230 THE CANADIAN NATURALIST. [June 



They gave a product weighing 5270 grains, and containing 

 2-33 per cent Cu soluble in water = 122-73 

 0-22 " " in dilute acid = 11-59 

 0-33 " insoluble = 17-16 



Unaccounted for = 6*96 



158.50 

 Neither was this result extremely satisfactory. This mixture 

 also was stirred diligently during the operation. 



In order to ascertain whether the stirring exercised any injurious 

 effect upon the completeness of the extraction, the following mix- 

 ture was calcined : 



2000 grains residue of 1-1 per cent = 22 grains copper. 

 1000 " fresh ore of 8-6 " =86 " 

 500 " salt 



3500 grains containing 108 grains copper. 



The operation was performed with as little stirring as possible,. 

 and the result weighed 3800 grains, containing 



2-55 per cent soluble in water = 96-90 grains copper. 

 •22 " " in dilute acid = 8-36 " 



•22 " left insoluble = 4-18 " 



109-44 

 It will be seen that this calcination was eminently successful, 

 and that all the copper contained in the fresh ore was extracted. 

 It was therefore very evident that diligent stirring was injurious. 

 Encouraged by this result I repeated the calcination with the 

 smaller quantity of salt which I had previously used ; the mixture 

 being left almost wholly undisturbed during the operation. The 

 ingredients were 



2000 grains residue of 1-1 per cent = 22 

 1000 " fresh ore of 8-6 " =86 

 250 " salt 



3250 grains with 108 grains copper. 



They gave on calcination a product of 3405 grains, containing 

 2*77 per cent, equal to 94-31 grains copper soluble in water ; a 

 result conclusively establishing that the more undisturbed the 

 materials are during calcination, the more complete is the ex- 

 traction. 



The foregoing experiment was performed with one fourth part 

 of salt to one of fresh ore. The result having been satisfactory,. 



