AMALGAMATION. 



of Wheeler's or Hepburn's pan, and it appears 

 that it is principally the friction between the 

 iron parts of the apparatus and the ore which, 

 in this process, causes a decomposition of the 

 silver ore, and its fitness to form an alloy with 

 the mercury. It ought to be remarked, how- 

 ever, that the presence of much antimony or 

 arsenic in the ore is greatly objectionable, and 

 that in such cases the ore has to be previously 

 calcined. "With ordinary care, the percentage 

 of silver extracted from the ore varies between 

 YO and 80 per cent., compared with the yield 

 of the assay, and it cannot be overlooked that 

 this system is of great importance in a country 

 where fuel is so scarce as in Nevada. 



The chemicals which are more or less used 

 in the mills in Nevada are numerous ; they are 

 employed, with the exception of the common 

 gait, in a state of solution. We give a list of 

 the more important ones : 



1. Sulphate of copper (bluestone). Out of a 

 solution of this salt metallic copper is precipi- 

 tated, when in contact with iron. The freed 

 copper forms an alloy with the quicksilver 

 amalgam, which is again decomposed by sul- 

 phide of silver, through electro-chemical action, 

 producing silver amalgam, and probably sul- 

 phide of copper. 



2. Sulphate of iron (copperas). 



i 3. Bisulphate of soda. This salt gives up one 

 atom of its acid, and is reduced to a neutral salt. 

 : 4. Alum. 



5. Sulphuric acid. The acid is used in a 

 diluted state, and appears to act directly on 

 sulphides of silver, which may be seen by the 

 development of sulphuretted hydrogen gas, 

 immediately after the application of the acid. 



6. Chloride of sodium (common salt). It 

 does not act directly on the sulphides of silver, 

 but must be first decomposed by some agency 

 before its chlorine can act on the ore. 



' 7. Proto and deuto-chloride of copper. These 

 salts act similar to the sulphate of copper. 



These and many other substances are used 

 with or without success in the Nevada mills. 

 An untold number of experiments have been 

 made, many patents issued for so-called new 

 processes, while some " inventors " kept their 

 method strictly secret ; but to the present day 

 no treatment has been discovered for amal- 

 gamating such complicated silver ores, which 

 would give all the silver contained therein, and 

 more especially under such difficult circum- 

 stances as prevail in Nevada. 



It leads us too far, considering the space for 

 this article, to describe the different systems of 

 amalgamators, and it could hardly be done 

 without figures. But it may be interesting to 

 give a short description of the modus operandi 

 followed in the process of amalgamation. In 

 some pans, chemicals and raw ore are used ; in 

 other cases, the ore is first roasted, and often 

 no chemicals are resorted to. In the first case, 

 some water is first put in the 'pan and finely- 

 pulverized ore, enough to give a certain consist- 

 ency to the mass, which is of much importance, 



as too much fluidity will cause the settling of th 

 sand and prevent a uniform division of the 

 mercury, while, on the contrary, the particles 

 of ore cannot change their places quick enough, 

 and prolong, therefore, the operation. The 

 pan being filled in this manner, the quicksilvei 

 is added in quantities of thirty to eighty pounds, 

 and, if salt is to be used, it may be done so 

 immediately, while all other chemicals are only 

 applied a little afterward. The temperature is 

 kept, as near as possible, uniform, and near the 

 boiling-point of water. The number of revo- 

 lutions of the agitator is from ten to fifteen 

 per minute, but they can be increased without 

 inconvenience. The operation is finished in 

 about three or four hours; at that time the 

 mass is diluted with water, and after half an 

 hour tapped carefully in an adjoining vat, where 

 such traces of amalgam are separated as might 

 have gone with the fluid mass. The great 

 quantity of amalgam now on the bottom of the 

 pan remains, and acts on a new portion of ore 

 until it has become sufficiently solid, when it 

 is removed and pressed through a filter of 

 leather or strong linen cloth. As already re- 

 marked, the pans known as " Wheeler's " and 

 " Hepburn's " seem to give the most favorable 

 results, in consequence of their peculiar con- 

 struction. It is believed that they give a better 

 percentage than other pans, and some estimate 

 the difference as much as ten per cent. The 

 actual loss of mercury has not yet been accu- 

 rately ascertained, or if so, has not been made 

 public. 



A Hepburn pan of ordinary size can treat 

 about four tons of ore in twenty-four hours, 

 and requires two and a half horse-power. 



The amalgam, after. being pressed, is distilled 

 in retorts, generally made of cast iron, four 

 feet long, eleven inches wide, and nine inches 

 high. The same is connected with a condens- 

 ing apparatus, which is kept cool by water, 

 and in which the vapors of mercury are con- 

 densed and liquefied. 



It may be interesting to finish our remarks 

 about amalgamation, with a description of this 

 process as applied to so-called speiss and black- 

 copper, the first being a product from treating 

 arsenical and antimonial ores, also containing 

 silver, nickel, and copper the other (black- 

 copper), an impure metal from mixed copper 

 ores containing 80$ copper, and remainder iron, 

 sulphur, lead, and antimony, besides some sil- 

 ver. These classes of ores and products are not 

 yet known well in this country, but there can 

 be no doubt that the amalgamation or humid 

 extraction of the precious metals from these 

 substances, will have to be resorted to, with the 

 increased development of the mineral resources. 



The following methods are practised in the 

 Stephanshutte, in Hungary. Black-copper, af- 

 ter being granulated and ground fine by stamp- 

 ers and arrastras, is mixed with 10$ common 

 salt, and calcined in a double calcining furnace, 

 with a low, slowly increasing heat during ten 

 hours. The silver is thus converted into 3 



