C 214* 6W THE NATIVE SOLPHL'RETS OF IRON. 



very abundant mixture of carbonic gas and fulpluireous hidro- 



gen. The firft ariles from the decomposition of the carbonate, 



and the fecond from that of the fulphuret. 



This new ful- it i s extremely eafy to afeertain the exigence of this new 

 phuret of man- r , , _,. !_ . J r „ , ,. . 



ganefe v-ry ea- lu'pnuret. tint, becauie among all thole we are acquainted 



lily known. with there is none which is fo eafily decompofed, and with 

 fuch abundance of this gas. Secondly, becaufe the artificial 

 fulphuret of manganefe obeys the action of this acid with the 

 fame celerity. And thirdly, becaufe we do not difcover any 

 thing elfe in the folution but oxide of manganefe, and a very 

 minute quantity of that of iron. The fpecimen does not con- 

 tain either gold, tellurium, lead, or any other metal. 



Ore of teilu- In the true ore of tellurium, I found that the fulphurets of 



lead and of tellurium are combined together, and that the 



gold is native, and not at all mineralized. 



Is the manga- I fliall add nothing: further refpectine: the fpecies of fulphu- 



nefe, metallic, „ 3 . ,° . - _ r , ° r ', 



or oxided? ret nere mentioned, becauie I have not enough to decide 

 whether the manganefe exifts in the ftate of oxide or metal. 

 If it be. an oxide, its fulphuret may probably derive from a 

 very condenfed aggregation the power of eluding the activity 

 of the atmofpheric oxigen ; for the artificial fulphuret palTes 

 with considerable fpeed to the ftate of black oxide mixed with 

 fulphate. 



Concerning the Dif-oxidation of Iron. 



On dlfoxidatlon. When we confider the facility, or low temperature which 

 feveral oxides require to return to the metallic ftate, we can- 

 not help thinking, that thofe which refift the effort of our fur- 

 naces, would alfo become difoxided, if it were poflible for us 

 to heat them to the neceffary degree. 



incident refpeft- In order that iron may no longer remain in the clafs of oxides 



jng t e re uc- w j 1 j c j 1 are incapable of reduction without the aftiftance of char- 



tion of iron by ' r 



ine.e heat. coal, I think it proper to record in this place an experiment, 



for which I am indebted to the friendship of Naft, manufac- 

 turer of porcelain, at that time eftabliflied in the Fauxbou-rg 

 St. Antoine. 

 A bar of iron The mouth of his furnace for fecond firing, which is above 



oxided nearly aU the furnace itfelf, was fupported by a bar of iron about an 



through was re- . . 



duced by heat in inch in diameter. The oxidation had approached fo near its 

 a porcelamc fur- cen tre, that being no longer fupported but by a thread of iron 



of 



