Proportion of 

 ox i gen there- 

 tore variable. 



226 OXIDATIONS OF IRON. 



Jled oxide with Thus we have a red oxide of iron made in fifteen minutes, 



is of oxigen: w hj c h gives a fine blue with alkaline prussiates, is precipu 



tated black, or rather of a very deep blue, by galls, and is 



not distinguishable from the oxide at 56, at least by any of 



the means hitherto employed for this purpose. 



All these facts prove the sagacity of the learned author 

 of the Statics, when he says, not from elective attractions, 

 but from the properties of oxigen and metals, that the pro- 

 portion of oxigen to metal may vary from the point at 

 which the combination is possible, to that in which it has 

 attained its highest degree, and that a multitude of circum- 

 stances may check or increase the proportion. 



I did not carry this experiment farther, but I conceive, 

 that by favouring the division of the iron by all possible 

 means, and at the same time opposing obstacles to the ac- 

 tion of the oxigen, we might obtain red oxides of iron with 

 only 6 or 8 per cent of oxigen. And who knows whether 

 by preventing the action of this principle altogether, wc 

 and iron soluble might not obtain powders of iron soluble without effer- 

 vescence in acids, and enjoying the same properties as 

 oxides ? For my part I am the more persuaded of it, as I 

 pay little regard to the principle generally received, that 

 metals must be previously combined with oxigen before they 

 will unite with acids. I consider the oxidation rather as a 

 consequence of the means we employ to divide the metals, 

 and reduce them to the degree of fineness required for their 

 solution in acids, than as an indispensable condition of 

 their solution. On this subject I intend to make some 

 researches, and I may then explain the motives that oblige 

 me to question this principle. 

 To -what arc Before finishing my report concerning the oxides of iron 



virtues^/these ^7 calcination, I would wish to make one remark respect, 

 oxides owing ? ing their most interesting application, their medicinal use, 

 It is not yet known, whether these owe their virtues to the 

 iron or to the oxigen ; and as the proportions of these in the 

 various preparations of this metal are undetermined, we are 

 wholly ignorant which deserves the preference : this there, 

 fore is an object, that merits a careful investigation. 



(To be continued.) 

 it is known to be present. Digestion for half an hour however in 

 very dilute muriatic acid will dissolve it, or rather the iron it con-r 

 tains, without attacking the red oxide, 



SCIENTIFIC 



Perhaps red 

 oxides with 

 6 or 8, 



in acids with 

 out being 

 oxided. 



Other metals 

 the same. 



