PN THl OXIDES OP IftOK* IQl 



foreigtt matter.: and if we may suppose the seconcl to have 

 contained the sume quantity, and each of the buttons to 

 have fetiiined O'Ol of carbon, it would follow, that these 

 oijiidules were composed of 33 oxigento 100 of iron. 



Priestley and ChauBsier both disoxidated iron by raising it and with hi. 

 to a hi^h temperature, and thus exposing it to tlie action !'''"^p^ ^'|'/ 

 •f hidrogen gas. Amedee Berthollet has since announced Chaussier, A, 

 the same result in a paper read to the Institute for I8O7. Bertholkt, 

 As neither of these gentlemen has pointed out the diminu- 

 tion of weight of the oxidule in those experinaents, Mr* 

 Charbaut, a pupil at the Practical School at Moustier, and ^jj^^^j^^^j ^^^ 

 myself repeated them in the summer of I8O7. We found, Haffenfratz. 

 that 11*58 grains of oxidule of iron from the island of Elba 

 lost in reduction 3'34 grains ; whence it would follow, that 

 140*53 of oxidule contained 40*53 of oxigen to 100 of iron; 

 supposing it to be perfectly pure, which is very probable; 

 though of this we are not certain, as we did not analj^se 

 it. 



From these experiments we may conclude, that it is very Remarks on 

 difficult, if not impossible, to carry back the oxide, t'itlier '^Ij^T^^^^'i'^"' 

 by means of heat alone, or of heat and carbon, to the state 

 of oxidule. From the reduction of the oxidule of the 

 valley of Aost by charcoal it would appear to consist, takino^ 

 the nearest round numbers, of 77 "'O" and 23 oxigen. 



At the conclusion of these observations we will examine, 

 to what the difference between the oxidules of Aost and Elba 

 ig ascribable. 



3d Method. Oxidation of iron hy metallic oxides. 



Iron has not yet been oxided by the help of any other Oxidattofi of 



metallic oxides, that have less affinity than itself for oxigen, 'run by oxides 



, of other mt- 



but those of arsenic and mercury; becauss these two \ne- ^^u, 



tals, when disoxidi'ted, evaporate at a high ternpeiature. 



Guyton fused in a closed crucible equal parts of iron and by Guyton, 

 pxide of arsenic. The latter metal evaporated, and the 

 iron was oxided. The increase of weight was 27*1 on 100 

 of iron, 



Lavoisier fused iion both with oxide of arsenic and oxide and Laroisi-r. 



♦ Dif Acad. DUs. sur le PhJggi'^tiqtie, p. 1^9. 



of 



