68 GOLD AND COPPER. 



One hundred grms. of galenite, finely powdered, are 

 fused with 30 grms. of nitre and 100 grms. of litharge. 



Or 1 part of the ore is fused together with 30 to 50 

 parts of litharge. 



Or 1 part of ore may be fused with 3 parts of anhy- 

 drous acetate of lead and 2 parts of potashes, under a 

 layer of common salt. 



In the button of lead obtained, the silver is deter- 

 mined by cupellation, or in the moist way. 



43; GOLD AND COPPER. 

 (Coins.) 



li The alloy is dissolved in a mixture of hydrochlo- 

 ric and nitric acids, care being taken that none of the 

 latter shall remain undecomposed after the solution is 

 effected ; the liquid is heated with oxalic acid, which 

 precipitates all the gold in the metallic state. For the 

 complete precipitation of the gold, the solution must 

 be dilute, and not contain a large excess of hydrochlo- 

 ric acid, or alkaline chlorides. It is washed, dried, 

 transferred to a porcelain crucible, the filter completely 

 incinerated, and the gold, together with the ashes, ig- 

 nited and weighed* From the filtrate the copper may 

 be precipitated by sulphuretted hydrogen, or by potassa 

 at a boiling heat. 



II. The gold is first precipitated by a solution of 

 pure protosulphate of iron, and the copper is after- 

 wards separated from the solution, either by sulphu- 

 retted hydrogen, or by a piece of bright iron placed in 

 the liquid, which must not be too acid, and should be 

 heated nearly to boiling. The precipitated copper is 

 washed, dried, and ignited in air, when it is converted 

 into oxides 



