222 THE CANADIAN NATURALIST. [June 



it cannot make up for a deficiency of sulphur in the original ore ; 

 and with or without common salt that ore will be treated with the 

 greatest advantage which contains the largest proportion of sul- 

 phur. In proof of this the two following experiments may be 

 cited : 



] 000 grains of slimes from the Bruce Mines, containing 

 5.20 per cent, of copper in the state of copper pyrites, but 

 no admixture of iron pyrites, were calcined with 100 grains 

 of common salt. The result yielded to water 13.7 grains of copper. 

 Hence only 37.9 per cent, of the copper was extracted. 



500 grains of ore from Escott, containing 10.4 per cent, of 

 copper and an admixture of iron pyrites, were calcined with 100 

 grains of salt. The product yielded to water 40 grains of cop- 

 per. Consequently 76.9 per cent, of the metal was removed. 



In reflecting on the necessity of a sufficient supply of sulphur, 

 it occurred to me that any means which would facilitate the con- 

 version of the sulphur into sulphuric acid, instead of allowing it to 

 escape as sulphurous acid, would be of advantage if applied in such 

 calcining operations as those here referred to. Having in former 

 experiments* demonstrated that the addition of peroxide of iron 

 increased the amount of sulphuric acid formed in such calcinations, 

 it occurred to me that it might be possible even with an ore con- 

 taining no more sulphur, in proportion to the copper, than copper 

 pyrites, to convert so much of it into sulphuric acid, as would in 

 the presence of common salt develop sufficient chloride to render 

 the whole of the copper soluble. I accordingly calcined the follow- 

 ing materials together : 



200 grains copper pyrites. 

 400 grains ferric oxide. 

 200 grains salt. 



800 grains in all. 

 The copper pyrites, which was from Escott, contained 23.5 per 

 cent ; = 47 grains of copper. The residue after calcination weighed 

 657 grains, and on analysis gave — 



Insoluble iron oxide 67.9 



Insoluble cupric oxide 2.2 = 1.8 copper. 



Sulphate of soda 10.1 



Chloride of copper 3.4 = 1.6 copper. 



Chloride of sodium (by difference.)... 16.4 



100.0 

 * Canadian Naturalist, vol. vii, p. 196. 



