porcelain dish, and add a few drops of nitric acid before the boiling is stopped, and heat slightly for a few moments to allow oxidation to take place. The solution is then slowly evaporated to dryness over the lamp. A few drops of HC1 are added to the dry mass, and then some distilled water, and it is again warmed over the lamp. After warming filter, and add the filtrate to the first solu- tion. The residue, collected on the filter, should be silica. Add a few drops of sulphuric acid to the solution and stir. If anything like a white precipitate is seen baryta is present, and the solution must be allowed to settle. The sulphate of baryta is separated from the iron solution by filtering. If the iron ores are pure, the troublesome operations of dissolving the sediment and separating the baryta, &c., are dispensed with, and the assay is quickly finished. Add ammonia to the iron solution. Iron and alumina are both thrown down together by the above alkaline pre- cipitant. To obtain an oxide of iron sufficiently pure to weigh, it is always necessary to separate alumina from the iron oxide. M 162 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III. Alumina is separated from the iron oxides by attack- ing the moist precipitate with caustic potash ; the latter dissolves the alumina, leaving the iron oxide. The assay is now proceeded with by drying the pre- cipitate of iron oxides and alumina remaining on the filter paper. Before the paper becomes quite dry remove the precipi- tate from the filter paper with a spatula or small knife. The filter paper should be placed in a porcelain dish with a little HC1 and washed with a little warm water, and this solution added to the main precipitate. In a small beaker or large test tube boil the iron and alumina pre- cipitate with a strong solution of caustic potash. Then dilute with water and collect the sesquioxide of iron on a filter. Warm the filter containing the precipitate, and when the filter is nearly dry remove the iron oxide from the filter to a porcelain capsule. Burn the filter paper by the blowpipe over a porcelain or platinum dish, and add the ash and what iron oxide it contains to the main precipitate. Dry the precipitate and apply a good red heat to the capsule containing it. The iron oxide is now weighed, and after deducting the weight of the ash contained in the filter paper the metallic iron may, according to Plattner, be estimated as follows: — 6 100 parts of the sesquioxide of iron correspond almost exactly to 70 parts of metallic iron ; so that it may be conveniently calculated as 70 parts. If the percentage of raw iron which a dry assay in a charcoal crucible would give is required, it may be easily, calculated by assuming the raw iron from the crucible to contain on an average, in 100 parts, 96 parts of iron and 4 parts of carbon.' The above-described method of assaying iron ores affords accurate results, and when such a small quantity PART III. NICKEL. 163 as 1^ grain is operated upon the assay can be completed in about 30 minutes and a correct report given. NICKEL. Nickel ores have generally a pale colour and a metallic lustre. The principal ores of nickel are : — Copper nickel (kupfernickel) has a specific gravity of 7*3 to 7*5, and consists of 44 per cent, of nickel and 56 per cent, of arsenic. White nickel, an arsenical ore, contains from 20 to 30 per cent, of nickel. Nickel glance is an arsenical ore, but contains sulphur. It carries from 20 to 38 per cent, of nickel. Antimonial nickel contains about 29 per cent, of nickel and no sulphur. Millerite is a brass-yellow sulphide of nickel, containing 64 per cent, of nickel. Pentlandite is a double sulphide of iron and nickel, and contains from 10 to 21 per cent, of nickel. Assay. The assay for nickel alone will be confined to the ore called kupfernickel, and the remaining varieties will be treated fully under the head of 'Nickel and Cobalt.' Kupfernickel, when pure, consists of arsenic 55- 93, nickel 44-07, but it generally contains about 1 per cent, of foreign matter, such as iron, cobalt, lead, and sulphur. Take 1 grain of the finely powdered ore and mix with £ grain of borax glass, and fuse on charcoal with the E.F. After the assay is in a state of fusion treat it with the outer point of the O.F. until the arseniate of nickel commences to oxidise ; then dip the globule and slag whilst still hot in water, to separate the slag, which is easily M 2 164 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III. done with the fingers ; then heat the globule in a deep bore (in charcoal) with a weak K.F., keeping it in fusion with a bright surface until all excess of arsenic is vola- tilised. The globule that remains will weigh about 0*71 grain, and is JN"i4As, which contains arsenic 38-825 and nickel 61-175, and the impurities present account for the loss. Care must be taken not to use an excess of borax glass, as sufficient surface would not be exposed for oxidation. COBALT. Cobalt ores generally have a tin-white to steel-grey colour. The principal ores : — Smcdtine has a specific gravity of 6*4 to 7*2, and con- tains from 3 to 14 per cent, of cobalt, with from 60 to 75 per cent, of arsenic; the remainder is generally nickel and iron, with sometimes a trace of copper. Cobaltitd, or glance cobalt, has a specific gravity of 6 to 6-3, and contains about 35*5 per cent, of cobalt, with sulphur 19-3 and arsenic 45*2. The cobalt is sometimes largely replaced by iron and sparingly by copper. Erytkrite (cobalt bloom) has a pinkish purple colour, resembling that of a peach blossom, and when scratched it affords a greenish streak. It is composed of about 39 per cent, of cobalt oxide, of 37 per cent, of arsenic anhydride, and 22 per cent, of water. Cobalt sometimes is found in mispickel (arsenic pyrites). Assay. A full description of the assay of the ores of cobalt will be described under the head of 'Nickel and Cobalt,' and only one variety of cobalt ore will be treated separately for cobalt. PART III. COBALT. 165 Skutterudite contains, when pure, arsenic 79*26 and cobalt 20-74, with the occasional replacement of about 2 per cent, of the cobalt by some nickel and iron. Take 1 grain of the crushed ore and mix with 0-5 grain of soda and 0-15 grain of borax glass in a soda- paper cornet, and treat on charcoal with a K.F. until all the metallic particles are united in one globule. By this means the small quantity of iron present is slagged and the greater part of the arsenic volatilised. If sulphur is present it unites with the flux, but causes the latter to become in a great part absorbed in the charcoal. If the metallic globule be now freed from adhering slag, and be heated in a deep bore in charcoal with a E.F., and kept fluid until no more arsenic volatilises, the globule left will weigh about 0*33 grain. The R.F. must be only strong enough to keep the metal fluid with a bright surface. If too violent a flame is applied the assay will boil and spurt, causing a mecha- nical loss. The globule now consists of cobalt 61' 131, and arsenic 38-869. NICKEL AND COBALT ASSAYS. Plattner's method of conducting the above assay is the one chiefly adopted in this work, but with many modifications. As cobalt and nickel cannot be separated from their compounds in the metallic state by fusion, like silver, gold, lead, &c., they are separated by combining them with arsenic. The mixed combination of nickel, cobalt, and arsenic is weighed ; the arsenide of cobalt is then slagged off, leaving an arsenide of nickel, which can be weighed as such, and the amount of metallic nickel calculated from 166 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III. it. The percentage of cobalt is estimated from the differ- ence in weight between the mixed arsenides and that of the arsenide of nickel found. The assay is not only easy but accurate. The assay has been divided into two classes, called A and B. Class A. Consists of all nickel and cobalt ores and products which are not combined with arsenic. Class B. Consists of all nickel and cobalt ores and products which are in combination with arsenic. Class A (a). — If nickel and cobalt compounds are not in the state of arsenides they require to be made so and then fused to form a button of metallic arsenides before they can be estimated quantitatively by the blowpipe ; therefore Class A treats of the arsenides solely. Take H grain of the ore or product, and if any sul- phides are present roast according to directions given in Copper Assay (p. 147). Finish the roasting (when all odour has ceased to be evolved) by an addition of 1 grain of carbonate of ammonia, which must be previously tritu- rated with the assay in the agate mortar. If sulphur is absent the roasting is dispensed with. Take the oxidised assay and mix it with 1 to 2 grains of metallic arsenic in a small clay crucible; place the crucible in the charcoal furnace on an iron wire ring, and fuse at a mild heat. It is generally advisable to cover the crucible with a clay capsule. This assay should be conducted outside, as the arsenical fumes are poisonous in a room. The contents of the crucible are carefully detached, and are then treated according to 'Class B. If the arsenicising must be done in the room, take 0*75 PART III. NICKEL AND COBALT ASSAYS. 167 grain of the nickel and cobalt oxides and mix with 1*5 grain powdered metallic arsenic, and wrap in a small soda- paper cornet. Place the assay in the bottom of a small tube closed at one end. Place in the mouth of the tube a small roll of dry filter paper, to absorb the moisture evolved from the charred soda paper. Heat the assay gradually over the spirit lamp to redness. Turn the tube every now and then, to prevent the charred paper adhering to the sides of the tube. Con- tinue the heat until no more sublimate of arsenic is found on the inside of the tube. Cut off the lower portion of the tube (by using a file) containing the assay, and remove carefully. The assay is now treated as Class B. If the oxide consists chiefly of protoxide of nickel and oxides of cobalt in which the former prevails, the resulting arsenides can easily be melted to one button during the fusion in the crucible ; if, however, oxide of cobalt prevails, the result- ing arsenides melt with difficulty, and about 0-25 grain of iron filings must be added, so as to form arsenide of iron, which produces a fusible combination with the arsenide of cobalt in the subsequent fusion. Class B (a) consists of nickel and cobalt, combined with arsenic and some iron. Take 1^ grain of the finely powdered mineral, and mix on the agate mortar with 0*8 grain soda, 0*20 grain borax glass. Place a soda-paper cornet in a deep bore in charcoal, and fuse with a moderate E.F. until the flux has become a slag and the metallic particles have united to a button. Cool the button in water to remove the slag* Fuse the button on a cavity in charcoal with a mild E.F. until the button shows a bright surface and assumes a rotary motion. The iron has then been slagged off. Con- 168 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III. tinue to keep the button in fusion until all fumes of arsenic have ceased to be evolved. Allow the button to cool, and weigh ; the weight gives the sum of (CoNi)4As. The amount of metal in the weighed arsenides is as follows : — Co4As . . 61 '5 percent, cobalt. Ni4As . . 607 „ nickel. Sometimes it is difficult to slag off the last traces of the iron ; in such a case add a little borax glass, and fuse until the button shows a perfectly bright surface. The button having been weighed, the cobalt is next slagged off by fusing with a moderate E.F. in a cavity on charcoal, a small quantity of borax glass having been pre- viously added. Cobalt separates slowly, and until it is all gone the solidified button is always covered with a black crust of oxide. The brightening of the button continues on add- ing fresh borax so long as the arsenide of cobalt is present ; but when all of the cobalt is separated, and the arsenide of nickel begins to oxidise, a film of basic arseniate of nickel forms, which moves slowly about the surface. If the blast is stopped as soon as the phenomenon above described can be distinctly perceived, and a part of the glass immediately pinched out and slowly raised, re- maining still connected with the main portion, it appears generally rather violet than blue against the daylight, provided it is not too strongly coloured with cobalt. If all the cobalt had been separated the glass would only appear pale brown. On the surface of the remain- ing arsenide of nickel beside the purple glass is seen an apple-green film of basic arseniate of nickel, which indicates that only Ni4As remains. PART III. NICKEL AND COBALT ASSAYS. 169 The Co4As is completely slagged off, while the Ni4As retains none of the arsenic from it, and therefore both metals can be quantitatively determined in the compounds. If proper care is taken in making the above assay the loss of nickel (even if a large film is observed on the sur- face of the assay) is so small that it can scarcely be de- termined on the fine assay balance. Class B (6) consists of ores and products in which nickel, cobalt, copper, and iron are combined with a small quantity of arsenic. Take 1 J grain for assay and treat in a similar manner to Class A. After the cobalt has been slagged off any copper that is present will be found combined with the nickel compound as Ni4As and Co6As. If the amount of copper present exceeds that of nickel it must be treated by the humid method. After weigh- ing the button of nickel, copper, and arsenic, add 1 grain of pure gold, and fuse with a moderate heat on a cavity on charcoal with a small quantity of salt of phosphorus. Allow air to get access to the button. Arsenide of nickel soon dissolves in the glass, making the glass a pure yellow colour. When the salt has become saturated, cool the button in water, remove the slag, and again fuse with a fresh portion of the salt, and treat until its surface ceases to be covered with a film of oxide and begins to show a bluish green colour. Cool the button in water, and then separate the last portions of arsenide of nickel by fusing as usual with a little borax on charcoal. If the cupriferous gold button shows a clean, metallic, lustrous surface, and does not crack wh^n beaten out cold, 170 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III. it is weighed, and the copper determined from the in- crease in weight. Arsenide of copper has the following composition : — Cu6As . . 71 '7 per cent, copper. 28-3 „ arsenic. Class B (c) consists of arsenides of nickel, cobalt, iron, copper, also brass and products containing lead, bismuth, zinc, sulphur, and earthy matters. 1£ grain of the finely powdered mineral is roasted according to directions given in Class A, and also after- wards arsenicised as there directed. Mix the assay with 3 grains soda, 2 grains potash, and 0*5 grain borax glass. Add 1 grain pure silver. Place the mixture in the clay crucible, in which a small piece of iron has been added, cover with a thin layer of salt, and, after covering with a clay cup, fuse as directed in the Lead Assay (p. 151). The heat must be sharp towards the end, to collect the arsenide in one button. In five or six minutes the arsenides collect in a round button at the bottom, and the earthy matters and oxides, which do not separate in the metallic state, are completely slagged off. The iron passes into the metallic arsenides^ and the lead or bismuth passes into an alloy with the silver, which unites with the arsenides in one button, but which can be easily mechanically separated. The quantity of lead or bismuth present can be estimated by first weighing the alloy and then cupelling it, when the loss will be either lead or bismuth. The presence of either should be looked for by the qualitative test before- hand. If any zinc or antimony is present it is volatilised when the arsenide of iron is removed with borax. PART III. NICKEL AND COBALT ASSAYS. 171 The assay is now finished according to instructions given in Class B (6) (p. 169). Class B (d). — Some ores are so poor in nickel and cobalt that they require a collecting agent, which can afterwards be easily slagged off. Take 1^ grain of the powdered ore ; mix with 0-40 grain of arsenide of iron (made by fusing iron filings with metallic arsenic in a clay crucible), 2 grains potash, 3 grains soda, and 0'5 grain borax glass ; cover with a thin layer of salt, and finish as directed in c and d, Class B. Alloys of copper and nickel in which copper pre- dominates cannot be estimated by the fire assay, but have to be determined by the wet way. Alloys of nickel, cobalt, and antimony cannot be determined by the blowpipe. COAL. Coal (or rather mineral coal) occurs in beds inter- stratified with shales, sandstones, and conglomerates, and sometimes limestones, forming distinct layers, which vary from a fraction of an inch to 30 feet or more in thickness. Its hardness varies from 0'5 to 2*5, and its specific gravity from 1 to 1'80. Lustre dull to brilliant, and either earthy, resinous, or submetallic. Colour black, greyish black, brownish black, and occasionally iridescent ; also sometimes dark brown and opaque. Fracture conchoidal to uneven. Brittle ; rarely somewhat sectile. Without, taste, ex- cept from impurities present. The origin of coal is mainly vegetable, though animal life has contributed somewhat to the result. Coal beds were once beds of vegetation, which have been buried during different geological ages. The car- 172 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III. boniferous period furnishes the greatest and best supply, but it is also found in beds of the Triassic, Oolitic, Cre- taceous, and Tertiary eras. The principal varieties of coal are as follows : — Anthracite^or Hard Coal. — Hardness 2-2-5 ; spec. grav. = 1*32— 1*70. Contains volatile matter after drying, 3 to 6 per cent. Contains carbon, 80 to 95 per cent. It has a high lustre and burns without flame, as it contains little or no bitumen. It is totally devoid of impressions of plants, and is, geologically speaking, the oldest of all kinds of fossil charcoal and is regarded as the last stage of carbonisation. It yields from 1 to 7 per cent, of ash, but 3 per cent, may be called the average. Brown Coal,or Lignite, contains from 57 to 70 per cent. of carbon, and represents the first stage of carbonisation, and is a coal of comparatively recent formation. It is composed of fossil plants more or less mineralised, and when burnt it evolves much smoke and affords a dull flame, and generally yields a large quantity of ash. It contains from 2 to 19 per cent, ash and gives from 30 to 50 per cent. coke. Caking Coal. — A bituminous coal which softens and becomes pasty in the fire, and after the heat has been continued for a time the volatile ingredients are driven off, and a greyish black fretted mass is left. The coke obtained from this coal varies from 50 to 85 per cent. Non-Caking Coal resembles the above in its external character, but burns freely without softening or showing any appearance of incipient fusion. Cannel Coal. - A bituminous coal which generally cakes. It is compact, with little or no lustre, and has a dull black or greyish black colour. On distillation it affords, after drying, 40 to 66 per cent, of volatile matter. PART III. COAL. 173 When held in the flame of a candle it easily ignites, burning with a steady bright flame. It is used ex- tensively for the manufacture of illuminating gas, of which it affords a better quality than any other species of coal. Coal can be examined and its commercial properties determined by the blowpipe with great accuracy. Assay. The assay is divided into five heads : — 1st. The moisture determination. Select from the mass of coal to be examined a few lumps representing as nearly as possible the average quality. Crush them up in the agate mortar into small pieces about the size of a mustard seed. Weigh out 5 grains, place in a small porcelain dish, and dry at a gentle heat over the spirit lamp. Hard coals sometimes fly when heated, so it is best to cover the dish with a watch glass whilst heating. After about 5 minutes remove the assay and weigh; then repeat the heating and again weigh. As soon as the weights agree the assay is ready to be converted into coke. Plattner states that the percentage of moisture is lowest in anthra- cite; in bituminous coals it is usually 3 to 4 per cent., seldom 6 to 7, and reaches its maximum in lignite and brown coals, which contain 20 per cent, and sometimes more. 2nd. Determination of the coke production. Take the dried coal and remove to a clay or platinum crucible, and cover with a small roasting clay dish or plati- num cup. Place the crucible on a triangle of platinum wire on the blowpipe stand under the flame, using alcohol, and cover it with a small sheet-iron funnel (the same that is used in roasting copper ores). The heat is continued until all the volatile gas has escaped, when the assay generally 174 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III. will appear to possess a fused porous appearance, and to have a metallic lustre. The coke so made is now removed and weighed. It should be weighed quickly, as coke absorbs moisture from the air rapidly. The coking takes about 10 minutes, and the crucible should not be allowed to get beyond a red heat. 3rd. The estimation of the amount of ash. After the percentage of coke has been determined remove the assay to a small clay or platinum capsule, and, without using a cover, again heat over the lamp — this time to a bright red colour — until all the carbon has been con- sumed. The operation is much facilitated by occasionally stirring the assay with a piece of platinum wire, also by applying the blowpipe flame to the bottom of the cup when the assay is nearly finished. If alcohol cannot be obtained the assay for coke and ash can be conducted in the charcoal furnace by using the blowpipe flame, as in the copper assay, and if the ash amounts to more than 5 per cent, the value of the coal is much diminished. If the ash presents a brown, red, or grey colour, sesquioxide of iron has been formed by the oxidation of the pyrites in the coal. 4th. Determination of the absolute heating power by Berthier's process. Take an average sample of the coal and crush it up to the finest powder. Weigh out 0'3 grain of the coal dust and mix it with 12 grains of oxy chloride of lead, and after placing the mixture in the crucible cover it with an ad- ditional 12 grains of oxy chloride of lead. Oxychloride of lead fuses more readily than litharge; therefore, owing to the large quantity of material which must be brought into a state of fusion in this determina- tion, it is employed instead of litharge. PART III. COAL. 175 The assay is next covered with a little powdered glass, also with a few spoonfuls of borax glass. A clay cup is placed over the crucible, and the assay is then fused in the charcoal furnace in a similar manner to the silver assay when litharge is used (see p. 122). About 7 or 8 minutes suffices to melt the assay, and the lead button produced by the carbon in the coal acting on the lead oxychloride will be found lying upon the bottom of the .crucible when the assay is cool and the crucible is broken. The weight of the button, when cleaned from the slag, divided by 20, gives the quantity of lead that 1 part of the fuel under examination can reduce ; and since 1 part of carbon reduces 34 parts of lead, the heating power of the fuel may be easily ascertained. The amount of lead reduced by 1 part of coal varies with the different pit coals between 21 and 32 parts, with the lignites between 16 and 25 parts. In making this assay the heat must be applied at first very gradually, and afterwards increased to a bright redness. Dr. Ure's experiments, published in the ' Supplement to the Dictionary of Arts, Mines, and Manufactures,' have appeared to be unsatisfactory in regard to the accuracy of Berthier's method. Mitchell, however, has found the method correct, and the author has found it equally so. The lead oxychloride should always be pure. 5th. "Estimation of sulphur in a sample of coal. Sulphur generally exists in coal as a sulphide of iron, and as the presence of more than 2 per cent, of sulphur depreciates the market value of coal, owing to its destroy- ing the iron boilers and grates under and over which the coal is consumed, it is always an important part of the examination of coal to ascertain the quantity present. Mitchell, in his ' Manual of Practical Assaying,' re- commends the following process : — 176 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III. 'Take 1 part of the finely pulverised coal and mix with 7 to 8 parts of nitre, and 1 6 parts of common salt, and 4 parts of carbonate of potash, all of which must be per- fectly pure. The mixture is then placed in a platinum crucible and gently heated at a certain temperature ; the whole ignites and burns quietly. The heat is then in- creased until the mass is fused ; the operation is finished when the mass is white. It must, when cold, be dissolved in water, the solution slightly acidulated by means of hydrochloric acid, and chloride of barium added to it as long as a white precipitate forms. This precipitate is sulphate of baryta, which must be collected on a filter, washed, dried, ignited, the filter burnt away, and the remaining sulphate of baryta weighed : every 116 parts of it indicate 16 of sulphur.' The above-described methods of examining coal are all that are required for commercial purposes. The assay may be carried on still further by estimating the iron oxide contained in the ash, according to the instructions given in the quantitative iron assay. The ash can also be examined qualitatively for silica, lime, soda, and potash (see ' Qualitative Determination '). PART IV. TABLES OF ENGLISH AND AMERICAN VALUES OF GOLD ACCORDING TO ITS FINENESS; ALSO THE VALUE OF GOLD COINS IN THE UNITED STATES OF AMERICA. PART IV. ENGLISH VALUE OF GOLD. 179 Table of the English Mint Value of Gold per Ounce Troy, at Different Degrees of Fineness. Fineness of Gold Value per Ounce Fineness of Gold Value per Ounce £ x. d. £ s. d. 1000 4 4 11-4545 962 4 1 8-7152 999 4 4 10-4350 961 4 1 7-6958 998 4 4 9-4156 960 4 1 6-6763 997 4 4 8-3961 959 4 1 5-6569 996 4 4 7-3767 958 4 1 46374 995 4 4 6-3572 957 4 1 3-6179 994 4 4 5-3378 956 4 1 2-5985 993 4 4 4-3183 955 4 1 1-5790 992 4 4 3-2989 954 4 1 05596 991 4 4 2-2793 953 4 0 11-5401 990 4 4 1-2600 952 4 0 10 5207 989 4 4 02405 951 4 0 9-5012 988 4 3 11-2210 950 4 0 8-4818 987 4 3 10 2016 949 4 0 7-4623 986 4 3 9-1821 948 4 0 6-4429 985 4 3 81627 947 4 0 5-4234 984 4 3 7-1432 946 4 0 4-4039 983 4 3 6-1238 945 4 0 3-3835 982 4 3 5-1043 944 4 0 2-3650 981 4 3 4-0849 943 4 0 13456 980 4 3 3-0654 942 4 0 03261 979 4 3 20459 941 3 19 11-3067 978 4 3 1-0265 940 3 19 10-2872 977 4 3 0-0070 939 3 19 9-2678 976 4 2 10 9876 938 3 19 8 2483 975 4 2 99681 937 3 19 7-2289 974 4 2 8-9487 936 3 19 6-2094 973 4 2 7-9292 935 3 19 5-1899 972 4 2 69098 934 3 19 4-1705 971 4 2 5-8903 933 3 19 3-1510 970 4 2 4-8709 932 3 19 2-1316 969 4 2 3-8504 931 3 19 1 1121 968 4 2 28319 930 3 19 00927 967 4 2 1-8125 929 3 18 11 0732 966 4 2 07930 928 3 18 10-0538 965 4 1 11-7736 927 3 18 9-0343 964 4 1 10 7541 926 3 18 8-0149 963 4 1 9-7347 925 3 18 6-9954 N 2 180 ENGLISH AND AMERICAN VALUES OF GOLD. PART IV. Table of the English Mint Value of Gold — continued. Fineness of Gold Value per Ounce Fineness of Gold Value per Ounce £ j». d. £ s. d. 924 3 18 5 9759 882 3 14 11-1589 923 3 18 4-9565 881 3 14 10-1394 922 3 18 3 9370 880 3 14 91199 921 3 18 2-9176 879 3 14 8-1005 920 3 18 1-8981 878 3 14 7-0810 9] 9 3 18 0-8787 877 3 14 6-0616 918 3 17 11 8592 876 3 14 5-0421 917 3 17 10-8398 875 3 14 4-0227 916 3 17 9-8203 874 3 14 3-0032 915 3 17 8-8009 873 3 14 1 9838 914 3 17 7 7814 872 3 14 0-9643 913 3 17 6-7619 871 3 13 11-9449 912 3 17 5 7425 870 3 13 109254 911 3 17 4-7230 869 3 13 99059 910 3 17 3 7036 868 3 13 88865 909 3 17 2 6841 867 3 13 7-8670 9u8 3 17 1 6647 866 3 13 6-8476 907 3 17 0-6452 865 3 13 5-8281 906 3 16 11-6258 864 3 13 4-8087 905 3 16 10-6063 863 3 13 37892 904 3 16 9-5869 862 3 13 2 7698 903 3 16 8-5674 861 3 13 1-7503 902 3 16 7-5479 860 3 13 0-7309 901 3 16 6-5285 859 3 12 11-7114 900 3 16 5-5090 858 3 12 10-6919 899 3 16 4 4896 857 3 12 9-6725 898 3 16 3-4701 856 3 12 8-6530 897 3 16 24507 855 3 12 7*6336 896 3 16 1-4312 854 3 12 6-6141 895 3 16 0-4118 853 3 12 5-5947 894 3 15 11-3923 852 3 12 4 5752 893 3 15 10 3729 851 3 12 3-5558 892 3 15 9-3534 850 3 12 2-5363 891 3 15 8-3339 849 3 12 1-5169 890 3 15 7-3145 848 3 12 0-4974 889 3 15 6 2950 847 3 11 11-4779 888 3 15 5-2756 846 3 11 10-4585 887 3 15 42561 845 3 11 9-4390 886 3 .15 3-2367 844 3 11 8-4196 885 3 15 2-2172 843 3 11 7-4001 884 3 15 1-1978 842 3 11 6 3807 883 3 15 0-1783 841 3 11 5-3612 PART IV. ENGLISH VALUE OF GOLD. 181 Table of the English Mint Value of Gold — continued. Fineness of Gold Value per Ounce Fineness of Gold Value per Ounce & s. d. £ s. d. 840 3 11 4-3418 798 3 7 9-5247 839 3 11 3-3223 797 3 7 8-5052 838 3 11 2-3029 796 3 7 7-4858 837 3 11 1-3834 795 3 7 6-4663 836 3 11 0-2639 794 3 7 5-4469 835 3 10 11 2445 793 3 7 4-4274 834 3 10 10-2250 792 3 7 3-4979 833 3 10 9-2056 791 3 7 2-3885 832 3 10 8-1861 790 3 7 1-3690 831 3 10 7-1667 789 3 7 0-3496 830 3 10 6-1472 788 3 6 11-3301 829 3 10 5 1278 787 3 6 10-3107 828 3 10 4-1083 786 3 6 92912 827 3 10 3-0889 785 3 6 8-2718 826 3 10 2 0694 784 3 6 7-2523 825 3 10 1-0499 783 3 6 6-2329 824 3 10 0-0305 782 3 6 5-2134 823 3 9 11-0110 781 3 6 41939 822 3 9 9-9916 780 3 6 31745 821 3 9 8-9721 779 3 6 2-1550 820 3 9 7-9527 778 3 6 1-1356 819 396 9332 777 3 6 0-1161 818 3 9 5-9138 776 3 5 11-0967 817 3 9 4-8943 775 3 5 100772 816 3 9 3-8749 774 3 5 9-0578 815 3 9 2-8554 773 3 5 8-0383 814 3 9 1-8359 772 3 5 7-0189 813 3 9 0-8165 771 3 5 5-9994 812 3 8 11 7970 770 3 5 4-9799 811 3 8 10-7776 769 3 5 3-9605 810 3 8 97581 768 3 5 2-9410 809 3 8 8-7387 767 3 5 1-9216 808 3 8 7-7192 766 3 5 09021 807 3 8 66998 765 3 4 11-8827 806 3 8 5-6803 764 3 4 10-8632 805 3 8 46609 763 3 4 9-8438 804 3 8 3-6414 762 3 4 8-8243 803 3 8 2-6219 761 3 4 7-8049 802 3 8 1-6025 760 3 4 6-7854 801 3 8 0-5830 759 3 4 57659 800 3 7 11-5636 758 3 4 47465 799 3 7 10-5441 757 3 4 3-7270 182 ENGLISH AND AMERICAN VALUES OF GOLD. PART IV. Table of tlis English Mint Value of Gold— continued. Fineness of Gold Value per Ounce Fineness of Gold Value per Ounce £ 5. d. & s. d. 756 3 4 2-7076 714 3 0 7-8905 755 3 4 1-6881 713 3 0 6-8710 754" 3 4 0-6687 712 3 0 5-8516 753 3 3 11-6492 711 3 0 48321 752 3 3 10-6298 710 3 0 3-8127 751 3 3 96103 709 3 0 2-7932 750 3 3 8-5909 708 3 0 1-7738 749 3 3 7-5714 707 3 0 0-7543 748 3 3 6-5519 706 2 19 11-7349 747 3 3 55325 705 2 19 10-7154 746 3 3 4-5130 704 2 19 9-6959 745 3 3 3-4936 703 2 19 86765 744 3 3 24741 702 2 19 7-6570 743 3 3 1-4547 701 2 19 6-6376 742 3 3 0-4352 700 2 19 5-6181 741 3 2 11-4158 699 2 19 4-5987 740 3 2 10-3963 698 2 19 3-5792 739 3 2 9-3769 697 2 19 2-5598 738 3 2 8-3574 696 2 19 1-5403 737 3 2 7-3379 695 2 19 05209 736 3 2 6-3185 694 2 18 11-5014 735 3 2 5-2990 693 2 18 10-4820 734 3 2 42796 692 2 18 9-4625 733 3 2 3-2601 691 2 18 84430 732 3 2 2-2407 690 2 18 7-4236 731 3 2 1-2212 689 2 18 6-4041 730 3 2 0-2018 688 2 18 5 3847 729 3 1 111823 687 2 18 4-3652 728 3 1 10-1629 686 2 18 3-3458 727 3 1 91434 685 2 18 2-3263 726 3 1 8-1239 684 2 18 1-3069 725 3 1 7-1045 683 2 18 0-2874 724 3 1 6-0850 682 2 17 11 2680 723 3 1 5-0656 681 2 17 10 2485 722 3 1 4-0461 680 2 17 9-2290 721 3 1 3-0267 679 2 17 8-2096 720 312 0072 678 2 17 7-1901 719 3 1 0-9878 677 2 17 6-1707 718 3 0 11-9683 676 2 17 5-1512 717 3 0 10-9489 675 2 17 4-1318 716 3 0 9-9294 674 2 17 3-1123 715 3 0 8-9099 673 2 17 2-0929 PART IV. ENGLISH VALUE OF GOLD. 183 Table of the English Mint Value of Gold — continued. Fineness of Gold Value per Ounce Fineness of Gold Value per Ounce & s. cl. £ s. d. 672 2 17 1-0734 630 2 13 6-2563 671 2 17 00540 629 2 13 5-2369 670 2 16 11-0345 628 2 13 4-2174 669 2 16 100151 627 2 13 3-1979 668 2 16 8-9956 626 2 13 2-1785 667 2 16 7-9761 625 2 13 1-1590 666 2 16 6 9567 624 2 13 0-1396 665 2 16 5-9372 623 2 12 11-1201 664 2 16 4-9178 622 2 12 10 1007 663 2 16 3-8983 621 2 12 90812 662 2 16 2-8789 620 2 12 8-0618 661 2 16 1-8594 619 2 12 7 0423 660 2 16 0-8399 618 2 12 6-0229 659 2 15 11-8205 617 2 12 5 0034 658 2 15 10-8010 616 2 12 3-9839 657 2 15 9-7816 615 2 12 2-9645 656 2 15 8 762] 614 2 12 1-9451 655 2 15 7-7427 613 2 12 0 9256 654 2 15 6-7232 612 2 11 11-9061 653 2 15 5-7038 611 2 11 10-8867 652 2 15 4-6843 610 2 11 9-8672 651 2 15 3 6649 609 2 11 8-8478 650 2 15 2-6454 608 2 11 7-8283 649 2 15 1-6259 607 2 11 6 8089 648 2 15 0 6065 606 2 11 5-7894 647 2 14 11 5870 605 2 11 4-7699 646 2 14 10-5676 604 2 11 3 7505 645 2 14 9-5481 603 2 11 2-7311 644 2 14 8-5287 602 2 11 1-7116 643 2 14 7-5092 601 2 11 0-6921 642 2 14 6-4898 600 2 10 11-6727 641 2 14 5-4703 599 2 10 10-6532 640 2 14 4-4509 598 2 10 9-6338 639 2 14 3-4314 597 2 10 8-6143 638 2 14 2-4120 596 2 10 7-5949 637 2 14 1-3925 595 2 10 6-5754 636 2 14 0-3730 594 2 10 5 5559 635 2 13 11-3536 593 2 10 4-5365 634 2 13 10-3341 592 2 10 3-5170 633 2 13 9-3147 591 2 10 2-4976 632 2 13 8-2952 590 2 10 1-4781 631 2 13 7-2758 589 2 10 0-4587 184 ENGLISH AND AMEEICAN VALUES OF GOLD. PART IV. Table of the English Mint Value of Gold — continued. Fineness of Gold Value per Otmce Fineness of Gold Value per Ounce £ .?. (1. £ s. d. 588 2 9 114392 546 2 6 4-6221 587 2 9 10-4198 545 2 6 36027 586 2 9 9-4003 544 2 6 2-5832 585 2 9 8-3809 543 2 6 1-5638 584 2 9 73614 542 2 6 05443 583 2 9 6-3419 541 2 5 11-5249 582 2 9 5-3225 540 2 5 10 5054 581 2 9 4-3030 539 2 5 9-4859 580 2 9 3-2836 538 2 5 8-4665 579 2 9 2-2641 537 2 5 7-4470 578 2 9 12447 536 2 5 6-4276 577 2 9 0-2252 535 2 5 5-4081 576 2 8 11-2058 534 2 5 4-3887 575 2 8 10-1863 533 2 5 33692 574 2 8 9-1669 532 2 5 2-3498 573 2 8 8-1474 531 2 5 13303 572 2 8 7-1279 530 2 5 0-3109 571 2 8 6-1085 529 2 4 11-2914 570 2 8 5-0890 528 2 4 10-2719 569 2 8 4-0696 527 2 4 9-2525 568 2 8 3-0501 526 2 4 8-2330 567 2 8 2-0307 525 2 4 7-2136 566 2 8 1-0112 524 2 4 6-1941 565 2 7 11-9918 523 2 4 5-1747 564 2 7 109723 522 2 4 4-1552 563 2 7 9-9529 521 2 4 3-1358 562 2 7 8-9334 520 2 4 21163 561 2 7 7-9140 519 2 4 1-0969 560 276 8945 518 2 4 0-0774 559 2 7 5-8751 517 2 3 11-0579 558 2 7 4-8556 516 2 3 10-0385 557 2 7 3-8361 515 2 3 9-0190 556 2 7 2-8167 514 2 3 7-9996 555 2 7 1-7972 513 2 3 6-9801 554 2 7 0-7778 512 2 3 5-9607 553 2 6 11-7583 511 2 3 4-9412 552 2 6 10-7389 510 2 3 3-9218 551 2 6 97194 509 2 3 2-9023 550 2 6 8-6999 508 2 3 1-8829 549 2 6 7-6805 507 2 3 0-8634 548 2 6 6-6611 506 2 2 11-8439 547 2 6 5-6416 505 2 2 10-8245 i FART IV. ENGLISH VALUE OF GOLD. 185 Table of tlie English Mint Value of Gold— continued. Fineness of Gold Value per Ounce Fineness of Gold Value per Ounce £ .?. d. £ s. d. 504 2 2 9-8051 462 1 19 2-9879 503 2 2 8-7856 461 1 19 1-9685 502 2 2 77661 460 1 19 0-9490 501 2 2 6-7467 459 1 18 11-9296 500 2 2 5-7272 458 1 18 10-9101 499 2 2 4-7078 457 1 18 9-8907 498 2 2 3-6883 456 1 18 8-8712 497 2 2 2-6689 455 1 18 7-8518 496 2 2 1-6494 454 1 18 6-8323 495 2 2 0-6300 453 1 18 5-8129 494 2 1 11-6105 452 1 18 4-7934 493 2 1 10-5911 451 1 18 3-7739 492 2 1 9-5716 450 1 18 2-7545 491 2 1 8-5521 449 1 18 1-7351 490 2 1 7-5327 448 1 18 0-7156 489 2 1 1-5132 447 1 17 11-6961 488 2 1 5-4938 446 1 17 10-6767 487 2 1 4-4743 445 1 17 9-6572 486 2 1 3-4549 444 1 17 8-6378 485 2 1 2-4354 443 1 17 7-6183 484 2 1 1-4159 442 1 17 6-5989 483 2 1 0-3965 441 1 17 5-5794 482 . 2 0 11-3770 440 1 17 4-5599 481 2 0 10-3576 439 1 17 3-5405 480 2 0 9-3381 438 1 17 2-5211 479 2 0 8-3187 437 1 17 1-5016 478 2 0 7-2992 436 1 17 0-4821 477 2 0 6-2798 435 1 16 11-4627 476 2 0 5-2603 434 1 16 10-4432 475 2 0 4-2409 433 1 16 9-4238 474 2 0 3-2214 432 1 16 8-4043 473 2 0 2-2020 431 1 16 7-3849 472 2 0 1-1825 430 1 16 6-3654 471 2 0 0-1630 429 1 16 5-3459 470 1 19 11-1436 428 1 16 4-3265 469 1 19 10-1241 427 1 16 3-3070 468 1 19 9-1047 426 1 16 2-2876 467 1 19 8-0852 425 1 16 1-2681 466 1 19 7-0658 424 1 16 0-2487 465 1 19 6-0463 423 1 15 11-2292 464 1 19 5-0269 422 1 15 10-2098 463 1 19 4-0074 421 1 15 9-1903 186 ENGLISH AND AMERICAN VALUES OF GOLD. PART IV. Table of tlw English Mint Value of Gold — continued. Fineness of Gold Value per Ounce Fineness of Gold Value per Ounce £ *. d. £ .?. d. 420 1 15 8-1709 378 1 12 1-3538 419 1 15 7-1514 377 1 12 0-3343 418 1 15 6-1319 376 1 11 11-3142 417 1 15 5-1125 375 1 11 10-2954 416 1 15 4-0930 374 1 11 9-2759 415 1 15 3-0736 373 1 11 8-2565 414 1 15 2-0541 372 1 11 7-2370 413 1 15 1-0347 371 1 11 6-2176 412 1 15 0-0152 370 1 11 5-1981 411 1 14 10-9958 369 1 11 4-1787 410 1 14 9-9763 368 1 11 3-1592 409 1 14 8-9569 367 1 11 2-1398 408 1 14 7-9374 366 1 11 1-1203 407 1 14 6-9179 365 1 11 0-1009 406 1 14 5-8985 364 1 10 11-0814 405 1 14 4-8790 363 1 10 10-0620 404 1 14 3-8596 362 1 10 9-0425 403 1 14 2-8401 361 1 10 8-0230 402 1 14 1-8207 360 1 10 7-0036 401 1 14 0-8012 359 1 10 5-9841 400 1 13 11-7818 358 1 10 4-9647 399 1 13 10-7623 357 1 10 3-9452 398 1 13 9-7429 356 1 10 2-9258 397 1 13 8-7234 355 1 10 1-9063 396 1 13 7-7039 354 1 10 0-8869 395 1 13 6-6845 353 1 9 11-8674 394 1 13 5-6651 352 1 9 10-8479 393 1 13 4-6456 351 1 9 9-8285 392 1 13 3-6261 350 1 9 8-8090 391 1 13 2-6067 349 1 9 7-7896 390 1 13 1-5872 348 1 9 6-7701 389 1 13 0-5678 347 1 9 5-7507 388 1 12 11-5483 346 1 9 4-7312 387 1 12 10-5289 345 1 9 3-7118 386 1 12 9-5094 344 1 9 2-6923 385 1 12 8-4899 343 1 9 1-6729 384 1 12 7-4705 342 1 9 0-6534 383 1 12 6-4511 341 1 8 11-6339 382 1 12 5-4316 340 1 8 10-6145 381 1 12 4-4121 339 1 8 9-5951 380 1 12 3-3927 338 1 8 8-5756 379 1 12 2-3732 3S7 1 8 7-5561 PART IV. ENGLISH VALUE OF GOLD. 187 Table of the English Mint Value of Gold— continued. Fine-ness of Gold Value per Ounce Fineness of Gold Value per Ounce & s. d. £ s. d. 336 1 8 6-5367 294 1 4 11-7196 335 1 8 5-5172 293 1 4 10-7011 334 1 8 4-4978 292 1 4 9-6807 333 1 8 3-4783 291 1 4 8-6612 332 1 8 2-4589 290 1 4 7-6418 331 1 8 1-4394 289 1 4 6-6223 330 1 8 0-4199 288 1 4 5-6029 329 1 7 11 4005 287 1 4 4-5834 328 1 7 10-3811 286 1 4 3-5639 327 1 7 9-3616 285 1 4 2-5445 326 1 7 83421 284 1 4 1-5251 325 1 7 7-3227 283 1 4 0-5056 324 1 7 6-3032 282 1 3 11-4861 323 1 7 5-2838 281 1 3 10-4667 322 1 7 4-2643 280 1 3 9-4472 321 1 7 32449 279 1 3 8-4278 320 1 7 22254 278 1 3 7-4083 319 1 7 1-2059 277 1 3 6-3889 318 1 7 0-1865 276 1 3 5-3694 317 1 6 11-1670 275 1 3 4-3499 316 1 6 10-1476 274 1 3 3-3305 315 1 6 9-1281 273 1 3 2-3110 314 1 6 8-1087 272 1 3 1-2916 313 1 6 7-0892 271 " 1 3 0-2721 312 1 6 6-0698 270 1 2 11-2527 311 1 6 5-0503 269 1 2 10-2332 310 1 6 4-0309 268 1 2 9-2138 309 1 6 3-0114 267 1 2 8-1943 308 1 6 1-9919 266 1 2 7-1749 307 1 6 0-9725 265 1 2 6-1554 306 1 5 11-9530 264 1 2 5-1351 305 1 5 10-9336 263 1 2 4-1165 304 1 5 9-9141 262 1 2 3-0970 303 1 5 8-8947 261 1 2 2-0776 302 1 5 7-8752 260 1 2 1-0581 301 1 5 6-8558 259 1 2 0-0387 300 1 5 5-8363 258 1 1 11-0192 299 1 5 4-8169 257 1 1 9-9998 298 1 5 3-7974 256 1 1 8-9803 297 1 5 2-7779 255 1 1 7-9609 296 1 5 1-7585 254 1 1 6-9414 295 1 5 0-7390 253 1 1 5-9219 188 ENGLISH AND AMERICAN VALUES OF GOLD. PART IV Table of the English Mint Value of Gold— continued. Fineness of Gold Value per Ounce Fineness of Gold Value per Ounce £ *. d. £ s. (I. 252 1 1 4-9025 210 0 17 10-0854 251 1 1 3-8830 209 0 17 9-0659 250 1 1 2-8636 208 0 17 8-0465 249 1 1 1-8441 207 0 17 7-0270 248 1 1 0-8247 206 0 17 6-0076 247 1 0 11-8052 205 0 17 4-9881 246 1 0 10-7858 204 0 17 3-9687 245 1 0 9-7663 203 0 17 2-9492 244 1 0 8-7469 202 0 17 1-9298 243 1 0 7-7274 201 0 17 0-9103 242 1 0 6-7079 200 0 16 11-8909 241 1 0 5-6885 199 0 16 10-8714 240 1 0 4-6690 198 0 16 9-8519 239 1 0 3-6496 197 0 16 8-8325 238 1 0 2-6301 196 0 16 7-8130 237 1 0 1-6107 195 0 16 6-7936 236 1 0 0-5912 194 0 16 5-7741 235 0 19 11-5718 193 0 16 4-7547 234 0 19 10-5523 192 , 0 16 3-7352 233 0 19 9-5329 191 0 16 2-7158 232 0 19 8-5134 190 0 16 1-6963 231 0 19 7-4939 189 0 16 0-6769 230 0 19 6-4745 188 0 15 11-6574 229 0 19 5-4551 187 0 15 10-6379 228 0 19 4-4356 186 0 15 9-6185 227 0 19 3-4161 185 0 15 8-5990 226 0 19 2-3967 184 0 15 7-5796 225 0 19 1-3772 183 0 15 6-5601 224 0 19 0-3578 182 0 15 5-5407 223 0 18 11-3383 181 0 15 4-5212 222 0 18 10-3189 180 0 15 3-5018 221 0 18 9-2994 179 0 15 2-4823 220 0 18 8-2799 178 0 15 1-4629 219 0 18 7-2605 177 0 15 0-4434 218 0 18 6-2410 176 0 14 11-4239 217 0 18 5-2216 175 0 14 10-4045 216 0 18 4-2021 174 0 14 9-3851 215 0 18 3-1827 173 0 14 8-3656 214 0 18 2-1632 172 0 14 7-3461 213 0 18 1-1438 171 0 14 6-3267 212 0 18 0-1243 170 0 14 5-3072 211 0 17 11-1049 169 0 14 4-2878 PART IV. ENGLISH VALUE OF GOLD. 189 Table uf the English Mint Value of Gold — continued. Fineness of ttold Value per Ounce Fineness of Gold Value per Ounce £ s. d. £ x. d. 168 0 14 3-2683 126 0 10 8-4512 167 0 14 2-2489 125 0 10 7-4318 166 0 14 1-2294 124 0 10 6-4123 165 0 14 0-2099 123 0 10 5-3929 164 0 13 11-1905 122 0 10 4-3734 163 0 13 10-1710 121 0 10 3-3530 162 0 13 9-1516 120 0 10 2-3345 161 0 13 8-1321 119 0 10 1-3151 160 0 13 7-1127 118 0 10 0-2956 159 0 13 6-0932 117 0 9 11-2761 158 0 13 5-0738 116 0 9 10-2567 157 0 13 4-0543 115 0 9 9-2372 156 0 13 3-0349 114 0 9 8-2178 155 0 13 2-0154 113 0 9 7-1983 154 0 13 0-9959 112 0 9 6-1789 153 0 12 11-9765 111 0 9 5-1594 152 0 12 10-9570 110 0 9 4-1399 151 0 12 9-9376 109 0 9 3-1205 150 0 12 8-9181 108 0 9 2-1010 149 0 12 7-8987 107 0 9 1-0816 148 0 12 6-8792 106 0 9 0-0621 147 0 12 5-8598 105 0 8 11-0427 146 0 12 4-8403 104 0 8 10-0232 145 0 12 3-8209 103 0 8 9-0038 144. 0 12 2-8014 102 0 8 7-9843 143 0 12 1-7819 101 0 8 6-9649 142 0 12 0-7625 100 0 8 5-9454 141 0 11 11-7430 99 0 8 4-9259 140 0 11 10-7236 98 0 8 3-9065 139 0 11 9-7041 97 0 8 2-8870 138 0 11 8-6847 96 0 8 1-8676 137 0 11 7-6652 95 0 8 0-8481 136 0 11 6-6458 94 0 7 11-8287 135 0 11 5-6263 93 0 7 10-8092 134 0 11 4-6069 92 0 7 9-7898 133 0 11 3-5874 91 0 7 8-7703 132 0 11 2-5679 90 0 7 7-7509 131 0 11 1-5485 89 0 7 6-7314 130 0 11 0-5290 88 0 7 5-7119 129 0 10 11-5096 87 0 7 4-6925 128 0 10 10-4901 86 0 7 3-6730 127 0 10 9-4707 85 0 7 2-6536 190 ENGLISH AND AMERICAN VALUES OF GOLD. PART IV. Table of the English Mint Value of Gold — continued. Fineness of Gold Value per Ounce Fineo ess of Gold Value per Ounce & s. d. £ s. d. 84 0 7 1-6341 42 0 3 6-8170 83 0 7 0-6147 41 0 3 5-7976 82 0 6 11-5952 40 0 3 4-7781 81 0 6 10 5758 39 0 3 3-7587 80 0 6 9-5563 38 0 3 2-7392 79 0 6 8-5369 37 0 3 1-7198 78 0 6 7-5174 36 0 3 0-7003 77 0 6 6-4979 35 0 2 11-6809 76 0 6 5-4785 34 0 2 106614 75 0 6 4-4590 33 0 2 9-6419 74 0 6 3-4396 32 0 2 8-6225 73 0 6 24201 31 0 2 7-6030 72 0 6 1-4007 30 0 2 6-5836 71 0 6 0-3812 29 0 2 5-5641 70 0 5 11-3618 28 0 2 45447 69 0 5 10-3423 27 0 2 3-5252 68 0 5 9-3229 26 0 2 2-5058 67 0 5 8-3034 25 0 2 1-4863 66 0 5 7-2839 24 0 2 0-4669 65 0 5 6-2645 23 0 1 11 4474 64 0 5 5-2451 22 0 1 10-4279 63 0 5 4-2256 21 0 1 9-4085 62 0 5 3-2061 20 0 1 8-3890 61 0 5 2-1867 19 0 1 7-3696 60 0 5 1-1672 18 0 1 6-3501 59 0 5 01478 17 0 1 5-3307 58 0 4 11-1283 16 0 1 4-3112 57 0 4 10-1089 15 0 1 3-2918 56 0 4 9-0894 14 0 1 2-2723 55 0 4 8-0699 13 0 1 1-2529 54 0 4 7-0505 12 0 1 0-2334 53 0 4 6-0310 11 0 0 11-2139 52 0 4 5-0116 10 0 0 10 1945 51 0 4 3-9921 9 0 0 9-1750 50 0 4 2-9727 8 0 0 8-1556 49 0 4 1-9532 7 0 0 7-1361 48 0 4 09338 6 0 0 6-1167 47 0 3 11-9143 5 0 0 5-0972 46 0 3 10-8949 4 0 0 4-0778 45 0 3 9-8754 3 0 0 3-0583 44 0 3 8-8559 2 0 0 2-0389 43 0 3 7-8365 1 0 0 1-0194 PART IV. GOLD COINS IN THE U.S. OF AMERICA. 191 GOLD COINS IN THE UNITED STATES OP AMERICA. The following table of gold coins is taken from the annual report of the Director of the United States Mint. From the value of the gold coins a deduction of a half of one per cent, is made to cover the cost of recoin- age. The weights of coins are usually expressed in grains, but in this table they have been reduced to troy ounces and decimals ; but these weights are readily converted into grains again by multiplying them by 480, or grains into ounces and decimals by dividing them by 480. U.S.A. gold eagle, weighing 258 grs. or 0*5375 oz., is worth $10-00. Table of the Value of Gold Coins in the United States of America. Country Denominations Weight Fine- ness Value Value after De- duction I Oz. Dec. lOOOths $ $ Australia . Pound of ] 852 0-281 916-5 5-32-37 5-29-71 Australia . Sovereign of '55-60 0-256-5 916 4-85-58 4-83-16 Austria Ducat . 0-112 986 2-28-28 2-27-04 Austria Souverain 0-363 900 6-75-35 6-71-98 Austria New Union Crown (assumed) 0-357 900 6-64-19 6-60-87 Belgium . Twenty-five francs 0-254 899 4-72-03 4-69-67 Bolivia Doubloon 0-867 870 15-59-25 15-51-46 Brazil Twenty milreis 0-575 917-5 10-90-57 10-85-12 Central America Two escudos . 0-209 853-5 3-68-75 3-66-91 Central America Four reals 0-027 875 0-48-8 0-48-6 Chili Old doubloon 0-867 870 15-59-26 15-51-47 Chili Ten pesos ' condor ' 0-492 900 9-15-35 9-10-78 Denmark . Ten thaler . 0-427 895 7-90-01 7-86-06 Ecuador . Four escudos 0-433 844 7-55-46 7-51-69 England . Pound or sovereign, new . 0-256-7 916-5 4-86-34 4-83-91 England . Pound or sovereign, average 0-256-2 916 4-84-92 4-82-50 France Twenty f rancs,new 0-207-5 899-5 3-85-83 3-83-91 France Twenty francs, av. 0-207 899 3-84-69 3-82-77 192 ENGLISH AND AMEEICAN VALUES OF GOLD. PART IV. Table of the Value of Gold Coins — continued. Country Denominations Weight Fine- ness Value Value after De- duction Oz. Dec. lOOOths $ • Germany, North Ten thaler . 0-427 895 7-90-01 7-86 06 Germany, North Ten thaler, Prussian 0-427 903 7-97-07 7-93-OD Germany, North Krone (crown) 0-357 900 6-64-20 6-60-88 Germany, South Ducat . 0-112 986 2-28-28 227-14 Greece Twenty drachms . 0-185 900 3 44-19 3-42-47 Hindostan Mohur . 0-874 916 7-08-18 7-04-64 Italy Twenty lire . 0-207 898 3-84-26 382-34 Japrtn Old cobang . 0362 568 4-44-0 4-41-8 Japan New cobang . 0-289 572 3-57-6 3-55-8 Mexico Doubloon, average 0-867-5 866 15-52-98 15-45-22 Mexico Doubloon, new 0-867-5 870-5 15-61-05 15-53-25 Naples Six ducati, new 0-245 996 5-04-43 5-01-91 Netherlands Ten guilders . 0-215 899 3-99-56 3-97-57 New Granada . Old doubloon (Bogota) . 0-868 870 15-61-06 15-53-26 New Granada . Old doubloon (Popayan) 0-867 858 15-37-75 15-30-07 New Granada . Ten pesos, new 0-525 891-5 9-67-51 9-62-68 Peru . Old doubloon 0-867 868 15-55-67 1547-90 Peru . Twenty soles (solde • oro) . 1-035 898 19-21-8 19-12-2 Portugal . Gold crown . 0-308 912 5-80-66 5"77"76 Prussia New Union crown (assumed) .* 0-357 900 6-64-19 6-60-87 Rome 2^ scudi, new 0-140 900 2-60-47 2-59-17 Russia Five roubles . 0-210 916 3-97-64 3-95-66 Spain 100 reals 0-268 896 4-96-39 4-93-91 Spain 80 reals 0-215 869-5 3-86-44 3-84-51 Sweden Ducat . 0-111 975 2-23-72 2-22-611 Tunis 25 piastres . 0-161 900 2-99-54 2-98-05 Turkey 100 piastres . 0-231 915 4-3693 434-75 Tuscany . Sequin . 0-112 999 2-31-29 2-30-14 Explanation of Gold Table. The values per oz. of gold in the following tables are computed from the simple formula that 387 oz. of pure gold (1,000 fine) are worth $8,000. Hence 1 oz. is worth $20-671834625 and the r^-of an oz. (decimally expressed as -001 fine) is worth $0-020671834625. What we usually call fineness, therefore, is simply the PART IV. GOLD COINS IN THE U.S. OF AMERICA. 193 •weight of fine metal contained in any given quantity of mixed metals or alloys. For instance, in a gold or silver bar which is reported to be 850 fine, it is simply meant that in 1,000 parts by weight 850 are fine gold or fine silver, as the case may be. In our mints the value of gold is computed from standard weight — that is, gold which is 900 fine, that being the fineness of our gold coin as required by law. The formula in this case is, 43 oz. of standard gold are worth $800. Hence multiply standard ozs. by 800 and divide by 43, and you obtain the value. Example.— Take 123TW oz. at 843 fine, and we ob- tain the result thus : — 123*13 oz. gross weight. 843 fineness of gold. 36939 49252 98504 U.S. standard 900 ) 103J98-59 oz. of fine gold. 115331 800 43 ) 92264-800 #2145-69 value. To find value per oz., divide total value (2145-69) by standard ozs. (115-331), and you have $18-60.46, which will be seen, by reference to the table, is the value of 1 oz. of gold at 900 fine. The value in this case would have been ascertained o 194 ENGLISH AND AMERICAN VALUES OF GOLD. PART IV. thus : — By reference to the gold table and opposite '843 the value of 1 oz. -843 fine is #17-4264. Hence 123-13 174264 492-52 73878 24626 49252 86191 12313 £2145-69 value. PART IV. VALUE OF GOLD IN THE U.S. OF AMERICA. 195 Table of the Value of Gold per Ounce Troy, at Different Degrees of Fineness, in the United States of America. B £ ^H CO 1 1 £3 1 5 3 ^ 1 I I a) I s 8 E 1 <§ 0 0 00-00 10 0 20-67 20 0 41-34 30 0 62-02 40 0 82-69 i 0 01-03 0 21-71 0 42-38 0 63-05 0 83-72 i 0 02-07 II2 0 22-74 21 0 43-41 31 0 64-08 41 0 84-75 i 0 03-10 4- 0 23-77 1 0 44-44: | 0 65-12 £ 0 85-79 2 0 04-13 12 0 24-81 22 0 45-48 32 0 66-15 42 0 86-S2 1 0 05-17 i 0 25-84 i 0 46-51 i 0 67-18 A 0 87-86 32 0 06-20 13 0 26-87 23 0 47-55; 33" 0 68-22 43' 0 88-89 I 2 0 07-24 £ 0 27-91 1 0 48-581 i 0 69-25 1 0 89-92 4 0 08-27 14 0 28-94 24 0 49-61: 34 0 7028 44 0 90-96 i 0 09-30 l 0 29-97 i 0 50-65 _L 0 71-32 i 0 91-99 5 0 10-34 15 0 31-01 25 2 0 51-68 352 0 72-35 45 0 93-02 1 0 11-37 i 0 32-04 l 0 52-71 i 0 73-39 JL 0 94-06 6 0 12-40 16 0 33-07 26' 0 53-75 36 0 74-42 46 0 95-09 i 0 13-44 1 0 34-11 1 0 54-78 ± 0 75-45 l 0 96-12 7' 0 14-47 17" 0 35-14 27' 0 55-81 37 0 76-49 47 0 97-16 i i 0 15-50 1 0 36-18 l 0 56-85 i. 0 77-52 ^ 0 98-19 8 0 16-54 is' 0 37-21 28 0 57-88 38 0 78-55 48 0 99-22 £ 0 17-57 | 0 38-24 | 0 58-91 i 0 79-59 i 1 00-26 9 0 18-60 19 0 39-28 29 0 59-95 39' 0 80-62 49 1 01-29 * 0 19-64 2 0 40-31 * 0 60-98 * 0 81-65 *] 1 02 '33 | 1 -s H 8 £ 1 1 Q ° 1 E 2 CO •5 "S 1 0 1 1 I 5 d o> e S I 1 50 1 03-36 60 1 24-03 70 1 44-70 80 1 65-37 90 1 86-05 i 1 04-39 i 1 25-06 i 1 45-74 J 1 66-41 ^ 1 87-08 51 1 05-43 61 1 26-10 71 1 46-77 81 1 67-44 91 1 88-11 i 1 06-46 i 1 27-13 i 1 47-80 1 1 68-48 1 1 89-15 52' 1 07-49 62' 1 28-17 72' 1 48-84 82' 1 69-51 92 1 90-18 i 1 08-53 i. 1 29-20 i 1 49-87 i 1 70-54 i 1 91-21 53' 1 09-56 ;63 1 30-23 73 1 50-90 83 2 1 71-58 93 1 92-25 1 1 10-59 ^ 1 31-27 i 1 51-94, l 1 72-61 i 1 93-28 54' 1 11-63 64 1 32-30 74 1 52-97 84' 1 73-64 94 1 94-32 i 1 12-66 i 1 33-33 i 54-01 i 1 74-68 i 1 95-35 55 1 13-70 65 1 34-37 75 55-04 85' 1 75-71 95' 1 96-38 l 1 14-73 i 1 35-40 i 56-07 i 1 76-74 i 1 97-42 562 1 15-76 66 1 36-43 76 57-11 i 862 1 77-78 96' 1 98-45 1 1 16-80 i 1 37-47 1 58-14) i 1 78-81 | 1 99-48 57 1 17-83 67 1 38-50 77 59-171 87 1 79-84 97 2 00-52 £ 1 18-86 i 1 39-53 i 60-21 i 1 80-88 ^ 2 01-55 68 1 19-90 68 1 40-57 ! 78 61-24 88" 1 81-91 98 2 02-58 i 1 20-93 ± 1 41-60 l 62-27 i 1 82-95 £ 2 03-62 59 1 21-96 69 1 42-641 79 1 63-31 89' 1 83-98 99' 2 04-65 * 1 23-00 * 1 43-67 | 2 1 64-34 * 1 85-01 2 2 05-68 o 2 196 ENGLISH AND AMERICAN VALUES OF GOLD, PART IV. Table of the Value of Gold — continued. 0) | 42 ' p 2 2 i " o 2 w o 1 a 1 1 a s 1 <3 £ 1 £ 1 B E 1 i 100 2 06-72 110 2 27-39 120 2 48-06 130 2 68-73 140 2 89-41 \ 2 07-75 £ 2 28-42 I 2 49-10 j i 2 69-77 1 2 90-44 101 2 08-79 111 2 29-46 121 2 50-13 131" 2 70-80 141 2 91-47 ft 2 09-82 £ 2 30 49 l 2 51-16 | ft 2 71-83 JT 2 92-51 102 2 10-85 112 2 31-52 122 2 52-20 132 2 72-87 142 j 2 93-54 ft 2 11-89 1 2 32-56 l 2 53-23 ft 2 73-90 ft! 2 94-57 103" 2 12-92 113' 2 33-59 123' 2 54-26 133" 2 74-94 143" 2 95-61 i 2 13-95 i 2 34-63 ft 2 55-30; £ 2 75-97 ft 2 96-64 104 2 14-99 114 2 35-66 124 2 56-33 j 134 2 77-00 144" 2 97-67 ft 2 16-02 ft 2 36-69 £ 2 57-36 ft 2 78-04 i 2 98-71 105 2 17-05 115 2 37-73 125" 2 58-40 | 135" 2 79-07 145" 2 99-74 i 2 18-09 1 2 38-76 l 2 59-43 ^ 2 80-10 ft 3 00-78 106 2 19-12 116 2 39-79 126' 2 60-46 136'" 2 81-14 146" 3 01-81 i 2 20-16 l 2 40-83 £ 2 61-50' .j. 2 82-17 i 3 02-84 L07' 2 21-19 117 2 41-86 127 2 62-53 137' 2 83-20 147' 3 03-88 ft 2 22-22 ^ 2 42-89 l 2 63-57 ' i 2 84-24 1 3 04-91 108" 2 23-26 118 2 43-93 128 2 64-60 138" 2 85-27 148" 3 05-94 i 2 24-29 2 44-96 ft 2 65-63 £ 2 86-30 Jf 3 06-98 109 2 25-32 119' 2 45-99 129 2 66-67 139 2 87-34 149 3 08-01 * 2 26-36 ft 2 47-03 ft 2 67-70 ft 2 88-37 ft 3 09-04 q 1 3 q 1 3 2 1 5 a 1 | • 2 . s ? s Q ° s S 1 o & 1 * £ 1 <3 K 1 i 150 3 10-08 160 3 30-75 170 3 51-42 180 3 72-09 190 3 92-76 i 3 11-11 i 3 31-78 \ 3 52-45 \ 3 73-13 ft! 3 93-80 151 3 12-14 161 3 32 82 171 3 53-49 181 3 74-16 191 3 94-83 ft 3 13-18 ' i 3 33-85 i 3 54-52 ft 3 75-19 i 3 95-87 152" 3 14-21 162 3 34-88 172 3 55-56 182 3 76-23 192 3 96-90 i 3 15-25 i 3 35-92 \ 3 56-59 ft 3 77-26 k 3 97-93 153 3 16-28 163 3 36-95 173 3 57-62 183" 3 78-29 193 3 98-97 i 3 17-31 ft 3 37-98 ft 3 58-66 i 3 79-33 \. 4 00-00 154 3 18-35 164 3 39-02 174 3 59-69 184 3 80-36 194 4 01-03 i 3 19-38 ft 3 40-05 i 3 60-72 k 3 81-40 \ 4 02-07 155 3 20-41 165 3 41-09 175 3 61-76 185 3 82-43 195 4 03-10 ft 3 21-45 ^ 3 42-12 ft 3 62-79 * 3 83-46 k 4 04-13 156 3 22-48 166"! 3 43-15 176 3 63-82 186 3 84-50 196 4 05-17 i 3 23-51 ft{3 44-19 i 3 64-86 ft 3 85-53 % 4 06-20 157 3 24-55 167"! 3 45-22 177" 3 65-89 187 3 86-56 197 4 07-24 i 3 25-58 ftj 3 46-25 | 3 66-93 1 \ 3 87-60 i 4 08-27 158 3 26-61 168" 3 47-29 178" 3 67-96 188 3 88-63 198": 4 09-30 i 3 27-65 i 3 48-32 | 3 68-99 ! * 3 89-66 £ 4 10-34 159 3 28-68 169" 3 49-35 179 3 70-03 189" 3 90-70 199 4 11-37 i 3 29-72 £J3 50-39 i 3 7106 i i 3 91-73J! i:4 12-40 PART IV. VALUE OF GOLD IN THE U.S. OF AMERICA. 197 Table of the Value of Gold — continued. __ 1 1 0> & S 1 s | I 1 1 1 1 1 1 i 200 4 13-44 210 4 34-11 !220 4 54-78 230 4 75-45 240 4 96-12 £ 4 14-47 ! 4 35-14 i £ 4 55-81 i 4 76-49 i 4 97-16 201 4 15-50 211" 4 36-18 221 4 56-85 231 4 77-52 241 4 98-19 i 4 16-54 ^ 4 37-21 I! ^ 4 57-88 i 4 78-55 i 4 99-22 202 4 17-57 212 :4 38-24 222 4 58-91 232" 4 79-59 242 5 00-26 i 4 18-60 i 4 39-28 ! i 4 59-95 & 4 80-62 i 5 01-29 203 4 19-64 213" 4 40-31 ; 223 . 4 60-98 :233" 4 81-65 f 243' 5 02-33 i 4 20-67 £ 4 41-34 4 62-02 j| | 4 82-69 i 5 03-36 204" 4 21-71 214" 4 42-38 224" 4 63-05 234 4 83-72 244' 5 04-39 i 4 22-74 i 4 43-41 J 1 4 64-08 £; 4 84-75 I 5 05-43 205 4 23-77 215 4 44-44 225 4 65-12 235 4 85-79 245 5 06-46 i 4 24-81 1 4 45-48 i 4 66-15 i 4 86-82 i 5 07-49 206 4 25-84 216 4 46-51 226" |4 67-18 236" 4 87-86 246 5 08-53 ^. 4 26-87 £ 4 47-55 I | 4 68-22 ^ 4 88-89 * 5 09-56 207" 4 27.-91 217 4 48-58 227" i 4 69-25 '237 4 89-92 247 5 10-59 £ 4 28-94 ^ 4 49-61 i| \ 4 70-28 | £ 4 90'96 i 5 11-63 208 4 29-97 218 4 50-65 228 4 71-32 238 4 91-99 248 5 12-66 i 4 31-01 i 4 51-68 4 - 4 72-35 £ 4 93-02 1 5 13-70 209 4 32-04 219 4 52-71 229 4 73-39 239 4 94-06 249 5 14-37 2 4 33-07 £ 4 53-75 i 4 74-42 2 4 95-09 * 5 15-76 <a £ i 3 1 <B 1 1 1 § 5 3J 5 1 1 S ^ | 2 S 1 * I 3 a S 1 i 250 5 16-80 260 5 37-47 ; 270 5 58-14 280 5 78-81 290 5 99-48 i 5 17-83 ! £ 5 38-50 ^ 5 59-17 ± 5 79-84 i 6 00-52 251 5 18-86 261 5 39-53 271 5 60-21 281 5 80-88 1291 6 01-55 i 5 19-90 i 5 40-57 , i 5 61-24 $ 5 81 '91 * 6 02-58 252" 5 20-93 262 5 41-60 272 5 62-27 282 5 82-95 292 6 03-62 I 5 21-96 | 5 42-64 * 5 63-31 |! 5 83-98 * 6 04-65 253 5 23-00 263 5 43-67 !273~ 5 64-34 283 5 85-01 293 6 05-68 i 5 24-03 i 5 44-70 £ 5 65-37 i 5 86-05 •i 6 06-72 254 5 25-06 264 5 45-74 274 5 66-41 284 5 87-08 294 6 07-75 I 5 26-10 il 5 46-77 !l ^ 5 67-44 £!5 88-11 * 6 0879 255 5 27-13 265" 5 47-80 275 5 68-48 285 5 89-15 295 6 09-82 i 5 28-17 i 5 48-84 i 5 69-51 1 5 90-18 i 6 10-85 256 5 29-20 266 5 49-87 276 5 70-54 286 5 91-21 296 6 11-89 i 5 30-23 i 5 50-90 i 5 71-58 i 5 92-25 i 6 12-92 257 5 31-27 267 5 51-94 277 5 72-61 287 5 93-28 297" 6 13-95 1 5 32-30 |! 5 52-97 * 5 73-64 £l 5 94-32 fj 6 14-99 258" 5 33*33 1268 5 54-01 278 5 74-68 288 5 95-35 298" 6 16-02 * 5 34-37 £ 5 55-04 i 5 75-71 £ 5 96-38 i 6 17-05 259 5 35-40 269 5 56-07 1279 5 76-74 289 i 5 97-42 ! 299" 6 18-09 i 5 36-43 i 5 57-11 j * 5 77-78 £ 5 98-45 i 6 19 12 198 ENGLISH AND AMERICAN VALUES OF GOLD. PART IV. Table of the Value of Goli — continued. 0> P a 2 I | <a 1 5 a> 1 3 2 3 ti g 1 3 S o ^ 1 ft S I 1 <§ & 1 <s 300 6 20-16 310 6 40-83 320 6 61-50 330 6 82-17 340 7 02-84 4 6 21-19 * 6 41-86 * 6 62-53 * 6 83-20 * 7 03-88 301 6 22-22 •311 6 42-89 321 6 63-57 331 6 84-24 341 7 04-91 1 6 23-26 * 6 43- y 3 k 6 64-60 * 6 85-27 2 7 05-94 302 6 24-29 312 6 44-96 322 6 65-63 332 6 86-30 342 7 06-98 i 6 25-32 i 6 45-99 1 6 66-67 ^ 6 87-34 ± 7 08-01 303" 6 26-36 313" 6 47-03 323^ 6 67-70 3331 6 88-37 343" 7 09-04 i 6 27-39 * 6 48-06 .J. 6 68-73 £ 6 8941 i 7 10-08 304 6 28-42 314 6 49-10 324" 6 69-77 334 6 90-44 344" 7 11-11 i 6 29-46 1 6 50-13 1 6 70-80 * 6 91-47 1 i 7 12-14 305 6 30-49 315" 6 51-16 325" 6 71-83 335 6 92-51 345" 7 13-18 * 6 31-52 } 6 52-20 } 6 72-87 A! 6 93-54 f 7 14-21 306 6 32-56 316 6 53-23 326 6 73-90 336" 6 94-57 346 7 15-25 * 6 33-59 £| 6 54-26 k 6 74-94 £ 6 95-61 £ 7 16-28 307 6 34-63 317 6 55-30 327 6 75-97 337 6 96 64 347 7 17-31 * 6 35-66 * 6 56-33 ^ 6 77-00 1 6 97-67 f 7 18-35 308 6 36-69 318" 6 57-36 328" 6 78-04 338L 6 98-71 348 I 7 19-38 * 6 37-73 1 6 58-40 * 6 79-07 | 6 99-74 f 7 20-41 309 6 38-76 319' 6 59-43 329 6 80-10 339' 7 00-78 349 7 21-45 * 6 39-79 * 6 60-47 * 6 81-14 ' * 7 01-81 £ 7 22-48 2 1 1 j 1 5 I 1 3 2 S a 2 1 5 E S o 1 1 3 £ 1 3 K a « £ 1 1 350 7 23-51 360 7 44-19 370 7 64-86 380 7 85-53 390 8 OiV20 i 7 24-55 * 7 45-22 * 7 65-89 I 7 86-56 | 8 07-24 351 7 25-58 361 7 46-25 371 7 66-93 381 7 87-60 391" 8 08-27 * 7 26-61 * 7 47-29 $ 7 67-96 i 7 88-63 * 8 09-30 352 7 27-65 362" 7 48-32 372 7 68-99 382 7 89-66 392" 8 10-34 * 7 28-68 i 7 49-35 i 7 70-03 i 7 90-70 * 8 11-37 353 7 29-72 363" 7 50-39 373 7 71-06 383 7 91-73 393 8 12-40 * 7 30-75 $ 7 51-42 | 7 72-09 | 7 92-76 A 8 13-44 354 7 31-78 364" 7 52-45 374 7 73-13 384 7 93-80 894 8 14-47 * 7 32-82 i 7 53-49 | 7 74-16 i 7 94-83 $ 8 15-50 355 7 33-85 365 7 54-52 375 7 75-19 385 7 95-87 395 8 16-54 } 7 34-88 $ 7 55-56 A 7 76-23 | 7 96-90 | 8 17-57 356 7 35-92 366 7 56-59 376 7 77-26 386 7 97-93 396 8 18-60 * 7 36-95 } 7 57-62 4 7 78-29 * 7 98-97 i 8 19-64 357 7 37-98 367 7 58-66 377 7 79-32 387 8 00-00 397" 8 20-67 * 7 39-02 1 7 59-69 | 7 80-36 £ 8 01-03 | 8 21-71 358 7 40-05 368' 7 60-72 ^78" 7 81-39 388 8 02-07 398" j 8 22-74 * 7 41-09 $ 7 61-76 | 7 82-43 $ 8 03-10 i' 8 23-77 359 7 42-12 369 7 62-79 379* 7 83-46 389 8 04-13 399 | 8 24-81 i 7 43-15 * 7 63-82 * 7 84-50 1 8 05-17 : | 8 25-84 PART IV. VALUE OF GOLD IN THE U.S. OF AMEKICA. 199 Table of the Value of Gold — continued. 1 s 1 1 1 ^ 1 «3 c3 +-> 2 i I 1 2 £ 2 5 1 1 o £ 1 2 1 & 400 8 26-87 410 8 47-55 '420 8 68-22 430 8 88-89 440 9 09-56 £ 8 27-91 £ 8 48-58 £ 8 69-25 * 8 89-92 * 9 10-59 401 8 28-94 411 8 49-61 421 8 70-28 431 8 90-96 441 9 11-63 ^ 8 29-97 i 8 50-65 | £ 8 71-32 \ 8 91-99 i 9 12-66 402" 8 31-01 412 8 51-68 422 8 72-35 432 8 93-02 442 9 13-70 * 8 32-04 * 8 52-71 i 8 73-39 £ 8 94-06 \ 9 14-73 403 8 33-07 413 8 53-75 423 8 74-42 433 8 95-09 443 9 15-76 * 8 34-11 £ 8 54-78 i 8 75-45 £ 8 96-12 k 9 16-80 404 8 35-14 414 8 55-81 424 8 76-49 434 8 97-16 444 9 1783 * 8 36-18 £ 8 56-85 | £ 8 77-52 i 8 98-19 * 9 18-86 405 8 37-21 415 8 57-88 425 8 78-55 435 8 99-22 445 9 19-90 £ 8 38-24 £ 8 58-91 i 8 79-59 £ 9 00-26 i 9 20-93 406" 8 39-28 416 8 59-95 426 8 80-62 436 9 01-29 446 9 21-96 * 8 40-31 £ 8 60-98 £ 8 81-65 £ 9 02-33 £ 9 23-00 407 8 41-34 417 8 62-02 427 8 82-69 437 9 03-36 447 9 24-03 | 8 42-38 £ 8 63-05 £ 8 83-72 \ 9 04-39 i 9 25-06 408 8 43-41 418 8 64-08 428" 8 84-75 438 9 05-43 448 9 26-10 * 8 44-44 i 8 65-12 £ 8 85-79 £ 9 06-46 i 9 27-13 409 8 45-48 419 8 66-15 429" 8 86-82 439 9 07-49 449 9 28-17 i 8 46-51 \ 8 67-18 £ 8 87-86 } 9 08-53 \ 9 29-20 8 s 1 1 1 * 2 £ 1 1 1 * 2 1 | | 1 S <D 1 1 1 1 " 1 1 450 9 30-23 460 9 50-90 470 9 71-58 480 9 92-25 490 10 12-92 i 9 3127 i 9 51-94 * 9 72-61 * 9 93-28 \ 10 13-95 451 9 32-30 461 9 52-97 471 9 73 64 481 9 94-32 491 10 14-99 £ 9 33-33 ^ 9 54-01 ^ 9 74-68 ^ 9 95-35 £ 10 16-02 452 9 34-37 462 I) 55-04 472 9 75-71 482 9 96-38 492 10 17-05 £ 9 35-40 i 9 56-07 i 9 76-74 * 9 97-42 i 10 18-09 453 9 36-43 463 9 57-11 473 9 77-78 483 9 98-45 493 10 19-12 £ 9 37-47 | 9 58-14 i 9 78-81 \ 9 99-48 £ 10 20-16 454 9 38-50 464 9 59-17 474 9 79-84 484 |10 00-52 494 10 21-19 ^ 9 39-53 k 9 60-21 ^ 9 80-88 £10 01-55 £ 10 22-22 455 9 40-57 465 9 61-24 475 9 81-91 485 10 02-58 495" 10 23-26 * 9 41-60 i 9 62-27 \ 9 82-95 i!lO 03-62 £ 10 24-29 456 9 42-64 466 9 63-31 476 9 83-98 486 10 04-65 496 10 25-32 i 9 43-67 i 9 64-34 \ 9 85-01 ilO 05-68 £ 10 26-36 457 9 44-70 467 9 65-37 477 9 86-05 487 !10 06-72 ,497 10 27-39 i 9 45-74 | 9 66-41 ^ 9 87-08 £10 07-75J £ 10 28-42 458 | 9 46-77 468 9 67-44 478 9 88-11 488 ilO 08-79 498 10 29-46 A! 9 47-80 i 9 68-48 ^- 9 89-15 £10 09-82= £ 10 30-49 459 9 48-84 469 9 69-51 479 9 90-18 489 10 10-85 499 10 31-52 i -2 9 49-87 * 9 70-54 * 9 91-21 £10 11-89 £,10 32-56 200 ENGLISH AND AMERICAN VALUES OF GOLD. PART IV. Table of the Value of Gold— continued. I 1 1 ^ o P 1 £ 2J * I S 1 1 | 1 1 1 E 1 % 1 <§. 500 10 33-59! 510 10 54-26 520 10 74-94 530 10 95-61 540 11 16-28 £10 34-631 £ 10 55-30 £ 10 75-97 £10 96-64 £ 11 17-31 501 10 35-66 1511 10 56-33 521 10 77-00 531 10 97-67 541 11 18-35 £110 36-69 £ 10 57-36 ± 10 78-04 ±10 98-71 £ 11 19-38 502 10 37-73 512 10 58-40 522 10 79-07 532 |10 99-74 542 11 20-41 ±10 38-76 i 10 59-43 £ 10 80-10 ±11 00-78 £ 11 21-45 503" 10 39-79 513 10 60-47 523 10 81-14 533 [11 01-81 543 11 22-48 ±10 4083 £ 10 61-50 £ 10 82-17 £11 02-84 i 11 23-51 504 |10 41-86 514 10 62-53 524 10 83-20 534 11 03-88 544" 11 24-55 ± 10 42-89 ± 10 63-57 £ 10 84-24 £11 04-91 £ 11 25-58 505 10 43-93 515 10 64-60 525 10 85-27, 636 11 05-94 545 11 26-61 £10 44-96 £ 10 65-63 £ 10 86-30 £lll 06-98 £ 11 27-65 506"! 10 45-99 516 10 66-67 526 10 87-34i 536 11 08-01 546 11 28-68 £ 10 47-03 ± 10 67-70 £ 10 88-37 £11 09-04 £ 11 29-72 507 10 48-06 517" 10 68-73 527 10 89-41 537 11 10-08 547 11 30-75 £110 49-10 £ 10 69-77 £ 10 90-44 £jll 11-11 £ 11 31-78 508 10 50-13 518 10 70-80 528 10 91-471 538 11 12-14 548 11 32-82 £10 51-16 £ 10 71-83 ± 10 92-51 £ 11 13-18 i 11 33-85 509 10 52-20 519 10 72-87 529" 10 93-54 539 11 14-21 549'" 11 34-88 * 10 53-23 ±10 73-90 * 10 94-57 * 11 15-25 * 11 35-92 a 1 | S 1 1 § 1 1 i I 45 j i 5 £ I ! £ 2 1 S 1 § n o £ 1 J E 1 1 550 11 36-95 560 11 57-62 570 11 7S29 580 11 98-97 5<)0 12 19-64 £ 11 37-98 £ 11 58-66 £ 11 79^ £ 12 00-00 £ 12 20-67 551 11 39-02 561 11 59-69 571 11 80 d^ 581" 12 01-03 591 12 21-71 £11 40-05 £ 11 60-72 £ 11 81'4°J £ 12 02-07: £ 12 22-74 552 ill 41-09 562 11 61-76 572 11 82-43,582 12 03-10 592 12 23-77 £11 42-12 £ 11 62-79 £ 11 83-46 ± 12 04-13' £ 12 24-81 553 11 43-15 563 11 63-82 573 11 84-50 '583 12 05-17 593" 12 25-84 £ 11 44-19 £ 11 64-86 £ 11 85-53i £ 12 06-20 £ 12 26-87 554 11 45-22 564 11 65-89 574 11 86-56 584 12 07-24 594 12 27-91 £11 46-25 £ 11 66-93 _£ 11 87-60; £ 12 08-27 £ 12 28-94 555 11 47-2^1 565 ill 67-96 575 11 88-63 585 12 09-30 595 12 29-97 £ 11 48-32 £11 68-99 £ 11 89-06 I 12 10-34 i 12 31-01 556 11 49-35 566 11 70-03 576 11 90-70:586" 12 11-37 596 12 32-04 £ 11 50-39 £ 11 71-06 _£ 11 91-73 i 12 12-40 £ 12 33-07 557 11 51-42 567 |11 72-09 577 11 92-76 587" 12 13-44 597 12 34-11 £ 11 52-45 £11 73-13 £ 11 93-80 i 12 14-47 £ 12 35-14 558 ill 53-49 568 11 74-16 578 11 94-83! 588" 12 15-50 598 12 36-18 £11 54-52 £ 11 75-19 £ 11 95-87 £ 12 16-54 £ 12 37-21 559 11 55-56 569 11 76-23 579 11 96-90 589 12 17-57 599 12 38-24 £ 11 56-59 £11 77-26 i 11 97-93 i 12 18-60 t 12 39-28^ PART IV. VALUE OF GOLD IN THE U,S, OF AMERICA. 201 Table of the Value of Gold— continued. 8 £ 1 A =3 § ft o 9i .5 K 1 S =3 3 ft 0 2 c3 -2 s 1 | <u 1 ! o " | £ I 4 1 3 600 12 40'31 610 12 60*98 620 12 81'65 630 13 02'33 640 13 23-00 i 12 41'34 * 12 62-02 £12 82-69 * 13 03-36 * 13 24-03 601 12 42-38 611 12 63-05 621 12 83-72 631 13 04-39 641 13 25-06 £ 12 43-41 £12 64-08 £12 84-75 * 13 05-43 * 13 26-10 602" 12 44-44 612 12 65-12:622 12 85'79 632 13 06-46 642 13 27-13 i 12 45-48 4rl2 66*16 £12 86-82 £ 13 07-49 £ 13 28 17 603 12 46-51 613~J12 67'18 623 12 87-86 633 13 08-53 643 13 29-20 * 12 47-55 £12 68-22) £12 88-89 * 13 09-56 * 13 30-23 604 12 48-58 614 12 69-25 624 12 89'92 634 13 10-59 644 13 31-27 * 12 49-61 £ 12 70-28 £12 90-96 £ 13 11-63 £ 13 32-30 605 12 50-65 615 12 71-32 625 12 91-99 635" 13 12-66 645 13 33-33 i 12 51-68 } 12 72-35 £12 93-02 £ 13 13-70 i 13 34-37 606 12 52-71 616 12 73-39 626 12 94-06 636 13 14-73 646 13 35-40 * 12 53-75 £ 12 74-42 £12 95-09 £ 13 15-76 * 13 36-43 607 12 54-78 617 12 75-45 627 12 96-12 637 13 16-80 647 13 37'47 i 12 65-81! £ 12 76-49 £12 97-16 £ 13 17-8311 £ 13 38-50 608" 12 56-85 618 12 77-52 628" 12 98-19 638" 13 18-86 648 13 39-53 * 12 57-88' * 12 78-55 £12 99-22 £13 19-90 £ 13 40-57 609 |12 58-91 619 ,12 79-59 629 13 00-26 639 13 20-93 649 13 41-60 1 12 59-95 £12 80-62 £13 01-29 £13 21-96!l £ 13 42-64 g i 1 1 a o 1 1 A 1 1 1 I 1 ft ^ I J.8 i ft « 0> 1 .2 ^j S p CJ> 650 13 43-67 660 13 64-33 670 13 85-01 680 14 05-68 690 14 26-86 £13 44-70 £13 65-37 £|13 86-05 i 2 14 06-72 £ 14 27-39 651 13 45-74 661 i!3 66-41 671 13 87-08 681 14 07-75 691 14 28-42 £13 46-77 £13 67-44 £ll3 88-11 £ 14 08-79 £ 14 29-46 652 13 47-80 662 |13 68'48 672 13 89-15 682 14 09-82 692 14 30-49 £13 48-84 £13 69-51 £ 13 90-18 * 14 10-85|| £ 14 31-52 653 :13 49-871 663" 13 70'54 673 13 91-21 683 14 11-89 693 14 32-56 £13 50-90| £13 71-58 £13 92-25 £ 14 12-92 \ 14 33-59 654 13 51-94 664 13 72«61 674 113 93-28 684 14 13-95 694 14 34-63 £13 52-97 £13 73-64 £13 94-3'2 £ 14 14-99 1 14 35-66 655 13 54-01 665~|13 74'68 675 13 95'35 685 14 16-02 695 14 36-69 £|13 55-04 £,13 75-71 £ 13 96-38 £ 14 17-05 £ 14 37-73 656" |13 56-07 666 |l3 76-74 676 13 97'42 686 14 18-09 696 14 38-76 £13 57-11 £ 13 77-78 * 13 98-45 % 14 19-12 i 14 39-79 657" 13 58-14 667 13 78-81 677 13 99'48 687 14 20-16 697 14 40-83 £ .13 59-17 £13 79-84 £ 14 00-52 £ 14 21-19 £ 14 41-86 658 13 60-21 668" 13 80-88 678" 14 01-55 688 14 22-22 698 14 42-89 * 13 61-24 * 13 81-91 * 14 02-58 £ 14 23-26 \ 14 43-93 659 13 62-27 669 13 82-95 679 14 03-62 689 14 24-29 699 14 44-96 * 13 63-31 £ 13 83-98 i 14 04-65 £ 14* 25-32 \ 14 45-99 202 ENGLISH AND AMERICAN VALUES OF GOLD. PABT IV, Table of the Value of Gold— continued. I 1 1 § 3 § £ 1 * "o § Q O 1 I 3 1 * § £ I i a S 1 1 1 3 700 14 47-03 710 14 67-70 720 14 88-37 730 15 09-04 740 15 29-72 * 14 48-06 * 14 68-73 1 i 14 89-41 * 15 10-08 tH5 30-75 701 14 49-10 711 14 69-76 721 14 90-44 731 15 11-11 741" 15 31-78 * 14 50-13 * 14 70-80 * 14 91-47 i 15 12-14 i 15 32-82 702 14 51-16 712 14 71-83 722 14 92-51 732 15 13-18 742 115 33-85 i 14 52-20 * 14 72-87 i £ 14 93-54 1 15 14-21 i 15 34-88 703 14 53-23 713 14 73-90 723 14 94-57 733 15 15-25 743 15 35-92 i 14 54-26 114 74-94 ? 14 95-61 i 15 16-28 i 15 36-95 704 14 55-30 714 14 75-97 724 14 96-64 734 15 17-31 744 15 37-98 * 14 56-33 * 14 77-00 \ 14 97-67 i 15 18-35 i 15 39-02 705 14 57-36 715 14 78-04 '725 14 98-71 735 15 19-38 745 15 40-05 \ 14 58-40 i 14 7907 \ 14 99-74 £ 15 20-41 i 15 41-09 706 14 59-43 716 14 80-10 ,726 15 00-78 736 15 21-45 746 15 42-12 * 14 60-47 * 14 81-14 \ 15 01-81 115 22-48 i 15 43-15 707 14 61-50 717 14 82-17 727 15 02-84 737 16 23-51 747 15 44-18 * 14 62-53 * 14 83-20 "2 15 03-88 1 15 24-55 -j 15 45-22 708 14 63-57 718 114 84-24 '728 15 04-91 738 15 25-58 748 15 46-25 \ 14 64-60 £14 85-27 1 15 05-94 i 15 26-61 -* 15 47-29 709 14 65-63 719 !l4 86-30 729 15 06-98 739 15 27-65 749 15 48-32 \ 14 66-67 £14 87-84 1 115 08-01 115 28-68 115 49-35 1 2 w 1 I § £ Dollars Cents 1 1 ! Q 1 1 i 8 R a o 750 15 50-39 760 15 71-06 770 15 91-73 780 16 12-40 790 16 33-07 i 15 51-42 i 15 72-09 1 15 92-76 i 16 13-44 £ 16 34-11 751 15 52-45 761 15 73-13 771 15 93-80 781 16 14-47 791 |16 35-14 £ 15 53-49 | 15 74-16 £ 15 94-83 i 16 15-50 116 36-18 752 15 54-52 762 15 75-19 772 15 95-87 782" 16 16-54 792"|16 37-21 i 15 55-56 i 15 76-23 l 15 96-90 i 16 17-57 116 38-24 753' 15 56-59 763" 15 77-26 773 15 97-93 783' 16 18-60 793" 16 39-28 i 15 57-62 * 15 78-29 115 98-97 i 16 19-64 £16 40-31 754 15 58-66 764 15 79-33 774 |16 OO-Ooi'784 16 20-67 794 16 41-34 i 15 59-69 i;i5 80-36 £16 01-03 £ 16 21-71 116 42-38 755' 15 60-72 765 15 81-40 775 16 02-07! 785 16 22-74 795 J16 43-41 £ 15 61-76 £ 15 82-43 116 03-10|! i 16 23-77 i!16 44-44 756 15 62-79 766 15 83-46 776 il6 04-131,786 16 24-81 796 16 45-48 i 15 63-82 i 15 84-50 116 05-17 £ 16 25-84 * 16 46-51 757 15 64-86 767 15 85-53 777 16 06-20;:787 16 26-87 797 16 47-55 i 15 65-89 £ 15 86-56 1 16 07-24 i 16 27-91 £ 16 48-58 758 15 66-93 768 15 87-60 778 16 08-27 788' 16 28-94 798' 16 49-61 i 15 67-96 i 15 88-63 116 09-30 i. 16 29-97 i 16 50-65 759 15 68-99 769" 15 89-66 779 16 10-34 789" 16 31-01 799" 16 51-68 * 15 70-03 * 15 90-70 116 11-37 2 16 32-04 * 16 52-71 PAKT IV. VALUE OF GOLD IN THE U.S. OF AMERICA. 203 Table oftlie Value of Gold — continued. . I 2 03 1 EG o c3 ^ ' C> ci OT © Q) cfl -JS S o5 co £ 1 1 £ 1 1 1 1 3 (2 £ 1 1 a £ 1 i 800 16 53-75 810 16 £4-42 !820 16 95-09 830 17 15-70 840 17 36-43 i 16 54-78 16 75-45 £ 16 96-12 £ 17 16-80 £17 37-47 801 16 55-81 8112 16 76-49 821 16 97-16 831 17 17-83 841 17 38-50 i 16 56-85 £ 16 77-52 £ 16 98-19 £ 17 18-86 £17 39-53 802 16 57-88 812 16 78-55 822 16 99-22 832 17 19-90 842 !17 40-57 i 16 58-91 £ 16 79-59 i 17 00-26 £ 17 20-93 £17 41-60 803 16 59-95 813 16 80-62 823 17 01-29 833 17 21-96 843 17 42-64 i 16 60-98 £ 16 81-65 £ 17 02-33 £ 17 23-00 J|17 43-67 804 16 62-02 814 16 82-69 824 17 03-36 834 17 24-03 844 17 44-70 £ 16 63-05 £ 16 83-72 ^ 17 04-39 £ 17 25-06 £ 17 45-74 805 16 64-08 815 16 84-75 1825 17 05-43 835 17 26-10 845 17 46-77 i 16 65-12 i 16 85-79 \ 17 06-46 I 17 27-13 £ 17 47-80 806 16 66-15 816 16 86-82 '826 17 07-49 836 17 28-17 846 17 48-84 £ 16 67-18 i 16 87-86 i 17 08-53 i L7 29-20 i!l7 49-87 807 16 68-22 817 16 88-89 827 17 09-56 837 17 30-23 847 17 50-90 i 16 69-25 £ 16 89-92 £ 17 10-59 £ 17 31-27 £17 51-94 808 16 70-28 818 16 90-96 828 17 11-63 838 17 32-30 848 17 52-97 £ 16 71-32 £ 16 91-99 £ 17 12-66 £ 17 33-33 £17 54-01 809 16 72-35 819 16 93-02 829 17 13-70 839 17 34-37 849 17 55-04 * 16 73-39 * 16 94-06 £ 17 14-73 * 17 35-40 * 17 56-07 2 1 -S £ 05 <£> CO tri *£ 1 -e £ £ » £ Q 1 1 ^ £ 1 <§ c £ £ . g p ° a 1 1 850 17 57-11 860 17 77-78 870 17 98-45 880 18 19-12 890 18 39-79 £ 17 58-14 * 17 78-81 i 17 99-48 1 18 20-16 i 18 40-83 851 17 59-17 861 17 79-84 871 18 00-52 881 18 21-19 891 18 41-86 1 17 60-21 \ 17 80-88 ] i 18 01-55 £ 18 22-22 i 18 42-89 852 17 61-24 862 17 81-91 872 18 02-58 882 18 23-26 892' 18 43-93 4 17 62-27 J 17 82-95 i 18 03-62 i 18 24-29 i 18 44-96 853" 17 63-31 863 17 83-98 873 18 04-65 883 18 25-32 8932 18 45-99| 1 17 64-34 i 17 85-01 £ 18 05-68 -i 18 26-36 £ 18 47-03 854 17 65-37 864' 17 86-05 874 18 06-72 884 18 27-39 894 18 48-06 -| 17 66-41 i 17 87-07 i 18 07-75 i 18 28-42 i 18 49-10 855 17 67-44 865 17 88-11 875 18 08-79 885 18 29-46 895 18 50-13 i 17 68-48 £ 17 89-15 * 18 09-82 £ 18 30-49 £18 51-16 856 17 69-51 866 17 90-18 876 18 10-85 886 18 31-52 896 18 52-20 i 17 70-54 i 17 91-21 i 1 Q 18 11-89 i 18 32-56 i 18 53-23 857 17 71-58 867 17 92-25 877^ 18 12-92 887' 18 33-59 8972 18 54-26 i 17 72-61 ^ 17 93-28 18 13-95 i 18 34-63 i 18 55-30 858 17 73-64 868 17 94-32 8782 18 14-99 888 18 35-66 898' 18 56-33 3 17 74-68 i 17 95-35 i 18 16-02 i 18 36-69 i 18 57-36 859" 17 75-71 869 17 96-38 879 18 17-05 889' 18 37-73 899 18 58-40 « 17 76-74 A 17 97-42 18 18-09 £ 18 38-76 18 59-43 204 ENGLISH AND AMERICAN VALUES OF GOLD PART IV. Table of the Value of Gold— continued. § s ! I 1 1 1 3 « 1 S 1 1 a | 1 1 * m P o 900 18 60-46 010 18 81-14 920 19 01-81 980 19 22-48 940 19 43 15 i 18 61-50 £ 18 82-17 £ 19 02-84 4 19 23-51 419 44-19 901 2 18 62-53 911 18 83-20 921 19 03-88 931" 19 24-55 941" 19 45-22 £ 18 63-57 £ 18 84-24 £ 19 04-91 i 4 19 25-58 419 46-25 902 18 64-60 912 18 85-27 922 19 05-94 982 19 26-61 942" j!9 47-29 £ 18 65-63 £ 18 86-30 4 19 06-98 £ 19 27-65 £19 48-32 903 18 6667 9L3 18 87*84 J988" 19 08-01 933 19 28-68 943* 19 49-35 £ 18 67-70 £ 18 88-37 4 L9 0904 419 29-72 4 19 50-39 904 18 68-73 914 18 89-41 1 924" 19 1008 934" 19 30-75 944" 10 51-42 £ 18 69-77 £ 18 90-4411 £ 19 11-11 £19 81-78 4 10 52-45 905 18 70-SO 915 18 91-47 925 19 12-14:985" 19 32-82 945" 19 53-49 £ 18 71-83 £ 18 92-51 £ 19 13-18 £ 19 83-S5 419 54-52 906 18 72-87 916 18 93-54 926 19 14-21 936 19 34-88 946" 19 55-561 £ 18 73-90 £ 18 9457 £ 19 15-25 1 * 19 35-92 4 19 56-59 907 18 74-94 917 18 95-61 927 19 16-28 937 19 36-95 947" 19 57-62 4 18 75-97 £ 18 96-64 £ 19 17-31 4 19 37-98 4 19 58-66 908 18 77-00 918 18 97-67i928" 19 18-35 938" 19 39-02 948 19 59-69 £18 78-04 4 18 98-71 £19 1938] £ 19 40-05 4 19 60-72 909 i!8 79-07 919" 18 99-74 929 19 20-41 939" 19 41-08 949" 19 61-76 £18 80-10 £ 19 00-78 £19 21-45 * 19 42-12 * 19 62-79 S I 5 S 1 * t I f (U £ a 2 i - £ 1 3 £ 1 - <§ i 1 3 S 1 oS i 1 1 950 19 63'82 960 19 84-50 970 20 05-17 980 20 25-8-1 990 20 46-51 * 19 64-86 * 19 85-53 i 20 06-20 £ 20 26-87 ! £ 20 47-55 951 19 65-89 961 19 86-56 971 20 07-23 981 20 27-91 5)91" 20 48-58 £ 19 66-93 i 19 87-60 i 20 08-27 1 20 28-9-1 J •20 49-61 952 19 67-96 962 19 88-63 972 20 09-30 982 20 29-97 992" 20 50'65 £ 19 68-99 £ 19 89-66 1 20 10-34 4 20 31-01! £ 20 51-68 953 19 70-03 963 19 90'70 973 20 11-37 983' 20 82-04 993 20 52-71 i 19 71-06 i 19 91-73 £ 20 12-40 i 20 33-07 i 20 53-75 954 19 72-09 964 19 9276 974 20 13-44 984 20 34-11 994" 20 54-78 ^ 19 73-13 £ 19 93-80 i 20 14-47 A 20 35-14 i 20 55-81 955 19 74-16 965 19 94-83 975" 20 15-50 985" 20 36-18 >995" 20 56-85 1 19 75-19 i 19 95-87 £ 20 16-54 £ 20 37-21 £ 20 57-88 956" 19 76-23 1966 19 96-90 976 20 17-57 986 20 38-24 996 20 58*91 i 19 77-26] £ 19 97-93 £ 20 18-60 £ 20 39-281 ^20 59-95 957 19 78-29 967 19 98-97 977 20 19-64 987 20 40-31 997" 20 60-98 £ 19 79-33 1 20 00-00 £20 20-67 £ 20 41-34 £ 20 62-02 958 19 80-36 968 20 01-03 978 20 21-70 988 20 42'38 :998 20 63-05 i 19 81-40 £ 20 0207 42022-74 £2043-41! 42064-08 959" 19 82-43 !969 20 03 10 979" [20 23-77 989 20 44-44 999 20 65-12 £ 19 83-46 i 420 04-13 £20 24-81 £20 45 48 420 66-15 I ii 1000 20 67-1 S INDEX. ALU A LUMINIUM, qual. determina- J\. tion, 52 Amalgams described, 136 Ammonia, 33 — carbonate of, 33 Ammonium, sulphide of, 33 Anthracite, 172 Antimony, qual. determination, 65, 56 Anvil, steel, 23 Aragonite, 49 Argentiferous sulphide of copper, 98 Argentite, 97 Argol, 33 Arsenic, metallic, 33 — qual. determination, 80-82 Assay balance, description and capacity, 17, 18 — grain weights, 18 Attwood, Melville, on the batea, 29, 30 Azurite, 146 BALANCE for large quantities and capable of weighing 32 oz., 19-22 — experiments with large, 22 Barium, qual. determination, 47 Batea, 29-32 Beaker glasses, 28 Berthier, on the heating power in coals, 174, 175 Berzelius, on the form of blow- pipe, 4 — on the blowpipe lamp, 7 BRO Berzelius, on preparing pure iron, 39 — on fluorine, 75 — on chlorine, 75 — on bromides and chlorides, 77 — on palladium oxides, 89 Bismuth, pure, how to make, 38 — qual. determination, 68, 69 — native, 153 — ores, 153 — sulphide, 153 — carbonate of, 153 — acicular, 153 — blende, 153 — metallic description of, 153, 154 — assay, a previous qualitative examination, 154 roasting and fusing, 155 Blowpipe capabilities, 3 — description, 4 — tips, 4 — mouthpiece, 4 — how to use it, 5 - fuel, 6 Bone ash, 33 Boracic acid, 33 Borax, 32 Borers for charcoal, 24, 25 Bornite, 146 Boron, qual. determination, 83 Bottle for washing precipitates, i"J — drop, for holding acids, 29 Bournonite, 146 Bromine, qual. determination, 76, 77 Bromyrite, 98 206 INDEX BEU Brucite, 51 Brush, on blowpipe gas lamp, 10 /CADMIUM, qual. determination. \J 65, 66 Cassium, qual. determination, 47 Calcium, qual. determination, 49, 50 Calomel, 135 Capsules, mixing, 26 Carbon, qual. determination, 82, 83 Cassiterite, 166 Cerargyrite, 98 Cerium, qual. determination, 89, 90 Chalcopyrite, 146 Charcoal as a blowpipe support, 12 — holder, 27 Chilenite, 98 Chlorine, qual. determination, 75, 76 Chromium, qual. determination, 57 Cinnabar, 135 Coal, description of, and probablt origin, and where found, 171. 172 — hard (hard coal), 172 — brown (brown coal), 172 — caking (caking coal), 172 — non-caking (non-caking coal), 172 — cannel (cannel coal), 172, 173 — assay, moisture determinatior , 173 — coke production, 173 — the amount of ash, 174 heating power determina tion, 174 — sulphur estimation, 175, 17( Cobalt, qual. determination, 61, 61 — nitrate of, 33 — ores, 164 - assay, 164, 165 Cobaltite, 164 Columbium, qual. determinatior, 91, 92 Copper oxide, 33 — sulphate of, 33 FLA Copper, pure, how to make, 37 — qual. determination, 66 — native, 145 — glance, 146 — red, 146 — phosphate of, 146 — arseniate of, 146 — assay, classification, 146] description of method adopt- ed to extract the metal from its matrix, 146, 147 roasting the ore, 147, 148 fusion of the roasted ore or product, Class B, 148, 149 refining the copper and lead alloy, Class C (a), 149 alloy of copper and anti- mony, 150 Covelline, 146 Cupel mould, 29 Cupellation, method of, 106-108 Cupels,, how to make them, 29 Cyanosite, 146 Cylinder, hard-wood, for preparing soda-paper cornets, 27 DIDYMIUM, qual. determina- tion, 90, 91 Dishes, evaporating, 27, 28 Dolomite, how to distinguish from ordinary limestone, 51, 52 Domeykite, 14G Domeyko, on the assay of mer- cury, 143-145 TWBOLITE, 981 Jj Epsomite, 51 Erbium, qual. determination, 91 Erythrite, 164 Explanation of American gold table, 192-194 T7AHLEKZ, 98, 146 r Filter paper, 29 Fire-clay crucibles and capsules, how to make them, 15, 16 Flames, oxidising and reducing, 10 INDEX 207 FLE Fletcher, paraffin lamp, 9, 10 Fluorine, qual. determination, 75 Forbes, David, on colours of sub- limates on charcoal, 43, 44 on the determination of the silver globule obtained by cu- pellation, 109-116 Forceps with platinum tips, 25 — brass, 25 — iron, 25 Franklinite, 160 Fuchs, on detection of oxygen, 73 Funnels, glass, 28 Furnace, description of the char- coal furnace and holder em- ployed in the distillation of mercury and in the assays of gold, silver, lead, &c., 142-144 GAHN on the construction of the blowpipe, 4 Gold, pure, how to make, 35 — qual. determination, 56 — native, its forms and places of occurrence, 125 — alloys, native and artificial, 126 — assay, explanation of the me- thods of assaying, 126, 127 classification of, 127 of free milling ores, Class A O), 127, 128 of pyrites, Class A (J), 128 of river and ocean sands, Class A O), 128, 129 of alluvial deposits and placer washings, Class A (d\ 129 of slags, Class ,4 0), ] 30 of sweeps,' Class A (/), 130 • universal method for ores and minerals, Class A (#), 130 of alloys, coins, and fine gold, Class B O), 130-132 quantity of lead required to cupel different qualities of gold, 131 separation from silver, 131, 132 of dust and nuggets, 132 « in copper plates, 133 ISO Gold'assay when more than 10 per cent, of platinum is present, 133 • containing iridium, 133 when palladium is present, and not more than 10 per cent, of platinum, 133 when platinum and silver are present, 133, 134 when rhodium is present, 134 — with mixed metals, as in Class B (i), 134 a rapid assay of coins, nuggets, &c., Class B (7), 134, 135 amalgams, 135 Glucinum, qual. determination, 84, 85 Graphite, 33 HAMMER, steel, for breaking rocks, &c., 22 for flattening metallic but- tons, 23 Hanks, Henry, on the batea, 31, 32 Hessite, 98 Holder, platinum wire, 14 Hydrochloric acid, 33 Hydrogen, qual. determination, 73, 74 Hydromagnesite, 51 TLMENITE, 160 I Indium, qual. determination, 68 lodyrite, 98 Iodine, qual. determination, 77 Iridium, qual. determination, 93 — estimation of, 133 Iron, pure, how to make, 39, 40 - protosulpbate, 33 — qual. determination, 57-61 — native, 159 — sulphides, 159 — ores, 159 — ore, brown, 159 — carbonate of, 160 — assay, description of the me- thods adopted, 160-163 208 INDEX. KUP TTUPFERNICKEL, 163 jy T AMBOKN, on blowpipe flames, _L 10-12 Lamp, used by Plattner, 7 — for burning alcohol, 9 — for burning paraffin, 9 — using gas according to Brush, 10 j Lanthanum, qual. determination, 85,86 Lead oxychloride, 33 — pure, how to make, 36 — qual. determination, 66-68 — native, 150 — ores, 150 — assay, classification of, 151 method employed and results obtained by same, 151 preparation of sample and instructions in fusion, &c., 151, 152 of Class By 152 Lignite, 172 Litharge, 33 Lithia, Turner's method »f detect- ing, 72 Lithium, qual. determination, 72, 73 Litmus paper, 33 MAGNESITE, 51 Magnesium wire, 33 — qual. determination, 50-52 Magnet, steel, 24 Makins, on the fusing power of the blowpipe, 3 Malachite, 146 Manganese, qual. determination, 52-54 Menaccanite, 160 Mercury, pure, how to make, 38, 39 — qual. determination, 71 — description and occurrence of, 135 — assay, classification of, 136, 137 preparation and description of method adopted and mode of making retorts to determine Class A, 137-139 NIT Mercury assay of Class 7?, 139 amalgams that spurt on heat being applied, 140 of amalgams, 140-143 description of the steel retorts, distillation pipe, re- ceiver, &c., 141, 142 Millerite, 163 Mitchell, on estimation of sulphur in coal, 175, 176 Molybdenum, qual. determination, 92, 93 Mortar, steel, 23 — agate, 23 NICKEL, oxalate of, 33 — qual. determination, 62, 63 — ores, 163 — white (white nickel), 163 — antimonial, 163 -glance, 163 — copper (copper nickel), 163 — assay, 163, 164 — and cobalt assays, the method adopted, 165, 166 assay classification of , 166 roasting, 166 fusing with metallic arsenic, 166, 167 nickel, cobalt, arsenic, and iron, 167, 168 separating the cobalt from the nickel by slagging, 168, 169 ores and products in which nickel, cobalt, copper, and iron are combined with a small quantity of arsenic, 169, 170 when nickel, cobalt, iron, and copper, &c., are present, 170, 171 alloys of copper and nickel, 171 poor ores requiring a collecting agent, 171 Niobium, qual. determination, 91 Nitre, 33 Nitric acid, 33 INDEX. 209 NIT Nitrogen, qual. determination, 74 Nitrous acid, 33 OSMIUM, qual. determination, 93 Oxygen, qual. determination, 73 "PALLADIUM, qual. determina- JL tion, 88, 89 Pan, used with large balance, 21 Pans, horn, 19 — metal, 19 Paper prepared for making cornets in the silver and gold assays, 29 Pentlandite, 163 Periclase, 51 Phillips, J. A., on occurrence of tin, 156 Phosphorus, qual. determination, 78-80 Phosphorus salt, 32 Platinum foil, 13 — wire, 13 instructions how to use it, 14 — spoons, 15 — qual. determination, 71 Plattner, on blowpipe lamp, 7 — on iron compounds, 59 — on detecting cobalt in nickel alloys, 62 — on detecting a small quantity of nickel in oxides of cobalt, manganese, and iron, 63 — on lithia, 72 — on sulphur, 78 — on sesquioxide of iron, 162 Pliers, steel, 26 Polybasite, 98 Potash, caustic, 33 — carbonate of, 33 Potassa, neutral oxalate of, 32 - bisulphate of, 33 Potassium, cyanide of, 32 — qual. determination of, 45, 46 Proustite, 97 Pyrargyrite, 97 Q UAETZ, 33 SIL T)HODIUM,qual. determination, XI 93 Riders gold, 19 Roach, John, on the batea, 30 Rubidium, qual. determination, 47 Ruthenium, qual. determination, 89 SALT, common, 33 Saw for cutting charcoal, 13 Scorifier, 104 Screens, punched, 27 Selenic silver, 98 Selenium, qual. determination, 93, 94 Shears, cutting, 25 Sieves, wire, 27 Silicium, qual. determination, 83, 84 Silver, pure, how to make, 34 — qual. determination, 56 — native, 97 — in sea water, 97 — minerals and ores, 97, 98 — in products and refuses, 98 — explanation of the modus operandi employed in assay- ing its ores and compounds, 99 — assay, classification, 99, 100 — amount of lead required for different ores, 101, 102 preparation of the ore and the reduction to silver lead, 100-104 how to scorify and concen- trate the silver lead, 104-106 — of argentiferous molybde- nite, 119, 120 of Class A (c), 120 of Class A (d), 120, 121 — of Class A (0), being a gene- ral method adapted to the assay of silver ores, 121, 122 of Class B (a), being alloys ready for cupellation, 122, 123 of alloys requiring cleansing before cupellation, 123 — of alloys and quantity of test lead required, 123 of amalgams, 123 210 INDEX. SIL Silver assay, determination in brass and black copper, 123, 124 — - — in antimony, tellurium, and zinc, 124 in tin and gun metal, 124 — - — in silver-steel and iron, 124, 125 in alloys of lead or bismuth, 125 in copper coins, wire, and cement, 125 Skutterudite, 164, 165 Smaltine, 164 Smyth, W.W., Prof., on the batea, 31 Soda, carbonate of, 32 Sodium, qual. determination, 46, 47 Spar, fluor, 33 Spoon, horn, 24 — ivory, for mixing, 27 Stand to hold cupels, 27 Stein, on nitrogen, 74 Stephanite, 97 Sternbergite, 98 Strontium, qual. determination, 48,49 Sublimates on charcoal, colour, 43, 44 Sulphur, roll, 33 — qual. determination, 77, 78 Sulphuric acid, 33 Synthetical assays, 109 HHABLE for calculating the gold JL and silver in a ton of 2,240 Ibs., 117, 118 — for calculating the gold and silver in a ton of 2,000 Ibs., 118, 119 — of English Mint value of gold, 179-191. — of the value of gold in the United States of America, 195-205 Tantalum, qual. determination, 86, 87 Tellurium, qual. determination, 94 Terbium, qual. determination, 86 Thallium, qual. determination, 92 ZIE Thorium, qual. determination, 92 Tiemannite, 135 Tin, pure, how to make, 37 — qual. determination, 55 — metallic, 156 — assay, classification of, 156 — oxides, 156 — assay, fusion of pure oxides, 157 — ores containing silica, 157, 158 - — when sulphur, arsenic, and tungsten are present, 158, 159 — — ores with less than 5 per cent,, 159 Titanium, qual. determination, 69-71 Tubes, glass, open at both ends, 1 6 -- closed and bulb -shaped, 17 -- test, for parting gold and silver, 28 Tungsten, qual. determination, 87, 88 Turner, on lithia, 72 — on boron, 83 URANIUM, qual. determination, 87 Ure, Dr., on Berthier's process of determining absolute heating power, 175 VALUE of gold coins in the United States of America, 191, 192 Vanadium, qual. determination, 88 Von Kobell, on tungstite, 87 TT70LFSBERGITE, 146 VV Wollastonite, 49 TTTTRIUM, qual. determination, I 86 on distinguishing i 1 limestones, 51 Zinc, qual. determination, 63, 64 Zirconium, qual. determination, 94 SpottiswoQde & Co., Printers, New-street Square, London, SCIENTIFIC BOOKS PUBLISHED BY D, VAN NOSTRAND, 23 Murray Street and 27 Warren Street, NEW YORK Any Book in this Catalogue, sent free by mail on receipt of price Weisbach's Mechanics. 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