224 THE CANADIAN NATURALIST. [J 



une 



seven of chlorine liberated. The latter quantity was sufficient to 

 convert fifty-nine grains of copper into proto-chloride. It becomes 

 therefore difficult to say why the whole copper contents, 47 

 grains, where not extracted. Since the temperature was kept very 

 moderate, the only other cause which may possibly have affected 

 the result unfavorably, was the continuing of the calcination 

 beyond the proper point, and the consequent decomposition of 

 proto-chloride into insoluble sub-chloride of copper. 



In order to ascertain whether the copper unaccounted for in the 

 last experiment remained in the residue or was volatilized, the fol- 

 lowing experiment was made. 



200 grains copper pyrites. 



500 grains iron oxide. 



200 grains salt. 



900 grains were mixed together. 



The pyrites contained 23.6 per cent, equal to 47.2 grains 

 of copper. The mixture was calcined at a low temperature until 

 the evolution of sulphurous acid and then of chlorine ceased. 

 The result weighed 911 grains, and contained — 



Iron oxide and other insoluble matter.. . . 67.33 



Cupric oxide 1.87 = 1.5 copper. 



Sulphate of soda 12.6 



Chloride of copper 8.14 ■=. 3.8 copper. 



Chloride of sodium (by difference) 10.06 



100 00 



It is evident from this that seventy-three per cent of the copper 

 contained in the original ore was rendered soluble, and that twenty- 

 seven per cent was left in the residue insoluble, but whether in 

 the state of sub-chloride or oxide I did not ascertain. If we cal- 

 culate from the amount of sulphate of soda formed in this experi- 

 ment, it would appear that but a very little more chlorine was de- 

 veloped than was necessary to take up the whole of the copper as 

 proto-chloride, so that it is most reasonable to suppose that the 

 copper which remained insoluble was in the state of oxide, and 

 had never had an opportunity of uniting with chlorine. The result 

 of the experiment as to the volatilization of the copper was decisive, 

 inasmuch as the whole of the copper was found in the product ; 

 therefore none could have been sublimed. The experiment also 

 indicated that in order to a perfect extraction, an excess of chlorine 

 must be presented to the copper. 



