734 PLiJCKER ON THE DETERMINATION OF THE 



chanical mixture of peroxide with protoxide of iron, we should 

 obtain for the magnetism of the peroxide in the mixture, 



69 . 1-34 = 92; 

 consequently, on deducting this number from the magnetism of 

 the magnetic iron ore, we have the number 40135 for the mag- 

 netism of the 31 per cent, of protoxide of iron. If we reduce 

 this number to our unity of weight, we get 



132694 

 for the magnetism of the protoxide, which would consequently 

 exceed the magnetism of iron itself. 



Treating this question as a mathematical problem, we should 

 obtain a more probable result, were we to convert the chemical 

 formula for magnetic iron ore (FeO + Fe^ O^) into the quanti- 

 tative equivalent (2 FeO + FeO'"') ; for if the magnetic iron ore 

 contained 62*01 per cent, of protoxide of iron, and we entirely 

 neglected the magnetism of the hypothetical FeO^, we should 

 have for the magnetism of the protoxide, after reduction to the 

 unit of weight, 



64S70. 



27. Shall we, on the other hand, suppose that in the magnetic 

 iron ore, by the chemical combination of a powerfully magnetic 

 body, the protoxide of iron, with one feebly magnetic, the per- 

 oxide of iron, a body is produced which is still more powerfully 

 magnetic than the former? 



I shall not at present venture to express an opinion upon the 

 intensity of the magnetism of the protoxide of iron. 



28. The most natural supposition is, that in most cases a 

 small quantity of protoperoxide of iron is mixed with the 

 oxides. Adopting this view, 1 per cent, for instance of the 

 former would augment the magnetism of the remaining 99 per 

 cent, to 402 ; hence, assuming the magnetism of the red haema- 

 tite to be that of the oxide, we should have as its magnetic in- 

 tensity 



535, 

 which nearly corresponds to that of micaceous iron ore. Thus 

 the increase in the magnetism of the latter would be produced 

 by the admixture of about one-third per cent, of protoxide of 

 iron. This would only make a difference of about one-twelfth 

 per cent, in the total amount of oxygen, which would be difficult 

 to estimate by chemical analysis. 



29. In accordance with the view we have taken, we might cal- 

 culate the admixture of the protoperoxide of iron, if we knew the 



