Volume 28 (1874) (430 pages)

22 MINING AND SCIENTIFIC PRESS. (January 10, 1874. The Chilian Method of Amalgamation. Mr. Frederick Prime, Professor of Motallurgy in Lafayette College, Haston, Pennsylyania, has furnished from a French source tbe following account of this process to the American Chemist: Tbe first process employed in Cbili was/that of the ordinary patio, but this was soon supplanted by another method which formed the basis of that now in use, This consisted of treating rich sulphurets in copper vessels witb oupric sulphate, sodium chloride, and mercury. At the end of a little time almost the whole of the silver was amalgamated, heing, however, only accomplished at the expense of a large amonnt of mercury, the loss frequently being 200 to 250 per 100 of silver; in spite of which this process was frequently employed for tbe treatmeut of o1es coutaining more than 0:02 per cent. silver, owing hoth to tbe rapidity of the operation, it taking less thau two hours when aided by heat, as also to the small percentage of metal (searcely 0-0002 to 0.0003 per cent.) left in the tailings. The enormous amouuts of argentic chloride, iodide, and chloro-hromide prodnced at Chanarcillo soon demanded a more rapid, though less exact, process than the older one. In order to obtain some idea of the amount of ore requiring treatment, it will suffice to mention that the single mine of Descuhridora produced in the years 1831—51, the sum of ninety three millions of dollars. In the new process applied to these-ores, they were crushed and nulverised as in the old method. The pulverised ore was carried bya stream of water to settling basins of sheet iron, 614 feet in diameter, and 934 feet deep. The stream was conducted iu turn to different basins, which, when once filled, are left to stand from eight to ten hours to permit the slimes suspended in the water to settle at the bottom. At the end of this period the clarified water wae decanted off and the slimes were transferred to tinas. These tinas consist of wooden yats, haying a cast iron bottom, and are 5 feet 10 inches by 3 feet 11 inches. These are provided in the line of their axes with a shaft hay‘ing cast iron arms which slide over the bottom of the vat. The charge placed in these tinas was aboutaton andahalf. The ores are a mixture of chlorides, iodides and bromides, haying a gangue composed of the carhonates of lime and baryta as well as clay and oxide of irou. The charge of tbe vat was completed by the addition of mercury, about twenty times as much of thisbeing added as there is silver in the ore, Tbe shaft was then set in rotation, making ahout fonr revolutions per minute. This opperation lasted twenty-fonr hours, at the end of wbicb the amalgamation was supnosed to be completed. A stream of water was then introduced, and the rotation continued. The slimes were removed by the water, and carried into settling basins. When the water ran clear from the vats an orifice was opened in the lower portion of the vat, and the mercury aud amalgam which ran out were received in a cast iron vessel, called cocha. The amalgam was then sqneezed in athick piece of cotion, and then laid aside for distillation. Tbe wages, loss of mercury, arid various expenses cost $9 30 per ton for ores containing less than 0.005 per cent. silver. The entire operation, including crushing, took about sixteen hours. The tailings carried off by the current of water, whicb were caught in settling hasing, contained 0.0008 to 0.001 per cent. silver, in the case of ores of the ahove mentioued richness, and never exceeded 0.002 for richer ores of the same character. The silver obtained contained scarcely 0.01 per cent. of impurities. The process just described subsequently underwent several modifications. The time oocupied in treating the orein tbe vats, exclusive of lixiviation, was reduced to six hours; and ores were treated in this manner containjug as high as 30 per cent. silver. Owing to the increase in tbe proportion of sulphurets as the mines were suuk deeper, the results of the method of amalgamation just described nnderwent modifications; the percentage of metal in tbe tailings being angmented to euch a degree as to diminish the yield of silver. The tailinge, which were thrown to one side at the time of amalgamation, formed near the works enormoue masses of poor ores, whose contente increased daily; the more so, as to theee were added snch ores as were thrown aside when picking over the ores. Attempte were made to recover the silver contained in these large bodiee of tailinge, for whicb purpose various experiments were tried. The first ouetried was the Freiherg process of roaeting and chlorination; the results obtained were very unsatisfactory, owing to the inexpetience of the workmen, Sixperiments were then made by chlorination and subsequent treatment with ammonia, which were still more uneuceeseful, owing to the high price of ammonia. The argentic sulpbate process (Ziervogel’e) did not yield any more satisfactory resulte, Recourse was then had to the process wbicb we have first described, and which had been so long abandoued, As we have stated, rich ores called negrillo, which were sulphurets, were treated in copper kettlee together with cupric sulphate, sodium cbloride and mercury. The reactions which took place were the followiug: The cupric eulphate was transformed iuto protochloride in the presence of sodium chlotide, thus: CnSO;+2NaCl=CuCle+Naz,S0,. ‘Tbe heated cupric protochloride coming in contact with the copper of the kettle formed cubchloride—Cu2Cl+ Ou=Cu2Clo.° The cupric subchloride, in the presence of argentic sulphide and mercury, reacted on the sulphide, the affiuity of the mercury for silver p:omoting tbe reaction—Ag2S+CuzCle +nHg=2AgHe+ CuCl, +CuS+(n-2)Hg. In tbis manner tbe amalgam was formed. As we have seen, this process, as formerly carried on, occasioned the loss of a large amount of mercury. The reaction by which the cupric protoohloride was converted into suhchloride was at that period at the expense of the copper kettles and the mercury. Tbns @ great loss of mercury was occasioned, and the copper vessels were rapidly destroyed. Wheu, therefore, aretnrn was made to this process, the first thing sought for was the production of the suhchloride in special vessels and by other means. Recourse was bad to the following method:— The sodium chlorideis dissolved in water; 5 parts of salt per 100 of ore. Cupric sulphate is also dissolved in water nntila Baumé’s aerometer indicates 209. Sudium cbloride is added to satnration. By this means the oupric sulpbate ‘is converted to protocbloride. ‘Tbe protochloride is then transferred to a wooden vat, into which metallic copper is charged at tho same time, The liquors in the vat are then made to boil by introducing steam at a pressure of three atmospheres. At a temperature of 100° CG, the enprie chloride reacts on the metallic copper, and thns forms tbe subchloride which is subsequently employed iu tbe amalgamation. Tbe reaction is known to be finished when, on taking 50 c. o. of the solution, and introducing it into a liter of water, the oxychloride precipitates as a white powder, leaving the liquid entirely colorless. The subchloride is used as soon as made, and care must he taken to preserve it from contact with the air so as to avoid the formation of insoluble oxychloride. To prevent this oxidation the solution is slightly acidulated with sulphuric acid. We will now proceed to the treatmeut proper of tbe ores. The ores are first crnshed. For tbis purpose au apparatus called trapiche is employed, resembling the mill employed in the manufacture of oil. Two vertical cast-iron wheels, each weighing about four tons, form the chief portion of the machine; each of these has a rim of wrought iron or steel. These wheels are monnted on arms set in motion by a motor of some kind. Tbey are given a velocity of ten to twelve revolutions per miunte and rotate on a disk, called solera, made either of cast iron or steel, and.on which the ore to be pulverised is spread. The ore is thus crusbed to a fine powder. While the wheels are rotating a current of water is made to flow contiuuously, which carries off the ore as it is crushed. ‘The quantity of water depends on the fiueness to which the ore is to be crushed. ‘The current of water is theu made to flow through a succession of tanks, in which it deposits the ore it has carried off. The water escapes perfectly clear from tbe last reservoir. When the first tank is completely filled with ore, the current water is cut off, and the slimes allowed to precipitate for eight hours. The clarified water is decanted and the slimes, forming athick paste, are shovelled out on toa level floor, where they are left until they are oompletely dried by the air. The capacity of each tank is ahout 1614 feet by 6% feet at the base, and is 3 feet 4 inches high. In the amalgamation proper the ore, properly dried, is charged into casks wbose capacity varies from one to four tons; those of four tons capacity being preferred at present, whose dimensions are 5 feet 10 inches by 4 feet 10% iuches; the thickness of tbe staves is about 3 inebes. The arrangement of tbe casks is almost identical witb tbat formerly employed at Freiberg. A charge is composed of four tons of ore witha sufficient amount of saumure to form a tbick paste. A varyiug quantity of magistral is added, depending on the richuess of the ore and the natnre of the gangue. When the latter is calcareous, more magisiral is used than when itis argillaceous, or ferruginous, since the caleareous gangue decomposes a portion of the cupric subchloride. For an ore containing less tban 0.002 per cent. silver having a mixed gangue, from 28 to 38 liters of magistralis used. ‘The casks are made to rotate for twenty to thirty minutes, in order to give the paste time to form; then the mercury is introduced, being about twenty to twenty-five times the amount of the silver inthe ore. The rotation of the casks is then continned attbe rate of four or five revolutious per minnte. Six hours suffice to complete tbe operation. If thé ores eubjected to this treatment contain alarge proportion of argeutie chloride or bromide, 25 ibs. of lead are added to the mercury for every 100 ibs. of silver. This lead is added as amalgam; it eerves to prevent tne chloridation of the mercury, The reaction of the argentic chlorideis: 2AgCl+Cu2Cle +nHg=-2Cu Clo+2AgHg+(n—2)Hg. The lead chloridieee more readily than the merenry; tbe cblorine and bromine set at liberty by the decomposition of the argentic chlorides and bromides reacting on the metal; thue avoiding, in the first place, the loss of mereury which would result from the cbemical combination; and, secondly, another loss, much more cousiderahle and purely mechanical, due to the division of the mercury into little drope by the mercuric chloride, which, when once formed, envelops them in a thiu pellicle which destroys the homogeneity of tbe metal, and prevents it from reuniting. The mercury is thus reduced toa powder, occasioning great loss. The use of ae reduces this losg from 150 to 25 parts per 100. When the amalgamation is completed, the next step is to wash the amalgam, which oneration is performed the same as in the Freiberg process. After which follows the refining of the amalgam,which contains cupric oxide and sulphide. The first of these is formed by the reaction of the lime of the gangue on the protochloride, the last by the reaction of the magistral on the argentic snlphide. The refining is divided into two parts, the mechanical and the chemical. Tbe former is peiformed in a tina analogous to that already descrihed, the process beiug to oharge the amalgam into the vat, adding ten parts of mercury to 100 of the former. A current of water is then introduced, and the shaft is made to rotate at the rate of sixty revolutions per minute. Inthis manner the whole of the cupric sulphide and a very small qnautity of the oxide are removed. This operation is finished when tho water escapes perfectly clear. To proceed to the chemical refining, the water in the vat is permitted to escape, aud two parts of ammonium carbonate per 100 amalgam are added. The shaft is caused to rotate from four to five honrs, and the amalgam is then washed, when it is fouud to he entirely freed from cupric oxide. : The distillation of the amalgam takes place in a closed vessel per descensu. The furnace is formed hy a cast iron hell, the lower portion of which stands in a basin of water iu which the mercury condenses. The upper portiou of the bell is surrounded by a circular wall; the fuel being charged into the anuular space between tbe wall and tbe bsll, which is about 3 to5 inches. The spongy silver (pina) which is obtained is remelted in a reverberatory. It is necessary to thoroughly rable the meiallic bath; the remnant of arsenic remaining 1s thus removed by contact with the iron tools, forming au iron arsenide which floats on the surface and iseasily removed. The silver thus obtained is 980 thousanths fine. The process which has just bsen described is applicable to all silver ores, with the exception of argentlferons copper pyrites, palena, blende, and sucb ores as contain more than 1 per ceut. of free arsenic, the latter largely augmenting the loss of mercury. In this manner it is possible to treat tailiugs uot containing more than 0.0004 per cent., and ores nof containing over 0.0006 per cent. silver. So long as the richness of the ores subjected to this treatment doos not exceed 0.005 per cent., the tailings obtained do not contain more than 0.00015 to 0.0002 per cent. silver. The ores subjected to treatment are never reduced to an equal percentage by mixing, as it is found much more profitable to treat the rich ores separately. In this case the operation is completed much more rapidly, the interest on the capital thus running for a much sborter period, tbus compensating, toa great extent, for the cost of treating tbe refuse of the operatiou. Tbe mercury which has been used five or six times hecomes so charged with impurities as to retard the amalgamation. It is purified by adding 20 grammes of sodium amalgam to every 200 tbs. of mercury. The works are nsually placed near a stream of water, in order to have both the water and motive power necessary for the various operations. Works of sufficient capacity to treat eight tons per day cousist of—1. An area of 550 yards for dumping ores. 2. Two trapicheset in motion bya motor of six horse-power. 3. Four basins. 4, An area of 1,100 yards for drying the pulverized ores. 5. Two amalgamating casks, with a motor of eigbt horse-power. 6. Avat to receive the wasb-water of tbe casks and to recover the comminuted meroury. 7. A vat for washing the amalgam. 8. A distilling fnrnace. 9. A melting furnace. 10. A wooden vat for the preparation of the magistral with a small caldron. 11. Two vats in which to dissolve the sulphate. 12. A basin constructed of hydraulic cement for the saumure. 13. A caldron in which to treat tho saumure. To which must be added the basins for clarifying and purifying the waters. These last are made to pass through quicklime in order to recover tbe copper salts. They are thns rendered limpid and potable. The persons employed consist of a superintendent, an assistant superintendent, an assayer, a clerk, a foremau, and ten workmen. The cost per ton of ore, containing 0°002 per cent. silver, is—pulverizing, 1°49 dols.; mercury,. magistral saumure, 3°72 dole.; refiniug tbe amalgam, ‘04 dol.; distillation, -04 dol.; melting and refining, ‘09 dol.; tools and varioue expenses, ‘93 dol. to 1 dol. 0:03c. [These values are giveu in coin. J This does not include interest, the operation takiug euch a sbort time, nor a sinking-fund of the capital. The great charm of the Cbilian method of amalgamation isits great simplicity. This process eliminates a large number of the operations preceding the amalgamation, or considerably simplifies them. If, for example, it be compared with the European method of amalgamation as formerly carried on at Freiberg, it will be found to be infinitely superior both for rapidity aud eimplicity. It eutirely does away with the difficult operation of roasting, which is delicate in its manipulation and the cause of almost all the loss of silver. Even when compared with the American method of amalgamation as carried on iu Mexico, it is infinitely superior as regards rapidity. It replacesthe doubtful and hypothotical reactions of thie process by chemical reactions which are both exact and cloarly defined. In one word, it solves in the most simple manner a question in silver motallurgy wbicb has never been hitherto accomplished but by roundabout means, i. e., the elimination of the sulphur and tbe direct nnion of the silver and meroury. Finally it may be stated that, while elsewbere amalgamation must give way to the fusiou witb lead as soon as this hecomes possihle, as applied with us it will not he the case, sinco it greatly surpasses this process. Itis unkuown who was the inventor of this method; it can only be stated that this process hae been constantly in use at Copiapo siuce 1862. Divisibility of Quicksilver, Gold and Silver. The Virginia Enterprise says: ‘Tbe divisibility of quicksilver, and also of silver and gold, as shown by the mining operations conducted in this State, is almost incompreheusibly great, and would scem to bo almost illimitahle, particularly in the case of the metal first named, A globule of quicksilver may be divided until uo longer visible to tbe naked eye, and indeed scarcely visible under a powerful microscope, yet even the most minute subdivisions shall be fonnd to contain silver or gold, perhaps both. How infinitesimally small, then, must be the particles of silver or gold contaiued in one of tbese iuvisible and immeasurable globules of mercury! In regard to the astonishing divisibility of the metal mentioned, we bave just learned some interesting facts of Dr. Buncher, Superintendent of the Rock Point Mill, Daytou. This gentleman informs us, that some time since, when working in his mill for a considerable period, an ore in which gold largely predominated, he used every precantion to guard against loss. In additiou to the usual settling tanks, he eaused to be dug in the grouud a numher of large pits, into which the waste water flowed after leaving the tanks. After loaving these pits, the water passed off in a small flume, and to the eye appeared as clear as tbe water of the purest monntain stream. For the sake of experiment, Mr. Buncber ooated a copper bowl with quicksilver, and placedit in such a position that tbe wator of the flume shonld fall into it. He also placed in the flume, below the bowl, some copper riffles, properly coated with quicksilver. Altbough the water passing through tbe flume seemed to be perfectly clear, yet at tbe end of three months the bowl and rifflss were cleaned up and over $100 worth of amalgam ohtained. His mill is driven by water from Carson River, and carried for a considerahle distance through a large wooden flume. A month or two since it became necessary to shut off the water and repair a portion of tbis flume. In making the necessary repairs it was found that in many places tbe heads of the nails driven into its bottom had been thickly coated with amalgam. Witbin the distance of about three rods aloug the bottom of the flume the workmen engaged in making the flumo collected over an ounco of amalgam. This was where there were no copper plates or other special facilities for catebing the floating particles of quicksilver. The water flowing through tbe flume was taken from the river below a number of large mills, and, tbough far from heing clear, would never have been suspected of contuining floating quicksilver in such quautities as to amalgamate the heads of iron nails. In order to amalgamate iron it must bescratched or polisbed while immersed in quicksilver, tberefore, it will be seen that much material must have passed by before the occurrence of tbe accideuts required for the commencement of the aocumnlations found on tbe nails. As anotber evidence that qnicksilver in sousiderable qnantities floats iu the water of flumes and streams below reductiou works in a state of invisible divisiou, and yet carries with it the precious metals, Dr. Buneber gave us this additional evidence: On a certain occasion one of his workmen required a piece ofcopper. Remembering to have eeen some old sbeets of tbat metal lying near the waste gate of the main flume, he went to the spot, and hauled them out of « puddle in wbich they were lying, and found tbem beavily coated with amalgam, and so eateu up that they were hardly thicker thau writing paper. The water pouring out througb the waste-gate had a fall of about fifteen feet. It did not fall directly upon the oopper plates, but in sucb a manner 2s to keep them constantly splashed and wet. Mr. Buncher thinks the plates had lain in the place four or five years. Over a pound of amalgam was scraped off them. It appears to us that in these soveral etriking instancee of the treacherous and unspecting floating away of the precious metals there is for mill-men food for reflection, and for inventors a field in which to reap hoth profit and distinction.” Countrerreirino Trap— Marks. — Reporte have been received at the Treasury Department from Mr. Denman, Special Agent at Shaughae, stating that he expected to bein Calcutta on the 10th of January. He investigated the cause of the decrease on American exportation of drills to China, and ascertained that it was caused by British drills, the mannfactnrere of which imitated American trademarks and undersell American goods. The Chinese prefer American drills, butthe fraudulent trade-marks on British goods have deceived purchasers. Our exportation has fallen off from 250,000 to 40,000 pieces per annum, while the British exportatious increased from 14,000 to 250,000 picces.

22 MINING AND SCIENTIFIC PRESS. (January 10, 1874. The Chilian Method of Amalgamation. Mr. Frederick Prime, Professor of Motallurgy in Lafayette College, Haston, Pennsylyania, has furnished from a French source tbe following account of this process to the American Chemist: Tbe first process employed in Cbili was/that of the ordinary patio, but this was soon supplanted by another method which formed the basis of that now in use, This consisted of treating rich sulphurets in copper vessels witb oupric sulphate, sodium chloride, and mercury. At the end of a little time almost the whole of the silver was amalgamated, heing, however, only accomplished at the expense of a large amonnt of mercury, the loss frequently being 200 to 250 per 100 of silver; in spite of which this process was frequently employed for tbe treatmeut of o1es coutaining more than 0:02 per cent. silver, owing hoth to tbe rapidity of the operation, it taking less thau two hours when aided by heat, as also to the small percentage of metal (searcely 0-0002 to 0.0003 per cent.) left in the tailings. The enormous amouuts of argentic chloride, iodide, and chloro-hromide prodnced at Chanarcillo soon demanded a more rapid, though less exact, process than the older one. In order to obtain some idea of the amount of ore requiring treatment, it will suffice to mention that the single mine of Descuhridora produced in the years 1831—51, the sum of ninety three millions of dollars. In the new process applied to these-ores, they were crushed and nulverised as in the old method. The pulverised ore was carried bya stream of water to settling basins of sheet iron, 614 feet in diameter, and 934 feet deep. The stream was conducted iu turn to different basins, which, when once filled, are left to stand from eight to ten hours to permit the slimes suspended in the water to settle at the bottom. At the end of this period the clarified water wae decanted off and the slimes were transferred to tinas. These tinas consist of wooden yats, haying a cast iron bottom, and are 5 feet 10 inches by 3 feet 11 inches. These are provided in the line of their axes with a shaft hay‘ing cast iron arms which slide over the bottom of the vat. The charge placed in these tinas was aboutaton andahalf. The ores are a mixture of chlorides, iodides and bromides, haying a gangue composed of the carhonates of lime and baryta as well as clay and oxide of irou. The charge of tbe vat was completed by the addition of mercury, about twenty times as much of thisbeing added as there is silver in the ore, Tbe shaft was then set in rotation, making ahout fonr revolutions per minute. This opperation lasted twenty-fonr hours, at the end of wbicb the amalgamation was supnosed to be completed. A stream of water was then introduced, and the rotation continued. The slimes were removed by the water, and carried into settling basins. When the water ran clear from the vats an orifice was opened in the lower portion of the vat, and the mercury aud amalgam which ran out were received in a cast iron vessel, called cocha. The amalgam was then sqneezed in athick piece of cotion, and then laid aside for distillation. Tbe wages, loss of mercury, arid various expenses cost $9 30 per ton for ores containing less than 0.005 per cent. silver. The entire operation, including crushing, took about sixteen hours. The tailings carried off by the current of water, whicb were caught in settling hasing, contained 0.0008 to 0.001 per cent. silver, in the case of ores of the ahove mentioued richness, and never exceeded 0.002 for richer ores of the same character. The silver obtained contained scarcely 0.01 per cent. of impurities. The process just described subsequently underwent several modifications. The time oocupied in treating the orein tbe vats, exclusive of lixiviation, was reduced to six hours; and ores were treated in this manner containjug as high as 30 per cent. silver. Owing to the increase in tbe proportion of sulphurets as the mines were suuk deeper, the results of the method of amalgamation just described nnderwent modifications; the percentage of metal in tbe tailings being angmented to euch a degree as to diminish the yield of silver. The tailinge, which were thrown to one side at the time of amalgamation, formed near the works enormoue masses of poor ores, whose contente increased daily; the more so, as to theee were added snch ores as were thrown aside when picking over the ores. Attempte were made to recover the silver contained in these large bodiee of tailinge, for whicb purpose various experiments were tried. The first ouetried was the Freiherg process of roaeting and chlorination; the results obtained were very unsatisfactory, owing to the inexpetience of the workmen, Sixperiments were then made by chlorination and subsequent treatment with ammonia, which were still more uneuceeseful, owing to the high price of ammonia. The argentic sulpbate process (Ziervogel’e) did not yield any more satisfactory resulte, Recourse was then had to the process wbicb we have first described, and which had been so long abandoued, As we have stated, rich ores called negrillo, which were sulphurets, were treated in copper kettlee together with cupric sulphate, sodium cbloride and mercury. The reactions which took place were the followiug: The cupric eulphate was transformed iuto protochloride in the presence of sodium chlotide, thus: CnSO;+2NaCl=CuCle+Naz,S0,. ‘Tbe heated cupric protochloride coming in contact with the copper of the kettle formed cubchloride—Cu2Cl+ Ou=Cu2Clo.° The cupric subchloride, in the presence of argentic sulphide and mercury, reacted on the sulphide, the affiuity of the mercury for silver p:omoting tbe reaction—Ag2S+CuzCle +nHg=2AgHe+ CuCl, +CuS+(n-2)Hg. In tbis manner tbe amalgam was formed. As we have seen, this process, as formerly carried on, occasioned the loss of a large amount of mercury. The reaction by which the cupric protoohloride was converted into suhchloride was at that period at the expense of the copper kettles and the mercury. Tbns @ great loss of mercury was occasioned, and the copper vessels were rapidly destroyed. Wheu, therefore, aretnrn was made to this process, the first thing sought for was the production of the suhchloride in special vessels and by other means. Recourse was bad to the following method:— The sodium chlorideis dissolved in water; 5 parts of salt per 100 of ore. Cupric sulphate is also dissolved in water nntila Baumé’s aerometer indicates 209. Sudium cbloride is added to satnration. By this means the oupric sulpbate ‘is converted to protocbloride. ‘Tbe protochloride is then transferred to a wooden vat, into which metallic copper is charged at tho same time, The liquors in the vat are then made to boil by introducing steam at a pressure of three atmospheres. At a temperature of 100° CG, the enprie chloride reacts on the metallic copper, and thns forms tbe subchloride which is subsequently employed iu tbe amalgamation. Tbe reaction is known to be finished when, on taking 50 c. o. of the solution, and introducing it into a liter of water, the oxychloride precipitates as a white powder, leaving the liquid entirely colorless. The subchloride is used as soon as made, and care must he taken to preserve it from contact with the air so as to avoid the formation of insoluble oxychloride. To prevent this oxidation the solution is slightly acidulated with sulphuric acid. We will now proceed to the treatmeut proper of tbe ores. The ores are first crnshed. For tbis purpose au apparatus called trapiche is employed, resembling the mill employed in the manufacture of oil. Two vertical cast-iron wheels, each weighing about four tons, form the chief portion of the machine; each of these has a rim of wrought iron or steel. These wheels are monnted on arms set in motion by a motor of some kind. Tbey are given a velocity of ten to twelve revolutions per miunte and rotate on a disk, called solera, made either of cast iron or steel, and.on which the ore to be pulverised is spread. The ore is thus crusbed to a fine powder. While the wheels are rotating a current of water is made to flow contiuuously, which carries off the ore as it is crushed. ‘The quantity of water depends on the fiueness to which the ore is to be crushed. ‘The current of water is theu made to flow through a succession of tanks, in which it deposits the ore it has carried off. The water escapes perfectly clear from tbe last reservoir. When the first tank is completely filled with ore, the current water is cut off, and the slimes allowed to precipitate for eight hours. The clarified water is decanted and the slimes, forming athick paste, are shovelled out on toa level floor, where they are left until they are oompletely dried by the air. The capacity of each tank is ahout 1614 feet by 6% feet at the base, and is 3 feet 4 inches high. In the amalgamation proper the ore, properly dried, is charged into casks wbose capacity varies from one to four tons; those of four tons capacity being preferred at present, whose dimensions are 5 feet 10 inches by 4 feet 10% iuches; the thickness of tbe staves is about 3 inebes. The arrangement of tbe casks is almost identical witb tbat formerly employed at Freiberg. A charge is composed of four tons of ore witha sufficient amount of saumure to form a tbick paste. A varyiug quantity of magistral is added, depending on the richuess of the ore and the natnre of the gangue. When the latter is calcareous, more magisiral is used than when itis argillaceous, or ferruginous, since the caleareous gangue decomposes a portion of the cupric subchloride. For an ore containing less tban 0.002 per cent. silver having a mixed gangue, from 28 to 38 liters of magistralis used. ‘The casks are made to rotate for twenty to thirty minutes, in order to give the paste time to form; then the mercury is introduced, being about twenty to twenty-five times the amount of the silver inthe ore. The rotation of the casks is then continned attbe rate of four or five revolutious per minnte. Six hours suffice to complete tbe operation. If thé ores eubjected to this treatment contain alarge proportion of argeutie chloride or bromide, 25 ibs. of lead are added to the mercury for every 100 ibs. of silver. This lead is added as amalgam; it eerves to prevent tne chloridation of the mercury, The reaction of the argentic chlorideis: 2AgCl+Cu2Cle +nHg=-2Cu Clo+2AgHg+(n—2)Hg. The lead chloridieee more readily than the merenry; tbe cblorine and bromine set at liberty by the decomposition of the argentic chlorides and bromides reacting on the metal; thue avoiding, in the first place, the loss of mereury which would result from the cbemical combination; and, secondly, another loss, much more cousiderahle and purely mechanical, due to the division of the mercury into little drope by the mercuric chloride, which, when once formed, envelops them in a thiu pellicle which destroys the homogeneity of tbe metal, and prevents it from reuniting. The mercury is thus reduced toa powder, occasioning great loss. The use of ae reduces this losg from 150 to 25 parts per 100. When the amalgamation is completed, the next step is to wash the amalgam, which oneration is performed the same as in the Freiberg process. After which follows the refining of the amalgam,which contains cupric oxide and sulphide.

The first of these is formed by the reaction of the lime of the gangue on the protochloride, the last by the reaction of the magistral on the argentic snlphide. The refining is divided into two parts, the mechanical and the chemical. Tbe former is peiformed in a tina analogous to that already descrihed, the process beiug to oharge the amalgam into the vat, adding ten parts of mercury to 100 of the former. A current of water is then introduced, and the shaft is made to rotate at the rate of sixty revolutions per minute. Inthis manner the whole of the cupric sulphide and a very small qnautity of the oxide are removed. This operation is finished when tho water escapes perfectly clear. To proceed to the chemical refining, the water in the vat is permitted to escape, aud two parts of ammonium carbonate per 100 amalgam are added. The shaft is caused to rotate from four to five honrs, and the amalgam is then washed, when it is fouud to he entirely freed from cupric oxide. : The distillation of the amalgam takes place in a closed vessel per descensu. The furnace is formed hy a cast iron hell, the lower portion of which stands in a basin of water iu which the mercury condenses. The upper portiou of the bell is surrounded by a circular wall; the fuel being charged into the anuular space between tbe wall and tbe bsll, which is about 3 to5 inches. The spongy silver (pina) which is obtained is remelted in a reverberatory. It is necessary to thoroughly rable the meiallic bath; the remnant of arsenic remaining 1s thus removed by contact with the iron tools, forming au iron arsenide which floats on the surface and iseasily removed. The silver thus obtained is 980 thousanths fine. The process which has just bsen described is applicable to all silver ores, with the exception of argentlferons copper pyrites, palena, blende, and sucb ores as contain more than 1 per ceut. of free arsenic, the latter largely augmenting the loss of mercury. In this manner it is possible to treat tailiugs uot containing more than 0.0004 per cent., and ores nof containing over 0.0006 per cent. silver. So long as the richness of the ores subjected to this treatment doos not exceed 0.005 per cent., the tailings obtained do not contain more than 0.00015 to 0.0002 per cent. silver. The ores subjected to treatment are never reduced to an equal percentage by mixing, as it is found much more profitable to treat the rich ores separately. In this case the operation is completed much more rapidly, the interest on the capital thus running for a much sborter period, tbus compensating, toa great extent, for the cost of treating tbe refuse of the operatiou. Tbe mercury which has been used five or six times hecomes so charged with impurities as to retard the amalgamation. It is purified by adding 20 grammes of sodium amalgam to every 200 tbs. of mercury. The works are nsually placed near a stream of water, in order to have both the water and motive power necessary for the various operations. Works of sufficient capacity to treat eight tons per day cousist of—1. An area of 550 yards for dumping ores. 2. Two trapicheset in motion bya motor of six horse-power. 3. Four basins. 4, An area of 1,100 yards for drying the pulverized ores. 5. Two amalgamating casks, with a motor of eigbt horse-power. 6. Avat to receive the wasb-water of tbe casks and to recover the comminuted meroury. 7. A vat for washing the amalgam. 8. A distilling fnrnace. 9. A melting furnace. 10. A wooden vat for the preparation of the magistral with a small caldron. 11. Two vats in which to dissolve the sulphate. 12. A basin constructed of hydraulic cement for the saumure. 13. A caldron in which to treat tho saumure. To which must be added the basins for clarifying and purifying the waters. These last are made to pass through quicklime in order to recover tbe copper salts. They are thns rendered limpid and potable. The persons employed consist of a superintendent, an assistant superintendent, an assayer, a clerk, a foremau, and ten workmen. The cost per ton of ore, containing 0°002 per cent. silver, is—pulverizing, 1°49 dols.; mercury,. magistral saumure, 3°72 dole.; refiniug tbe amalgam, ‘04 dol.; distillation, -04 dol.; melting and refining, ‘09 dol.; tools and varioue expenses, ‘93 dol. to 1 dol. 0:03c. [These values are giveu in coin. J This does not include interest, the operation takiug euch a sbort time, nor a sinking-fund of the capital. The great charm of the Cbilian method of amalgamation isits great simplicity. This process eliminates a large number of the operations preceding the amalgamation, or considerably simplifies them. If, for example, it be compared with the European method of amalgamation as formerly carried on at Freiberg, it will be found to be infinitely superior both for rapidity aud eimplicity. It eutirely does away with the difficult operation of roasting, which is delicate in its manipulation and the cause of almost all the loss of silver. Even when compared with the American method of amalgamation as carried on iu Mexico, it is infinitely superior as regards rapidity. It replacesthe doubtful and hypothotical reactions of thie process by chemical reactions which are both exact and cloarly defined. In one word, it solves in the most simple manner a question in silver motallurgy wbicb has never been hitherto accomplished but by roundabout means, i. e., the elimination of the sulphur and tbe direct nnion of the silver and meroury. Finally it may be stated that, while elsewbere amalgamation must give way to the fusiou witb lead as soon as this hecomes possihle, as applied with us it will not he the case, sinco it greatly surpasses this process. Itis unkuown who was the inventor of this method; it can only be stated that this process hae been constantly in use at Copiapo siuce 1862. Divisibility of Quicksilver, Gold and Silver. The Virginia Enterprise says: ‘Tbe divisibility of quicksilver, and also of silver and gold, as shown by the mining operations conducted in this State, is almost incompreheusibly great, and would scem to bo almost illimitahle, particularly in the case of the metal first named, A globule of quicksilver may be divided until uo longer visible to tbe naked eye, and indeed scarcely visible under a powerful microscope, yet even the most minute subdivisions shall be fonnd to contain silver or gold, perhaps both. How infinitesimally small, then, must be the particles of silver or gold contaiued in one of tbese iuvisible and immeasurable globules of mercury! In regard to the astonishing divisibility of the metal mentioned, we bave just learned some interesting facts of Dr. Buncher, Superintendent of the Rock Point Mill, Daytou. This gentleman informs us, that some time since, when working in his mill for a considerable period, an ore in which gold largely predominated, he used every precantion to guard against loss. In additiou to the usual settling tanks, he eaused to be dug in the grouud a numher of large pits, into which the waste water flowed after leaving the tanks. After loaving these pits, the water passed off in a small flume, and to the eye appeared as clear as tbe water of the purest monntain stream. For the sake of experiment, Mr. Buncber ooated a copper bowl with quicksilver, and placedit in such a position that tbe wator of the flume shonld fall into it. He also placed in the flume, below the bowl, some copper riffles, properly coated with quicksilver. Altbough the water passing through tbe flume seemed to be perfectly clear, yet at tbe end of three months the bowl and rifflss were cleaned up and over $100 worth of amalgam ohtained. His mill is driven by water from Carson River, and carried for a considerahle distance through a large wooden flume. A month or two since it became necessary to shut off the water and repair a portion of tbis flume. In making the necessary repairs it was found that in many places tbe heads of the nails driven into its bottom had been thickly coated with amalgam. Witbin the distance of about three rods aloug the bottom of the flume the workmen engaged in making the flumo collected over an ounco of amalgam. This was where there were no copper plates or other special facilities for catebing the floating particles of quicksilver. The water flowing through tbe flume was taken from the river below a number of large mills, and, tbough far from heing clear, would never have been suspected of contuining floating quicksilver in such quautities as to amalgamate the heads of iron nails. In order to amalgamate iron it must bescratched or polisbed while immersed in quicksilver, tberefore, it will be seen that much material must have passed by before the occurrence of tbe accideuts required for the commencement of the aocumnlations found on tbe nails. As anotber evidence that qnicksilver in sousiderable qnantities floats iu the water of flumes and streams below reductiou works in a state of invisible divisiou, and yet carries with it the precious metals, Dr. Buneber gave us this additional evidence: On a certain occasion one of his workmen required a piece ofcopper. Remembering to have eeen some old sbeets of tbat metal lying near the waste gate of the main flume, he went to the spot, and hauled them out of « puddle in wbich they were lying, and found tbem beavily coated with amalgam, and so eateu up that they were hardly thicker thau writing paper. The water pouring out througb the waste-gate had a fall of about fifteen feet. It did not fall directly upon the oopper plates, but in sucb a manner 2s to keep them constantly splashed and wet. Mr. Buncher thinks the plates had lain in the place four or five years. Over a pound of amalgam was scraped off them. It appears to us that in these soveral etriking instancee of the treacherous and unspecting floating away of the precious metals there is for mill-men food for reflection, and for inventors a field in which to reap hoth profit and distinction.” Countrerreirino Trap— Marks. — Reporte have been received at the Treasury Department from Mr. Denman, Special Agent at Shaughae, stating that he expected to bein Calcutta on the 10th of January. He investigated the cause of the decrease on American exportation of drills to China, and ascertained that it was caused by British drills, the mannfactnrere of which imitated American trademarks and undersell American goods. The Chinese prefer American drills, butthe fraudulent trade-marks on British goods have deceived purchasers. Our exportation has fallen off from 250,000 to 40,000 pieces per annum, while the British exportatious increased from 14,000 to 250,000 picces.