METALLURGY. (SILVER, GOLD.) 



529 



is dissolved, not as a sulphate, but as a chloride. 

 This method has the advantage of reducing the 

 waste of iron in the precipitation tanks, by 

 .avoiding the formation of ferrous and ferric sul- 

 phates. The produce of the mine is divided into 

 five different classes, each of which has its own 

 method of treatment. 



It has been generally believed that there were 

 no known deposits of tin ore in the United 

 States that could be worked with profit. Those 

 in the Black Hills, at King's Mountain, N. C., 

 in Virginia, Georgia, and California had hitherto 

 proved unremunerative. The mines at San Ja- 

 cinto, Cal., have been sold to an English corpo- 

 ration, which is understood to be intending to de- 

 velop them. The tin veins are found in the low, 

 rolling hills of the San Jacinto mountains, the 

 Gabilan hills, at an elevation of several hundred 

 feet above the creek. The country rock is com- 

 posed of syenitic granite, syenite, and slate; 

 but the veins apparently extend only a short dis- 

 tance into the latter. They are of widths varying 

 from 18 inches to 30 or more feet, while the widest 

 one measured was found to be 24 paces, or say 

 60 feet in width. Along the distance of about 

 three miles and a half from the most westerly to 

 the most easterly vein more than seventy lines 

 of croppings of as many apparently different veins 

 have been found. They are practically identical 

 in character a sort of syenitic rock, which, in 

 Cornwall is known as " tin capel," or "lode gran- 

 ite/' Silver, gold, and nickel are said to be 

 found also. 



In B. Schultze's method for utilizing waste tin 

 plate, the tin-plate scrap is collected into iron 

 pails and immersed in wooden tubs containing an 

 acid solution of ferric sulphate. The tin is dis- 

 solved, and the stripped iron remaining in the 

 pail is clean enough to be at once transferred to 

 the heating furnace. The solution of the tin in 

 the acid ferric solution takes place as long as 

 there remain any unreduced ferric salts in the 

 liquor. After the reaction, the stannous and 

 ferrous sulphates are associated with a consider- 

 able amount of free acid. It is necessary, there- 

 fore, before precipitating the tin, to neutralize 

 the liquid, and this is effected by allowing it to 

 remain in a vat containing metallic tin and iron 

 rust. The neutralized solution is next run over 

 clean iron scraps, when the tin is precipitated 

 on the metal in a crystalline form. The liquors 

 from this last operation are practically free from 

 tin, and are allowed to concentrate, when crystals 

 of ferrous sulphate separate which, on recrystal- 

 lization, can be sold, or the liquor use in prepar- 

 ing the iron solution required in the stripping 

 process. 



A report made by Thomas Bolitho & Sons to 

 "The Ironmonger" concerning a sample of tin 

 stone from Dakota shows that 18 hundred-weight 

 10 pounds of black tin was obtained from 17 

 tons 15 hundred-weight 2 quarters and 12 pounds 

 of ore, or, about 114 pounds, rather over 5 per 

 cent, of black tin per ton of rock. The black tin as- 

 sayed 70 per cent, for metallic tin. The actual 

 yield of refined tin was 12 hundred-weight 1 

 quarter, 14 pounds, 



Silver and Gold. The treatment of silver 



ores of too low a grade to- justify smelting or 



preliminary roasting, and yet not " free" enough 



to permit of raw amalgamation, has been a seri- 



VO*L. xxx. 34 A 



ous problem. The Combination Mining and 

 Milling Company, Black Pine, Montana, deal 

 with it by saving their slimes. These being 

 too light to permit their being thoroughly set- 

 tled, provision was made for pumping them 

 into the tank whence water is supplied to the 

 stamps. The immediate effect of turning this 

 concentrated slime into the battery was to " salt " 

 the battery sample, and it became important to 

 find a means of determining the percentage of 

 the salting. This was done. Other provision 

 was made for stopping the loss of the escape 

 from the settling tanks of water carrying rich 

 slimes. During the year ending with May, 1889, 

 the mill overran its assays 2*49 per cent., a re- 

 sult which may be safely credited to the use of 

 slime water in the pans. 



The principle on which a method of refining 

 silver electrically is based consists in using in an 

 ordinary electrolytic bath anodes of an argentif- 

 erous matte and" a thin plate of pure silver as 

 the cathode. The method is most suitable for 

 refining auriferous silver containing about 11 

 per cent, of gold. The bath consists of a very 

 weak solution of nitric acid. 



The value of sulphur iron and copper as well 

 as of lead in the concentration of silver and gold 

 by smelting in blast furnaces is insisted upon by 

 Mr. F. L.. Bartlett. This author has been able 

 in his own experience by the aid of a small per- 

 centage of copper to make a higher concentra- 

 tion of the silver and gold present than when 

 the matte is made wholly of sulphide of iron. 

 The ores most suitable for matte smelting in the 

 blast furnace are those containing considerable 

 iron or manganese, and the sulphur contents 

 must be regulated by partial roasting when high, 

 or by the addition of raw sulphurets when low, 

 since the amount of sulphur present determines 

 almost exactly the quantity of matte made. 

 Mr. C. T. Torrance, who has reviewed and sup- 

 plemented Mr. Bartlett's paper, expresses the be- 

 lief that smelting is the cheapest as well as the 

 most effective and perfect means for concentrat- 

 ing all ores that can be worked into a fluxing 

 mixture. The conditions of working such a 

 process are: An ore mixture that can be melted, 

 the presence of a sufficient quantity of matte- 

 forming material to separate from the slag, and 

 the presence of an excess of sulphur the most 

 important condition. 



Superior efficiency is claimed for the gold-ex- 

 traction apparatus of Mr. T. Rowland Jordan, 

 particularly in respect to the proportion of metal 

 that can be extracted with it from the ore. The 

 machine is of simple construction. Its rotation 

 causes a series of heavy bars or rnullers to roll 

 continuously over an inclined plane. The ma- 

 terial to be crushed is fed automatically on to 

 this inclined plane, and the mullers roll over 

 and reduce the particles to any required degree 

 of fineness. The ore in the machine is continu- 

 ally washed over large surfaces of screens of the 

 necessary mesh, so that the finely reduced mate- 

 rial passes out of the machine, and the coarse 

 particles return automatically to the crushing 

 plane, where they are again acted on by the 

 mullers. The amalgamator receives the gold- 

 bearing sand direct from the reducer, and dis- 

 tributes the particles over a large area of the 

 amalgamated surfaces. The mechanical action 



