184. 



ex THE OXIDES OP IRON. 



feTcntcpn 

 irilw' distant 

 from this. 



where that soil was found is about a mile tVom the town of 

 Helstone, and it is distant above seventeen miles, in a di- 

 rect line, from the spot described in this letter. It is po^si* 

 ble, that this sort of soil may frequently occur, although 

 it has, I believe, been unnoticed — the ()resence of a free 

 acid and the muriate of mant^anese romniunicate to it pro- 

 perties, by which it may be quickly and easily recog- 



WILLIAM GREGOR. 



Creed, Jan, l6, 1811. 



An accurate 

 knowledge of 

 the oxides of 

 iron of great 

 injporlnnce in 

 chemistry. 



and chemists 

 differ much on 

 the subject. 



BerthoHet as- 

 serts, that ox- 

 igen may 

 combine «'Uh 

 a metal in any 

 proportion, 

 from the jni- 

 rniuim to the 

 Uiiixinriumt 



IV. 



Observations on the Oxides of Iron, with a Discussion of 

 their lKature\ hy Mr. J. H. IIjlssenfratz*. 



JJlRON is the most useful of all metals ; and is that which 

 is most generally met with in all the substances we know. 

 It is found in them either in the metallic slate, or com- 

 bined with oxigen. Chemists separate it in the state of 

 oxide in most of their analyses ; sometimes indeed they 

 obtain it in the metallic form, but in this case it always 

 retains a portion of the carbon employed in its reduction. 

 The proportion of oxigen combined with the iron before 

 and after analysis, in the oxide previously existing, or in 

 the oxide obtained, has long teen the subject of a dis- 

 cussion, which has occasioned errours in the estimations of 

 products, from the little agreement that has existed and 

 still exists among chemists. 



The celebrated author of the Chemical Statics is per» 

 suaded, " that the proportions of oxigen in metals may 

 vary progressively, from the limit at which combination 

 tirst becomes possible, to that at which it has attained its 

 highest degreef". 4 A chemist whose opinions are of great 

 weight, Proust„ endeavours to establish the principle, that 

 metallic oxides, and that of iron in particular, have but 



* Annales de Chim. toI. LXIX, p. 113. For a vahiable paper on 

 this subject by Dr. T. Thomson, see our last volume, p. Si 5. 

 I Sutique che^i. torn. 11, p> 37j0. 



two 



