168 Prof. G. Wiedemann on the Magnetic 



action of magnetizing forces arrange themselves all more or 

 less in determinate directions, then the intensity of rotation 

 of the molecnlar magnets in different substances under the 

 action of the same external magnetizing forces depends, first, 

 on the quantity of their own invariable magnetic moment, 

 and, next, on the resistance oj^posed by the molecular forces 

 to their rotation. 



But we have observed, first, that in the solutions of the 

 above-mentioned different kinds of salts of the same magnetic 

 metal the molecular magnetism is the same. Therefore it 

 cannot be essentially affected by the variable constituents of 

 the salts. Indeed most of these possess, in relation to the 

 magnetism of the majority of the salts themselves, only a 

 very feeble magnetism or diamagnetism. The same is true 

 also of the oxygen contained in the oxygen salts, since the 

 haloid and oxygen salts behave precisely alike with respect 

 to magnetism. Also the supposition, expressed by Schonbein 

 among others, that oxygen may be contained in the salt- 

 formers, cannot be maintained, since, for example, the copper 

 compound of the (by itself) feebly diamagnetic ferrocyanic 

 hydrogen acid (which certainly contains no oxygen) pos- 

 sesses the same quantity of molecular magnetism as the rest 

 of the copper-salts. Accordingly the temporary magnetism 

 of salts under the influence of magnetizing forces can only 

 proceed from the magnetic position of the metallic atoms 

 contained in their molecules. 



We know, further, again through magnetical investiga- 

 tions, how very much the molecular forces operative in every 

 individual magnetic group of molecules are affected by ex- 

 ternal circumstances, pressure for instance. If an amorphous 

 pulveriform body were suspended at its centre of gravity 

 in a homogeneous magnetic field, between two magnetic poles, 

 so that the magnetic forces acted vs ith equal intensity upon 

 all the molecules, the body would, as under the influence of 

 gravity, remain in equilibrium in all positions, even when the 

 particles were brought nearer to one another by a pressure in 

 one or another direction — provided that their magnetic action 

 upon one another could be neglected, which would eftect a 

 diminution of the diamagnetic moment in diamagnetic, an 

 increase of the magnetic moment in magnetic bodies. We 

 find, how^ever, that by one-sided pressure not only the mag- 

 netism but also the diamagnetism of pulveriform substances 

 is increased in the direction of the pressure. This, therefore, 

 cannot arise only, as was at first assumed, directly from an 

 alteration of the density of aggregation of the molecular 

 groups, but the groups themselves must be altered. 



