INTENSITY OF MAGNETIC AND DIAMAGNETIC FORCES. 733 



nected with their very different appearances, and also to the cor- 

 responding very different molecular states in which the peroxide 

 is formed both in natm'e and in the laboratory. Without wish- 

 ing to speak positively upon this point, the supposition appears 

 to me however as yet best founded, that the different intensity 

 of the magnetism arises from an admixture of protoxide. The 

 first peroxide of iron which I examined, and which is denoted by 

 III. in the 21st paragraph, was procured from the hydrate which 

 occurs in the table in the 18th paragraph, by heating it strongly 

 to redness in a furnace ; it was so strongly magnetic, that it was 

 taken up by a very weak magnet. In comparison with the hy- 

 drate it was a hundred times stronger ; hence the intensity of 

 its magnetism was 



15204. 



This peroxide evidently contains a considerable quantity oi prot- 

 oxide in admixture. Hence also I think it probable that the 

 oxide I., the magnetism of which is = 500, is not free from 

 protoxide, and contains more of it than the oxide II. I dare 

 not yet venture to determine, from the above data, the number 

 which corresponds to the pure peroxide. Red haematite is much 

 less magnetic than micaceous iron ore ; that which I examined 

 has not been subjected to a chemical analysis ; if it were chemi- 

 cally pure, I should consider 134 as about the magnetism of the 

 peroxide. 



Were we to deduce the magnetism of the peroxide of iron 

 from the magnetism of the hydrated peroxide of iron prepared 

 in the chemical laboratory, for which we found 156, on the sup- 

 position that the water which is added to the peroxide in the hy- 

 drate exerts no influence upon its magnetism, we should obtain 

 the number 206, which by the last assumption, that the red 

 haematite possessed the normal magnetism, would be too great. 

 But this supposition is entirely unsupported, and the two num- 

 bers would not be inconsistent, if (as in the case of nickel, only 

 not in the same degree) the water added to the hydrate increased 

 the magnetism of the oxide (protoxide). 



26. The powerful magnetism of the magnetic iron ore is re- 

 markable in more than one respect. That which I examined, 

 and which I obtained through the kindness of M. Noggerath, 

 together with other minerals from the Poppelsdorf collection, 

 caine from Sweden, and, as stated, was pure protoperoxide, con- 

 taining therefore nearly 31 per cent, of protoxide of iron and 

 6y per cent, of the peroxide. If we were to regard it as a me- 



VOL. v. FART XXI. 3 U 



