1865.] MACFARLANE — EXTRACTION OF COPPER. 227 



10,000 grains of the ore were first calcined with 2,000 grains of 

 salt, and without oxide of iron. The result weighed 10,860 grains. 

 Water extracted from it 0*8 per cent of copper, and diluted 

 sulphuric acid dissolved further a quantity of flocculent matter con- 

 taining 1*8 per cent. Of the 860 grains copper contained in the 

 original ore there were therefore, 



Dissolved by water 86-88 grains = 10 per cent. 



Dissolved by dilute acid 195-48 " ■■ 22 " 



Left in the residue 577-64 " « 68 " 



860-00 



The product of the foregoing experiment after lixiviation and 

 drying assayed 6-4 per cent, copper. A second calcination was 

 performed with it and other substances having copper contents, as 

 follows : 



400 grains lixiviated product of above experi- 

 ment containing 6*4 per cent = 256 grains copper. 



2000 grains fresh ore of8*6 per cent .= 172 " 



1200 grains salt 



7200 grains mixture with 428 grains copper. 



After being calcined in the usual manner the whole weighed 

 7850 grains, and contained four per cent of copper soluble in water 

 slightly acidulated with sulphuric acid, and 1*11 per cent of 

 copper insoluble therein. Of the 428 grains there were therefore, 



Dissolved 314 grains. 



Left insoluble 87 " 



Unaccounted for 27 " 



428 grains. 



Thus 73*3 per cent of the original copper contents were obtained 

 in a soluble form. 



The product of the foregoing experiment was, as in the first case, 

 lixiviated and dried. It then contained 1J- per cent of copper, 

 and was calcined a third time, with fresh ore and salt in the fol- 

 lowing proportions : 



4800 grains residue with 1£ per cent. . . .= 64-0 grains copper. 



2400 grains fresh ore of 8*6 per cent = 204 -5 " 



1440 grains common salt 



8640 grains, containing 270*4 grains copper. 



