334 PLUCKER ON THE THEORY OF DIAM AGNETISM. 



In order to be sure that in the last experiment the observed 

 action was not due to any foreign cause, I convinced myself 

 by direct experiment and making use of nine cells, that when 

 the spiral was placed upon a parallelopiped of soft iron and 

 a current sent through it, no sensible magnetism was excited 

 in the iron, and on the other hand, when the bismuth was 

 suspended close to the same mass, there was neither attraction 

 nor repulsion when the mass did not rest upon the electro- 

 magnet. 



13. These experiments prove to a certainty that the spiral 

 acts upon the bar of bismuth, and that this action is reversed 

 by the reversion of the cuiTent, and hence is a polar action. 

 The action of the magnetic poles on the bismuth either coin- 

 cides with the action of the spiral or is opposed to it ; and the 

 whole is completely explained if we assume that the pole of the 

 magnet as well as the spiral excites on the bismuth a polarity 

 which is exactly the reverse of that of iron, so that, for example, 

 in the original experiment, when the direction of the current is 

 the same in both spirals, the polarity of the ends of the iron 

 and bismuth cylinder turned towards each other possess the 

 same polarity. 



14. The intensity of the magnetism assumed by a bar of iron 

 within a spiral is so great, that the result of the described expe- 

 riments, although feeble, cannot be doubted if the assumption, 

 which it is intended to confirm, be the correct one. Let us 

 assume in the original experiment that the end of the iron bar, 

 which has become a magnetic pole, excites in the adjacent end 

 of the bar of bismuth a polarity 10,000 times less than what it 

 could excite in a similar cylinder of iron (I assume this number 

 too small, and at the same time do not take into account that 

 the two iron cylinders, by mutual induction, strengthen each 

 other), then the repulsive force upon the bismuth will be 10,000 

 times smaller than the attraction of the iron would be, and in 

 this case, with the assistance of a fine balance, we can always 

 observe the action. This repulsion evidently increases or 

 diminishes before a constant magnet, in the same ratio as the 

 polarity of the bismuth increases or diminishes. Assuming, 

 therefore, that the magnetic induction of the bismuth by the 

 upper spiral is to its induction by the cone of iron in the ratio 



