RESEARCH LIBRARY THE GETTY RESEARCH INSTITUTE Raympnd Pettibon * THE ASSAYEB’S GUIDE. Digitized by the Internet Archive in 2016 https://archive.org/details/assayersguideorpOOIieb THE ASSAYER’S GUIDE; OR, PRACTICAL DIRECTIONS TO ASSAYERS, MINERS, AND' SMELTERS, FOR THE TESTS AND ASSAYS. BY HEAT AND BY WET PROCESSES. OF THE ORES OF ALL THE PRINCIPAL METALS, OF GOLD AND SILVER COINS AND ALLOYS, AND OF COAL &c. BY OSCAR M. LIEBER, LATE GEOLOGIST TO THE STATE OF MISSISSIPPI. PHILADELPHIA : HENRY CAREY BAIRD & CO., INDUSTRIAL PUBLISHERS, BOOKSELLERS AND IMPORTERS, 810 Walnut Street. 1880 . Entered according to Act of Congress, in tl e year 1852, by HENRY CAREY BAIRD, the Clerk’s Office of the District Court of the United States in and for the Eastern District of Pennsylvania. PREFACE. iv i/r * tenting this little volume to the ^ablio^ I x rust that I am filling a void in our chemical literature. I believe there is no work in the English language on assaying which combines with practical usefulness a sufficiently popular character for those read- ers who have not made metallurgy, and its kindred sciences, objects of their especial study. My desire is, to offer a book which fully treats of all the subjects of assay- ing, and whose price will yet place it within the reach of all persons profession- ally interested in this important branch of knowledge. The more compendious works on chemis- try, if they allude to assaying at all, give so sparing and incidental remarks, that they do not throw any light upon it for technical 1 * 5 6 PREFACE. purposes, as indeed it does not fall within their province to do. The immense mineral wealth of the United States, to which the discoveries in California have so largely added, makes this art a very desirable acquirement for every one engaged in any business connected with the metals; and it would appear indispensa- ble to those desirous of deriving the great- est advantage from a residence in that promising and alluring part of our country. Although these pages principally treat of the processes by heat, I have thought it proper to describe also some wet processes, either where they serve as methods to rectify the former, or where no others exist; as, for instance, is the case with platinum. For the coins, I have selected those em- ployed at mints, and which are therefore generally considered the most serviceable for the analysis of those alloys. I feel induced here to recommend at least a partial study of blowpipe assaying, to those who may wish to make use of the PREFACE. T instructions given in this treatise. This infant branch of chemistry was first created, I may say, in Sweden by Cromsted, and established more firmly by Gahn and Ber- zelius, both his countrymen; and has of late been made by Plattner a method even for quantitatively ascertaining the contents of most minerals. The requisite blowpipe utensils for the mere detection of the principal components of ores are so few, can so easily be com- manded, and may be so readily carried about one’s person, that, at least for the purpose of a prior test, it is very advisable to possess some knowledge of their application, which can be acquired with great facility. I beg to refer those readers who may be desirous of pursuing assaying more sci- entifically, in particular to two works of merit, neither of which is written in our language. The one is the Trait6 des Essais par la Yoie seche, by Berthier, Paris, 1834; the other is in German, — Instructions on Assaying, for Miners and Smelters, by 8 PREFACE. Bodeman, Clausthal, 1845. The last men- tioned work has been of much use to me in writing this volume. I cannot conclude these brief remarks without seizing upon the opportunity of acknowledging the liberality of a distin- guished officer at Freiberg in Saxony, Mr, F r itz s ch e, ch ief a s say er of that mining district. I have made frequent use of his notes and hints, given me while I had the advantage of a personal intercourse with him. 0. M. L. Columbia, S. C., 10 th April , 1851. CONTENTS. PASS, Preface . 5 Explanation of Technical and Scientific Terms.. . 11 Introduction . 13 I. Description of Implements and Utensils used 17 II. Assay of Silver Ores by Heat — Cupellation 39 [II. A Table to rectify the Loss in the Silver Assay 52 IY. Gay-Lussac’s Process for Silver Alloys 54 Y. Assay y>f Gold Ores by Heat — Quartation . 56 VI. by Amalgamation 61 YII. by Washing 63 VIII. by a Wet Process 66 IX. Assay of Silver Coins, or Alloys of Silver and Copper 68 X. Assay of Gold Coins, or Alloys of Gold, Silver, and Copper 71 XI. To find the Proportion of Gold in a Mixture of Gold and Quartz, by Calculation... 77 XII. Assay of Platinum Ores 80 9 10 CONTENTS. XIII. Assay of Copper Ores by the German or Hungarian Method XIY. Assay of Copper Ores by the English Method XY. Assay of Lead Ores by Heat XYI. by a Wet Process.... XYII. Assay of Iron Ores by Heat XYIIL Fuchs’s Process for Iron Ores and Iron. . . XIX. Assay of Ores of Mercury XX. Assay of Sulphurets in Ores XXI. Mode of Testing the Calorific Power of Coal and other Fuels.. XXII. Tables 125- 85 92 97 100 103 108 111 119* 121 •129 EXPLANATION OF TECHNICAL AND SCIENTIFIC TEEMS USED. Alkaline, containing an alkali, viz. potash, soda, or am- monia. Ammoniacal, containing ammonia or hartshorn. ^Assays by Heat, or processes by the sole means of fire. Black flux. See Copper Assays. Carats fine , a term used in designating the value of gold alloys. Carbonate, applied to oxides, where carbonic acid is united with them. Chlorides are combinations of chlorine with metals, &c. Crucible. See Utensils, &c. Cupel. See Utensils, &c. Fluxes , ingredients added to produce slags. Fuming nitric acid, the strongest kind, emitting red vapours. Galena, a lead ore. Hygroscopic water, the moisture bodies attract from the atmosphere. Muffle. See Utensils, &c. 11 12 EXPLANATION OF TECHNICAL TERMS. Oil-baths, heated oil, to warm solutions, &c. Oxidation, the combining with oxygen (rusting, &c.) Peroxide, the oxide containing the greatest amount of oxygen. Phosphates, combinations of phosphoric acid with metals, earths, (earthy,) &c. Precipitation, the production of insoluble compositions, &c. in wet processes. Protoxide , containing the least amount of oxygen. Quartation. See Gold Assays. Sand-bath, heated sand, to warm solutions, &c. Sulphates, combined with sulphuric acid. Sulphurets, combined with sulphur. Test-glass, a glass tube closed at one end for chemical purposes. Water-bath, heated water to warm solutions at 212° Fahrenheit. Water of crystallization, the water contained in crystals, and by evaporating which, they crumble. Wet 'processes are those in which acids and solutions are used, and where fire is never directly employed. White flux. See Copper Assay. THE AS SAYERS GUIDE. INTRODUCTION. Assaying is the science whic'h treats of the various methods of ascertaining the amount of one or of several ingredients of a chemical compound, such as an ore or alloy, but is solely intended for practical purposes. For this reason one of its main objects is to be able to attain to a very great accuracy with the smallest and cheapest means, and in the shortest possible time. In this it is con- tradistinguished from inorganic analytical chemistry, properly so called. The aim of the latter is to ascertain all the different composing elements of an inorganic com- pound, and also the exact amount of each. 2 13 14 THE ASSAYER’S GUIDE. and for this reason the chemist should never be deterred by a great waste of time and money, if an accurate result should require extravagant means. As assaying is only an aid to technical operations, and these never can extract the whole amount of a metal or other component part contained in a com- position, (be the latter a natural or artificial one,) with true chemical precision, it is self- evident that much time and labour would be unnecessarily lost, if the same attention were devoted to it as would be requisite in an analysis. This, however, also shows that it is utterly inadequate for purely scientific ends. Assaying was the earliest known branch of chemistry, and in fact that one which afterward, through the medium of the various investigations of alchemy, drew attention to theoretical chemistry, and thus founded that science. The art of assaying is so ancient, and it has so constantly and imperceptibly re- INTRODUCTION. 15 ceived new additions and perfections, that its origin is entirely unknown. Agricola of Saxony, who lived in the earliest half of the sixteenth century, was the first to col- lect the facts and \^rite on this subject, (G. Agricola de Re Metallica, libr. XII. Basil, 1546.) Since then the manifold dis- coveries of more enlightened periods have vastly enlarged and developed this branch of study. It is not by any means always necessary that the same measures be employed for these tests as are used in the separation of the single constituent from the rest of the compound in large quantities; as, for in- stance, in the processes of smelting and amalgamation, although, if convenient, it is very advisable, as it facilitates the metal- lurgist in the detection of the best fluxes and admixtures to be added to his peculiar ores. The assayer should be guided in his operations by chemistry, and the study of 16 THE ASSAYER'S GUIDE. the latter, particularly as far as regards the principal and more common substances, should never be omitted. In other respects, all that can be recommended to one who desires to perfect himself in assaying, is the most scrupulous cleanliness, order, and pre- cision as regards his assays and implements, and the most unwearying adroitness and attention in performing the manipulations required by his science. 17 I. Description of the Implements and Utensils used in the course of Assays by Heat. Among the articles necessary for an assayer’s office, of course the first that requires a description is the furnace. For most purposes the muffle furnace suffices, and it is the only one used for gold, silver, and copper ores ; but for iron, lead, &c. we require another, though much simpler one. I shall first describe the muffle furnace, (Plate I. figs. 1, 2, and 3.) The character- istic part, the one from which this furnace derives its name, is the muffle, illustrated on the same plate, in figs. 7 and 8. Both these diagrams give a perspective view, the first a semilateral, the second one from m front. They can be procured in most of our larger cities, and are manufactured in 3 * 18 THE ASSAY ER’S GUIDE. great quantity in Hessia, of a very firm and fire-proof siliceous clay, the same material as that used for the well-known Hessian crucibles, (Plate II. fig 5.) The one from which the drawing was taken in Plate I. measures eight inches across the bottom from mouth to back outside, arid four inches down the back. The holes opening upwards towards the interior measure each an inch and a half lengthways, but their number of course varies according to the size of the muffle, which again should depend on the quantity of assays expected to be performed at once. The back and the mouth of the muffle are. equal in size. The muffle furnace is exhibited from in front in fig. 1, in a lateral section in fig. 3, and in a transverse perpendicular section in fig. 2. A scale, showing the proportionate dimensions in English feet, is attached, to facilitate the use of the drawings in build- ing a furnace ; for though very small, they have been made with much care, and, with DESCRIPTION OF IMPLEMENTS. 19 the little sketches attached, are fully capa- ble of being employed to that effect. As will be seen from the first figure, the line A B is seven feet long, while the external width of the furnace,' C D, is two feet nine inches. The furnace consists of three chief parts, the chimney, r, in figs. 2 and 3, (which need only be 3i feet high if it enters the chief chimney of the laboratory, which should then measure at least 9 — 12 feet,) the part above C D, in fig. 1, containing the muffle, and the part below that, the grate, ashes box, &c. &c. In fig. 1 we see imme- diately below the chimney a representation of bricks, { firebricks , for all in immediate contact with the heat should be of this kind ; the external ones are common burnt bricks.) These, though fastened in tight, are placed so that they can be taken out, to put in a new muffle, or make other repairs when necessary. In this brickwork we have two openings, d and a. The former is only a small aperture, for insert- 20 THE ASSAYER’S GUIDE. ing pieces of sheet iron, upon which to dry the cupels. It is, however, not immediately necessary, and, if present, is always closed with a tight brick when the muffle is in use. a is the opening of the muffle, which can be closed by a piece of fire-proof brick repre- sented in fig. 4, having an iron piece pro- truding on the exterior, with a narrow opening, into which fits the handle fig. 5, which we apply on removing it. To the right and a little below the muffle is a loose brick, e, to be taken out whenever it becomes necessary to remove the fire-proof clay bar, o, which holds the muffle, (vid. fig. 2.) As seen in fig. 3, this bar as well as the three others shown in the little sketch affixed to fig. 2, and of which the centre one is a little the longest, are slightly inclined, thus elevating the back of the muffle an inch above the front, and giving a better circulation of heat, as should be the case where stone-coal or cokes are used. In burning charcoal it may be horizontal, DESCRIPTION OF IMPLEMENTS. 21 although this inclination has another ad- vantage, inasmuch as it enables us to clean out the muffle easier, should a cupel upset, the contents running forward. The three fireclay bars, s s's, are loose, while o is inlaid on one side, and on the other fastened in with a loose piece of brick and an iron wedge, which can be removed, as already remarked, through e. On inserting the bars and muffle, the parts where they meet, and where the former touch the other bricks, should be powdered over with bone-ashes, to prevent a possible adhesion from the intense heat. Small cracks in the muffle should be mended with coarsely powdered burnt clay, p, in fig. 2, is the open space left round the muffle about an inch and a half wide, and into which the opening d in figs. 1 and 3 leads. Immediately below C D we have the door b exhibited in all three figures. It is for the introduction of fuel, and is just above the grate, x x, in figs. 2 and 3, which consists of six iron bars placed in the same 22 THE ASSAYER’S GUIDE. inclination as the muffle. The door /, fig, 1, is of iron, with an inside coating of fire-clay, an inch and a quarter thick, kept in place by iron rivets, thus protecting the assayer from the radiating heat of the iron, which would otherwise soon be white-hot. Below the grate stretches the chamber q , in figs. 2 and 3, both for draught and for the cinders. The plane at the bottom of this is inclined like the grate and muffle, and has the opening c to take out the ashes. To intro- duce a regular and sufficient quantity of atmospheric air, the channel k has to be constructed, which enters q at A, and passing under the floor of the laboratory opens outside at i, fig. 3 : l is a small piece of sheet iron, by pulling out or pushing in which, we open or close the passage h at pleasure, and accordingly as we require a great influx of air or not, for a high or low temperature. The little figure annexed to fig. 1, shows the construction of the little opening and slide in the lower door. It is DESCRIPTION OF IMPLEMENTS. 2b exactly as with a common iron stove, y being the hole, while the slide a (3 can be closed over it by means of the handle, or removed, as may be desirable for different degrees of ventilation. This furnace is of the kind proposed by Professor Plattner for the Freiberg assay office for the use of stone- coal and cokes, and where it has been employed to great advantage, as regards economy and practicability in general. Having thus pretty minutely given a description of the muffle furnace, as it can best be constructed when not required to be movable, I shall proceed to the furnace for tests of iron ores, lead ores, &c., also in a shape not intended to be moved, as repre- sented by a lateral section in fig, 6, Plate I. Those parts in immediate contact with the heat should be constructed of fire-proof bricks, which ought to reach some distance up the chimney. The main body of the furnace B and A is either square or round, and twelve inches in diameter. The back 24 THE ASSAYER S GUIDE. is about three feet nine inches high, while the front measures slightly less, as the top has a little slant, merely for convenience in easier being able to get at the bottom. A is the part where the ashes collect, with a door at H having one or several openings, as is represented in the door < 7 , in fig. 1 , for the sake of regulating the ventilation. If this furnace is to be used for iron assays, in which case a very intense heat is requk site, a similar channel as illustrated in K, fig. 3, should be attached, the longer the better, and, if possible, opening into some cool place, e. g. a cellar, thus creating a stronger current of air, and consequently a better ventilation. Above A are the bars forming the grate F G, which ought to vary in distance from one another according as we use charcoal or stone-coal and cokes, in the former case being closer to one another* B is the part in which the crucibles are placed, as well as the fuel, and which has one opening for the introduction of the same DESCRIPTION OF IMPLEMENTS. 25 with the cover E, suspended, when open, by a chain, but which is shut when the furnace is in use. This cover is commonly of iron, covered with fireproof clay. C is the channel leading off to the chimney D, which may vary in width from one half to one quarter the width of B. For assays of lead and copper it is not necessary to have the chimney very high, as no very severe draught is required ; but for iron assays it should be about thirty feet. Iti the assay office in Clausthal it measures forty-eight feet. In this case, of course, if there is also a muffle furnace on the same hearth, it is best to conduct the chimneys of both into one large one. On placing the crucibles in this furnace- — twelve have room in it at once — a piece of firebrick, K in the drawing, is first placed on the grate, which, to avoid adhesion of the crucibles, may be powdered with bone-ashes. This brick is employed to have the crucibles more in the focus of heat, by elevating 3 26 THE ASSAYEE’S GUIDE. them above the coal around it, and also — clay being a bad conductor — to keep them from immediate contact with the cold blast. The fuel should never be heaped above I, the mouth of the channel C, and large coals should be placed below, to keep the grate from choking. If several crucibles are used at once, they ought to stand sufficiently apart to admit coals between them, as they otherwise might melt partially in the course of the process, and form one compact mass. On the foregoing pages I have furnished descriptions and measurements of furnaces, which, as I have already remarked, though easily constructed, are not portable; and it is proper that, before closing this chapter, I should devote a few lines to the mention of those, which, from their being movable, and thus obviating the difficulty and incon- venience of constructing one, might, in many cases, be preferred, although their smaller dimensions, as a matter of course, make it more difficult to perform good DESCRIPTION OF IMPLEMENTS. 27 assays, and impossible to attend to many at a time. Among these we have both muffle furnaces, and wind furnaces such as last described. They are made of sheet iron, strongly fastened wdth iron hoops and coated inside with fireclay, (see also Chap. XVI.) They can generally be procured at all larger stores of chemical apparatus. Luhme & Co. of Berlin, who have one of the largest assortments of such articles in Europe, and for comparatively cheap prices, furnish a kind which may be used for both purposes, for 50 Prussian dollars, about $35.00 our money. There is another kind of portable furnace with an iron muffle, but which can only be applied to silver and gold assays, (coin,) which may suffice for the wants of many, and which is more durable than the others. After having thus given a description of the furnaces used in the course of the experiments elucidated in the following pages, I shall venture to call the reader’s attention to 28 THE ASSAYER’S GUIDE. other instruments used in the assays of ores. Among these, probably, the balance will appear most conspicuous. There ought to be two in use, one very accurate, the other less so, for more common purposes, as weighing off the ingredients or admixtures, such as pure lead, borax, &c. The other one should be made with great care, and only used to weigh off the small buttons of gold and silver procured. Accurate ana- lytical scales are required; and should it be more practicable to possess them in a small and compact shape, I would propose the blowpipe balance suggested by Professor Plattner of Freiberg, and made in that place by a very careful workman of such instruments, Mr. Beschorner, who furnishes them for all the students of the mining academy there. This balance can be pro- cured most simply from Luhme & Co. in Berlin,* who are in constant connection * J. F. Luhme & Co., 51 Kurstrasse, Berlin. DESCRIPTION OF IMPLEMENTS. 29 with the United States, and furnish them handsomely got up, with an elegant ma« hogany box, containing weights of platinum down to one-tenth of a milligramme, 01 0.003543402 grs. Troy, for about $16. The same firm can also provide common balances, from Professor Wackenrode’s (of Jena) description, for $4 or $5. It would be very advisable to have a medium balance to employ with the baser metals, marking a milligramme with about twenty-five grammes weight, costing about $13 or $14. It will be unnecessary to give a drawing of these balances, and I believe the short de- scription is- sufficient to define the accuracy and qualities required. I may add, how- ever, that it is highly advisable to have wires of platinum used everywhere in the more exact ones, since then an unequal extension or contraction of the silk cords, otherwise commonly used, and which neces- sarily cause variations, is avoided. We must now cast a glance at th« 3 * 30 THE ASSAYER’S GUIDE. smaller and less costly utensils, but all of which are necessary for the accomplish- ment of the operations to be performed as directed in the following pages. I allude to the crucibles, cupels or cups, and tongs, &c., illustrated in Plate II. The former, figs. 1, 2, 3, 4 and 5, are all of their natu- ral size in the drawings. Figs. 1, 3, and 4, should be made from accurate descriptions by a potter, of a pure clay, containing as little silica mechanically combined as pos- sible, since its presence prevents the ves- sels from being sufficiently porous to allow the oxidizing metals to enter, which would, as will hereafter be seen, become a great drawback to the assay. Some hundreds must always be kept on hand, for they can only be used once, as the lead, almost al- ways present, glazes them immediately. Fig. 1 represents a cupel used in the operation technically termed cupellation of the gold and silver ores : a shows it from above, b from the side. The concave inner DESCRIPTION OF IMPLEMENTS. 31 surface should not be too shallow, thus letting the contents run over ; nor, on the other hand, too deep, in which case too small a surface would be exposed to the oxidizing power of the heat. The line given in b shows the proper inclination within. Fig. 2 is a truncated cone, with a very slightly concave surface at the wider ex- tremity or top. It is made in great part of bone-ashes, being among the most porous substances that can stand a high tempera- ture. I give here a recipe for their pre- paration, furnished me by Mr. Fritzsche. It shows the relative quantity of the ingre- dients as used for these cupels at his office, where they are made by the laboratory servant in wooden moulds, using a rod, shaped like a pestle, to make the hollow at the top. The mass consists of 4 parts of wood-ashes previously freed of the pot- ash by filtration, I part of lime, and 1 part of bone-ash. 32 THE ASSAYER'S GUIDE. Fig. 3 shows a flat, shallow crucible / made of the same pure clay as that repre- sented in fig. 1 : a is the cup as seen from above, while b gives a lateral view, show- ing also the curve of the inner surface. This vessel is used in the assay of copper, as well as fig. 4. Fig. 3 is termed in Ger- man u Kupfer Garscherbe ,” from the fact that with its use the copper assay is finished. Fig. 4 is a high crucible, as mentioned above, used for copper and lead. It is made of the same material as the former. The reason of its having so great a height compared with its width, and otherwise so peculiar a form, is to concentrate all the heat round about the bottom of the in- terior. In some places, in lieu of better, the Hessian crucible (fig. 5) is used; but No. 4 is much better adapted, from the height of the foot-piece, which also protects the contents from the cooling influence of the iron bars on which they are placed, DESCRIPTION OF IMPLEMENTS. 83 and from a too direct contact with the colu draught. Some assay ers use an extra cover for this crucible, a very superfluous addition, since the bottoms of the old cru- cibles answer admirably as covers to the new. As mentioned before, these also are useless after once having been employed, and before throwing them away it is there- fore well first to break off the feet. Fig. 5 gives a drawing of a Hessian cru- cible, which is used chiefly in the assays of iipn ores. These are imported into the United States, and can be procured in al- most every crockery store. Their dimen- sions are very different, and so contrived that one fits into the next in size, being in sets of about a dozen. They are com- monly triangular above, and round below, as shown in the figure; but sometimes they are made round above and below, and where these can be had, they should be preferred. If they cannot be procured, similar crucibles of pure clay may be sub- 34 THE ASSAYER’S GUIDE. stitated, and in fact they are sometimes considered preferable. The latter are then commonly made with a foot-piece, some- what as in fig. 4, though not quite so strongly separated from the main bulk of the vessel. These or the Hessian crucibles, as will be seen hereafter, should be kept constantly on hand thickly coated with charcoal. They are prepared in this man- ner. Charcoal of any oak-wood, except red-oak, which contains much oxide of iron, is the best on account of its density. It should be pulverized with the utmost care, since a coarse powder will never furnish a consistent mass. To this we carefully add water until we procure a tough paste or dough, and with this fill the crucible very tightly, always ramming down every new portion introduced, with a pestle or piece of wood. When the whole interior is filled up, we cut out a hole in the middle with a penknife, leaving a margin of about half DESCRIPTION OE IMPLEMENTS. 35 an inch at least, below and all round. (See Assay of Iron Ores.) Fig. 6 furnishes a sketch of an imple- ment, which, though not immediately ne- cessary, will be found extremely useful, inasmuch as it tends to keep up order ' and accuracy, great requisites for an able assayer. As will be seen from the dif- ferent views a and b , it consists simply of a piece of sheet-iron, having a wooden handle and several semi-circular cavities, the number of which may vary according to the number of assays expected to be performed at once. If a large muffle is used in the furnace, it is well also to have this large; and, in fact, I would suggest having the number of holes in each row equal to the number of cupels, of the sort illustrated in fig. 1, that can, without col- lision, be placed across the muffle from side to side. (See Silver and Gold Ores.) This pan, or whatever we may otherwise term it, is used to cool the buttons of metal and 36 THE ASSAYER S GUIDE. their surrounding slag after having oxi- dized part of the lead, &c., and separated the gangue-rock, as is the case with silver and gold (q. v.) The holes should be Ih inch wide and £ inch deep. Figs. 7 and 8 represent two different kinds of tongs. Fig. 7 is only shown in a lateral view, since its characteristics are thus exhibited, while fig. 8 is sketched from above. They are both very necessary in the progress of our investigations. The first is shaped like common fire-tongs, only that the ends, instead of widening into a flat circular lobe, are bent downward like a poker, thus enabling us to handle the crucibles with great care. The second tongs has each piece ending in a semi- circle, the diameter of which circle, when united, should be so that it may exactly embrace the lower part of fig. 1. It is used to place those cupels into the muffle, as we are thereby prevented from touch- ing the contents. In using this latter in- DESCRIPTION OF IMPLEMENTS. 37 strument great caution should be taken not to upset the cupels. Let me first remark, that on introducing the cupels into the muffle, we always commence with No. 1, i. e. first assay on hand, behind on the left. It may seem a very superfluous precaution to dwell thus long on so simple a manipu- lation as the one I am now describing; but I know from experience, how many failures carelessness in this procedure oc- casions to the uninitiated. Let us now suppose, that we have the crucible, fig. 1, filled with the powdered mineral to be tested, and the other additions, such as lead or borax. Grasping the cupel firmly at the bottom, we lift it up high, so that, when pushed into the mouth of the muffle, it is a good deal above its floor, and cannot knock against it. As soon as it is within the muffle, without leaving hold of it, and keeping it up high, we hold the side of the tongs up against the side of the muffle to steady them, then run them along quietly 4 38 THE ASSAYER S GUIDE. though not too slowly, for that only causes the hand to tremble, until the crucible is just above the spot where we intend to place it, (when once down it should never be moved,) and then slowly lower it, not letting go till it stands secure. These tongs should be made light enough conveniently to handle them with one hand. The handles are made of some good firm wood, though No. 8 is generally held lower down than the handles, and, I may add, never so that the end of the tongs, the handle, passes under the arm, but exactly as the savages hold their darts when about to hurl them. It may seem awkward at first, and yet I know many accidents, as regards the assays, having occurred from not attending to it. The length of the tongs ought to be about three feet. It may be well to supply oneself with a third pair, with straight and rather pointed ends. 89 II. Assay of Silver Ores by Heat — Cwpellaticm. Silver occurs in nature chiefly in lead ores, (galena,) and native, as in the Lake Superior copper mines, or less commonly as chloride of silver, as is the case in the extensive mines of Chili. The following directions, however, refer equally to the assays of all. As with all minerals to be investigated by these methods, the ore must previously be reduced to the finest possible powder, for which purpose, where many assays are made, a large iron bowl is used as a mortar, the pestle having a wooden handle attached at right angles to the iron part, enabling us thus to employ a much greater force than if it were straight, as commonly is the case. The usual shape of a mortar, 40 THE ASSAYER’S GUIDE. used in kitchens is not so good, for its depth prevents its being cleaned sufficiently to insure accuracy. In lieu of the former, and when small quantities only are de- sired to be pulverized, an agate mortar may suffice. Of the ore we weigh off one part,— about 3 grammes, equal to 46 grs. Troy, (say 50 grs.) is a good standard weight, — and mix it with ten parts by weight of pure lead, and from one-tenth to one-fifth part of borax, in the manner de- scribed below. The lead is added to extract all impuri- ties, such as copper, nickel, &c., and in cases where these occur in great abun- dance, should be used in the proportions even up to fifteen and twenty parts, though it is always injurious, and tends to create a loss, to add too much. To the rules for testing the quality of alloys of silver and copper, will be found subjoined a table by Erker, to regulate this. The lead of commerce contains many im- ASSAY OF SILVER ORES BY HEAT. 41 parities, in the shape of other metals, which, since silver always is among them, is very injurious to our assays, and it is therefore necessary to obtain a purer article. At silver furnaces lead is produced as an extra product, sufficiently pure for our pur- poses. That, for instance, thus procured from the smelting works at Freiberg in Saxony, and used there by the assayers, contains, to 6.40000 parts of lead, from 0.00001 to 0.000015 parts of silver, too slight an impurity to affect the result of the assay. If so situated as not to be able to get it in this manner, the best way is to reduce it by a galvanic process from acetate of lead. This, the sugar of lead of com- merce, we can readily dissolve in luke- warm water, after which we should filter off the solution, and introduce a rod of zinc, by which process all the lead is re- duced and collected round that metal. After some time remove it, and continue in this manner until all the lead is pre* 4 * 42 THE ASSAYER’S GUIDE. cipitated. It is then to be repeatedly washed with care to remove the acid, and afterward dried between blotting paper. If not in a sufficiently pulverized shape, it need only be shaken a little in a towel and finally sieved. A spoon containing a given amount — five parts, equal to 250 grs., is con- venient— is used to measure the quantity for each assay, thus avoiding the tedium of weighing each time, a matter of consider- able consequence in an assaying office, where frequently hundreds of assays are made in a day. The vessel into which the mineral, to- gether with the lead and borax, is placed, to be introduced into the muffle of the fur- nace, is represented in fig. 1, Plate II. (See the description given a few pages back.) We first put one-half of the lead to be used in it, and on the top the silver ore, mixing the two with great care, not to spill the least particle, and afterward cover it with the rest of the lead, and ASSAY OF SILVER ORES BY HEAT. 43 sprinkle the borax over the whole. The latter is used to facilitate the melting of the lead, and to produce a good slag. When much tin, zinc, or lime is present in the ore, the borax ' should be increased in quantity up to the largest amount before mentioned. If we desire to test ores containing very little silica, and our crucibles are not as perfect as we might wish them to be, it is very advisable to make use of some quartz or glass-powder, to be added immediately, or, better still, when the slag is forming, and the process of calcining is thus at an end. We should, for the sake of economy with the fuel, make several assays at once, and always five or six of each ore, afterward taking the average, and thus regulating our own labour. After previously firing the furnace, and bringing the muffle to a regular and con- stant red-heat, we may introduce the cru- 44 THE ASSAYER’S GUIDE. cibles. To quicken the melting of the lead, we place some pieces of well-dried charcoal, which should always be kept on hand, in front of the crucibles. Vapours will be observed to be emitted, caused by the discharge of volatile substances. The door of the muffle, previously closed, should be kept perfectly open as soon as the operation of calcining or roasting the ore has properly commenced, to admit fresh air, and prevent the heat from in- creasing too much. This process generally lasts about twenty minutes, after which, by introducing fresh coals into the muffle and again closing the door, we raise the heat, and continue it sufficiently long to let the slags collect and flow easily, so as to make a crust round the white-hot metal. When not employing a sufficiently high temperature, the slag will remain thick or tough, and retain the metallic alloy of silver and lead in small particles disseminated throughout the mass. ASSAY OF SILFER ORES BY HEAT. 45 From the circular portion of argentiferous lead, which appears to be in a constant rotary motion in the centre of the slag, vapours of lead rise incessantly. The time that should be occupied by this process of melting varies much according to the character and quality of the ore, which sometimes, though rarely, may even require something more than half an hour. Gene- rally much less time is wanted with a good fire, and the assayer can always see at what time the encircling slag has been properly separated from the metal, and even with very little practice is enabled to regulate it. We now again open the muffle, and by oxidizing some more lead during the space of ten minutes, cover the metal entirely, and after that, once more apply a strong heat for a few minutes to make the slags flow easy, and then taking out the crucibles, pour the whole contents into the different hollows of the iron plate, illustrated by fig. 6, Plate II. This should be done very 46 THE ASSAYER’S GUIDE. quickly, for otherwise the lead will not collect in one button, but be distributed in small particles all over the molten slag as above. A little practice will soon accus- tom any one to all these operations. On cooling, with a stroke or two of the hammer we separate the slags from the metallic buttons, and with a few more easily shape the latter into cubes as regular as possible. The crucibles shown in fig. 2, Plate II. come into use at this part of the assay. If well made and dried, they should be very porous, and so friable as to be crushed between the fingers with ease. In these cupels we expose the metal cubes to a moderate red-heat, which we are enabled to regulate by inserting cold pieces of pottery — old crucibles will be found very serviceable— and leaving the furnace open. The rising vapours are from the lead, and continue until that peculiar bright flash of light is observed, termed silberblick , (silver- ASSAY OF SILVER ORES BY HEAT. 47 gleam,) in German mining and smelting technology, and from which we know that the silver is pure. The utmost attention should be paicT to this part of the assay, to ascertain the moment when this occurs. The coolers are then carefully removed, the aperture closed, and the most intense heat possible kept up for a few moments. To do this well is, I may say, the chef d' oeuvre of an assayer, and on it depends, in a great measure, the accuracy of the assay ; for the silver, when pure, requires a much greater heat to bring it to the melting point than when it contains even a very small admix- ture of lead ; and for this reason, if we do not instantly elevate the temperature when the ceasing of the rainbow colours and the bright light of the globule of pure silver inform us that all the lead has left, — then the silver would cool suddenly, and, of course, quicker at the surface than in the interior or at the bottom, and by this subitaneous contraction cause a spattering 48 THE ASSAYER’S GUIDE. motion of the yet unconsolidated particles, and be productive of great loss to the assay. There is an old adage current among German smelters and assayers, — probably known to all who may have had the advantage of studying this art in that country, where it has been brought to such perfection,— which, since it is many centu- ries old, shows how long it has been re- garded as the great aim, in this mode of testing silver ores, to keep up a moderate temperature as long as any lead is left, and to apply intense heat as soon as all has de- parted. I insert them here : u Kiihl getrieben, heisser Blick 1st des Probierer’s Meisterstiick.” In English it would be : To evaporate coolly and to use heat when pure, is the masterpiece of an assayer. When the buttons of pure silver have cooled, we grasp them firmly with a pair of pincers, tight enough to compress the ASSAY OF SILVER ORES BY HEAT. 49 sides, thus exposing the bottom more, and with a wire brush remove the adhering particles of litharge, and dust of the cupel. Turning them half round so as to make the base a square, we repeat the operation, and then weigh, but only when quite cold, since otherwise the heat, by increasing the bulk, might tend to create a varia- tion. The silver produced in this manner, it should be remarked, is not perfectly pure, chemically speaking, but the slight impu- rities are too insignificant to deserve any attention from an assayer, who has nothing but technical purposes in view, though they might require it from a scientific cnemist ; and for this latter reason, I have thought proper in the third chapter to sug- gest a method to ascertain the exact amount of silver in this button, should it be deemed necessary, though, I must add, that such precision can only be required at mints, if the investigations are not con- 5 50 THE ASSAYER’S GUIDE. ducted for science’ sake, in which case, the wet process would, of course, be preferred from the beginning. Besides this, small inaccuracies in the shape of losses, as has already been re- marked, cannot be averted, even though the assay be performed with the greatest care, as the evaporating, or rather oxid- izing lead probably carries off small par- ticles of silver, particularly when too much heat is used during that process. It is im- possible to give any perfect rules how to obviate such faults, since so much depends on the care and attention paid, as well as on the acquired practice and innate prac- tical skill of the assay er ; yet, pre-supposing all this as perfect, the Parisian mint has established a table to regulate their assays, which will be found on pages 52 and 53. From this it is seen that the different losses with different quantities of silver vary con- siderably, nor is the loss a per-centage, being greatest where the original or true ASSAY OF SILVER ORES BY HEAT. 51 amount of silver in the ore or alloy is seven hundred. This table should always be referred to, as it enables us to calculate the true amount of silver, and to rectify those un- avoidable faults which may be occasioned by the lead carrying off portions of the silver entirely, or else drawing them along with it into the pores of the crucible. 52 III. A Table to rectify the Loss incurred during the Silver Assay. Real amount of silver. Amount of silver found by the assay. Loss during process. 1000 998*97 108 975 973*24 l-7o 950 947*50 2-50 925 921*75 8-25 900 896*00 4-00 875 870*93 4 07 850 845*85 4-15 825 820*78 4-22 800 795*70 4-30 775 770*59 4-41 750 745*48 4-52 725 720*36 4-64 700 695*25 4-75 675 670*27 4-73 650 645*29 4-71 625 620*30 4-70 600 595*32 4-68 575 570*32 4-68 LOSS DURING THE SILVER ASSAY. 53 Real amount of silver. Amount of silver found by the assay. Loss during the process. 550 545-32 4-68 525 520-32 4-68 500 495-32 4-68 475 470-50 4-50 450 445-69 4-31 425 420-87 4-13 400 396-05 3-95 375 371-39 3-61 350 346-73 3-27 325 322-06 2-94 300 297-40 2-60 275 272-42 2-58 250 247-44 2-56 225 222-45 2-55 200 197-47 2-53 175 172-88 2-12 150 148-30 1-70 125 123-71 1-29 100 99-12 0-88 75 74-34 0-66 50 49-56 0-44 25 24-78 0-22 5 * m IV. Gay-Lussacs Process for assaying Silver Alloys . This modus ojperandi is one which, from its very simplicity and shortness, almost necessarily insures success, but it is only intended for alloys, such as coins, and can, therefore, if applied to ores, only be used to ascertain the real amount of silver in the button produced in the last assay, which, as already observed, contains a very minute amount of spurious metals in an alloyed state. It was proposed by Gay-Lussac, and from the indubitableness of its results, has since been introduced in France, and most parts of Germany, to regulate the assays of the mint. They dissolve a given weight of the GAY-LUSSAC S PKOCESS. 55 alloy in nitric acid, and then find a solu- tion of common salt — of which, a large as- sortment of different known degrees of strength is constantly kept on hand in bottles— sufficiently strong to precipitate all the silver as chloride of silver, when used in a certain established quantity. In this manner, the amount of silver is found by the quantity of salt used. (Gay-Lussac on Assays of Silver, q. v.) 56 V„ Assay of Gold Ores by Heat. Those properties of silver, which enable us to assay its ores by the process of cupellation, are so equally characteristic of gold and its ores, that, were I to dwell more at length on this first part of the operation, it would be a mere repetition of what has been said under the head of Silver, and therefore I shall only refer the reader to the remarks given above. When, however, that process is com- pleted, and when therefore with silver we would have procured the final result, the real gold assay only commences, for gold, though always native, contains silver, pla- tinum, &c. I must remark that, since gold ores are almost invariably excessively poor, com- ASSAY OF GOLD ORES BY HEAT. 57 pared with those of other metals, we should arrange our assays accordingly, and commence w r ith a larger amount of ore than is necessary in other cases. For this purpose it is common to begin with six different parts of ore of 50 grs. each, which, after being mixed with lead and borax as with silver, are committed to the muffle in as many separate crucibles. The products are then melted up into two buttons, in two different cupels of the same kind, and these again in the process of extracting the lead are concentrated into one. Of course, when the assay is finished we are obliged to divide the produce by six to ascertain the per-centage amount of gold in the specimen under examination. After having proceeded thus far, it is neces- sary to procure some perfectly pure silver, for which we have the following methods: first, by producing chloride of silver, which is done by precipitating the silver from the nitric acid solution, with muriatic acid, and 58 THE ASSAYER’S GUIDE, melting it in a porcelain crucible, with pot- ash; chloride of potash and the pure silver being thus formed : or secondly by the galvanic process, the virgin metal being thus collected round a rod of zinc immersed in the acid (nitric) liquid from which, as above, the silver has been extracted by adding muriatic acid, but which precipitate must remain in the same vessel. The silver is then preserved in the shape of filings. It is necessary to make use of this silver whenever the quantity of gold in the last produced button is more than one fourth, (hence the term quartation) since experi- ence has shown that if there are not at least about three quarters the amount of silver (rarely the case with ores) in this alloy, the gold would protect the particles of silver from the action of the acid, which, as will become evident from the sequel, would prove fatal to our investigations. Of the pure silver, two and a half times ASSAY OF GOLD ORES BY HEAT. 59 the weight of the buttons of impure gold, and about half the weight of both in pure lead, should be melted up with them in one crucible, (fig. 2, Plate II.) This single button of gold and silver alloy is to be hammered flat on a little steel anvil, and slightly curved, as this shape will allow it more easily to pass through the mouth of a little vial, in which it is now placed to be boiled with nitric acid (2 drams) of from 1 to 3 specific gravity. The vial should be round at the bottom as this is performed over a spirit-lamp. We allow the liquid to boil until the yellowish vapours of nitrous acid gas have ceased to be emitted. The gold is then pure, and requires only to be boiled a couple of times in water to remove the acid, and then to be heated to redness to evapo- rate the water, to enable us to weigh it, which, as with all other assays, should never be done till the metal is perfectly cold. 60 THE ASSAYER’S GUIDE. If a small portion of platinum be in the ore, it will be found in the nitric acid solution of silver. (See Platinum.) The original amount of silver may be ascertained by deducting the weight of the gold from the button produced before the other pure silver was added. Assay of Gold Ores by Amalgamation . This method is founded on the fact, that gold unites with quicksilver to form an amalgam, for thus the alloys of mercury and other metals are termed. It is one that may answer for peculiar circum- stances, though it is not accurate enough to serve as a regular dokimastic* test, since lead and silver also produce amalgams. We require pure mercury for this pur- pose; and as the quicksilver of commerce generally contains some lead, we must pu- rify it by pressing it through a piece of buckskin. The powdered gold ore, which ought * A technical term, derived from the Greek verb to try, to test the purity of a thing. 62 THE ASSAYER’S GUIDE. first to be reduced in volume by washing, is brought in contact with the quicksilver, the sand or gangue-rock removed by sift- ing the mass through a coarse cloth; after which, by forcing the quicksilver through some buckskin, the amalgam is retained. By evaporating the mercury in an iron spoon over a lamp, the gold is procured, which will, however, still be found to con- tain silver or lead, if these occur in the ore. 63 VII. / Assay of Gold by Washing . This is a way of ascertaining the ap- proximate value of a gold ore, which hardly deserves being called an assay, although, with an experienced hand, tolerable accu- racy may be attained. . It is based on the fact, that gold is much heavier than quartz or other ganguerock, and therefore the rock should be well pounded for this operation. The process is precisely the same as that used to extract gold from the sand of river beds, and which is now so extensively em- ployed in California. Even the vessels used are frequently of the same kind, though it is better to have a small glass cylinder, about three times the length of the part that will be occupied by the ore, 64 THE ASSAYER’S GUIDE. and three-quarters of an inch in diameter, closed at the end, like a common chemical test-glass. I would suggest, if, where used, the gangue-rock or sand be always of the same kind, having a mark round the tube made with a slight scratch of the diamond, up to where a certain quantity by weight of the ore would reach. One hundred grains would not be too much, if, for in- stance, the rock is quartz; and it is also the most convenient amount, from the facility thus afforded in afterward calcu- lating the per-centage. Under circum- stances where we have to deal with ores in which the original rock is not always the same, it would be well to have several such tubes, to each of which its peculiar rock might be allotted; or one with dif- ferently marked lines. In this manner, one such line might indicate the part of the tube which would be filled by a hun- dred grains of the quartzose ore, another the portion which would be occupied by ASSAY OF GOLD BY WASHING. 65 the same weight of a talcose one, and so on. The lines will vary in height as the ratio of the various specific gravities of the respective ores. When the properly pulverized ore has been placed in the glass tube, the latter should be filled up two-thirds with water, and tightly corked ; after which, by repeated shakings, the gold will be collected below. By careful decanting and continual shak- ing, we can remove the sand and particles of rock, and retain the gold as a matter of course, though only in its natural, alloyed state. This method will be found to be a con- siderable improvement on the washing in pans. If the ore contains iron pyrites, it is best to calcine it first, though carefully, so that no gold is carried off mechanically by the gases formed. 6 * 66 VIII. Assay of Gold Ores hy a Wet Process . Although I have tried to make it a point to introduce as few wet processes as possible into this treatise, I now venture to give directions for one which will be found very available to ascertain the true amount of gold, when the gold has been extracted in its natural state by the last- given methods. It is characterized by the ease with which it can be performed. The residue of alloyed gold produced by washing the ore or sand should be sub- mitted to the action of concentrated aqua regia, (consisting of from three to four parts of muriatic acid, to one of nitric,) by which all the gold is extracted. All the plati- num, if that metal be present, will be pre- cipitated as below from this liquid. ASSAY OF GOLD ORES BY A WET IROCESS. 67 The solution should then be filtered off with the greatest care, water being after- ward poured on to wash the insoluble parts, and to procure the whole of the dis- solved gold. Sal-ammonia is then to be added, and if causing a precipitate, the in- fusion filtered again. This latter is then evaporated to dryness, and alcohol of 0*84 specific gravity repeatedly added, and after digesting poured off, until no more coloured by the dissolving chloride of gold. Iron vitriol (copperas) in solution, if poured into it, will precipitate the pure gold as a brown powder, which may then be filtered, washed, heated to redness, and weighed. 68 IX. Assay of Silver Coins , or Alloys of Silver and Copper. As a matter of course, with these alloys it is not necessary to perform the operation, which is done with the ores, of first sepa- rating the gangue-rock. We proceed with the cupellation, as soon as by prior tests we have ascertained the probable amount of silver and copper. To know this more accurately no method exists, except a previous hasty cupellation, though to a practised assayer it is cognisable from the greater specific gravity, whiter colour, and increased malleability of the more argen- tiferous alloys. It is necessary previously to become acquainted with this, as the quantity of lead must be taken accordingly. By adding too much, a loss of silver is ASSAY OF SILVER C; INS. 69 incurred, while, if too little is used, we will not be able to procure a pure silver button, as not all the copper will pass over into the litharge. The table to regulate the requisite quan- tity of lead, was calculated by Erker. Still later, D’Arcet arranged another, which, though less simple, experience has shown to be no more accurate, and it is for this reason that I have subjoined the former. 32 parts of the Alloy containing Require in parts of Lead. Relative quanti- ties of Copper to Lead. Parts in Silver. Parts in Copper. 31 1 128 1 : 128 80 2 192 1 : 96 28 4 256 1 : 64 24-26 8-6 320 1 : 40-53 18-24 14-8 448 1 : 32-54 8-16 24-16 480 1 : 20-30 2-8 30-24 512 1 : 16-21 From this table, it is evident that the relative amount of lead should decrease as the copper increases, although the more copper the alloy contains, the more lead should be used. 70 THE ASSAYER’S GUIDE. The only way to pulverize a coin or alloy is to file off small portions. About a gramme or fifteen grains of the filings should be carefully weighed off, wrapped in paper, (satin paper is the best, giving little ashes,) to prevent small particles from being lost, and placed in the muffle furnace on the cupel, fig. 2. When the paper is burnt to ashes, the lead is added according to the table. The rest of the assay is exactly as with silver ores. As long as lead and copper are being oxidized, no severe heat should be employed, which is, however, done as soon as the bright flash appears. The alloy or coin may also be treated according to Gay-Lussac’s process, already described. Having thus ascertained the amount of silver, we are easily enabled to calculate that of the copper, by subtraction. 71 X. / Assay of Gold Goins , or Alloys containing Gold , Silver , and Copper. Before making the regular assay, it is necessary to ascertain the probable contents of the alloy, as with silver. The method commonly used is the touchstone or hesanite test, the same employed by goldsmiths when purchasing coin or bullion. A dark fine-grained basalt or siliceous slate is re- quired, and on this a line is drawn with the gold coin. Those whom business has fre- quently brought in contact with such alloys are generally able to judge pretty accurately by this alone, as the purer it is, the brighter the yellow, silver making it whitish, copper of a redder hue. To carry this test out farther, the mark is moistened with an acid, which, dissolving the baser 72 THE ASSAY E-Il’s GUIDE. metals, leaves the gold in its virgin state. This acid consists, in thousand parts, of 784 parts of pure nitric acid, of 1.340 specific gravity. 16 “ “ u muriatic acid, of 1.173 spec. gray. 200 u u u distilled water. 1000 As with gold ores, several assays should be made at once, to regulate one another. When some of the alloy has been filed off • — too small pieces ought not to be taken, on account of their liability to be blown away- — these particles should be carefully brushed, to remove the fine dust, which might otherwise only drop off after weigh- ing, and thus cause a decided loss. For the assays, 5 grains are used in each, and the value of the gold is afterward given in carats fine, pure gold being reckoned at 24 carats fine. In this way an alloy containing 91.666 per cent, of gold will be 22 carats fine, or in other words, it contains | or ~ of pure gold to ^ of the alloyed metal. ASSAY OF GOLD COINS. 73 After having weighed off the above quantity of the gold to be tested, three times the weight of the expected amount of gold, as ascertained by the prior inves- tigations, are taken in pure silver. Some deem two and a half sufficient. The gold and the silver are then carefully wrapped in a piece of paper. It is now necessary to ascertain the required quantity of pure lead, which varies according to the per-centage of cop- per in the coin or alloy. As this metal has a much greater affinity for gold than for silver, it is much more difficult to sepa- rate it from its alloys with the former than with the latter, and for this reason the lead used should be about twice as much as would be necessary, were we assaying a coin consisting of silver and copper. The following table is given by D’Arcet to regulate the amount to be used : — 7 74 THE ASSAYER’S GUIDE. If the contents allce In 1,000 parts. of gold in the is In carats fine. The quanti- ty of lead re- quired is Relative quantity of lead to the copper. 1.000 24. 1 0 0.900 21.6 10 100.000 to 1 0.800 19.2 16 80.000 to 1 0.700 16.8 22 73.333 to 1 0.600 14.4 24 60.000 to 1 0.500 12.0 26 52.600 to 1 0.400 9.6 34 56.666 to 1 0.300 7.2 34 48.571 to 1 0.200 4.8 34 42.500 to 1 0.100 2.4 34 37.777 to 1 As with silver assays, if too much be employed, it will produce a loss, while too little would not extract all the copper. The lead is first placed in the cupel, (fig. 2,) and only when the process of oxid- ation has commenced, is the paper contain- ing the gold and silver to be added. The rest is performed exactly as with gold ores. The button should be hammered to a very thin sheet, before being submitted to the nitric acid; and to do this well, it should be perfectly cold, as otherwise marginal ASSAY OF GOLD COINS. 75 cracks are often produced, which again may be productive of loss. It may not be quite out of place here to give the contents of pure gold in carats fine, and the weight and value of the United States gold coins, as well as of those of other nations, made legal tender with us, according to the act of Congress of June, 1834. By an act of that date, the standard value of our eagles, and other gold coins in proportion, was changed; as will be seen from the subjoined table, which has been taken from the American Almanac of 1835, page 153. Names of Coins, and Countries where minted. Weight. Cont. in pure Gold. Assay. NewValue since July 31, 1831. United States. Eagle coined be- dwt. grs. grs. ear. grs. dol. cts. m. fore July 31, 1834 Do. since then, double and 11 6 247-5 22 — 10 66 5 shares in proportion Brazil , Johannes, * in propor.. 10 18 18 — 232 21 21* 21 3| 10 17 6 4 Dobraon 34 12 759 22 — 32 70 6 Dobra 18 G 401-5 22 — 17 30 1 Moidore, * in proportion 6 22 152-2 22 — 6 55 7 Crusado 16* 14-8 21 3$ — 63 8 : Colombia. Doubloon 17 9 300-5 20 3 15 63 5 England. Guinea, * in propor. 5 8* 118-7 22 — 5 7 5 , Sovereign do 5 2* 113-1 22 — 4 83 8 76 THE ASSAYER S GUIDE. Names of Coins, and Countries where minted. Weight. Cont. in pure Gold. Assay. New Value since July 31, 1834. dw. grs. grs. car. • grs. dol. cts. m. England. Seven Shilling Piece. 1 19 39-6 22 1 69 8 France. Double Louis coined before 1786 10 11 224*9 21 2 9 68 8 Louis do 5 112*4 21 2 4 84 3 Double Louis coined since 1786 9 20 212*6 21 9 16 2 Louis coined since 1786 4 22 106*3 21 4 4 58 1 Double Napoleon, or 40 frs... 8 7 179 21 7 70 3 Napoleon, or 20 francs 4 H 89*7 21 2* 3 86 6 Mexico. Doubloons, shares in proportion 17 9 360*5 20 3 15 53 5 Portugal. Dobroan .. 34 12 759 22 32 70 6 Dobra 18 6 401*5 22 17 30 1 Johannes 18 __ 17 6 4 Moidore, J in proportion 6 22 152*2 21 CO 6 55 7 Piece of 16 Testoons, or 1600 rees 2 6 49*3 22 2 12 1 Old Crusado, or 400 rees — 15 13*6 21 8| — 58 8 New do. or 480 rees — 161 14*8 21 8* — 63 7 Milree coined in 1755 — 19f 18*1 21 3§ — 78 New Dobra... 17 6 22 16 25 3 Joannese, double in propt. ... 9 6* 21 3f 8 76 3 i do. 4 15 21 3f 4 37 1 Piece of 12 Testoons, or 1200 rees 1 16i 21 1 57 4 Do. of 8 Testoons, or 800 rees. 1 21 3-f 1 12 - Spain. Quadruple Pistole, or Doubloons, 1772, double, single, and shares in propt. 17 8* 37*2 21 2* 16 3 8 Doubloon, 1801 17 9 360*5 20 3 15 53 5 Pistole, 1801... 4 H 90*1 20 3 3 88 4 Coronilla, Gold Dollar or | Yintem, 1801............ ...... 1 3 22*8 20 1*1 — 98 3 77 *!■ To find the Proportion of Gold in a mixture of Gold and Quartz by Calculation* The specific gravity of gold =19.000 The specific gravity of quartz = 2.600 These numbers can be corrected when ^experiment shows the specific gravities to be different. A. Ascertain the specific gravity of the mixture of gold and quartz. Suppose it to be 8.067. B. Deduct the specific gravity of the * This article is taken from J. A. Phillips’s “Gold Mining and Assaying/’ (London, 1852,) p. 85, a work published since the first edition of this little volume, and one which, like the other productions of its author, it is needless more particularly to recommend to those who pay attention to the recent publications in this department of applied chemistry. 7* 78 THE ASSAYER’S GUIDE. mixture from the specific gravity of the gold : the difference is the ratio of the quartz by volume : — 19.000 — 8.067 = 10.933 C. Deduct the specific gravity of the quartz from the specific gravity of the mix- ture : the difference is the ratio of the gold by volume 8.067 — 2.600 = 5.467 D. Add these ratios together, and pro- ceed by the rule of proportion. The pro- duct is the per-centage of gold by bulk : — - 10.983 + 5.467 = 16.400 16.4 is to 5.467 as 100 is to 33,35 E. Multiply the per-centage of gold by bulk, by its specific gravity. The product is the ratio of gold in the mixture by weight 33.35 x 19.00 = 633.65 F. Multiply the per-centage of quartz by bulk, by its specific gravity. The product PROPORTIONS OP GOLD. T9 is the ratio of the quartz in the mixture by weight : — 66.65 x 2.60 = 173.29 G. To find the per-centage of gold, add these ratios together, and proceed by the rule of proportion : — 633.65 + 173.29 = 806.94 806.94 is to 633.65 as 100 is to 78.53 Hence, a mixture of quartz and gold, having the specific gravity of 8.067, con- tains 78.53 per cent, of gold by weight. 80 XII. Assay of Platinum Ores . This metal lias as yet occurred in the United States only in gold ores, and even then in the merest traces, and hence, per- haps, it would barely deserve a mention in these pages ; but the great interest attached to its occurrence, as so rare a metal all over the world, and its useful application to chemical purposes, has caused me to insert some rules for its assay. If the ore contain platinum in no larger amount than three or four per cent, of the gold, the former, as already observed in Article V. on quartation, will be entirely dissolved in the nitric acid used on ac- count of the silver. From this solution of the two metals precipitate the silver with common salt, or muriatic acid, as chloride ASSAY OF PLATINUM ORES. 81 of silver; filter and wash until the water dropping from the funnel no longer con- tains any of the platinum solution. This latter evaporate to dryness, after adding sal-ammonia. Wash it with alcohol, (see Gold, art. VIII.) and heat the double chlo- ride of platinum and ammonium to red- ness, thus producing a spongy mass of pure platinum. If there be more than three or four per cent, of platinum in the gold, its presence is readily perceived, from various circum- stances: thus, in evaporating the lead a higher temperature is necessary than is commonly the case, to make the metal flow and acquire a round form ; secondly, the bright light cannot be observed; thirdly, the surface of the button is crystalline or rough, and when large, flat and quite ir- regular, besides looking dull and having a more or less grayish colour; fourthly, the nitric acid is frequently discoloured; and fifthly, the little roll of gold is not of a 82 THE ASSAYED' S GUIDE. pure gold yellow, but rather inclining to- wards steel gray. After having thus recognised a larger quantity of this metal, it becomes neces- sary, since copper is frequently present, to make a prior test, to ascertain, by cupella- tion, the amount of the alloy of gold and platinum. After that, two assays should be made; the one, to ascertain the exact conjoint per-centage of the two; the other, inquartation (pure) silver being added, to discover the amount of the gold alone. The difference of the two results gives the amount of platinum. The inquartation silver should not be more than from two and a half to three times the weight of the alloy of gold and platinum ; and it is often well to add a certain, accurately weighed quantity of pure gold at the same time, so that the gold may afterward be procured in one connected sheet or piece. This ought particularly to be done, when there is as much as a third the weight of the ASSAY OF PLATINUM ORES. 83 gold in platinum, as, for instance, in the platinum grains of the Ural Mountains, which contain about 80 per cent. The button is hammered flat, and proceeded with exactly as gold ores, the platinum dissolving with the silver in nitric acid. But as it does not do so as easily as the latter, at least when in large quantities, it is necessary to repeat the process from the quartering on once or twice, using silver and lead over again. This should be done until nothing but the silver used is dis- solved in the nitric acid, or, in other words, until two assaj's following one another have produced the same results, a thing that may not occur until the fifth time. It should be remarked, that it is neces- sary to add a little more lead for cupella- tion, than would be done if no platinum were in the ore; and also, that just before the bright flash of light occurs during the operation of quartering, it is well to shake the cupel a little, to make the button 84 THE ASSAYER’S GUIDE. stiffen, as soon as the last lead has entered the former, by which the platinum will be more regularly distributed in the alloy, and cannot so well collect in different uncon- nected lumps, unexposed afterward to the action of the acid. The platinum may then be extracted and reduced from the solution, as above. 85 XIII. Assay of Copper Ores — German and Hun- garian Method. This ore, if a sulphuret, as is very gene- rally the case, should, after having been reduced to the finest possible powder, be submitted to the process of roasting, vul- garly termed calcining. For this purpose one part by weight of the ore is mixed up with one fifth of graphite, (black-lead,) which, consisting of carbon in a more con- densed state than that element occurs in charcoal, is, therefore, so much the more effectual in driving off the sulphur. This mixture of the two should be exposed to an intense red-heat in the cupel, (fig. 1,) (painted over on the inside with red chalk, or Spanish red, to prevent adhesion,) for about twenty minutes, after which it is 8 86 THE ASSAYER’S GUIDE. to be taken out, and stirred up with a small iron ladle to expose the unburnt parts of graphite, when it should again be exposed in the muffle. In about a quarter of an hour we take it out again, pound it over, for the mass is generally clogged, and mix it with about twice its weight of charcoal- dust, after which we continue the roasting for about one-half to a full hour, according as the ore contains a little or much sul- phur, vapours of which may be seen rising during the whole of this process. After this the ore has a reddish, or what is generally called a ferruginous colour, and we now take it from the first, crucible, and introduce it into that represented in fig. 4, Plate II., or if not in possession of such, into a Hessian crucible, fig. 5, on the same plate. For this purpose, however, some black flux should be provided. It consists of carbonate of potash and lime, and is made by igniting together one part by weight of saltpetre, and two of com- ASSAY OF COPPER ORES. 87 mon tartar. The flux produced should be kept carefully corked to prevent the ab- sorption of hygroscopic water. It is still better to make it only when required for immediate use. If the ore is poor, one tenth part by weight of oxide of antimony, (antimonious acid,) or of arsenic, (arsenious acid,) or if it is richer, fifteen per-cent, of pure lead* are requisite, as will hereafter be seen to make the particles of copper unite. One of these 'together with three parts of black flux, one half the weight in borax, and two parts of table salt, must then be added to the roast- ed ore, though none except a part of the * Some assayers use neither of these three, on the ground that the arsenic, as occasionally even 40 per- cent. may be taken, is very difficult to separate from the copper, and that the antimony may unite with part of the same, forming an antimoniate. They therefore only employ borax and black flux, in about the same proportions, however, as given above. It is hard to say which is best, and it must be left to the discretion and experience of the assayer to act as may be most suitable to his peculiar ores. 88 THE ASSAYEIl’S GUIDE. flux are mixed with the mineral now in- vestigating. The salt is merely used to form a crust over the whole. When all have thus been placed in the crucible, they are covered over with a piece of charcoal, cut to match the size of the vessel ; after which the cover is put on. We then ex- pose it to a white-heat for about one-half to one full hour, as may be most conve- nient, either in the draught furnace, fig. 6, Plate I., or in the muffle furnace; in which latter case, we must allow the longest period of time. The carbon of the flux is intended to reduce the peroxide of copper produced by roasting, while its carbonate of potash unites with the earthy contents of the ore and the oxides of other metals present, such as iron, which would otherwise also be reduced to their metallic state. With these it forms a slag, the borax being added to make it flow easy, and allow the copper to collect in one button. ASSAY OF COPPER ORES. 89 On cooling, we break open the crucible, and, on removing the slag, extract a spheri- cal piece of' impure or alloyed copper, according as other metals may chance to occur in the ore. If any intermediate crust should have formed between the button and the slag, the ore was not proper- ly roasted, a part of the copper not reduced, and consequently the assay is worthless. In a good assay the slag should be black and vitreous in appearance, never of an 'earthy texture. If striated or speckled with red, we may know that protoxide of copper is dissolved in it, and again that the whole cannot be productive of an accurate result. Much attention is required during this test, and, as already mentioned under the heads of silver and gold, the final result depends entirely upon the care taken by the assayer. If well managed, however, as here directed, he can hardly fail to be suc- cessful. The button, as remarked above, may 8 * 90 THE ASSAYER’S GUIDE. vary in purity. It generally contains some iron, and (since these metals frequently exist in copper ores) lead, bismuth, tin, cobalt, nickel, antimony, and arsenic — the latter two in particular, if they were added in the process of reduction. Thus it very rarely, if ever, happens, that a copper ore is sufficiently pure to require no third process. The less admixtures the alloy con- tains, the less brittle and the more ductile it is. Nickel particularly tends to harden it. To remove the foreign metals, the button is put in a piece of paper, with sufficient borax to cover it, (one-fourth to one-third part by weight, rather more than less,) and if no lead occur in the ore, with about from five to ten per-cent, of that metal, which amount, however, should increase up to forty, or even more, if there are many impurities in the alloy. Even if this be not the case, it is always safer, and can never produce any bad effect, to add much. A crucible of the kind illustrated in fig. 3, ASSAY OF COPPER ORES. 91 Plate II., should be brought to a bright white-heat in the muffle. Coals may be placed round to increase the temperature, which should be so great, that the copper, on being introduced, trapped in paper with borax and lead, may melt in a few minutes. As long as the tongs held over the button are reflected, or rainbow colours are yet seen to flicker over its surface, lead is still present. As with silver and gold, too great heat ought not to be employed. When the lead has left, we immediately take out the crucible, and immerse it in water, to pre- vent any copper from oxidating unneces- sarily. The button of pure copper is then broken out and weighed. A slight loss can- not be prevented, as it is impossible to pre- vent some oxide of copper from being formed, and we must therefore grant a larger per- centage than the assay would direct. At least two assays should be made at once, to compare the results, and take the average. 92 XIV. Assay of Copper Ores — English Method . At the copper mines in Cornwall, a mode of assaying is employed, which in several of its minutiae differs considerably from the one just described. It should be remarked that this method is, properly speaking, only applicable to sulphurets, as all copper con- tained in the ore as a pure oxide, or com- bined with an acid, will pass over into the slag during the reduction process ; and that therefore if these latter are present, some means should be employed, as shall be shown hereafter, to extract them from the slags, when the other parts of the assay are concluded. The ore, being a sulphuret, should be roasted as directed in the foregoing Ger- man or Hungarian method, after which it ASSAY OF COPPER ORES. 93 is mixed with from one to one and a half parts of pounded glass, which should, how- ever, contain no lead or arsenic, from twenty-five to fifty per-cent, of saltpetre, / and fifty per-cent, of borax. Together with these, it is exposed to a strong melting heat in a clay crucible. On cooling, the button is removed, as is the case in the other mode of procedure, more common on the conti- nent of Europe. Having thus reduced the copper, it is ne- cessary to purify it, as was also done in the other assay. I must observe, however, that this part of the Cornwall process, again, can only be applied where very little lead is contained in the copper ore. For this purpose, some white flux should be prepared, which is done by igniting to- gether equal parts of saltpetre and tartar. Being as susceptible to the effects of atmo- spheric moisture as black flux, it requires the same precaution as regards its preser- vation. 94 THE ASSAYER’S GUIDE. The button of copper alloy is then ham- mered out flat, to a sheet as thin as it will allow of, without breaking. It is then ex- posed in a crucible, (fig. 3,) already red- hot, and, as soon as it melts, covered with white flux. Some table-salt, from which the water of crystallization has been re- moved by heat, is frequently added to give a covering and protect the copper from too immediate contact with the atmosphere, which, together with the heat, would un- avoidably create a free oxidation. A con- siderable ebullition is produced, on the sub- siding of which, and when therefore the mass flows quietly, the contents of the cru- cible are poured into an iron mould, (fig. 6, Plate II.,) greased over beforehand, from which the mass should be removed with a pair of tongs, as soon as sufficiently consoli- dated, to be dipped in water, which ena- bles us to separate the slag from the copper with greater ease. The purity of the latter is known by its malleability, and by its ASSAY OF COPPER ORES. 95 not cracking much at the margin, when stretched on the anvil under the blows of a hammer. Should this test prove its yet uncleansed state, it ought again to be sub- mitted to the operation just concluded. Sometimes it is necessary to repeat this several times. It has already been mentioned, that, par- ticularly when not all the copper in an ore is contained in the shape of a sulphu- ret, it is impossible to prevent some of this metal from escaping into the slag; and therefore, to diminish this loss as much as possible, English assayers collect the slags, both of the reducing and of the purifying processes, and, pounding them up together, mix them with an equal quantity of tartar and some powdered coke. This mixture is then melted in a Hessian crucible, after being covered over with com- mon salt. The little button produced in this way is of course impure, and requires the same treatment as the larger one, origi 96 THE ASSAYER’S GUIDE. ii ally procured. This second button is weighed together with the large one, and the result will give very accurately the per-centage of copper in the ore. 9T XV. Assay of Lead Ores by Heat . There is no way of assaying lead ores by heat which gives the full amount of the metal, as it is so easily oxidized by a high temperature. Generally, the loss varies from one-sixth to one-twelfth, or yet more commonly is about a tenth; and for this reason, the result of the assay should after- ward be increased by A, on giving the per- centage of lead. The assay is performed in the crucible, fig. 4, or in the Hessian one. The part of ore used ought to be about two hundred grains, as lead ores (galena, a sulphuret of lead is the most common) are very heavy, and therefore are comparatively small in bulk. Three parts, or here six hundred grains, of black flux are mixed up with the 9 98 THE ASSAYER’S GUIDE. powdered ore. A little piece of very thick wire, or of a round iron bar, weighing from thirty to forty per-cent, of the weight of the lead ore, is placed on the top, in the crucible. We then expose the whole to a strong, steady red-heat, for about an hour, in the bellows furnace, fig. 6, Plate I. This is ef- fected by first placing the crucible on the brick, and then making a layer of cold burnt coals, as high as the brick. On this come the live coals, and on them the un- burnt ones up to the top of the furnace. When burnt down, we take out the cruci- bles, and thus obtain a button of pure lead and some slag, besides a remaining portion of the iron. The latter should be added in excess, to insure the entire absorption of the sulphur. Galena contains, in hundred parts, 13.45 parts of sulphur to 86.55 of lead, which Would require 22.67 parts of metallic iron to form sulphuret of iron, consisting of 37.23 ASSAY OF LEAD ORES BY HEAT. 99 parts of sulphur to 62.77 of iron. If, there- fore, two hundred grains of the ore are used, the iron should weigh from 60 to 100 grains. Filings ought never to be used, as they are always covered, to a smaller or greater amount, with oxide. Besides, it is very difficult to get them as free from im- purities as wire. Weighed pieces of the latter should be kept in some vial or box for this purpose. 100 XVI. Assay of Lead Ores by a Wef Process. This method will be found much the more accurate of the two, although it may not often happen that a practical assayer has sufficient time for this proceeding. (See Woehler’s Anal. Chem.) The ore (galena) should be powdered much finer even than in the assay by heat, after which it is moistened with fuming nitric acid, and digested in the sand-bath, by which process it is entirely changed from the sulphuret to the sulphate of lead. If the mass be diluted with water and filtered, the merest traces only of lead can be found in the solution,— quantities too small to deserve any farther attention. If the ore contain copper, iron, or silver, they will be contained in this filtered solution ; ASSAY OF LEAD ORES BY A WET PROCESS. 101 the first are then discovered by ammonia, the latter by muriatic acid. Should fuming nitric acid not be at hand, and if therefore a weaker kind is used, a mixture of sulphate of lead and sul- phur is produced, together with a solution of nitrate of lead. From this latter the metal should be precipitated with sulphuric acid. By heating the dried residue, — after filtering and washing, by pouring water qver it while yet on the filter, — sulphur is evaporated and sulphate of lead is retained. In both cases, the lead produced is a sulphate, and in this shape it should be weighed, and from the result the amount of the former alone may be easily calcu- lated, as will be seen from the sequel. Sulphate of lead consists, in 100 parts by weight, of Oxide of lead . 73.56 Sulphuric acid . 26.44 9 * 100.00 102 THE ASSAYER’S GUIDE. and the oxide of lead, again, of Lead ..... 92.83 Oxygen .... 7.17 Hence we say, if 100 parts of oxide of lead contain 92.83 of pure lead, then 73.56 of pure lead contain 68.285748 parts; or, in other words, sulphate of lead consists ot Lead . . . 68.285748 Oxygen . . . 5.274252 Sulphuric acid . 26.440000 100.000000 For this assay about twenty grains only need be taken. A smaller amount might make us incapable of finding the real quan- tity of lead, while a larger one would only give us unnecessary trouble. 103 XVII. Assay of Iron Ores by Heat . One part of the ore, about a hundred grains, thoroughly pulverized, is mixed with from thirty to a hundred grains of calcined borax. The quantity of the latter varies according to the purity of the mineral, and increases when it contains many foreign admixtures. If the ore contains Sulphur, it ought first to be roasted, as was the case with the assays of other metals already described. A Hessian crucible is then prepared with coal, as already directed in the description of those vessels under the head of Utensils and Implements. Into the hollow in the centre, the mixture of ore and borax is poured, and on that some charcoal powder; after which the cavity is entirely covered 104 THE ASSAYER’S GUIDE. with a piece of charcoal. The crucible is then closed, the number of the assay being marked on the inner surface of the cover. This is then fastened down air-tight with some putty. The iron ore, after these preliminary arrangements, is to be submitted to a reduc- tion process in the furnace, fig. 6, Plate I., which lasts about three-quarters of an hour. At the extensive iron-works on the Hartz Mountains in the interior of Germany, a very simple apparatus is used instead of the other furnace, of which, on account of its portability, I here give a description. It consists simply of an open cast-iron pot or jar, measuring about a foot across, and one and a half in height, and having a plate of sheet-iron, perforated with many little holes an inch in diameter, instead of a grate. This leaves a vacant space of about two inches below, to receive the ashes. The latter partition has two open- ASSAY OF IRON ORES BY HEAT. 1G5 ings ; one, the door to take out these cin- ders — the other, to introduce the end of the bellows. Above the iron plate, on which r the crucibles are directly placed, without any brick, a coating of fire-clay, an inch thick, extends to the mouth of the jar. The latter is furthermore supplied with three or four short legs, and a handle on each side. In this furnace the process lasts about an hour and a quarter. In both cases, the button produced con- tains exactly the same impurities, carbon, earths, acids, or other metals, as pig-iron would, if procured from the same ore, and therefore this assay is only to be used for furnaces. For these it entirely suffices; but to ascertain the true amount of pure iron, the wet analysis should be resorted to, the same as with other ores ; and it is for this that I shall give directions in the next chapter how to discover or calculate the real per-centage of the pure metal, or to 106 THE ASSAYER’S GUIDE. assay the pig-iron produced in the process by heat. It may not be uninteresting to many, who may honour these pages with their perusal, to become acquainted with a me- thod for obtaining chemically pure iron, as given by Karsten in his famous and voluminous works on this metal. It is described in vol. i., pages 167, 168. He says, to procure chemically pure iron, take the best bar-iron of commerce, e. g. Swedish iron in the shape of small wire ; cut it up in short pieces, and then mixing it with about a fourth part by weight of oxide of the same metal, melt it in a Hessian cru- cible. To cover it, use a compound flux, consisting of pure quartz, pure lime, and equally pure carbonate of potash, in pro- portions capable of furnishing a glass or slag, not flowing too easily, but of rather a tough consistency. For the manufacture of an oxide of iron, free from all admixtures of foreign metals, ASSAY OF IKON ORES BY HEAT. 107 it is best to use small clean wire, oxidizing it by vapours of water. The button thus produced has a re- markably white colour, a strong metallic lustre, and is more ductile than the best varieties of soft bar-iron. Particularly cha- racteristic, however, is its great specific gravity, amounting to 7.9654, while that of wrought-iron is 7.6 to 7.9, and of cast- iron only from 7.0 to 7.5. The only im- purity this metal may be discovered to possess occurs as slight traces of silicium, and therefore it may be considered to be as pure as it possibly can be made, even by a process conducted only upon the rules and principles of wet analysis, and thus in this shape it is utterly unknown to the mere practical metallurgist or smelter. 108 XVIII. Fvdiss Process for Iron Ores and Iron. This method, though remarkable for its simplicity, is a very sure one, not only to ascertain the quantity of iron in an ore, but to acquaint us with the peculiar degree of oxidation in which it exists, and also the amount of each oxide, which it is often not only very interesting, but useful to know. Many ores, particularly the magnetic ones, contain both the peroxide and the prot- oxide, and the only ones to which this process cannot be applied are those con- taining arsenious acid, not a very common ingredient. The process discovered or invented by Fuchs is founded on the fact, that chemically pure muriatic acid, when atmospheric air is excluded, is incapable of dissolving any FUCHS’S PROCESS FOR IRON ORES. 109 copper; but that, when peroxide of iron is contained in it, a corresponding quantity of Jhat metal becomes soluble, a muriate or chloride of iron and chloride of copper being thus formed. The ore is dissolved in muriatic acid, and, if necessary, filtered. A small round-bot- tomed vial should be used. Into the solu- tion a clean weighed strip of copper is placed, and the vessel corked, and covered with a piece of bladder, tied down round the neck until we are ready to boil it. This is best done in a water-bath, and should last until no more copper is received by the acid. The former is then taken out, well washed in water, dried with a towel, and immediately weighed. The difference in the weight of the copper is all that is required to ascertain the amount of peroxide of iron in the ore, for we need only multiply this by the equivalent of peroxide of iron, which Fuchs takes to be 10, and divide the product by 10 no THE ASSAYER’S GUIDE. 31.7, the equivalent of copper. The quo- tient gives the quantity of peroxide con- tained in the solution or ore. To know the whole amount of iron in it, we need only weigh off another part, (10 — 15 grs.,) dissolve it in muriatic acid, and then digest with chlorate of potash, to transform the protoxide into peroxide, after which, copper will decompose the whole. Instead of 40, the equivalent of peroxide of iron, we insert 28, the equivalent of the pure metal, into our calculations. By sub- tracting the amount of the peroxide from the last result, the amount of the protoxide is found. The presence of alumina, silica, &c. has no effect on this assay, though the existence of copper in it would represent the ore as poorer than it really is. The latter, how- ever, rarely occurs in common iron or its ores except in mere traces, and, as such, it produces no material difference. Ill XJX. Assay of Quicksilver Ores . This metal is one of those which some- times occur in the virgin state, though by far the most common shape in which it presents itself is the bisulphuret, commonly termed cinnabar, which in its perfectly pure state consists of : — Mercury .... 86.287 Sulphur .... 13.713 100.000 Its formula being Hg S. A specimen from Japan, analyzed by Klaprcth, gave: — Mercury .... 84.50 Sulphur . . . . 14.75 99.25 Which, though it must have contained 112 THE ASSAYER’S GUIDE. 0.75 of other ingredients not mentioned in the analysis, shows that it possessed as much as, according to the above-calcu- lated composition, it could be expected to contain. It is not the place here to give the analyses of other casual occurrences of this metal, such as perhaps are only to be found in the cabinet of the mineralogist; and I shall therefore proceed to describe the manner in which the assays of mercurial ores are performed. In all cases the mercury is procured by simple distillation, for which purpose, where not originally uncombined, it is necessary first to disengage it. In distilling quicksilver, an iron retort covered outside with a coating of clay is commonly used. The neck should be so contrived that it can be unscrewed, to facilitate cleaning the interior. Ketorts or tubes of clay, glazed externally, are also applicable, and are preferred by some; but ASSAY OF QUICKSILVER ORES. 113 those of iron are safer, inasmuch as the vapors of mercury cannot possibly pene- trate and escape through them. To produce the necessary heat, which should not exceed a mild red, any conve- nient furnace, such as the one described on page 104, will answer. Any tumbler or beaker-glass containing cold water may be employed as a condenser. It must, however, be remarked here that the mouth of the retort ought not to be inserted into the water, because in that case, on cooling, the water would rise up into it. To avoid this, and yet to prevent the escape of the mercurial vapors, a wet wrapper of paper or linen is bound round the neck of the retort, protruding sufficiently to permit of the other end being completely immersed in the water. Some assayers employ a little bag tightly attached to the retort. The fluxes used are various, and, accord- ing to their efficiency, may be enumerated thus, the first being the best :■ — 10* 114 THE ASSAYER’S GUIDE. Black flux, from one-half to full weight of ore. Carbonate of soda or of potash, one-half u u Iron filings, from a quarter to a half u u Carbonate of lime, one-half to full u u With charcoal powder, one-tenth to one-eighth “ The black flux produces with cinnabar, besides liberating the mercury, sulphuret of potassium, while sulphates of soda and of potash are formed from the carbonates. The iron filings simply cause the formation of protosulphuret of iron, while the quick- silver is disengaged. The alkaline fluxes are chiefly used with the iron retorts. If the quicksilver is known to exist only in its virgin uncombined state, no flux is re- quired, and we may immediately proceed to distil it over. It has been remarked above that the heat employed during the assay should not exceed a moderate red. This point is of great consequence with cinnabar, because this sulphuret is capable of being sublimated in its undecomposed state, if the heat is in- creased beyond that temperature. If the ASSAY OF QUICKSILVER ORES. 115 ore* contain chloride or bromide of mercury, these, too, will pass over ; and, to avoid this, the ore, if their presence is suspected, must first be mixed with soda. To render the mixing more intimate, a little water is em- ployed, which must, however, be removed before placing the ore in the retort. It is also advisable to apply the heat gradually, and, when retorts are used, to be particular that they are everywhere heated equally, as otherwise quicksilver might be condensed in the interior of the retort. When it has been ascertained that drops of quicksilver are no longer leaving the retort or tube, and therefore that the process is about being completed, it is advisable to fire up a little before removing the receiving vessel, so that particles of the metal condensed in the neck of the retort or in the tube may be forced out, though, to insure this still more, it is neces- sary to brush out the neck of the vessel with a little brush or feather. The quicksilver which has collected in 116 THE ASSAYER’S GUIDE. the condensing vessel is frequently indis- posed to join and form a connected mass; but this is easily brought about by boiling it in water. Adhering moisture remaining when the water is decanted should be re- moved with blotting-paper. From one-half to three pounds of the ore are commonly employed for the assay, de- creasing in quantity as the value of the ore increases. Perfect accuracy can never be attained in the assay of quicksilver ores by heat, neither as regards the perfect chemical purity nor the full amount of the metal pro- duced; but, as the loss and impurity are yet greater with quicksilver produced on a large scale, this method of treating the ore will be sufficient for technical purposes. Berthier, in the Annales des Mines, iv. serie, t. iii. p. 820 , suggests that when the ore is a very poor one, and when therefore the large amount it would be necessary to use might be the cause of considerable in- ASSAY OF Ql' CKSILVER ORES. 117 convenience in the assay, the following pre- paratory process be resorted to. The ore should be digested with aqua regia, the supernatant liquid decanted or filtered off, the residue thoroughly washed with water, and the acid solution, together with the washings, evaporated to dryness. All the quicksilver in the shape of chloride is then contained in the last-dried residue, and can be further treated in the dry way, only that, as above remarked, it is always neces- sary carefully to mix with soda, when choride of quicksilver is present. Before closing this chapter it will be well to describe the treatment necessary when a quicksilver ore contains arsenic. I shall literally translate the remarks of Bodeman in the work quoted in the preface. He says : — “An ore from Huanca-V61ica, in Peru, containing arsenic (red sulphuret of arsenic, &c.) and cinnabar, having been submitted to Berthier’s inspection, he, after various 118 THE ASSAYER’S GUIDE. useless experiments, discovered the follow- ing process to be the most adequate for determining the mercury in it. “ The ore is mixed with four or five times its weight of litharge, and then heated in a retort. A flowing, slag-like mass is formed by the litharge, sulphuret of arsenic, &c., while the cinnabar is decomposed into sul- phurous acid and metallic mercury. The quicksilver is completely volatilized by a moderate heat, and collected in the condens- ing apparatus and the farther portion of the neck of the retort. The only precaution necessary during the operation consists in gradually and but moderately heating the clay or glass retort, to prevent its being perforated by the effects of the litharge be- fore the process is concluded.” XX. Assay of Sulphurets in Ores . It is often very necessary to know the quantity of sulphurets contained in ores, to be able to arrange accordingly the processes of smelting them. To one part of ore, 50 to 100 grains, one part of powdered glass and two of borax are required. The borax is first mixed with the ore, and when placed in the Hessian crucible, or in the lead and copper one, fig. 4, Plate II., both are covered with the glass. The crucible is then exposed to a bright red-heat, as with copper and lead, and on cooling the button is broken out, which may contain in the shape of sulphurets, copper, lead, iron, 120 THE ASSAILS GUIDE. &c., according as these exist in the ore, and it may then be examined for these metals by the means already given in their respect- ive assays. 121 x;xi. Mode of testing the Calorific Power of Coat and other Fuels* It must not be supposed that the amount of heat which a fuel is capable of producing is entirely dependent on its chemical com- position. Different means have been adopted to determine the efficacy of coal as a fuel. Thus, Despretz has made experiments of this kind by discovering the amount of water which a certain quantity of coal will elevate in temperature one degree of the centigrade thermometer. The varying tem- perature of the water, however, must ever prevent an accurate result. Rumford has proposed to determine the same by the *Karsten’s Eiscnhiittenkunde, vol. ii. ; p. 219, § 476. 11 122 THE ASSATER’S GUIDE. direct use of a thermometer in a closed vessel. Berthier has, however, proposed one that seems equally simple, and service- able for all practical purposes. According to his proposition, one gramme of the coal (or other fuel; for it is applica- ble to all) should be thoroughly pulverized. All coals are readily reduced to such a state. Wood should be used as shavings, or rasped. The powdered substance is then mixed with some litharge, but more than it is capable of reducing,— not less than twenty times its own weight nor more than forty. The quality of the fuel will enable the assayer, after a little practice, to deter- mine a priori with considerable accuracy what will be the requisite quantity. The mixture is placed in a clay crucible (Plate II., fig. 4 or 5) and carefully covered with about twenty to thirty grammes of litharge. The crucible must not be filled over one- half. This is then placed in a heated muffle and covered. The heat should not be too CALORIFIC POWER OF COAL. 123 severe and rapid. The contents will boil up. When the melting has thoroughly taken place, strong heat should be applied for ten minutes, so that the button may collect. The crucible is then taken out and cooled slowly, then broken, and the button extracted and weighed. This process rests upon the fact that the carbon will reduce the litharge ; and having, therefore, assumed one number for the amount of litharge reduced, from which to calculate our experiments, it will be easy to compare the different varieties of fueh When many experiments of this kind are made, the assayer will do well to establish a certain number as the basis. This will vary according to the general character of his coals. This number it will be well to assume as low as possible, to avoid the in- convenience of fractions. He would there- fore adopt a very inferior variety of coal as the one with which to compare the others in the following manner, though 124 THE ASSAYER’S GUIDE. be it remembered I am not now giving results of assays, but only imaginary examples. 1 part bone-coal reduced 10.00 parts by weight of lithaige “ rough bituminous 44 12.50 44 “ 44 44 good bituminous 44 20.00 44 44 • 44 anthracite 44 25.00 44 44 4 125 ll* Table of Analyses of different Clays, from which the most approved Crucibles are made. 126 Table showing , in Degrees of the Centigrade and Fah • renheit Thermometers , the Amount of Heat necessary to melt various Substances. Centigrade. Fahrenheit. Platina .... 2500 4532 Bar Iron . . 1500-1600 2732-3012 Steel 1300-1400 2372-2552 Cast iron, gray........ 1200 2192 Do. white....... 1050 1922 Gold.. 1100-1250 2012-2282 Silver 1000 1832 Bronze 900 1652 Antimony . 450 842 Zinc 360 680 Lead 330 658 Bismuth... 260 480 Tin 230 446 Alloys of Tin, Lead, and Bismuth. (in parts.) (in parts.) (in parts.) 1 3 _ 289 554 1 1 _ 241 464 3 _ 1 200 392 3 1 _ 186 365 2 — 1 167.7 333.5 S 1 _ 1 142.2 283.8 4 1 5 188-9 246.2 ! 3 2 5 100 212 3 5 8 100 212 1 1 4 94 203 Sulphur... 109 230 Mercury . . 39 38.2 127 Table of Troy Weights used with Gold , and Silver , and Platina. * 24 grains (gr.) make,! pennyweight (dwt.) 20 pennyweights — 1 ounce (oz.) 12 ounces — 1 pound (lb.) lb. oz. dwt. gr. 1 = 12 = 240 = 5760 1 = 20 = 480 1 = 24 The value of gold is given in carats fine, 24 c. f. being pure. One pound of gold 24 carats fine contains 5760 grs. of pure gold, as gold of that number of carats fine is unalloyed. One pound of gold 23 carats fine contains 5520 grs., and -so on, and one oz. of gold 20 c. f. has 400 grs. one dwt. of gold 15 c. f. has 15 grs. These are given as examples of the manner in which the amount of the pure metal ought to be calculated. Table of Avoirdupois Weights used with other Metals. (Tun,) (Hundredweight) (Quarter) (Pound) (Ounce) (Dram) T. cwt. qr. lb. oz. dr. 1 = 20 == 80 = 2240 = 35840 = 573440 1 = 4 = 112 = 1792 = 28672 1 = 28 = 448 = 7168 1 = 16 = 256 1 = 16 128 A Table of Comparison of Twelve different National Pound Avoirdupois. Austrian Pound. Bavarian Pound. Saxon (or Soil.) Pound. Wurtemburg Pound. Old Cologne Mark. 1 0.80998 9.90847 0.81000 9.90848 0.90720 9.95770 0.96979 9.98668 1.94001 0.28780 1.23460 0.09153 1 1.00002 0.00001 1.12002 0.04923 1.19730 0.07820 2.39514 0.37933 1.23457 0.09152 0.99998 9.99999 1 1.12000 0.04922 1.19728 0.07819 2.39508 0.37932 1.10230 0.04230 0.89284 9.95077 0.89286 9.95078 1 1.06900 0.02898 2.13847 0.33010 1.03115 0.01332 0.83521 9.92180 0.83523 9.92181 0.93546 9.97102 1 2.00044 0.30113 0.51546 9.71220 0.41751 9.62067 0.41752 9.62068 0.46762 9.66990 0.49989 9.69887 1 1.10078 0.04170 0.89160 9.95017 0.89162 9.95618 0.99862 9.99940 1.06752 0.02838 2.13551 0.32950 0.93770 9.97206 0.75952 9.88054 0.75953 9.88055 0.85068 9.92977 0.90937 9.95874 1.81915 0.25987 1.07916 0.03309 0.87410 9.94156 0.87412 9.94157 0.97901 9.99079 1.04656 0.01976 2.09359 0.32089 2.20460 0.34333 1.78568 0.25180 1.78571 0.25181 2.00000 0.30103 2.13800 0.33001 4.27693 0.63113 0.90283 9.95560 0.73127 9.86408 0.73129 9.86409 0.81904 9.91331 0.87555 9.94228 1.75149 0.24341 1.03111 0.01331 0.83518 9.92178 0.83520 9.92179 0.93542 9.97101 0.99996 9.99998 2.00037 0.30111 129 Weights , icith the Logarithms under each Number* Danish and Norwegian Pound. Swedish Pound. Old French Pound, (poids du marc.) French Kilo- gramme. Russian Pound. (pud.) Prussian Pound. 0.90845 9.95830 1.06644 0.02793 0.92664 0.96691 0.45360 9.65667 1.10763 0.04440 0.96982 9.98669 1.12157 0.04983 1.31662 0.11946 1.14404 0.05844 0.56001 9.74820 1.36748 0.13592 1.19735 0.07822 1.12155 0.04982 1.31660 0.11945 1.14401 0.05843 9.56000 9.74819 1.36746 0.13591 1.19732 0.07821 1.00138 0.00060 1.17553 0.07023 1.02144 0.00921 0.50000 9.69897 1.22094 0.08669 1.06904 0.02899 0.93675 9.97162 1.09966 0.04126 0.95551 9.98024 0.46773 9.66999 1.14214 0.05772 1.00004 0.00002 0.46827 9.67050 0.54971 9.74013 0.47765 9.67911 0.23381 9.36887 0.57094 9.75659 0.49991 9.69889 1 1.17391 0.06963 1.02003 0.00861 0.49931 9.69837 1.21925 0.08609 1.06756 0.02839 0-85186 9.93037 1 0.86892 9.93893 0.42534 9.62874 1.03863 0.01646 0.90941 9.95876 0.98037 9.99139 1.15086 0.06102 1 0.48951 9.68976 1.19532 0.07748 1.04660 0.01978 2.00277 0.30163 2.35106 0.37126 2.04288 0.31034 1 2.44188 0.38772 2.13807 0.33002 0.8017 9.91391 0.96281 9.98354 0.83660 9.92252 0.40952 9.61228 1 9.87558 9.94230 0.93672 9.97161 1.09962 0.04124 0.95548 9.98022 0.46771 9.66998 1.14210 0.05770 1 * Taken from Weisbach’s Ingenieur. INDEX Ag\te mortar Agricola Alloys, of gold, of silver, &c. . Antimony in copper. . Aqua regia Arsenic in copper Arsenious acid Balance Bellows furnace Besanite Berthier Berzelius Bismuth in copper.... Black flux............... Blowpipe Bodeman Borax.... Carats fine Clausthal assay office Coal Cobalt in copper... Coins Coins, table of Cooling pan Copperas Copper )res... PAGE 40 15 71 68 90 66 90 84 28 23 71 7 7 ........ 90 86 ....... 6 8 40 72 25 121 90 , 68 to 76 75 35, 45, 94 67 ..85 to 96 131 132 INDEX, PAGE Cromsted 7 Crucibles 30 Cupellation 39 Cupels 30 to 35 D’Arcet 69, 73 D’Arcet’s table . 74 English method for copper 92 Erker’s table 69 Freiberg 28 JFritsche 8 Gahn 7 Gay-Lussac’s process 54 German and Hungarian silver assay 85 Gold and Quartz 77 Gold coins 71 Gold ores, by amalgamation 61 by heat 56 by washing 63 by wet process 66 Graphite . 85 Hartz iron furnace 104 Hessian crucible 33 Implements and utensils 17 Inquartation silver 57, 82 Introduction 13 Iron muffle 27 Iron ores, Fuchs’s process 108 by heat 103 Iron vitriol 67 Lead in copper 90 Lead ores, by heat 97 by wet process 100 Lime in silver ores 43 Litharge 69 Luhme & Co 27, 28 Mercury, assay of. Ill Mortar, iron.. 39 INDEX. 133 PAGE Movable furnace . 2Q Muffle........ 17 Muffle furnace 17 Nickel in copper 90 Oxide of antimony 87 Parisian mint 50 Peroxide and protoxide of iron... 108 Platinum 80 Platner 7, 23 Pure iron 106 Pure lead. 40 Pure silver 57 Pyrites, iron, in gold 65 Quartation. 58 Quicksilver, how cleansed 61 assay of Ill Silberblick 46 Silver coins 68 Silver ores 39 Sulphur 82 Sulphurets, assay of 119 Table of analysis of different clays 125 Table of loss 52 Table of melting temperature of different metals 126 Table of national weights 127 Table of Troy weights 128 Tin in copper 90 Tin in silver 43 To find the proportion of gold in gold and quartz .... 77 Tongs...... 36 to 38 Touchstone 71 Ventilation of furnace 24 Washing gold 63 White flux 93 Zinc in silver ores 43 THE END. 12 Plate I.— Part I. ft Plate I. — Part II. Plate II Part I CATALOGUE O F PRACTICAL AND SCIIT1C BOOKS, PUBLISHED BIT HEERY CAREY BAIRD & CO, Industrial Publishers and Booksellers, NO. 810 WALNUT STREET, PHILADELPHIA. Any of the Books comprised in this Catalogue will be sent by mail, free of postage, at the publication price* 4®- A Descriptive Catalogue, 96 pages, 8m, will be sent, free of postage, to any one who will furnish the publisher with his address. ARLOT.— A Complete Guide for Coach Painters. Translated from the French of M. A.rlot, Coach Painter ; for eleven years Foreman of Painting to M. Eherler, Coach Maker, Paris. By A. A. FESQUET, Chemist and Engineer. To which is added an Ap- pendix, containing Information respecting the Materials and the Practice of Coach and Car Painting and Varnishing in the United States and Great Britain. 12mo $1.25 ARMENGAUD, AMOROUX, and JOHNSON.— The Practical Draughtsman’s Book of Industrial De- sign, and Machinist’s and Engineer’s Drawing Companion : Forming a Complete Course of Mechanical Engineering and Archi- tectural Drawing. From the French of M. Arrtiengaud the elder, Prof, of Design in the Conservatoire of Arts and Industry, Paris, and MM. Armengaud the younger, and Amoroux, Civil Engineers. Rewritten and arranged with additional matter and plates, selections from and examples of the most useful and generally employed mechanism of the day. By William Johnson, Assoc. Inst. C. E., Editor of “ The Practical Mechanic’s Journal.” Illustrated by 50 folio steel plates, and 50 wood-nuts. A new edition, 4to .... $10.00 1 2 HENRY CAREY BAIRD’S CATALOGUE. ARROWSMITH.— Paper-Hanger’s Companion : A Treatise in which the Practical Operations of the Trade are Sys- tematically laid down : with Copious Directions Preparatory to Paper- ing; Preventives against the Effect of Damp on Walls ; the Various Cements and Pastes Adapted to the Several Purposes of the Trade ; Observations and Directions for the Panelling and Ornamenting of Rooms, etc. By James Arrowsmith, Author of “Analysis of Dra- pery,” etc. 12mo., cloth. $1.25 ASHTON. — The Theory and Practice of the Art of De- signing Fancy Cotton and Woollen Cloths from Sample : Giving full Instructions for Reducing Drafts as well as the Methods of Spooling and Making out Harness for Cross Drafts, and Finding any Required Reed, with Calculations and Tables of Yarn. By Frederick T. Ashton, Designer, West Pittsfield, Mass. With 52 Illustrations. One volume, 4to $10.00 BAIRD — Letters on the Crisis, the Currency and the Credit System. By Henry Carey Baird. 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Oblong folio $5.00 BAIRD.— The American Cotton Spinner, and Mana- ger’s and Carder’s Guide : A Practical Treatise on Cotton Spinning; giving the Dimensions and Speed of Machinery, Draught and Twist Calculations, etc. ; with notices of recent Improvements: together with Rules and Examples for making changes in the sizes and numbers of Roving and Yarn. Compiled from the papers of the late Robert H. Baird. i2mo. $1.50 HENRY CAREY BAIRD’S CATALOGUE. 3 BAKER.— -Long-Span Railway Bridges : Comprising Investigations of the Comparative Theoretical and Prac- tical Advantages of the various Adopted or Proposed Type Systems of Construction ; with numerous Formulae and Tables. By B. Baker. 12mo. $2.00 BAUERMAN. — A Treatise on the Metallurgy of Iron : Containing Outlines of the History of Iron Manufacture, Methods of Assay, and Analysis of Iron Ores, Processes of Manufacture of Iron and Steel, etc., etc. By H. Bauerman, F. G. S., Associate of the Royal School of Mines. 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With over 600 Engravings, illus- trating every Branch of the Subject. 8vo $7.00 Cabinet Maker’s Album of Eurniture : Comprising a Collection of Designs for Furniture. Illustrated by 48 Large and Beautifully Engraved Plates. In one vol., oblong $3.50 HENRY CAREY BAIRD’S CATALOGUE. 7 CALLINGS AM.— Sign Writing and Glass Emboss- ing: A Complete Practical Illustrated Manual of the Art. By James Callingham. In one volume, 12mo $1.50 CAMPIN. — A Practical Treatise on Mechanical Engi- neering : Comprising Metallurgy, Mouldipg, Casting, Forging, Tools, Work- shop Machinery, Mechanical Manipulation, Manufacture of Steam- engines, etc., etc. With an Appendix on the Analysis of Iron and Iron Ores. By Feancis Campin, C. E. To which are added, Obser- vations on the Construction of Steam Boilers, and Remarks upon Furnaces used for Smoke Prevention ; with a Chapter on Explosions. By R. Armstrong, C. E., and John Bourne. Rules for Calculating the Change Wheels for Screws on a Turning Lathe, and for a Wheel- cutting Machine. By J. La Nice a. Management of Steel, Includ- ing Forging, Hardening, Tempering, Annealing, Shrinking, and Ex- pansion. And the Case-hardening of Iron. By G. Ede. 8vo. Illus- trated with 29 plates and 100 wood engravings . . . $6.00 C AMPIN.— The Practice of Hand-Turning in Wood, Ivory, Shell, etc. : With Instructions for Turning such works in Metal as may be re- quired in the Practice of Turning Wood, Ivory, etc. Also, an Appen- dix on Ornamental Turning. By Feancis Campin ; with Numerous Illustrations. 12mo., cloth $3.00 CAREY. — The Works of Henry C. Carey: FINANCIAL CRISES, their Causes and Effects. 8vo. paper . 25 HARMONY OF INTERESTS : Agricultural, Manufacturing, and Commercial. 8vo., cloth $1.50 MANUAL OF SOCIAL SCIENCE. Condensed from Carey’s “ Prin- ciples of Social Science.” By Kate McKean. 1 vol. 12mo. $2.25 MISCELLANEOUS WORKS : comprising “ Harmony of Interests,” “ Money,” “ Letters to the President,” “ Financial Crises,” “ The Way to Outdo England Without Fighting Her,” “Resources of the Union,” “The Public Debt,” “Contraction or Expansion?” “ Review of the Decade 1857 - 67 ,” “ Reconstruction,” etc., etc. Two vols., 8vo., cloth PAST, PRESENT, AND FUTURE. 8vo $2.50 PRINCIPLES OF SOCIAL SCIENCE. 3 vols., 8vo., cloth $10.00 THE SLAVE-TRADE, DOMESTIC AND FOREIGN ; Why it Ex- ists, and How it may be Extinguished (1853). 8vo., cloth . $2.00 LETTERS ON INTERNATIONAL COPYRIGHT (1867) . 50 THE UNITY OF LAW : As Exhibited in the Relations of Physical, Social, Mental, and Moral Science (1872). In one volume, Kvo., pp. xxiii., 433. Cloth $3.50 CHAPMAN. — A Treatise on Ropemaking : As Practised in private and public Rone yards, with a Description of the Manufacture, Rules, Tables of Weights, etc., adapted to the Trades, Shipping, Mining, Railways, Builders, etc. By Robert Chapman. 24mo $1.50 8 HENRY CAREY BAIRD’S CATALOGUE. COLBURN. — The Locomotive Engine : Including a Description of its Structure, Rules for Estimating its Capa- bilities, and Practical Observations on its Construction and Manage- ment. By Zeeah Colburn. Illustrated. A new edition. 12mo. $1.25 CRAIK. — The Practical American Millwright and Miller. By David Craik, Millwright. Illustrated by numerous wood en- gravings, and two folding plates. 8vo $5.00 DE GRAFF.— The Geometrical Stair Builders’ Guide : Being a Plain Practical System of Hand-Railing, embracing all its necessary Details, and Geometrically Illustrated by 22 Steel Engrav- ings ; together with the use of the most approved principles of Prac- tical Geometry. By Simon De Geaff, Architect. 4to. . $5.00 PE KONINCK.— DIETZ.— A Practical Manual of Che- mical Analysis and Assaying : As applied to the Manufacture of Iron from its Ores, and to Cast Iron, Wrought Iron, and Steel, as found in Commerce. By L. L. De Kon- inck, Dr. Sc., and E. Dietz, Engineer. Edited with Notes, by Robert Mallet, F.R.S., F.S.G., M.I.C.E., etc. American Edition, Edited with Notes and an Appendix on Iron Ores, by A. A. Fesquet, Chemist and Engineer. One volume, 12mo. $2.50 DUNC AN.— Practical Surveyor’s Guide: Containing the necessary information to make any person, of common capacity, a finished land surveyor without the aid of a teacher. By Andrew Duncan. Illustrated. 12mo., cloth. . . . $1.25 DUPLAIS.— A Treatise on the Manufacture and Dis- tillation of Alcoholic Liquors : Comprising Accurate and Complete Details in Regard to Alcohol from Wine, Molasses, Beets, Grain, Rice, Potatoes, Sorghum, Asphodel, Fruits, etc. ; with the Distillation and Rectification of Brandy, Whis- key, Rum, Gin, Swiss Absinthe, etc., the Preparation of Aromatic Wa- ters, Volatile Oils or Essences, Sugars, Syrups, Aromatic Tinctures, Liqueurs, Cordial Wines, Effervescing Wines, etc., the Aging of Brandy and the Improvement of Spirits, with Copious Directions and Tables for Testing and Reducing Spirituous Liquors, etc., etc. Translated and Edited from the French of MM. Dfplais, Aine et Jeune. By M. McKennie, M.D. To which are added the United States Internal Revenue Regulations for the Assessment and Collection of Taxes on Distilled Spirits. Illustrated by fourteen folding plates and several wood engravings. 743 pp., 8vo. ...... $10.00 DUSSAUCE. — A General Treatise on the Manufacture of Every Description of Soap : Comprising the Chemistry of the Art, with Remarks on Alkalies, Sa- ponifiable Fatty Bodies, the apparatus necessary in a Soap Factory, Practical Instructions in the manufacture of the various kinds of Soap, the assay of Soaps, etc., etc. Edited from Notes of Larme, Fontenelle, Malapayre, Dufour, and others, with large and important additions by Prof. H. Dussauce, Chemist. Illustrated. In one vol., 8vo, . $12.50 HENRY CAREY BAIRD’S CATALOGUE. 9 DUSSAUCE.— A General Treatise on the Manufacture of Vinegar : Theoretical and Practical. Comprising the various Methods, by the Slow and the Quick Processes, with Alcohol, Wine, Grain, Malt, Cider, Molasses, and Beets ; as well as the Fabrication of Wood Vinegar, etc., eic. By Prof. H. Dussauce. In one volume, 8vo. . . $5.00 DUSSAUCE. — A New and Complete Treatise on the Arts of Tanning, Currying, and Leather Dressing : Comprising all the Discoveries and Improvements made in France, Great Britain, and the United States. Edited from Notes and Docu- ments of Messrs. Sallerou, Grouvelle, Duval, Dessables, Labarraque, Payen, Rene, De Fontenelle, Malapeyre, etc., etc. By Prof. H. Dus- SAUCE, Chemist. Illustrated by 212 wood engravings. 8vo. $25.00 DUSSAUCE.— A Practical Guide for the Perfumer : Being a New Treatise on Perfumery, the most favorable to the Beauty without being injurious to the Health, comprising a Description of the substances used in Perfumery, the Formulae of more than 1000 Prepa- rations, such as Cosmetics, Perfumed Oils, Tooth Powders, Waters, Extracts, Tinctures, Infusions, Spirits, Vinaigres, Essential Oils, Pas- tels, Creams, Soaps, and many new Hygienic Products not hitherto described. Edited from Notes and Documents of Messrs. Debay, Ln- nel, etc. With additions by Prof. H. Dussauce, Chemist. 12mo. DUSSAUCE.— Practical Treatise on the Fabrication of Matches, Gun Cotton, and Fulminating Powders. By Prof. H. Dussauce. 12mo $3.00 Dyer and Color-maker’s Companion: Containing upwards of 200 Receipts for making Colors, on the most approved principles, for all the various styles and fabrics now in exist- ence; with the Scouring Process, and plain Directions for Preparing, Washing-off, and Finishing the Goods. In one vol., 12mo. . $1.25 EASTON.— A Practical Treatise on Street or Horse- power Railways. ' By Alexander Easton, C. E. Illustrated by 23 plates. 8vo., cloth $3.00 ELDER.— Questions of the Day: Economic and Social. By Dr. William Elder. 8vo. . $3.00 FAIRBAIRN.— The Principles of Mechanism and Ma- chinery of Transmission : Comprising the Principles of Mechanism, Wheels, and Pulleys, Strength and Proportions of Shafts, Coupling of Shafts, and Engaging and Disengaging Gear. By Sir William Fairrairn, C.E., LL.l)., F.R.S., F.G.S. Beautifully illustrated by over 150 wood-cuts. In one volume, $2.50 FORSYTH.— Book of Designs for Headstones, Mural, and other Monuments : Containing 78 Designs. By James Forsyth. With an Introduction by Charles Boutkll, M. A, 4to., cloth $5.00 10 HENRY CAREY BAIRD’S CATALOGUE. GIBSON. — The American Dyer: A Practical Treatise on the Coloring of Wool, Cotton, Yarn and Cloth, in three parts. Part First gives a descriptive account of the Dye Stuffs ; if of vegetable origin, where produced, how cultivated, and how prepared for use ; if chemical, their composition, specific gravities, and general adaptability, how adulterated, and how to de- tect the adulterations, etc. Part Second is devoted to the Coloring of Wool, giving recipes for one hundred and twenty-nine different colors or shades, and is supplied with sixty colored samples of Wool. Part Third is devoted to the Coloring of Raw Cotton or Cotton Waste, for mixing with Wool Colors in the Manufacture of all kinds of Fabrics, gives recipes for thirty-eight different colors or shades, and is supplied with twenty-four colored samples of Cotton Waste. Also, recipes for Coloring Beavers, Doeskins, and Flannels, with remarks upon Ani- lines, giving recipes for fifteen different colors or shades, and nine samples of Aniline Colors that will stand both the Fulling and Scour- ing process. Also, recipes for Aniline Colors on Cotton Thread, and recipes for Common Colors on Cotton Yarns. Embracing in all over two hundred recipes for Colors and Shades, and ninety-four samples of Colored Wool and Cotton Waste, etc. By Richard H. Gibson, Practical Dyer and Chemist. In one volume, 8vo. . . $6.00 GILBART.— History and Principles of Banking : A Practical Treatise. By James W. Gilbart, late Manager of the London and Westminster Bank. With additions. In one volume, 8vo., 600 pages, sheep $5.00 Gothic Album for Cabinet Makers : Comprising a Collection of Designs for Gothic Furniture. Illustrated by 23 large and beautifully engraved plates. Oblong . . $2.00 GRANT. — Beet-root Sugar and Cultivation of the Beet. By E. B. Grant. 12mo $1.25 GREGORY.— Mathematics for Practical Men : Adapted to the Pursuits of Surveyors, Architects, Mechanics, and Civil Engineers. By Olinthus Gregory. 8vo., plates, cloth $3.0(1 GRISWOLD.— Railroad Engineer’s Pocket Compan- ion for the Field : Comprising Rules for Calculating Deflection Distances and Angles, Tangential Distances and Angles, and all Necessary Tables for Engi- neers ; also the art of Levelling from Preliminary Survey to the Con- struction of Railroads, intended Expressly for the Young Engineer, together with Numerous Valuable Rules and Examples. By W. Griswold. 12mo., tucks $1.75 GRTJNER.— Studies of Blast Furnace Phenomena. By M. L. Gruner, President of the General Council of Mines of France, and lately Professor of Metallurgy at the Ecole des Mines. Translated, with the Author’s sanction, with an Appendix, by L. D. B. Gordon, F. R. S. E„ F. G, •«. Illustrated. 8vo. . . . $2.50 HENRY CAREY BAIRD’S CATALOGUE. 1 ). GUETTIER.— Metallic Alloys: Being a Practical Guide to their Chemical and Physical Properties, their Preparation, Composition, and Uses. Translated from the French of A. Guettier, Engineer and Director of Foundries, author of “La Fouderie en France,” etc., etc. By A. A. Fesquet, Chemist and Engineer. In one volume, 12mo $3.00 HARRIS. — Gas Superintendent’s Pocket Companion. By Harris & Brother, Gas Meter Manufacturers, 1115 and 1117 Cherry Street, Philadelphia. Full bound in pocket-book form $1,00 Hats and Pelting: A Practical Treatise on their Manufacture. By a Practical Hatter. Illustrated by Drawings of Machinery, etc. 8vo. . . . $1.25 HOFMANN. — A Practical Treatise on the Manufac- ture of Paper in all its Branches. By Carl Hofmann. Late Superintendent of paper mills in Ger- many and the United States; recently manager of the Public Ledger Paper Mills, near Elkton, Md. Illustrated by 110 wood engravings, and five large folding plates. In one volume, 4to., cloth; 398 pages $15,00 HUGHES.— American Miller and Millwright’s Assist- ant. By Wm. Carter Hughes. A new edition. In one vol., 12mo. $1.50 IIURST.— A Hand-Book for Architectural Surveyors and others engaged in Building: Containing Formulae useful in Designing Builder’s work, Table of Weights, of the materials used in Building, Memoranda connected with Builders’ work, Mensuration, the Practice of Builders’ Measure- ment, Contracts of Labor, Valuation of Property, Summary of the Practice in Dilapidation, etc., etc. By J. F. IIurst, C. E. Second edition, pocket-book form, full bound $2.00 JERVIS.— Railway Property : A Treatise on the Construction and Management of Railways ; de- signed to afford useful knowledge, in the popular style, to the holders of this class of property; as well as Railway Managers, Officers, and Agents. By John B. JERVIS, late Chief Engineer of the Hudson River Railroad, Croton Aqueduct, etc. In one vol., 12mo., cloth $2.00 JOHNSTON.— Instructions for tho Analysis of Soils, Limestones, and Manures. By J. F. W. Johnston, 12mo, 12 HENRY CAREY BAIRD’S CATALOGUE. KEENE. — A Hand-Book of Practical Ganging : For the Use of Beginners, to which is added, A Chapter on Distil la- tion, describing the process in operation at the Custom House l'o r ascertaining the strength of wines. By James B. Keene, of H. M. Customs. 8vo. , $1.25 KELLEY.— Speeches, Addresses, and Letters on In- dustrial and Financial Questions. By Hon. William D. Kelley, M. C. In one volume, 544 pages, 8vo $3.00 KENTISH.— A Treatise on a Box of Instruments, And the Slide Rule ,- with the Theory of Trigonometry and Loga- rithms, including Practical Geometry, Surveying, Measuring of Tim. ber, Cask and Malt Gauging, Heights, and Distances. By Thomas Kentish. In one volume. 12mo. ..... $1.25 KOBELL.— ERNI.— Mineralogy Simplified : A short Method of Determining and Classifying Minerals, by means of simple Chemical Experiments in the Wet Way. Translated from the last German Edition of F. Yon Kobell, with an Introduction to Blow-pipe Analysis and other additions. By Henri Eeni, M. D., late Chief Chemist, Department of Agriculture, author of “ Coal Oil and Petroleum.” In one volume, f2mo. .... $2.50 LANBRIN— A Treatise on Steel: Comprising its Theory, Metallurgy, Properties, Practical Working, and Use. By M. H. C. Landrin, Jr., Civil Engineer. Translated from the French, with Notes, by A. A. Fesquet, Chemist and Engi- neer. With an Appendix on the Bessemer and the Martin Processes for Manufacturing Steel, from the Report of Abram S. Hewitt, United States Commissioner to the Universal Exposition, Paris, 1867. In one volume, 12mo. $3.00 LARKIN.— The Practical Brass and Iron Founder’s Guide : A Concise Treatise on Brass Founding, Moulding, the Metals and their Alloys, etc. : to which are added Recent Improvements in the Manu- facture of Iron, Steel by the Bessemer Process, etc., etc. By James Larkin, late Conductor of the Brass Foundry Department in Reany, Neafie & Co’s. Penn Works, Philadelphia. Fifth edition, revised, with Extensive additions. In one volume, 12mo. . . $2.25 LEAVITT.— Facts about Peat as an Article of Fuel : With Remarks upon its Origin and Composition, the Localities in which it is found, the Methods of Preparation and Manufacture, and the various Uses to which it is applicable ; together with many other matters of Practical and Scientific Interest. To which is added a chap- ter on the Utilization of Coal Dust with Peat for the Production of an Excellent Fuel at Moderate Cost, specially adapted for Steam Service. By T. H. Leavitt. Third edition. 12mo. . . . $1.75 HENRY CAREY BAIRD’S CATALOGUE. 13 LEROUX, C. — A Practical Treatise on the Manufac- ture of Worsteds and Carded Yarns : Comprising Practical Mechanics, with Rules and Calculations applied to Spinning; Sorting, Cleaning, and Scouring Wools; the English and French methods of Combing, Drawing, and Spinning Worsteds and Manufacturing Carded Yarns. Translated from the French of Charles Leroux, Mechanical Engineer, and Superintendent of a Spinning Mill, by Horatio Paine, M. D., and A. A. F'esquet, Chemist and Engineer. Illustrated by 12 large Plates. To which is added an Appendix, containing extracts from the Reports of the Inter- national Jury, and of the Artisans selected by the Committee appointed by the Council of the Society of Arts, London, on Woollen and Worsted Machinery and Fabrics, as exhibited in the Paris Universal Exposi- tion, 1867. 8vo., cloth $5.00 LESLIE (Miss).— Complete Cookery: Directions for Cookery in its Various Branches. By Miss Leslie. 60th thousand. Thoroughly revised, with the addition of New Re- ceipts. In one volume, 12mo., cloth $1.50 LESLIE (Miss).— Ladies’ House Book : A Manual of Domestic Economy. 4 20th revised edition. 12mo., cloth. LESLIE (Miss). — Two Hundred Receipts in French Cookery. Cloth, 12mo. LIEBER. — Assayer’s Guide : Or, Practical Directions to Assayers, Miners, and Smelters, for the Tests and Assays, by Heat and by Wet Processes, for the Ores of all the principal Metals, of Gold and Silver Coins and Alloys, and of Coal, etc. By Oscar M. Lieber. 12mo., cloth. . . $1.25 LOTH.— The Practical Stair Builder: A Complete Treatise on the Art of Building Stairs and Hand-Rails, Designed for Carpenters, Builders, and Stair-Builders. Illustrated with Thirty Original Plates. By C. Edward Lotii, Professional Stair-Builder. One large 4to. volume. .... $10.00 LOVE. — The Art of Dyeing, Cleaning, Scouring, and Finishing, on the Most Approved English and French Methods: Being Practical Instructions in Dyeing Silks, Woollens, and Cottons, Feathers, Chips, Straw, etc. Scouring and Cleaning Bed and Window Curtains, Carpets, Bugs, etc. French and English Cleaning, any Color or Fabric of Silk, Satin, or Damask. Bv Thomas Love, a Working Dyer and Scourer. Second American Edition, to which are added General Instructions for the Use of Aniline Colors. In one volume, 8vo., 343 pages. $5.00 14 HENRY CAREY BAIRD’S CATALOGUE MAIN and BROWN. — Questions on Subjects Con- nected with the Marine Steam-Engine : And Examination Papers : with Hints for their Solution. By Thomas J". Main, Professor of Mathematics, Royal Naval College, and Thomas Bkown, Chief Engineer, R. N. 12mo., cloth. . . . ^$1.50 MAIN and BROWN.— The Indicator and Dynamo- meter : With their Practical Applications to the Steam-Engine. By Thomas J. Main, M. A. F. R., Assistant Professor Royal Naval College, Ports- mouth, and Thomas Brown, Assoc. Inst. C. E., Chief Engineer, R. N., attached to the Royal Naval College. Illustrated. From the Fourth London Edition. 8vo. $1.50 MAIN and BROWN.— The Marine Steam-Engine. By Thomas J. Main, F. R. ; Assistant S. Mathematical Professor at the Royal Naval College, Portsmouth, and Thomas Brown, Assoc. Inst. C. E., Chief Engineer R. N. Attached to the Royal Naval Col- lege. Authors of “Questions connected with the Marine Steam-En- gine,” and the “ Indicator and Dynamometer.” With numerous Illus- trations. In one volume, 8vo. $5.00 MARTIN.— Screw-Cutting Tables, for the Use of Me- chanical Engineers : Showing the Proper Arrangement of Wheels for Cutting the Threads of Screws of any required Pitch ; with a Table for Making the Uni- versal Gas-Pipe Thread and Taps. By W. A. Martin, Engineer. 8vo 50 Mechanics’ (Amateur) Workshop: A treatise containing plain and concise directions for the manipula- tion of Wood and Metals, including Casting, Forging, Brazing, Sol- dering, and Carpentry. By the author of the “Lathe and its Uses.” Third edition. Illustrated. 8vo ■ $3.00 MOLES WORTH. — Pocket-Book of Useful Formulae and Memoranda for Civil and Mechanical Engi- neers. By Guilford L. Molesworth, Member of the Institution of Civil Engineers, Chief Resident Engineer of the Ceylon Railway. Second American, from the Tenth London Edition. In one volume, full bound in pocket-book form $2.00 NAPIER. — A System of Chemistry Applied to Dyeing. By James Napier, F. C. S. A New and Thoroughly Revised Edi- tion. Completely brought up to the present state of the Science, inclu- ding the Chemistry of Coal Tar Colors, by A. A. Fesquet, Chemist and Engineer. With an Appendix on Dyeing and Calico Printing, as shown at the Universal Exposition, Paris, 1867. Illustrated. In one Volume, 8vo., 422 pages. . . . . . . . . $5.00 HENRY CAREY BAIRD’S CATALOGUE, 15 NAPIER. — Manual of Electro-Metallurgy : Including the Application of the Art to Manufacturing Processes. By James Napier. Fourth American, from the Fourth London edition, revised and enlarged. Illustrated by engravings. In one vol., 8vo. $2.00 NASON. — Table of Reactions for Qualitative Chemical Analysis. By Henry B. Nason, Professor of Chemistry in the Rensselaer Poly- technic Institute, Troy, New York. Illustrated by Colors. . 03 NEWBERY- Gleanings from Ornamental Art of every style : Drawn from Examples in the British, South Kensington, Indian, Crystal Palace, and Mher Museums, the Exhibitions of 1851 and 1862, and the best English and Foreign works. In a series of one hundred exquisitely drawn Plates, containing many hundred examples. By Robert Newbery. 4to. ....... $12.50 NICHOLSON.— A Manual of the Art of Bookbinding: Containing full instructions in the different Branches of Forwarding, Gilding, and Finishing. Also, the Art of Marbling Book-edges and Paper. By James B. Nicholson. Illustrated. l_mo., cloth. $2.25 NICHOLSON.— The Carpenter’s New Guide: A Complete Book of Lines for Carpenters and Joiners. By Peter Nicholson. The whole carefully and thoroughly revised by H. K. Davis, and containing numerous new and improved and original De- signs for Roofs, Domes, etc. By Samuel Sloan, Architect. Illus- trated by 80 plates. 4to. NORRIS.— A Hand-book for Locomotive Engineers and Machinists: Comprising the Proportions and Calculations for Constructing Loco- motives ; Manner of Setting Valves ; Tables of Squares, Cubes, Areas, etc., etc. By Septimus Norris, Civil and Meehaiiical Engineer. New edition. Illustrated. 12mo., cloth $1.50 NYSTROM.— On Technological Education, and the Construction of Ships and Screw Propellers : For Naval and Marine Engineers. By John \V. Nystrom, late Act- ing Chief Engineer, U. S. N. Second edition, revised with additional matter. Illustrated by seven engravings. 12mo. . . $1.50 O’NEILL. — A Dictionary of Dyeing and Calico Print- ing: Containing a brief account of all the Substances and Processes in use in the Art of Dyeing and Printing Textile Fabrics; with Practical Receipts and Scientific Information. By Charles O’Neill, Ana- lytical Chemist ; Fellow of the Chemical Society of London ; Member of the Literary and Philosophical Society of Manchester; Author of “Chemistry of Calico Printing and Dyeing.” To which is added an Essay on Coal Tar Colors and their application to Dyeing and Calico Printing. By A. A. FkSQUET, Chemist and Engineer. With an Ap- pendix on Dyeing and Calico Printing, as shown at the Universal Exposition, Paris, 1867. In one volume, 8vo., 491 pages. . $5.00 16 HENRY CAREY BAIRD’S CATALOGUE. ORTON. — Underground Treasures : IIow and Where to Find Them. A Key for the Ready Determination of all the Useful Minerals within the United States. By James Orton, A. M. Illustrated, 12mo $1.50 OSBORN.— American Mines and Mining: Theoretically and Practically Considered. By Prof. H. S. Osborn. Illustrated by numerous engravings. 8vo. {In 'preparation.) OSBORN.— The Metallurgy of Iron and Steel : Theoretical and Practical in all its Branches ; with special reference to American Materials and Processes. By H. S. Osborn, LL. D., Professor of Mining and Metallurgy in Lafayette College, Easton, Pennsylvania. Illustrated by numerous large folding plates and wood-engravings. 8vo. $15.00 OVERMAN.— The Manufacture of Steel : Containing the Practice and Principles of Working and Making Steel. A Handbook for Blacksmiths and Workers in Steel and Iron, Wagon Makers, Die Sinkers, Cutlers, and Manufacturers of Files and Hard- ware, of Steel and Iron, and for Men of Science and Art. By Fred- erick Overman, Mining Engineer, Author of the “ Manufacture of Iron/’ etc. A new, enlarged, and revised Edition. By A. A. Fesquet, Chemist and Engineer $1.50 OVERMAN.— The Moulder and Pounder’s Pocket Guide : A Treatise on Moulding and Founding in Green-sand, Dry-sand, Loam, and Cement; the Moulding of Machine Frames, Mill-gear, Hollow- ware, Ornaments, Trinkets, Bells, and Statues ; Description of Moulds for Iron, Bronze, Brass, and other Metals ; Plaster of Paris, Sulphur, Wax, and other articles commonly used in Casting; the Construction of Melting Furnaces, the Melting and Founding of Metals ; the Com- position of Alloys and their Nature. With an Appendix containing Receipts for Alloys, Bronze, Varnishes and Colors for Castings; also, Tables on the Strength and other qualities of Cast Metals. By Fred- erick Overman, Mining Engineer, Author of “ The Manufacture of Iron.” With 42 Illustrations. 12mo $1.50 Painter, Gilder, and Varnisher’s Companion: Containing Rules and Regulations in everything relating to the Arts of Painting, Gilding, Varnishing, Glass-Staining, Graining, Marbling, Sign-Writing, Gilding on Glass, and Coach Painting and Varnishing; Tests for the Detection of Adulterations in Oils, Colors, etc. ; and a Statement of the Diseases to which Painters are peculiarly liable, with the Simplest and Best Remedies. Sixteenth Edition. Revised, with an Appendix. Containing Colors and Coloring - Theoretical and Practical. Comprising descriptions of a great variety of Additional Pigments, their Qualities and Uses, to which are added, Dryers, and Modes and Operations of Painting, etc. Together with Chevreul’s Principles of Harmony and Contrast of Colors. 12mo., cloth. $1.50 HENRY CAREY BAIRD’S CATALOGUE. 17 PALLETT.— The Miller’s, Millwright’s, and Engineer’s Guide. By Henry Pallett. Illustrated. In one volume, 12mo. $3.00 PERCY.— The Manufacture of Russian Sheet-Iron. By John Percy, M.D., F.R.S., Lecturer on Metallurgy at the Royal School of Mines, and to The Advanced Class of Artillery Officers at the Royal Artillery Institution, Woolwich ; Author of “ Metallurgy.” With Illustrations. 8vo., paper 50 cts. PERKINS.— Gas and Ventilation. Practical Treatise on Gas and Ventilation. With Special Relation to Illuminating, Heating, and Cooking by Gas. Including Scientific Helps to Engineer-students and others. With Illustrated Diagrams. By E. E. Perkins. 12mo., cloth $1.25 PERKINS and STOWE.— A New Guide to the Sheet- iron and Boiler Plate Roller : Containing a Series of Tables showing the Weight of Slabs and Piles to produce Boiler Plates, and of the Weight of Piles and the Sizes of Bars to produce Sheet-iron; the Thickness of the Bar Gauge in decimals ; the Weight per foot, and the Thickness on the Bar or Wire Gauge of the fractional parts of an inch ; the Weight per sheet, and the Thickness on the Wire Gauge of Sheet-iron of various dimensions to weigh 112 lbs. per bundle; and the conversion of Short Weight into Long Weight, and Long Weight into Short. Estimated and col- lected by G. H. Perkins and J. G. Stowe $2.50 PHILLIPS and DARLINGTON— Records of Mining and Metallurgy ; Or Facts and Memoranda for the use of the Mine Agent and Smelter. By J. Arthur Phillips, Mining Engineer, Graduate of the Imperial School of Mines, France, etc., and John Darlington. Illustrated by numerous engravings. In one volume, 12mo. . . $1.50 PRO TEAUX.— Practical Guide for the Manufacture of Paper and Boards. By A. Proteaux, Civil Engineer, and Graduate of the School of Arts and Manufactures, and Director of Thiers’ Paper Mill, Puy-de-Dome. With additions, by L. S. Le NORMAND. Translated from the French, with Notes, by Horatio Paine, A. B., M. I). To which is added a Chapter on the Manufacture of Paper from Wood in the United States, by Henry T. Brown, of the “American Artisan.” Illus- trated by six plates, containing Drawings of Raw Materials, Machi- nery, Plans of Paper-Mills, etc., etc. 8vo. . . . . $10.00 RE GN AULT.— Elements of Chemistry. By M. V. Regnaui.t. Translated from the French by T. Forrest Button, M. D., and edited, with Notes, by James C. Booth, Mel ter and Refiner IT. S. Mint, and Wm. L. Faber, Metallurgist and Mining Engineer. Illustrated by nearly 700 wood engravings. Comprising nearly 1500 pages. In two volumes, 8vo., cloth. . . . $7.50 18 HENRY CAREY BAIRD’S CATALOGUE. REID.— A Practical Treatise on the Manufacture of Portland Cement : By Henry Reid, C. E. To which is added a Translation of M. A, Lipowitz’s Work, describing a New Method adopted in Germany for Manufacturing that Cement, by W. F. Reid. Illustrated by plates and wood engravings. 8vo $5.00 RIFFAULT, VERGNAUD, and TOUSSAINT.— A Practical Treatise on the Manufacture of Var- nishes. By MM. Riffault, Vergnaud, and Toussaint. Revised and Edited by M. F. Malepeyre and Dr. Emil Winckler. Illustrated. In one volume, 8vo. {In 'preparation.') RIFFAULT, VERGNAUD, and TOUSSAINT.— A Practical Treatise on the Manufacture of Colors for Painting : Containing the best Formulae and the Processes the Newest and in most General Use. By M M. Riffault, Vergnaud, and Toussaint. Revised and Edited by M. F. Malepeyre and Dr. Emil Winckler. Translated from the French by A. A. Fesquet, Chemist and Engi- neer. Illustrated by Engravings. In one volume, 050 pages, 8vo. $7.50 ROBINSON.— Explosions of Steam Boilers: How they are Caused, and how they may be Prevented. By «T. R. Robinson, Steam Engineer. 12mo $1.25 ROPER. — A Catechism of High Pressure or Non- Condensing Steam-Engines : Including the Modelling, Constructing, Running, and Management of Steam Engines and Steam Boilers. With Illustrations. By Stephen Roper, Engineer. Full bound tucks . . . $2.00 ROSELEUR.— Galvanoplastic Manipulations : A Practical Guide for the Gold and Silver Electro-plater and the Galvanoplastic Operator. Translated from the French of Alfred Roseleur, Chemist, Professor of the Galvanoplastic Art, Manufactu-. rer of Chemicals, Gold and Silver Electro-plater. By A. A. Fesquet, Chemist and Engineer. Illustrated by over 127 Engravings on wood. 8vo., 495 pages. . . . $6.00 This Treatise is the fullest and by far the best on this subject ever published in the United States. SCHINZ.— Researches on the Action of the Blast Furnace. By Charles Schinz. Translated from the German with the special permission of the Author by William H. Maw and Moritz Mul- ler. With an Appendix written by the Author expressly for this edition. Illustrated by seven plates, containing 28 figures. In one volume, 12mo. . , . $4.00 HENRY CAREY BAIRD’S CATALOGUE. 19 SHAW.— Civil Architecture : Being a Complete Theoretical and Practical System of Building, con- taining the Fundamental Principles of the Art. By Edward Shaw, Architect. To which is added a Treatise on Gothic Architecture, etc. By Thomas W. Silloway and George M. Harding, Architects. The whole illustrated by One Hundred and Two quarto plates finely engraved on copper. Eleventh Edition. 4to., cloth. . $10.00 SHUNK.— A Practical Treatise on Pailway Curves and Location, for Young Engineers. By William F. Shijnk, Civil Engineer. 12mo. . . $2.00 SLOAN.— American Houses : A variety of Original Designs for Rural Buildings. Illustrated by 20 colored Engravings, with Descriptive References. By Samuel Sloan, Architect, author of the “ Model Architect,” etc., etc. 8vo. $1.50 SMEATON- Builder’s Pocket Companion: Containing the Elements of Building, Surveying, and Architecture ; with Practical Rules and Instructions connected with the subject. By A. C. Smeaton, Civil Engineer, etc. In one volume, 12mo. $1.50 SMITH.— A Manual of Political Economy. By E. Peshine Smith. A new Edition, to which is added a full Index. 12mo., cloth $1.25 SMITH.— Parks and Pleasure Grounds: Or Practical Notes on Country Residences, Villas, Public Parks, and Gardens. By Charles H. J. Smith, Landscape Gardener and Garden Architect, etc., etc. 12mo. $2.25 SMITH. — The Dyer’s Instructor: Comprising Practical Instructions in the Art of Dyeing Silk, Cotton, Wool, and Worsted, and Woollen Goods: containing nearly 800 Receipts. To which is added a Treatise on the Art of Padding ; and the Printing of Silk Warps, Skeins, and Handkerchiefs, and tho various Mordants and Colors for the different styles of such work. By David Smith, Pattern Dyer. 12mo., cloth. , , . $3.00 SMITH.— The Dyer’s Instructor: Comprising Practical Instructions in the Art of Dyeing Silk, Cotton, Wool, and Worsted and Woollen Goods. Third Edition, with many additional Receipts for Dyeing the New Alkaline Blues and Night Greens, with Dyed Patterns affixed. 12wo., pp. 391, cloth. . $10.50 STEWART.— The American System. Speeches on the Tariff Question, and on Internal Improvements, princi- pally delivered in the House of Representatives of the United States. By Andrew Stewart, Into M. C, from Pennsylvania. With a Portrait, and a Biographical Sketch. In one volumo, 8vo., 407 pages. $3.00 20 HENRY CAREY BAIRD’S CATALOGUE. STOKES. — Cabinet-maker’s and Upholsterer’s Com- panion : Comprising the Rudiments and Principles of Cabinet-making and Up- holstery, with Familiar Instructions, illustrated by Examples for attaining a Proficiency in the Art of Drawing, as applicable to Cabi- net-work; the Processes of Veneering, Inlaying, and Buhl- work ; the Art of Dyeing and Staining Wood, Bone, Tortoise Shell, etc. Direc- tions for Lackering, Japanning, and Varnishing; to make French Polish ; to prepare the Best Glues, Cements, and Compositions, and a number of Receipts particularly useful for workmen generally. By J. Stokes. In one volume, l2mo. With Illustrations. . $1.25 Strength and other Properties of Metals: Reports of Experiments on the Strength and other Properties of Metals for Cannon. With a Description of the Machines for testing Metals, and of the Classification of Cannon in service. By Officers of the Ord- nance Department U. S. Army. By authority of the Secretary of War. Illustrated by 25 large steel plates. In one volume, 4to. . $10.00 SULLIVAN.— Protection to Native Industry. By Sir Edward Sullivan, Baronet, author of “ Ten Chapters on Social Reforms.” In one volume, 8vo. . . ‘ . . $1.50 Tables Showing the Weight of Pound, Square, Flat Bar Iron, Steel, ete., By Measurement. Cloth TAYLOR. — Statistics of Goal: Including Mineral Bituminous Substances employed in Arts and Manufactures ; with their Geographical, Geological, and Commercial Distribution and Amount of Production and Consumption on the American Continent. With Incidental Statistics of the Iron Manu- facture. By R. C. Taylor. Second edition, revised by S. S. IIal- DEMAN. Illustrated by five Maps and many wood engravings. 8vo., cloth $10.00 TEMPLETON.— The Practical Examinator on Steam and the Steam-Engine: With Instructive References relative thereto, arranged for the Use of Engineers, Students, and others. By Wm. Templeton, Engineer. 12mo. . $1.25 THOMAS.— The Modern Practice of Photography. By R. W. Thomas, F. C. S. 8vo., cloth 75 THOMSON.— Freight Charges Calculator. By Andrew Thomson, Freight Agent. 24mo. . . . $1.25 TURNING: Specimens of Fancy Turning Executed on the Hand or Foot Lathe: With Geometric, Oval, and Eccentric Chucks, and Elliptical Cutting Frame. By an Amateur. Illustrated by 30 exquisite Photographs. 4to. ............ $3.00 HENRY CAREY BAIRD’S CATALOGUE. Turner’s (The) Companion : Containing Instructions in Concentric, Elliptic, and Eccentric Turn- ing : also various Plates of Chucks, Tools, and Instruments ; and Di- rections for using the Eccentric Cutter, Drill, Vertical Cutter, and Circular Rest ; with Patterns and Instructions for working them. A new edition in one volume, 12mo. $1.50 URBIN.— BRTJLL.— A Practical Guide for Puddling Iron and Steel. By Ed. Urbin, Engineer of Arts and Manufactures. A Prize Essay read before the Association of Engineers, Graduate of the School of Mines, of Liege, Belgium, at the Meeting of 1865-0. To which is added A Comparison op the Resisting Properties of Iron and Steel. By A. Brull. Translated from the French by A. A. Fesquet, Che- mist and Engineer. In one volume, 8vo $1.00 VAILE. — Galvanized Iron Cornice- Worker’s Manual: Containing Instructions in Laying out the Different Mitres, and Ma- king Patterns for all kinds of Plain and Circular Work. Also, Tables of Weights, Areas and Circumferences of Circles, and other Matter calculated to Benefit the Trade. By Charles A. Vaile, Superin- tendent “ Richmond Cornice Works,” Richmond, Indiana. Illustra- ted by 21 Plates. In one volume, 4to $5.00 VILLE.— The School of Chemical Manures : Or, Elementary Principles in the Use of Fertilizing Agents. From the French of M. George Ville, by A. A. Fesquet, Chemist and Engi- neer. With Illustrations. In one volume, 12 mo. . . $1.25 VOGDES.— The Architect’s and Builder’s Pocket Com- panion and Price Book: Consisting of a Short but Comprehensive Epitome of Decimals, Duo- decimals, Geometry and Mensuration ; with Tables of U. S. Measures, Sizes, Weights, Strengths, etc., of Iron, Wood, Stone, and various other Materials, Quantities of Materials in Given Sizes, and Dimen- sions of Wood, Brick, and Stone; and a full and complete Bill of Prices for Carpenter’s Work; also, Rules tor Computing and Valuing Brick and Brick Work, Stone Work, Painting, Plastering, etc. By Frank W. Vogdes, Architect. Illustrated. Full bound in pocket- book form $2.00 Bound in cloth. 1-50 WARN— The Sheet-Metal Worker’s Instructor: For Zinc, Sheet-Iron, Copper, and Tin-Plate Workers, etc. Contain- ing a selection of Geometrical Problems; also, Practical and Simple Rules for describing the various Patterns required in the different branches of the above Trades. By Reuben II. Warn, Practical r .l in- plate Worker. To which is added an Appendix, containing instruc- tions for Boiler Making, Mensuration of Surfaces and Solids, Rules lor Calculating the Weights of different Figures of Iron and Steel, Tables of the Weights of Iron, Steel, etc. Illustrated by 32 Plates and 37 Wood Engravings. 8vo. $3.00 22 HENRY CAREY BAIRD’S CATALOGUE. WATSON.— A Manual of the Hand-Lathe : Comprising Concise Directions for working Metals of all kinds, Ivory, Bone and Precious Woods ; Dyeing, Coloring, and French Polishing; Inlaying by Veneers, and various methods practised to produce Elabo- rate work with Dispatch, and at Small Expense. By Egbert P. Watson, late of “ The Scientific American,” Author of “ The Modern Practice of American Machinists and Engineers.” Illustrated by 78 Engravings. . $1.50 WATSON. — The Modern Practice of American Ma- chinists and Engineers : Including the Construction, Application, and Use of Drills, Lathe Tools, Cutters for Boring Cylinders, and Hollow Work Generally, with the most Economical Speed for the same ; the Results verified by Actual Practice at the Lathe, the Vice, and on the Floor. Together with Workshop Management, Economy of Manufacture, the Steam- Engine, Boilers, Gears, Belting, etc., etc. By Egbert P. Watson, late of the “ Scientific American.” Illustrated by 86 Engravings. In one volume, 12mo . $2.50 WATSON.— The Theory and Practice of the Art of Weaving by Hand and Power: With Calculations and Tables for the use of those connected with the Trade. By John Watson, Manufacturer and Practical Machine Maker. Illustrated by large Drawings of the best Power Looms. 8 vo. $7.50 WEATHERLY.- Treatise on the Art of Boiling Su- gar, Crystallising, Lozenge-making, Comfits, Gum Goods. 12mo $2.00 WILL. — Tables for Qualitative Chemical Analysis. By Professor Heinrich Will, of Giessen, Germany. Seven* h edi- tion. Translated by Charles F. Himes, Ph. D., Professor of Natu- ral Science, Dickinson College, Carlisle, Pa. . . . $1.50 WILLIAMS. — On Heat and Steam : Embracing New Views of Vaporization, Condensation, and Explosions. By Charles Wye Williams, A. I. C. E. Illustrated. 8vo. $3.50 WOHLER. — A Hand-Book of Mineral Analysis. By F. Wohler, Professor of Chemistry in the University of Gottin- gen. Edited by Henry B. Nason, Professor of Chemistry in the Rensselaer Polytechnic Institute, Troy, New York. Illustrated. In one volume, 12mo $3 00 WORSSAM. — On Mechanical Saws: From the Transactions of the Society of Engineers, 1860. By S. W. Worssam, Jr. Illustrated by 18 large plates. 8vo. . . $o.uO HENRY CAREY BAIRD’S CATALOG (JE. 23 REGENT ADDITIONS TO OUR LIST. AUERBACH. — Anthracen : Its Constitution, Properties, Man- ufacture, and Derivatives', including Artificial Alizarin, An- thrapurpurin, with their applications in Dyeing and Printing. By G. Atjekbach. Translated and edited by Wm. Crookes, F. R. S. 8vo. $5.00 BECKETT. — Treatise on Clocks, Watches and Bells. By Sir Edmund Beckett, Bart. Illustrated. 12mo. . $1.75 BARLOW. — The History and Principles of Weaving, by Hand and by Power. Several Hundred Illustrations. 8vo , $10.00 BOURNE. — Recent Improvements in the Steam Engine. By John Bourne, C. E. Illustrated. 16ino. . . . $1.50 CLARK. — Fuel : Its Combustion and Economy. By D. Kinnear Clark, C. E. 144 Engravings. 12ino. . $2.25 CRISTIANI. — Perfumery and Kindred Arts. By R. S. Cristiani. 8vo. $5.00 COLLENS. — The Eden of Labor, or the Christian Utopia. 12mo. Paper, $1.00; Cloth, $i.25 CUPPER. — The Universal Stair Builder. Illustrated by 29 plates. 4to. $5.00 COOLEY. — A Complete Practical Treatise on Perfumery. By A. J. Cooley. 12mo $1.50 DAVIDSON. — A Practical Manual of House Painting, Grain- ing, Marbling and Sign Writing: With 9 Colored Illustrations of Woods and Marbles, and many Wood Engravings. 12mo. $3.00 EDWARDS. — A Catechism of the Marine Steam Engine. By Emory Edwards. Illustrated. 12mo. . . . $2.00 HASERICK. — The Secrets of the Art of Dyeing Wool, Cotton, and Linen : Including Bleaching and Coloring Wool and Cotton Hosiery and Random Yarns. By E. C. Haserick. Illustrated by 323 Dyed Pat- terns of the Yarns or Fabrics. 8vo $25.00 HENRY. — The Early and Later History of Petroleum. By J. T. Henry. Illustrated. 8vo. $4.50 24 HENRY CAREY BAIRD’S CATALOGUE. KELLOGG.— A New Monetary System. By Ed. Kellogg. Fifth Edition. Edited by Mary Kellogg Putnam. 12mo. Paper, $1.00; Cloth, .... $1.50 KEMLO. — Watch Repairer’s Hand-Book, Illustrated. 12mo. $1.25 MORRIS. — Easy Rules for the Measurement of Earthworks by means of the Prismoidal Formula. By Elwood Morris, C. E. 8vo. $1.50 McCULLOCH. — Distillation, Brewing and Malting. By J. C. McCulloch. 12mo $1.00 NEVILLE. — Hydraulic Tables, Co-Efficients, and Formulae for Finding the Discharge of Water from Orifices, Notches, Weirs, Pipes, and Rivers^ Illustrated. 12mo. . . $5.00 NICOLLS. — The Railway Builder. A Hand-book for Estimating the Probable Cost of American Railway Construction and Equipment. By Wm. A. Nicolls, C. E. Pocket- book Form • \ • • • $2.00 NORMANDY. — The Commercial Hand-book of Chemical Analysis. By H. M. Noad, Ph. D. 12mo $5.00 PROCTOR. — A Pocket-Book of Useful Tables and Formulae for Marine Engineers. By Frank Proctor. Pocket-book Form. . . $2.00 ROSE. — The Complete Practical Machinist: Embracing Lathe Work, Vise Work, Drills and Drilling, Taps and Dies, Hardening and Tempering, the Making and Use of Tools, etc., etc. By Joshua Rose. 130 Illustrations. 12mo. . . $2.50 SLOAN. — Homestead Architecture. By Samuel Sloan, Architect. 200 Engravings. 8vo. . $3.50 SYME. — Outlines of an Industrial Science. By David Syme. 12mo $2.00 WARE. — The Coachmaker’s Illustrated Hand-Book. Fully Illustrated. 8vo. . . . . ... $3.00 WIGHTWICK.— Hints to Young Architects. Numerous Wood Cuts. 12mo. $2.00 WILSON. — First Principles of Political Economy. 12mo. ........... $1.50 WILSON. — A Treatise on Steam Boilers, their Strength, Con- struction, and Economical Working. By Robt. WILSON. Illustrated. 12mo $2.50 >