DESUI.PIIURATION OF METALS, JQQ 



that liad come to my knowledge were made at no very high Powdered py- 

 temperature,. I put into a crucible line*! with charcoal some for^anhourina 

 powdered pyrites, covered it with churc(jal powder, and ex- forge fire, was~ 

 posed it for'^an hour to the heat of a forge., The result was \^^^ fj^'^ J^; 

 a mass still retaining all the characters of pyrites. It ap- of its sulphur, 

 peared to have been completely melted, and retains tvvo 

 thirds of the sulphur originally belonging to it. This ex- 

 periment, having been repeated, left me no doubt of the ef- 

 fects of heut alone on sulphuret of iron ; and I think I may 

 conclude from it, that, whatever be the temperature, only a 

 partial decomposition can be produced by it. 



On sulphuretted copper and pyritous copper heat pro- Sulphuretted 



duces effects analogous to those observed with irou. The ^"<^' pyntous 

 ,...,. V „ . rt. 1 1 i . 1- , copper similar. 



distillation (>f pyritous copper aftorded me but veiy little 



sulphur. T^hese two ores however may be considered as 



mixtures of the sulphurets of copper and of iron, and the 



sulphur separated by heat comes from that of iron almost 



wholly. 



The sulphuret of lead, or galena, is one of those mine- Galepa. 

 rals, the tieatment of which is most, varied. All chemists 

 agree in considering it as a compound of sulphur and lead 

 only, in the proportion of 15 parts sulphur to S5 of lead. I 

 was the more careful in observing the eiiiscts of caloric on 

 galena, as in separating the sulphur by its means I might 

 hope to obtain metallic lead, the weight and fusibility of 

 which would render its union ver}'" easy. I could likewise 

 without difficulty exclude the air in the process. 



Into a retort I put 30 gram. [463 grs.] of powdered ga- Heated gently 

 lena, which I heated for tvvo hours so gently as not to a^glu- g^ive out a lit- 

 ttnate it. Only a little sulphurous acid produced by the lcV,"but no"^ - 

 action of the air of the vessels was evolved, a^d I perceived sulphur. 

 no sulphur sublime in the neck of the retort. I then in- Heated nearly 

 creased the fire, and kept it thus two hours more, till both ^^ ^"sioii 

 5the galena and the retort experienced a commencement o^ ' 



fusion. The sulphur volatihzed in this second stage of the 

 operation was so little, that T could not detach it from the very little sul- 

 vessel and weigh it. The residuum had the metallic bril- P^"'^^"^^*"^®*^* 

 liancy, was agglutinated, and did not contain an atom of 

 ductile lead. 



As the heat in this experiment was not very great;» I sub- Fused in a 



jefted 



