Experimental Researches in Electricity, 21 



metals and carbon when they are moving, and in most cases 

 will probably be found to be not even magnetical, but the re- 

 sult of irregular causes not anticipated, and consequently not 

 guarded against." It therefore appears that there are in 

 reality very few bodies magnetic in the same manner as iron ; 

 and as warranted by the result of his investigations, Faraday 

 divides all substances into three classes with reference to 

 their relation to magnets ; first, those which are affected 

 when at rest, like iron, nickel, &c. being such as possess 

 ordinary magnetic properties ; then those which are affected 

 when in motion, being conductors of electricity in which 

 currents are produced by the inductive force of the magnet; 

 and, lastly, those which are perfectly indifferent to the mag- 

 net, whether at rest or in motion. 



Extended research will still be necessary to afford a 

 foundation for a theory including all these differences ; but 

 we may remark, that it appears as if iron and its associ- 

 ate bodies were constantly in that state into which copper 

 and other conductors are thrown temporarily, while by 

 their rotation they are intersecting magnetic curves, and 

 hence, since it is evident that electricity in motion is the 

 source of this state in the latter case, it follows that it must be 

 so likewise in the former : and from the researches on magneto- 

 electric induction of Faraday, the magnetic theory of Ampere 

 receives additional and powerful confirmation. 



We have now terminated our notice of the first and 

 second series of the researches, and we would fain hope that 

 in presenting, although it has necessarily been in general 

 terms, a view of their varied and important results, our la- 

 bour has not been in vain : we have still an extensive field 

 before us in the remaining researches, which increase in- 

 terest and value as they progress : to these we will return 

 on another occasion, and meanwhile would only in conclu- 

 sion state, that general law, to which the wonderful assem- 

 blage of new phenomena discovered by Faraday has been re- 



