•WEBER ON THE NATURE OF DIAMAGNETISM. 4S1 



constantly acts upon such poles in an opposite manner to iron 

 in its place, that it consequently repels ^vhere iron attracts, 

 and attracts where iron repels ; in short, that at other magnet- 

 poles than that which diamagnetizes the bismuth, we as fre- 

 quently observe attractive as repulsive forces of the bismuth. 

 For instance, if the one extremity of the bar of bismuth was 

 brought near the north end of a powerful magnet, w hile its other 

 extremity was approached to the north end of the magnet-needle, 

 the latter was attracted; but if the same extremity of the bar of 

 bismuth was brought near to the south end of the powerful 

 magnet, the north end of the magnet-needle was I'epelled by the 

 other extremity of the bar of bismuth approached to it. 



We may hence regard Faraday's supposition as proved, at 

 least in so far as it places the origin of the diamagnetic force, not 

 in the unvarying metallic particles of the bismuth itself, but in 

 a variable distribution which occurs in the bismuth, and acts 

 upon other magnets in the same manner as a definite distribu- 

 tion of magnetic fluids. 



In order, lastly, to remove every doubt as to its being really 

 nothing else than the magnetic fluids, or their equivalent. Am- 

 pere's currents, which are subject to this variable distribution in 

 the bismuth, it may be required to be shown by experiment, not 

 merely that the effects connected with the presence of the dia- 

 magnetic and of a certain magnetic state are equal, but likewise 

 that the effects connected with the origin of the two states are so. 



It is well known that, according to the laws of induction 

 discovered by Faiaday, the motion of the magnetic fluids in a 

 body, or the rotation of the molecular currents of Ampere, is 

 connected with an electrical action at a distance upon neigh- 

 bouring conductors, owing to which an electric current is ex- 

 cited or induced in the latter. 



Consequently, if the two magnetic fluids, or their equivalents, 

 Ampere's currents, are really present in the diamagnetic bodies, 

 which are set in motion or rotated under the influence of a 

 powerful magnet, they must induce an electric current in a 

 neighbouring conductor at the moment this change takes place. 



Now to observe this induced current itself, it is requisite that 

 no other current be induced in the same conductor, for instance 

 by the powerful magnet to which the bar of bismuth is ap- 

 proached. For this purpose therefore the force of this magnet 

 must be retained unaltered during the experiment, which pre- 



VOr>. v. I'AKT \i\. 2 K 



