On the De sulphur aiion of Metals. &5 



in certain cases. The following experiments, however, did 

 not warrant me in continuing of this opinion. 



First Experiment, — I made a mixture of ten grammes of 

 pyritous copper, the composition of which I knew, with four 

 grammes of iron filings : I put this into a crucible, covered 

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

 quarters of an hour. The proportion of the iron had been, 

 calculated so accurately that it was sufficient for taking up all 

 the sulphur combined with the copper in the mineral em- 

 ployed. I found in the crucible a perfectly homogeneous 

 mass, weighing thirteen grammes, which did not contain 

 the smallest glohule of metallic copper, nor anv appearance 

 of separation, between the sulphur et of iron and that of 

 copper *". 



Second Experiment. — Another trial was made by employ- 

 ing ten grammes of pyritous copper and five grammes of the 

 same roasted mineral. This is nearly the case with the fluxes 

 in which the ore or the mattes arc not completely desulphu- 

 rated ; the proportion of the iron was still sufficient for 

 separating copper, which was very abundant in the mixture. 

 I kept up the heat for three quarters of an hour, and found, 

 as in the preceding experiment, a homogeneous mass, with- 

 out any trace of metallic copper, nor of pure sulphuret of 

 copper ; this was a real matte of copper. 



Third Experiment .—On this occasion an equal mixture 

 of crude pyritous copper, and roasted copper, dipped in 

 olive oil, and heated strongly for half an hour in ^crucible, 

 presented nothing but a powder, which had not undergone 

 fusion, on account, without doubt, of the superabundance 

 of the iron. 



I think these few experiments are sufficient for proving 

 that the de sulphur at ion of copper by means of iron will be 

 always very difficult, because there is formed a triple com- 

 hination hetween the sulphur, iron and copper, or rather a 

 combination between the sulphurets of copper and of iron, 

 which prevents the separation of the copper. 



* In the decomposition of galena by iron, we observe, when the latter is in 

 too small quantity, three distinct substances of lead, sulphuret of lead, and 

 lastly., sulphuret of iron in the upper part. 



Fs Desulphuration 



