'385 



ON THE OXIDES OF IRON, 



Suphiiretted liidrogcn produces no effect on solutions of 

 iron at a minimum ; while fn doliitions where the iron is at 

 a maxinium oF OJcidation it is decomposHd, reducing the 

 iron to the state of oxidule. 

 lliose of Thenard distinguished these three kinds of oxides by the 



action of alkalis, of gallic acid, and of prussiates, on solu- 

 tions of iron ; particularly on the solutions in sulphuric 

 acid. 



Frotn their solutions in sulphuric acid alkalife precipitate 

 the oxide of iron at a iniuimiira white, the oxide at a me- 

 dium green, «nd the oxide at a maximum red. These 

 three oxides maty be separated in succession from a solution 

 irt which they are nhixed. 



The gallic acid precipitates nothing from solutions of iron 

 oxided at a minimum ; from sohrtions in which the iron is 

 Oixided it a fftediam it throws dovtn a green gallaie ; from 

 that in which it is at a maximum a blnck gallate. 



Lastly, the prussiates arc blue and green with iron oxided 



At » minimum ; green and blueiah with that which is oxided 



at a nnedium ; and blueish and blue with that which is at a 



maximum. 



Bti^holt ton- Mr, Bucholz having mfide some observations on the white 



rard^^s white* ^^^^^ ^^ Mr. Thenard* J and attempted to maintain, that 



oxide as a it was nothing but a combination of black oxide and sul- 



subsulphatc, pj^^-i^, ^cid ; the learned French chemist has pointed out a 



which the lat- pvocess, in a note published in the Bulletin des Sciences of 



\erts. ^h^ Philoriiathic Societyf, by which the white oxide of iron 



may be obtained pure, and freed from sulphuric acid, 

 llie pr.:>i>orii- The learned author of the Chemical Statics mentions 

 rot g^vcTby^^ none of the proportions of oxigen in oxide of iron. Indeed 

 Bertl.ollet, according to his principles he could have pointed out only 

 those of the two extreme terms, that at which the combi- 

 nation becomes possible, and that at which it attains the 

 highest degree ; but to make knowti these two proportions 

 \*e must be precisely acquainted with these two ex- 

 li'<*t1ies. 

 )»r Titnard* Thenard contents himself with giving the characters of 



♦ Journal fuer die Chemie undPhy^ic'k. Berlin. No. 12, p 721. 

 f Nouveau Bulletin, ann. I80d, No. 5, p. 96. 



tbe 



