194 Macfarlane on the Extraction of Cobalt Oxide 



ARTICLE XVIIL— O/z the Extraction of Cobalt Oxide from 

 the Iron Pyrites occurring near Brockville, C. W, By 

 Thomas Macfarlane. 



About two miles to the north-west of Brockville, in the town- 

 ship of Elizabethtown, C. W., there exists a deposit of iron pyrites 

 ofvery considerable extent and importance. It belongs to the Lau- 

 rentian system, but it is not known what rocks immediately ad- 

 join it, as they do not come to the surface. Although an exca- 

 vation of fifty feet long, and thirty broad, has been made in the 

 deposit, the limit of the minerals in either direction, has not been 

 reached. Two varieties of the pyrites are found here, the one 

 somewhat porous and dull, and the other compact, of a yellow- 

 ish-white colour, and a very bright lustre. Iron pyrites, as is 

 well known, contains one equivalent of iron and two of sulphur ; 

 or 45. YY per cent, of the former, and 54.23 per cent, of the lat- 

 ter element. It is a most important source of sulphur for the 

 manufacture of sulphuric acid. The iron pyrites of the above 

 mentioned locality contains the usual constituents, but in the com- 

 pact variety especially, a portion of the iron is replaced by a 

 small per centage of cobalt, equal, according to Dr. Hunt's anal- 

 ysis, to 0.52 per cent, of cobalt oxide, and according to my own 

 to 0.50 per cent. The occurrence of cobalt in many pyrites of 

 the Laurentian formation, has been repeatedly remarked by Dr. 

 Hunt, and I have detected its presence in many specimens of 

 pyrites occurring in the Primitive Gneiss formation in Norway. 

 While at the Modum Smalt works, and the Skuterud cobalt 

 mines in that country, I had opportunities of experimenting on 

 these pyrites, and of devising a process for economically extract- 

 ing the cobalt which they contain. The principal object of the 

 present paper is to describe the manner in which this process 

 might be advantageously applied in treating the Brockville py- 

 rites. 



When the compact variety of the cobaltiferous iron pyrites of 

 the above deposit, in fine powder, is mixed with one-tenth of 

 its weight of common salt, also finely divided, and calcined at a 

 low red heat, with free access of air, the following chemical 

 changes take place : — First, the greater part of the sulphur of 

 the pyrites is oxidized, and disengaged as sulphurous acid, the 

 iron also combining with oxygen and forming peroxide of iron. 

 At the same time the small proportion of cobalt present is con- 



