5S2 PLUCKER ON DIAMAGNETIC POLARITY. 



ferent distance, excites* diamagnetic or magnetic molecular cur- 

 rents in the same mass ; or, what I consider more probable, that 

 in phaenomena of this kind magnetic and diamagnetic substances 

 are always mixed, in which the different molecular currents simul- 

 taneously exist, and that then, as the distance between the poles 

 increases, the diamagnetic currents diminish in intensity more 

 rapidly than the magnetic. The following question appears im- 

 portant as regards theory : — Does the different distance of the 

 poles of the electro-magnet come under consideration directly as 

 such, or indirectly only, inasmuch as a diminution of the force 

 corresponds to a greater distance} In the first of these two 

 alternatives, I should unconditionally lay aside the theory; for 

 if magnetic and diamagnetic currents, when the magnetic force is 

 the same, diminish tvith the distance according to a different law, 

 I could not possibly regard the two as identical in their nature. 

 I can however far more easily imagine, that when two forces 

 produce opposite rotations, these rotations, when a different re- 

 sistance is to be overcome, are not proportional at the same 

 distance to the forces which produce them. If, e.g., l?y way of 

 comparison, we take two wheels, which two forces A and B 

 strive to rotate in opposite directions, and premise that the re- 

 sistance to the first direction of rotation is mucli greater than 

 that to the second ; the rotation of the first wheel may then be 

 slower than that of the second, although the force B is con- 

 siderably less than the force A, which however ceases to be the 

 case when, on the increase of the forces, the total resistance to the 

 magnitude of the force A ceases to be appreciable. In this point 

 of view the force A would correspond to the diamagnetic, and 

 the force B to the magnetic forces. 



7. For the purpose of determining which of these two alter- 

 natives occurs in nature, I made the following decisive experi- 

 ment : — 



I took a small piece of box-wood charcoal, which when at a 

 considerable distance from the poles of the electro-magnet acted 

 magnetically, whilst at a less distance it was diamagnetic. I 

 excited the curr^^nt by means of a single Grove's cell, and placed 

 the poles at such a distance from each other that the pieces of 

 charcoal assumed a decidedly axial position. I next used two 



* The magnetic currents must be considered as pre-existing, as in iron, and 

 merely turned by the magnet into the same direction as its own. — Poggen- 



DORFF. 



