METALS. 



497 



decoration of the "Order of Civil Merit," 

 which is rarely bestowed, and confers a rank 

 of nobility upon its possessor. 



METALS. Copper Manufacture. At the 

 copper-works on the Tyne, all the improved 

 processes of extracting metals from the poor- 

 est quality of ores are adopted with a suc- 

 cess probably unequalled in the world. The 

 source of the copper is the Cornish and Irish 

 pyrites. These are first treated for sulphur, in 

 the manufacture of sulphuric acid, when the 

 residuary ores are sent to the copper-works. 

 At that time the best of the ores contain only 

 from 3 to 5 per cent, copper, with 4 per cent, 

 sulphur, 4 per cent, silica, small percentages 

 of silver and lead, the remainder being per- 

 oxide of iron. After being mixed with a cer- 

 tain weight of common salt, the whole is 

 ground to a fine powder, and then placed in 

 long reverberatory furnaces, which are kept 

 at a moderate heat. During this operation 

 the raw sulphur is converted into sulphuric 

 acid, and the salt is at the same time decom- 

 posed; the hydrochloric acid acts upon the 

 copper, and, provided the heat in the furnace 

 is not kept too high, the whole of the copper 

 is rendered soluble and can be washed out of 

 the residue. A part of the copper chloride is, 

 however, driven off by the heat and passes 

 into the condensers along with the free hydro- 

 chloric acid, and is there condensed. The 

 material in the furnace is then thrown into 

 wooden tanks, and digested in water and the 

 acid solution from the condensers, the acid 

 assisting most materially in dissolving out the 

 metals. The liquors run off from the tank 

 consist of chlorides of copper, silver, and lead, 

 and undecomposed common salt, also sulphates 

 of soda and lead. To obtain the copper, the 

 liquors are treated with scrap-iron or spongy 

 metallic iron, which is also made from the 

 residue ores by treating with coal in a muffle 

 furnace. The copper is precipitated and then 

 washed frequently in water, to free it from 

 various salts, after which it is allowed to drain 

 and partly to dry. Then it is smelted in an 

 ordinary reverberatory furnace, the first smelt- 

 ing yielding what is termed " pimple copper." 

 This is again slowly melted, with a free cur- 

 rent of air passing over it to oxidize the im- 

 purities, and then run out, forming "blister 

 copper," which is refined into " cake or ingot 

 copper " for the market. Mr. R. 0. Clapham, 

 in a paper on this subject, gives the following 

 account of the treatment of Spanish pyrites 

 for the valuable metals which they contain in 

 addition to the copper : 



Most of the Spanish pyrites contain also notable 

 quantities of both silver and lead, and in some cases 

 gold ; but until very recently no attempt has been 

 made to separate these metals. M. F. Claudet has, 

 howeverj patented a process to effect this object. 

 The ore is treated as above described : the first two 

 or three washings, M. Claudet states, contain the 

 silver, the chloride of silver formed during the cal- 

 cination being rendered soluble in the large excess 

 of common salt which is used. The solutions to be 

 VOL. xi. 32 A 



treated for silver are run into large vats, where a 

 soluble iodide is added to precipitate the silver. 

 The precipitate thus collected is a mixture of iodide 

 of silver and sulphate of lead, with salts of copper. 

 The latter are dissolved out by 'weak acid, and the 

 remaining precipitate is decomposed by metallic 

 zinc, which reduces the iodide of silver. The zinc 

 iodide which is formed is used to precipitate chloride 

 of silver from other solutions. The precipitate also 

 contains gold. It will be seen, from the above state- 

 ment, that all the metals in the ores can be extracted 

 and made commercially useful, and that the only 

 article produced in any quantity, and not hitherto 

 utilized by the process, is sulphate of soda. 



Improved Process of extracting Gold and 

 Silver. M. Tessie* du Motay is the discoverer 

 of an entirely new process of extracting gold 

 and silver from arsenio-sulphurets of lead, 

 copper, etc., which is now practised on the 

 large scale at the metallurgic establishment of 

 Commines, Prance. Mr. C. Widemann, in a 

 contribution to the Journal of Applied Chem- 

 istry, thus describes the various steps of which 

 the treatment consists 



1. In roasting the simple or complex sulphurets, 

 the antimonial sulphurets, and the arsenio-sulphurets 

 containing silver or gold, in the presence of pure 

 silicates, of auriferous quartz or earthy and metallic 

 silicates, adding, in order to complete this roasting 

 and to expel all the sulphur contained in the min- 

 erals, either lead, which is intended to form oxide of 

 lead, or litharge, or any other metallic oxide capable 

 of producing, in contact with air or oxidizing flames, 

 peroxides or silicates of peroxides. 



2. In thus transforming, into the state of very fu- 

 sible basic silicates, the oxides of the desulphuretted 

 metals. 



3. In melting or running in the melted state the 

 silicates of this kind produced upon a matt of lead 

 also melted, and in stirring or agitating them, either 

 by paddles held in the hand or by mechanical 

 means, or by means of gases mechanically employed, 

 up to the moment when the gold and silver are en- 

 tirely dissolved in the melted lead. 



4. In separating the poor scoria deprived of the 

 precious metals of the lead, which has taken them 

 up, and in stirring or agitating upon the same mass 

 of lead a fresh quantity of rich scoria. 



5. In repeating this liquation an indefinite number 

 of times, until the moment when the capacity of 

 saturation of the lead for the precious metals, wnich 

 is lessened by each operation, no longer permits the 

 continuance of this mode of treatment. 



6. In testing the lead, saturated with silver or 

 gold, by the methods of cupellation now in use, in/ 

 order to extract therefrom the precious metals. 



7. In removing the poor scoria, the oxides of lead, 

 antimony, and copper, which, for the most part, are 

 contained therein, by bringing back these oxides to 

 the metallic state by the separate or united action of. 

 charcoal and iron. 



8. In separating the copper and antimony from, 

 the lead with which they are united. 



9. In reemploying, either wholly or partly, the- 

 purified lead in the treatment, by oxidation and sili- 

 cation, of fresh quantities of minerals. 



10. In reducing, either in reverberatory or cupola 

 furnaces, or in all other melting furnaces, the basic- 

 silicates enumerated above, by the action of charcoal 

 or iron, when the latter are the produce of minerals 

 containing copper pyrites in considerable quantities. 



The metallic matter thus obtained is an al- 

 loy of copper, lead, silver, and gold (free from 

 sulphur), which may all be separated by the 

 usual methods. The principal advantages of 

 the process are claimed to be these : the prevent 



