INTENSITY OF MAGNETIC AND DIAMAGNETIC FORCES. 735 



magnetism of the peroxide under examination. If e. y. we take 

 the strongly magnetic oxide III., and premise that it consists of 

 X per cent, of peroxide and y per cent, of protoperoxide, we have 



X -Yy — 100 

 1 -34 . X + 402-27 • y = 15204 ; 



hence 

 whence 



^ = 62-41, 2^ = 37-59; 



Peroxide =88-35 

 Protoxide = 11 "65. 



30. Chemical analysis usually points out directly the quanti- 

 ties only of the simple substances existing in bodies, but the 

 manner in which these are intimately combined is derived merely 

 from a theoretical combination. As regards iron in parti- 

 cular, the magnetic determination immediately yields a solution 

 of the latter point. Tourmaline, staurolite and basalt, which 

 when suspended between the poles of a magnet, even in the most 

 strongly magnetic liquid, do not cease to act magnetically, could 

 not possess this magnetism if the comparatively small quantity 

 of iron which they contain were mixed with them in the state of 

 peroxide. 



In the following paragraph we shall show, at least by a 

 striking example, how considerable quantities of iron (consti- 

 tuting as much as 12 per cent.), when in a state of definite che- 

 mical combination, may completely lose their magnetism. The 

 electro-magnet then ceases to pi'ove the presence of iron, or, 

 even supposing this presence, the kind of combination in which 

 it occurs. 



31. The great difference which occurs in the magnetic relation 

 of the peroxide to the protoxide, in the same way ceases to be 

 apparent in their saline compounds. When in solution, proto- 

 sulphate of iron is certainly more strongly magnetic than the 

 persulphate, but merely in the propoi'tion of 



133 : 219. 

 In those haloid salts which we have examined, this relation is 

 reversed. The solution of protoxide of iron in hydrochloric acid 

 is more feebly magnetic than the solution of the peroxide in the 

 proportion of 



190 : 224, 

 and the protochloride of iron is more feeble than the perchloride 

 in the proportion of 



216 : 251. 



3 u 2 



