On the De-sulphuration of Metals. 2 1 9 



cible, which receives the produce of a flnx of 24 or 48 hours, 

 and in which a separation, or rather a combustion, of the 

 sulphur lakes place. The wind of the bellows passes over 

 the surface wilh sufficient force for removing the scoriae, 

 and burning a part of the sulphur on the surface : the iron 

 is thus oxidized, and quartz is added in order to vitrify it in 

 proportion as the roasting goes on*. It is thus that we may 

 explain the concentration of the metal, and the general re- 

 sult of the flux, which surprised M. Jars very much. This 

 process is perhaps the (;nly one in which, at the same time, 

 the sulphur and iron are separated in any quantity. 



The de-sulphuralion of pyritous copper by roastmg, is, 

 in my opinion, produced, 1st, by the sublimation of a small 

 portion of sulphur, which may be collected or burnt in the 

 air: 2dly, by the extrication of sulphurous acid, so much the 

 more abundant as the operation is well conducted f; 3dly,by 

 the vaporization of a little sulphuric acid, the greatest part of 

 which, however, remains united to the copper. 



can be used, and which, in spite of the inconveniences it presents, may nc- 

 yerthtless be advantageous."—" Another very precious advantage is a coii- 

 centratinn of the metal contained in the Jluid mailer ivhich is cnnUuvally 

 agilated by the wind of Ihe ietious. They extract a smaller quantity of 

 mallcs, but they are richer. We confess our surprise at the flux of black 

 copper, when we see the small quantity of rich matfa which comes from 

 a very inferior sort of ore, and which does 7iot rueii seem lo have been 

 ruastcd." We should be of M. Jars' opinion, that this method of melting; py- 

 ritous copper is one of the best, if more copper was not volatihzcd than by 

 the other processes: but if, as I think, we may substitute the rcrcrl-eialon/ 

 furnace iur that used at Falliun, and in other respects following up he same 

 series of operations, there would certainly he great advantages derived over 

 fusion in the hand furnace. 



* Swedenborg {de cupro) thus expresses himself: " Plurhna ejus ars (mcaij- 



ing the melters) in co consislil, ut lapidem siliceum, juHo lempore el modo, sciat 



offcne." 



+ Recent experiments of Messrs Clements and Desormes show, that the 



combasiion of sulpliur does not produce sulphuric acid so ca-ily as imagineU •• 



but we know that its formation is determined by various peculiar circuni- 



stances, such as the presence of the alkalis, oxides, &c. 



[To be continued] 



XL. Essay 



