WEBER OX THE NATURE OF DIAMAGNETISM. 4S7 



Hitherto it has never been a question of induced molecular 

 cvTrents, but solely of fixed invariable molecular currents, ac- 

 cording to Ampere's definition, to whom indeed the origin of 

 currents by induction Avas unknown. But it is evident if the 

 existence of molecular currents be admitted, we must further 

 allow that their intensity may be increased or diminished, and 

 that even new currents of this kind may be produced by the very 

 forces which produce currents in larger circuits. 



If we go back to induction in order to explain diamagnetism, 

 it might at first sight be doubted whether it is really necessary 

 to admit induced molecular currents for this purpose, or whether 

 the currents induced in large circuits are not of themselves suffi- 

 cient. These currents would, it is true, be able to produce all 

 diamagnetic phaenomena if they were /^enrtflwew/ ; but as these 

 currents, which are subject to Ohm's laws, ai'e not pei-manent, 

 but instantly disappear with the inducing force, and can only be 

 maintained by continued induction, they can for this reason alone 

 not serve to explain diamagnetism. ■' 



But if the rapid disappearance of these ouiTents is the sole 

 reason of its being impossible to deduce thence the diamagnetic 

 condition of bodies, there appears to be no reason why the per- 

 sistent diamagnetic state of bodies should not be ascribed to 

 induced molecular currents, as these must behave in all other 

 respects like those currents, and differ only in possessing that 

 permanency which is wanting in the others. For the dif- 

 ference between those currentswhich move through conductors in 

 large circuits and these molecular currents, consists solely in the 

 circumstance that the circulating electricity of the former is so 

 quickly deprived of its active force in passing to the molecules 

 of the conductor, that it would come to rest in an immeasurably 

 small time if the loss it sustained were not constantly replaced 

 by continuous electro-motive forces, whence it results that cur- 

 rents of this kind are, according to the laws of Ohm, constantly 

 proportional to the existing electro-motive force, and instantly 

 ft disappear with the electro-motive force. The reverse applies to 

 the molecular currents which do not pass through a conductor 

 from molecule to molecule, but circulate around a single mole- 

 cule, to which consequently the above reason, deprivation of 

 their active force, does not apply. These currents therefore 

 persist of equal intensity without any electro-motive force. 



Now admitting an indiicmij. force which acts upon the clec- 



