<J22 OXIDATIONS OF IROX. 



oxides ; and the author of Chemical Statics has gone still 

 farther, asserting, " that the proportions of oxigen united 

 with metals vary, from the point at which the combination 

 is possible, to that in which it has attained its highest de- 

 gree ; " Prof. Proust has not considered the facts objected to 

 his doctrine as sufficient, and persists in the opinion, that 

 nature has fixed these two invariable terms of oxigenation. 



Though I consider the subject somewhat differently from 



the Madrid professor, I have a high opinion of his labours 



and observations, and incline to think with him, not that 



But we have the proportions of oxigen are invariably determined by na- 



not facts of suf- 1 but that most of the facts, on which the opinion of 



hcient accuracy ' » * 



to determine intermediary oxidations are founded, have not all the accu- 

 the question. raC y suc j 1 a ,}} scuss i on requires. 



Persuaded, that every research tending to elucidate this 

 point of theory cannot but be of great utility to the ad- 

 vancement of science, I proposed to myself to make some 

 Iron well adapt- experiments on iron, as one of the metals best adapted to 



«d to the inves- such researc h e s : and I shall relate them in the order I pur- 

 ugation, r 



sued in my labours, persuaded, that I could not adopt a 



better arrangement, than that of following the ideas that 



suggested them. 

 New oxides The first means that occurred to me for discovering new 



tai gh db e °h ox ^ es °f * ron were ? 1 st - to treat the red oxide with oxige- 

 aidofcompres- nizing substances, confining the expansibility of the oxigen 

 sion, by compression. As experiments of this kind relative to the 



carbonic acid succeeded so well with Sir James Hall, I had 

 or the electrical no doubt of thus increasing the oxigenation of iron. 2dly, 

 Sen* 6 " to sub J ect ^ oa wire l0 different discharges of electricity in 



air containing more or less oxigen.. Previously however I 



was desirous of ascertaining how iron comports itself in 



other modes of treatment, to which it has been already 



subjected. 



Oxides by Calcination. 

 Iron calcined I took one part of iron filings and three of nitrat of pot. 

 wit nitre, ^ ^^ p0W( j ere d, mixed them, and threw them into a red- 

 much passed not crucible. After keeping up the fire for three quarters 

 thiough the G f an hour, I withdrew. the crucible, and found a great part 

 of the potash and oxide of iron had passed through it. The 



mixture 



