172 WEBER ON THE CONNEXION OF DIAMAONETISM 



the contribution of all circular currents (molecular currents) the 

 normals of which form an angle </> with the direction of the mag- 

 netizing force to the electro-diamagnetic moment of the bismuth, 

 namely, 



^e 

 . Trr^X . sin <i> cos <f>^. 



cce ^ ^ 



Multiplying this by d<f>, and then, further, the integral taken be- 

 tween the limits </)=0 and <f>=--^'JT by the number of molecular 



currents, we obtain the total electro-diamagnetic moment of the 

 bismuth mass m, when ^m denotes the number of molecular 

 currents in the mass, 



= — - — . iir^e . wX. 

 3 cce ^ 



The electro-diamagnetic moment of a mass of bismuth is there- 

 fore proportional to the magnetizing force X and to the mass of 

 the bismuth m, and is found by multiplication with a constant 



factor - — , taken from the general theory of electricity, and with 



oCCG 



a factor fir^e dependent on the nature of the bismuth itself. 

 This last factor we may call the diamagnetic constant of bismuth. 

 In this determination of the electro-diamagnetic moment, 

 the molecular currents induced in the circular paths have been 

 regarded singly, as if on each molecule the electromotive force 

 calculated from the force of magnetization X had alone acted. 

 Strictly speaking, however, this is not the case. In each 

 circular path, on the contrary, electromotive forces, resulting 

 from the action of the molecules upon each other, come into 

 play; just as the particle of an iron bar is not affected by 

 the external magnetizing force, for example, the magnetism of 

 the earth, alone, but also by such forces as result from the reci- 

 procal actions among the iron particles themselves. Although 

 this mutual action of the diamagnetic molecules is so small as 

 scarcely to exert a sensible influence, still a remarkable antithesis 

 between the mutual action of magnetic and diamagnetic mole- 

 cules deserves consideration here. 



Comparison of the Mutual Actions of Diamagnetic and Magnetic 



Molecules, 

 When two particles of iron are situated in a line parallel to 

 the direction of a magnetizing force X acting upon them, calling 



