On the De-sulphur atlon of Metals. 215 



lure a little raised, I proceeded in the following manner: I 

 put into a crucible, pyrites of iron pulverized ; covered it 

 with charcoal in powder, and heated it in the forge for an 

 hour; I found a mass still preserving all the characters of 

 pyrites ; it seemed to have been completely melted, and re- 

 tained two thirds of the sulphur contained in the natural 

 pyrites. This experiment being repeated, left me in no un- 

 certainty upon the effects of heat by itself upon sulphuret 

 of iron, and I thought f might conclude, that, whatever be 

 the temperature, these effects produce a partial decompo- 

 sition. 



Sulphuretted copper and pyritous copper, submitted to 

 the action of heat, produce effects analogous to those ob- 

 served with respect to iron : the distillation of the pyritous 

 copper furnished but very little sulphur : these two kinds of 

 minerals of copper may in short be considered as mixtures 

 of the sulphurcts of copper and of iron, and the sulphur 

 which heat separates from it proceeds almost entirely from 

 the sulphuret of iron. 



The sulphuret of lead, or galena, is one of those minerals the 

 treatment of which is most various : all chemists agree in 

 regarding it as composed of sulphur and lead only, in the 

 proportion of 15 of the former, and 85 of the latter. I was 

 the more careful in observing the effects of caloric upon the 

 galena, because, by trying to separate the sulphur from it 

 by this agent, I expected to obtain lead in a metallic state, 

 the weight and fusibility of which render the re-union very 

 easy. It was, besides, very easy for me to operate without the 

 contact of atmospheric air. 



T put into a retort 30 grammes of galena reduced to pow- 

 der, which I heated for two hours, but not so strongly as 

 to make it agglutinate : a very little sulphuric acid only was 

 disengaged, produced by the action of the air of the vessels, 

 and I perceived no sulphur sublimed at the neck of the re- 

 tort. I increased the fire for about two hours more, until 

 both the galena and the vessel which contained it had un- 

 dergone a kind of fusion. The sulphur volatilized in this 

 second part of the operation was in so small a quantity that 

 it was not possiJjIe for me to detach and weigh it : the rc- 



4 siduc 



