228 THE CANADIAN NATURALIST. [June 



This mixture was treated in the usual manner. The product 

 weighed 8900 grains, and contained 



Soluble , 2 • 77 per cent. = 246 grains copper, 



Insoluble -25 " 22.2 " " 



Unaccounted for 1-3 " 



270.4 " " 

 Thus 91-4 per cent of the copper contained in the ore originally 

 used was recovered in a soluble form. 



The residue from the experiment last described, after thorough 

 lixiviation and drying, contained 0*44 per cent copper. Now 

 very few of the slags from copper furnaces contain less than this 

 per centage, and the refuse products of ordinary ore in dressing- 

 operations seldom assay less than 1*5 per cent. In having produced 

 therefore a residue containing as low a percentage as the above, it 

 may be assumed that a point was raised where its copper contents 

 might be disregarded. This residue consists, however, almost 

 exclusively of iron oxide and the earthy matrix of the ore, and by 

 virtue of the former is of value for mixing with fresh ore to pro- 

 duce the oxidation of the sulphur, and the consequent extraction 

 of the copper contained therein. In order to test its usefulness in 

 this respect a fourth calcination was made, with the following 



mixture : 



2000 grains residue of 0.44 per cent = 8-8 grains copper. 

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



600 « salt 



3600 94 '8 grains copper. 



The product weighed 3710 grains, and contained as follows : 



Iron oxide and insoluble matter 72-13 



Cupric oxide insoluble in water and di- 

 lute sulphuric acid. -27 = 0.22 copper. 



Cupric oxide soluble in dilute sulphuric 



acid -13 = 0.11 " 



Sulphate of 3oda 19-22 = 4-33 sulphur. 



Chloride of copper 4-7 = 2-22 copper. 



Perchloride of iron 1-42 



Chloride of sodium, by difference 2-13 



100.00 



Of the 94*8 grains copper contained in the original ore, there 



were consequently 



Dissolved by water 82-36 grains = 86-88 per cent. 



Dissolved by dilute acid.. 4-08 " = 4-3 " 



Left in residue 8-16 " =8-6 " 



Unaccounted for -20 " = -22 " 



94-80 



