220 PARTING* 



tion ; and this portion of silver converted by these 

 acids to sulphate of silver, and to muriate of silver, 

 would remain mingled with the gold. 



When the metallic mass is properly alloyed, it is 

 to be reduced to plates rolled up spirally, called 

 cornetSy or to grains. These are to be put into a 

 matrass, and upon them a quantity of aquafortis is 

 to be poured, the weight of which is to that of the 

 silver as three to two ; and as the nitric acid em- 

 ployed for this operation is rather weak, the solu- 

 tion is assisted, especially at first, by the heat of a 

 sand-bath, in which the matrass is to be placed. 

 When, notwithstanding the heat, no further mark 

 of solution appears, the aqua fortis charged with 

 silver is to be decanted. Fresh nitric acid is to be 

 poured into the matrass, stronger than the former, 

 and in less quantity, which must be boiled in the 

 remaining mass, and decanted as the former. 

 Aqua fortis must even be boiled a third timex)n the 

 remaining gold, that all the silver be certainly dis- 

 solved. The gold is then to be washed with boil- 

 ing water. This gold is very pure, if the operation 

 has been performed with due attention. It is called 

 gold of parting. 



The silver dissolved in the aqua fortis may be 

 separated either by distillation — in which case all 

 the aqua fortis is recovered very pure, and fit for 

 another parting — or it may be precipitated by some 

 substance which has a greater affinity than this 

 metal with nitric acid. Copper is generally em- 

 ployed for this purpose in the mint. 



The solution of silver is put into copper vessels. 

 The aqua fortis dissolves the copper, and the silver 

 precipitates. When the silver is all precipitated, 

 the new solution is decanted, which is then a solu- 

 tion of copper. The precipitate is to be well 



