on THE OXIDES OF IROX. 377- 



bj the denominator the quantity of metal: of course -*o^^ 

 mean an oxide composed of 100 iron and 48 oxigcii. lie 

 then proceeds to point out the true composition of the 

 oxides of iron, and thus to correct the above passage in 

 my work. But it is no; necessary to transcribe the rest of 

 his paper, as he had already published ah elaborate dis- 

 sertation on the subject in the Ixix volume of the Annales 

 de Chimie^ in whicl. the subject is much more fully dis- 

 cussed; and to whicti therefore I refer the reader*. 



The perusal of Mr. Iiassenfratz's paper, while it convin- Experiment? 



ced me of the mistake into which I had fallen, induced me insututedto 3"=- 



. . certain the true 



to make some experiments on the composition of the oxides pro;)ortions in 



of iron, in order to verify and establish the proportions °^^^^^<^f^''*°- 



obtained by others. My object at present is to state the 



results which I obtained. 



I. The red oxide of iron, or the oxide containing a maxi- Red oxide, 

 mum of oxigen, is too well known to require a particular 

 description here. Two methods have been followed by Two methods 

 chemists, to ascertain the proportion of oxigen wiiich it^'~'^P^'-^y'^<^- 

 coi'tains. The first is to expose a determinate weight of 

 iron to a red heat, triturating it occasionally, till it ceases 

 to acquire any additional weight. The second is to dissolve 

 iron in acids, and to expose the salt obtained to a heat suf- 

 ficiently high to decompose it. The red oxide remains, and 

 its weight gives the addition, which the iron has acquired 

 by its oxidizement. 



The first method appears at first sight easy, but it is in Iron filings cal- 

 reality exceedingly diificult. Accordingly the experiments'^'" 

 of Scheii'cr, Morveau, Lavoisier, Darso, Bucholz, and 

 Ilassenfratz differ so much from each other, that no satis- 

 factory conclusion can be drawn from them. I consider 

 the experiment of Ilassenfratz as the most accurate. ICO 

 ])arts of iron in his trial were converted into 145 of red 

 oxide h. In Darso's experiment 100 parts of iron were 

 augmented to 156 of red oxide +. But as this greatly ex- 



* A translatior, of this paper is intended for insertion in this 

 Journal at an early opportunity. A shorter paper of Hassenfratz on 

 the saincsubject occurs ill vol. xxvi, p, 47. C. 



f Ann. deChim. vol. Ixvii, p. 309. Journal, vol. xxvi, p. 147. 



X Journal de Phys. 1809 torn, ii, p. 294. Journal vol. xvii, p. 224. 



coeds 



