226 THE CANADIAN NATURALIST. [June 



of salt yielded, on calcination, a product from which water dis- 

 solved 18*6 grains of copper. The ore contained 20*4 grains; 

 hence 91*1 per cent of the copper were dissolved. 



200 grains of Escott copper pyrites of 23*6 per cent, 100 grains 

 of iron pyrites, 800 grains of iron oxide, and 200 grains of salt were 

 calcined together. The product weighed 1349 grains, from which 

 water dissolved 46-6 grains of copper. Consequently ninety-eight 

 per cent of the copper contents of the ore were rendered soluble. 



In order to prove that the iron oxide is essential to producing 

 this favorable result, the last experiment was repeated, the iron 

 oxide being excluded from the mixture. On calcining and lixiviat- 

 ing, only 33-4 grains of copper were dissolved ; that is, seventy per 

 cent only instead of ninety-eight per cent. 



The foregoing experiments were performed on plates of fire-clay 

 in the muffle of a cupelling furnace. . The iron oxide used was pre- 

 pared by calcining iron pyrites with salt, and then lixiviating and 

 drying. The following trials were made in a manner approxima- 

 ting more to the method that would necessarily be adopted in 

 carrying out the process on a large scale. The mixtures were 

 merely stirred on an iron plate lying upon two ignited billets of 

 wood in a common stove. And further it will be seen that the 

 oxide of iron necessary in the process was obtained from the ore 

 experimented on. This ore was from the Capel Mine near Lennox- 

 ville, and had the following chemical composition : 



Copper 8-60 



Iron 30-31 



Sulphur (by difference) 34*34 



Silica and argillaceous matter 26- 75 



100-00 

 These figures correspond to the following mineralogical compo- 

 sition : 



Copper pyrites 24 • 72 



Iron pyrites 49 • 79 



Quartz, &c 26-75 



101-26 

 It may be said that in round numbers this ore consisted of one 

 half iron pyrites, one fourth copper pyrites, and one fourth rock. 

 The first calcinations made with it were principally for the purpose 

 of obtaining the necessary iron oxide. Nevertheless, the quantity 

 of copper extracted was at the same time determined. 



