DESULP«tjRATION OF lilETALS. 209 



or any sign of ?'eparatioti between the sulphuret of iron and 

 that of copper*. 

 ' QdExp, Another trial was made with 10 gram. [155 grs] 2d experimetit. 



of pyiitous copper and 5 gram. [77 g's] of the same mineral 

 roasted, which is nearly the state of the product when the 

 ore or matts have not been completely desulphurated. The 

 proportion of iron was still insufficient to separjite any cop- 

 per, of which there was abundance in the mixture. I heated 

 it three quarters of an hour, and found, as in the preceding 

 experiment, a homogeneous mass, without any sign of me-^ 

 tallic copper, or pure sulphuret of copper : it was a tru6 

 coppfer matt. 



3d Exp. Equal pJirts of crude and roasted copper py- Sdexperimeat. 

 rites were mixed, moistened with olive oil, and heated 

 strongly for half an hour in a crucible lined with charcoal,; 

 The product was nothing but a powder, that had not un- 

 dergone airiy fusion, no doubt owing to the superabundance 

 of iron. 



These few trials I conceive are sufficient to prove, that th^ Iron, sulphur, 

 desulphuration of copper by means of iron will always be fr^m^a^tri^^le 

 f eiy difficult to effect, because a triple compound of sulphur, compound in 

 iron, and copper, is formed, or a combination tak,es place be- fj^^^^°^*^^* 

 tween the sulphurets of copper andiron, which obstructs the 

 Aeparatiou of the copper. 



Desulphurhtion of galena. 



Galena is one of those sulphurets, in which this decom- Sulphuret of 

 positioii is most readily effected; The fusibility of lead, 

 which facilitates the union of its particles, as Well as the little 

 affinity it has for sulphur, are the cailses of the Success of the 

 attempts of this kind. Lime and iron are employed in dif- by lime and 

 ferent circumstances for the desulphu ration of galena* The ^'■^'^- 

 use of lime is not very general, and it is impossible to judge Lime httle 

 of its effects from wl.at is known of the properties of sulphu- 

 ret of hme. The treatment of galena by malleable or cast iron pr^f^rsK* 

 iron in small pieces is more in use, and appears very advan- ble. 

 tageous. 



* In the decomposition of galena by iron, when the latter, is ill toa 

 *mall quantity, three distanct substances may be observed : lead, sulphu-? 

 ret of lead, and lastly sulphuret of iron at the upper part. 



Vol. XVI—Nov. IS07. P At 



