166 WEBER ON THE CONNEXION OF DIAMAGNETISM 



first case forms the basis of the magnetic theory of Coulomb 

 and Poisson. The third case forms the basis of the theory of 

 Ampere on the connexion of magnetism with electro-dynamics. 

 The second case may be reduced to the third, inasmuch as Am- 

 pere has proved that molecular magnets and molecular currents 

 are alike in all their actions, and hence the latter may be substi- 

 tuted for the former. The fourth case, therefore, which has 

 heretofore been unattended to, is the only one that remains to 

 be considered. 



For each of these four cases there exists a definite connexion 

 between the character of the ideal distribution and the direction 

 of the magnetizing force to which it corresponds. Calling that 

 direction along the line of magnetization in which the north pole 

 of a magnetic needle is driven i\\Q positive, and determining the 

 centre of gravity of the north and south fluids from their ideal 

 distribution, then for the first case, according to the theory of 

 Poisson, we find that the former of these two centres of gravity, 

 as compared with the latter, is situated in the positive direction. 

 For the third case this connexion has been developed by Am- 

 pere, and it has been found that the same dependence of the 

 ideal distribution upon the magnetizing force exists here also. 

 From the reduction of the second case to the third, already men- 

 tioned, it is evident that the same dependence exists in the 

 second case. Hence, in regard to this dependence, the fourth 

 case alone remains open to consideration. 



This fourth case assumes the existence of electric fluids which 

 can be thrown into molecular currents. But the possibility of 

 being thrown into molecular currents necessitates the inference, 

 that in the single molecules, or around them, closed paths exist 

 in which the said fluids can move without resistance ; from which 

 it follows that a current -ex citing force (a force which acts upon 

 the positive and negative fluids in opposite directions) in the 

 direction of the path is necessary to cause the fluids actually to 

 move along it. Now the facts of magneto-electricity prove that 

 by the increase or diminution of a magnetizing force, a current- 

 exciting force (electromotive) is obtained, which acts upon the 

 electric fluids in opposite directions, and hence nust throw them 

 into current motion. By the fundamental law of magnetic induc- 

 tion the direction of this molecular flux is given, in its depend- 



