510 



METALLURGY. (COPPER, TIN.) 



so as to leave a lining of the mixture about two 

 inches thick over the entire inner surface of the 

 pan. On the top of this, and confined by a 

 wrought-iron basket or grate, charcoal and bull- 

 ion are placed. As the bullion melts, it perco- 

 lates through the charcoal to the bottom of the 

 pan, and as it accumulates there it is, to a certain 

 extent, refined by the absorption of the base by 

 the bone and ash lining. The melted bullion 

 is drawn off directly into molds. The succeed- 

 ing bars can be melted and poured at intervals 

 of about fifteen minutes each. 



A gold-saving apparatus patented by Mr. John 

 II. Hobart comprises a novel arrangement of 

 amalgamating plates or copper plates, intended 

 more particularly for saving float gold, but 

 adapted for ordinary gold saving. The arrange- 

 ment is such that barriers or impediments are 

 formed in the course of the pulp, so as to cause a 

 whirling or eddying of the flowing material very 

 advantageous for the catching of the precious 

 particles. 



In the process of J. Buchanan, of Glasgow, 

 for precipitating gold and silver from the liquid 

 in which they are dissolved, in the process of ex- 

 tracting the same by chlorine, bromine, and 

 iodine the liquid is allowed to percolate through 

 iron or steel borings at the ordinary or at an 

 elevated temperature. The gold and silver are 

 claimed to be thus completely deposited on the 

 iron, from which they may afterward be removed 

 by riddling and washing, or otherwise. Copper, 

 brass, zinc, or any other metal or alloy capable 

 of precipitating gold and silver under the condi- 

 tions, may be used instead of iron, together with 

 charcoal. 



In J. Edlington Chaster's process for extract- 

 ing gold from refractory ores, the pulverized 

 quartz or ore is fed direct from the stamps into 

 the hopper of the machine; thence it passes by 

 gravity into mercury kept bright by a weak cur- 

 rent of electricity. 



In the Moebius electrolytic parting apparatus, 

 as operated at the works of the Pinos Altos 

 Company, Chihuahua, the dore bullion, which 

 varies in fineness from '800 to '900 in silver, and 

 25 to 50 in gold, is cast into thin plates. The 

 plates are hung in the cell and subjected to the 

 action of a current of small electro-motive force. 

 The silver passes into the solution (nitrate of 

 copper and nitrate of silver acidulated with ni- 

 tric acid) from the anodes, and is precipitated as 

 heavy needles and tree-like crystals at the cath- 

 odes. The copper from the anodes is also dis- 

 solved, but remains in solution provided the 

 exciting liquid is sufficiently acidulated or carries 

 enough nitrate of silver. All the lead (as per- 

 oxide), the platinum metals, antimony, and other 

 impurities remain with the gold in the bag 

 surrounding the anodes. The process is also 

 employed at one or two works in the United 

 States. 



The inventor, Mr. Molesworth, claims for the 

 Molesworth process for extracting gold from 

 pyrites or other refractory matrices that it will 

 save from 90 to 95 per cent, of the gold con- 

 tained in pyrites, at a cost of about 4s. per ton of 

 crushed ore. The process consists in calcining 

 the crushed ore or pyrites in a cylinder which 

 is kept slowly revolving in a furnace where only 

 a moderate heat is required, and exposing it 



during the process to a gas compound of oxygen 

 and nitrogen. By this the ore is heated to a 

 white heat, and is desulphurized. The gold is 

 then ready to be amalgamated, or is treated 

 with a bath of aqua regia. 



In the method of William West for treating 

 complex sulphide ores carrying silver, the ore 

 having been crushed to suitable dimensions, a 

 sufficient amount of pyrites is added to reduce 

 the zinc, if it exceeds that amount, to 21 per cent. ; 

 the charge is roasted till most of the sulphur 

 is driven off, and is then drawn, and when cool is 

 moistened with water. In this condition it is 

 placed upon a layer of pebbles in a false-bot- 

 tomed tank. The sulphurous-acid fumes from 

 the furnaces, having been cooled, are forced into 

 the tank, and with them a jet of steam at 

 low pressure is admitted to facilitate chemical 

 action. The result is the conversion of the zinc 

 oxide to zinc sulphite, which rapidly changes to 

 sulphate. The operation is usually repeated for 

 the oxidation of all the zinc. The ore is leached 

 with water in other vats, and, the zinc having 

 been thus removed, the residue, containing the 

 lead and precious metals, is dried on an iron 

 floor heated by the hot sulphurous-acid fumes 

 from the muffles, after which it is ready for the 

 lead smelters. 



Crude silver is refined at Lautenthal according 

 to Roessler's method by treating it in graphite 

 crucibles with powdered quartz and silver sul- 

 phate. The process occasions less than the 

 ordinary loss of silver, and purifies it almost 

 completely from bismuth. The slag consists 

 mainly of silicates, and is sold according to the 

 percentage of silver and bismuth. 



Copper and Tin. Experiments are de- 

 scribed by Mr. Percy C. Gilchrist, which he has 

 been making with the object of obtaining similar 

 advantages in copper smelting to those which re- 

 sulted from the replacement of the ordinary 

 siliceous linings of steel-melting furnaces by a 

 lining composed of basic material, or the Gil- 

 christ basic process. Improved results were 

 sought in the direction of lessened oxidation and 

 consequently increased yield. The removal of 

 arsenic was accompanied by an increased yield 

 of " blister," and advantages were gained in the 

 greater durability of the furnace bottom ; and 

 a considerable gain in output was obtained in 

 the treatment of white or " pimple " metal. 

 Analyses of various samples showed no practical 

 difference between the refined copper produced 

 from the basic blister and that produced from 

 acid blister when an acid-lined refinery is used. 

 When making ordinary tough cake, however, it 

 is doubtful whether the extra cost of the initial 

 basic lining and of the current repairs is com- 

 pensated by the slight increase in the yield, but 

 the saving in making " best-selected " copper 

 from ordinary arsenical blister is considerable. 



An important departure in electro-metallurgy 

 has been made by Messrs. Eltnore, of Leeds, Eng- 

 land, in their process for the manufacture of 

 tubes and articles of a similar character by the 

 electrical deposition of copper. The process for 

 the electrical deposition of copper on a large scale 

 for the purpose of producing pure copper was 

 Introduced several years ago. and is extensively 

 used. By the old processes the copper so pro- 

 duced is again cast and used where articles of 



