1868.] MACFARLANE EXTRACTION OF COPPER. 459 



had been furnished with various samples of ores from their mines. 

 Slimes from the Wellington and Copper Bay mines were first 

 operated on by calcining them with proto-chloride of iron in a 

 muffle furnace at a dull red heat. Fumes of volatilized chlorides 

 were abundantly developed, especially on stirring the mixture. 

 The results obtained were very variable. With Wellington Mine 

 slimes of 2.9 per cent., one experiment gave 0.5 per cent, copper 

 soluble in water, 0.7 per cent, insoluble and 1.7 per cent, volati- 

 lized. In a second trial with the same slimes and a larger 

 quantity of chloride, 1.5 per cent, were dissolved, 0.8 per cent, 

 left insoluble, and 0.6 per cent, volatilized. In a third experi- 

 ment with Copper Bay slimes of 2.1 per cent., the whole of the 

 copper was rendered soluble. But such a result as the last men- 

 tioned was only attainable occasionally, and it became very 

 evident that high temperature and unlimited access of air often 

 combined to make the result unfavorable and at least uncertain. 

 The temperature at which the sulphurets contained in the slimes 

 oxidized, seemed to be so high as to cause a sublimation both of 

 the chlorides of iron and copper. I therefore, in the subsequent 

 experiments, calcined the one previous to treating it with chloride 

 of iron. 



The ore next operated on was an average sample of the crush- 

 work at the Wellington Mine, as it comes from the crusher to 

 the jiggers in the ore dressing works. On shaking it on a sieve 

 having fifteen holes to the lineal inch, it was separated into a 

 coarser and finer part, the former assaying 2.6 per cent, and the 

 latter 5.2 per cent copper. On calcining and further pulverising 

 the finer part, and sifting it on a finer sieve, it separated into one 

 part, coarser in grain, and containing 4.4l per cent, and three 

 parts finer containing 5.58 per cent, copper. The latter sort was 

 heated over a spirit lamp, with one-fourth of its weight of proto- 

 chloride of iron, in a retort through which a current of air had 

 passage. In one experiment -3.9 per cent., and in another 4.3 per 

 cent, of the copper contents were rendered soluble in water. In 

 the first experiment water dissolved out proto-oxide of iron along 

 with the copper, but in the second, which had been heated longer, 

 all iron in the solution was present as peroxide. 



Having observed in one of these experiments, that the air con- 

 tained in the retort seemed sufficient for converting the proto- 

 chloride of iron into perchloride and peroxide, (6 Fe CI + 3 = 

 Fe 2 3 4- 2 Fe 2 Cl 3 ), it occurred to me that the current of air 



