488 WEBER OX THE NATURE OP DIAMAGXETISM. 



tricity of a conductor, the lattei' is set in motion, and this mo- 

 tion distributes itself according to laws in proportion to the 

 capacity for conduction between all the paths which the con- 

 ductor presents ; consequently a portion of the motion must 

 likewise take its course around the individual molecules of the 

 conductor, and form induced molecular currents, which because 

 they find no resistance in their course around the molecules, by 

 which they might be retarded, must continue in their full strength 

 until, in consequence of a new opposite induction, other in- 

 duced molecular currents are added which neutralize the previous 

 ones. 



If therefore, with Ampere, we admit molecular currents in the 

 doctrine of electro-magnetism, we must at present, as a neces- 

 sary consequence, after the discovery of induction, adopt induced 

 molecular currents in the doctrine of magneto-electricity, and 

 must ascribe permanence to all, whether they have always ex- 

 isted or been first produced by induction. Assuming this, it 

 results that all bodies in which diamagnetic efi'ects have been 

 observed, must have been acted upon by forces which must have 

 induced molecular currents, and indeed such as produce the 

 effects designated by the name of diamagnetic. 



The latter follows from the fact, that a magnetic force tends to 

 give such a direction to an existing current that its course is ex- 

 actly opposed to that of a current induced by the increase of that 

 magnetic force. Consequently, if this induced current is a mole- 

 cular current which is persistent, it will likewise have permanently 

 the opposite effects of another molecular current which existed 

 (for instance in iron) independently of the increase of that mag- 

 netic force, but has acquired its present direction by means of 

 that force. The opposite behaviour of the diamagnetized bis- 

 muth and of the magnetized iron follows according to this from 

 known laws. The essential difference between bismuth and 

 iron would then be this, that molecular currents, whose direc- 

 tion however is not unalterable, exist in iron independently of 

 any external excitation, but subject to the influence of external 

 forces, which is not the case in bismuth. However, bismuth and 

 iron may in so far be rendered equivalent as a decreasing or in- 

 creasing magnetic force induces in both fresh persistent molecu- 

 lar currents, which however must be much weaker in the iron than 

 those existing in it already, independently of such induction. 





