486 WEBER ON THE NATURE OF DIAMAGNETISM.- 



of the two fluids is, according to this, necessarily determined by 

 magnetic laws. But this direction is exactly the reverse of that 

 stated in the above rule. Exactly the same, however, obtains 

 upon the other assumption, which presupposes the existence of 

 Ampere's molecular currents in diaraagnetic bodies, instead of 

 the magnetic fluids, which on the approach of a pole of a magnet 

 should be rotated in a direction determined by electro-magnetic 

 laws. But this rotation is exactly the reverse of that indicated 

 by the above rule. There exists consequently a contradiction 

 between the above rule of excitation and the laws of the activity 

 of the diaraagnetic condition. Until this contradiction is re- 

 moved, all the diaraagnetic conditions of bodies continue to form 

 a group of isolated facts without any connection with other phae- 

 nomena, just as those of rotation-magnetism formed a similar 

 group until Faraday gave the key to their solution by his dis- 

 covery of induction. 



In the preceding observations which referred to the effects, it 

 was indifferent whether separate magnetic fluids or Ampere's 

 molecular currents of the same direction constitute the excited 

 diaraagnetic state of bodies. This is no longer the case in the 

 following considerations which relate to the causes, i.e. to the 

 forces exciting the diaraagnetic state of bodies. For if it were a 

 certain distribution of the magnetic fluids which constituted the 

 diaraagnetic condition of bodies, no account, as above shown, 

 could be given of the forces producing them, at least this distri- 

 bution could not be explained from the known magnetic forces 

 which act upon these fluids. But the case is different if the dia- 

 masrnetic condition of bodies is constituted by raolecular currents 

 of like direction ; for a system of raolecular currents of like di- 

 rection can obtain in a two-fold raanner. In the first place, it is 

 possible that the molecular currents existed previously in the 

 bodies, and that only one force acted upon these already existing 

 currents which coraraunicated the same direction to thera ; but, 

 secondly, it is also possible that the currents of like direction, 

 which form the diaraagnetic condition of bodies, did not pre- 

 viously exist, but first oriyinated or were induced on diamagne- 

 tizing the body. Now if one of these two possible cases falls to 

 the ground for the sarae reasons as that of the above considered 

 distribution of raagnetic fluids, the other possible case for the 

 molecular currents still remains, according to which they have, 

 been produced by induction. 



