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LIX, A >icu\ ra^y, and cheap Method i^\xepcrating Copper 

 from Silver. By M. Goktling*. 



XouR methods are known for separating copper from 

 silver, in ail of which tlie alloy is dissolved in the nitric 

 acid. As the price of ihis acid is high, M. Goetling, in 

 place of it, eniplovs sulphuric acid, which is much cheaper. 

 His process, which has fully answered his expectation, is 

 as follows; 



The proportion of silver in the alloy is first to be ascer- 

 tained by the touch, or in any other way. For each part 

 of silver one part of sulphuric acid, and for each part of 

 copper three and three-fifth parts of the same acid, are to 

 be taken. The acid, diluted with half its weight of water, 

 is to be poured into the matrass on the alloy, reduced to 

 small pieces. An addition of one part more of the acid to 

 everv sixteen parts of the alloy facilitates the solution. 

 Place the matrass in a sand heal, and bring the contents to 

 a state of ebullition. If care be taken to stir it frequently 

 with a frlass rod, the allov will be broken down and con- 

 verted Tnto a sulphate in two or three hours. It will be- 

 come thick, and sometimes hard. While still hot, six or 

 ei(2,ht times its weight of boiling water is to be added to it, 

 and the heat to be continued for some time. By this means 

 tlic sulphate will be dissolved, and a great part of the sul- 

 phate of silver will be precipitated. When the whole is 

 found to be completely dissolved, a clean plate of copper, 

 or a few pieces of clean copper money tied loosely in a 

 coarse cloth, is suspended in the fluid, and the boiling is 

 amtinued for some hours, bv which means all the sulphate 

 of silver is decomposed, and the metal separated in a me- 

 tallic fornj. 



To ascertain when the separation is complete, a small 

 quantity of the solution is taken out ar.d tried, by adding a 

 few drops of a solution of muriate of soda. If a ciirdly 

 precipitate is formed, it is a proof that some of the silver 

 still remains in it; in which case the boiling must be con- 

 tinued. 



When a complete separation is effected, the clear solution 

 is to be decanted oft" with care, and the precipitate washed. 

 To ascertain that all adhering sulphate of copper is removed, 

 drop into the water last poured off from the precipitate a 

 few drops of liquid ammonia. If any of that sulphate be 



• From 'Tu'cben Buch fur SKridckumtlcr, oic. 1S04.. 



Still 



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