of Magnetic and Non'magnetic Bodies. -tSS 



bodies subjected to the influence of a strong electro-magnet 

 clearly indicate a molecular derangement in them. The re- 

 cent researches of M. Matteucci, showing that a mechanical 

 action, such as compression, may annul or increase on the 

 same substance (heavy glass, for example) the effect obtained 

 by Faraday by means of an electro-magnet, confirm the fact 

 that this last effect is also a molecular phaenomenon. 



With regard to non-transparent but conducting bodies, if 

 they are magnetic, they experience a molecular modification 

 under the action of the magnet, as we have stated above. If 

 they are not magnetic, they are diamagnetic ; and then it is 

 very probable that the diamagnetism causes a change in the 

 position of their particles, as magnetism does in the others; 

 ibr it appears to be satisfactorily proved that diamagnetism 

 is attributable to a transversal polarity, as magnetism is due 

 to a longitudinal polarity*. Now whenever any cause pro- 

 duces a polarity in the particles, these must, in obedience to it, 

 arrange themselves in a determined relative position exactly 

 as takes place in the phaenomenon of crystallization. 



It is therefore probable that, under the influence of a mag- 

 net or of an external current, the particles of a diamagnetic 

 body tend to arrange themselves transversely; whilst under 

 that of a transmitted current, they take a longitudinal direc- 

 tion, as is shown by the force of projection which carries the 

 particles of a conductor from the positive to the negative pole, 

 at the point where the circuit is interrupted, in giving rise to 

 the voltaic arc. The struggle between these two contrary 

 tendencies, the one transversal, the other longitudinal, pro- 

 duces the oscillatory movements of the particles around their 

 position of equilibrium, and consequently the vibrations. 



In the production of the currents of induction, this mole- 

 cular derangement which is produced by the magnetic action 

 of a magnet or of a closed current must necessarily take place. 

 To this derangement is probably due the production of an 

 instantaneous electric current; just as when the molecular 

 derangement ceases on the disappearance of the cause which 

 has determined it, there arises a second electric current, ha- 

 ving a contrary direction to the first. It is easy to understand 

 why these two currents pass thus in opposite directions. 



A conductor placed under the influence of an electro- 

 magnet, or of molecular currents, must therefore be, as long 

 as that influence is exerted upon it, in peculiar molecular con- 

 ditions. This is shown by the affections of light in those which 

 are transparent; it remains to be demonstrated by other 



* The recent researches of Prof. Faraday on the magnetic polarity of 

 crystals of bismuth are quite favourable to this view. 



Phil. Mag. S. S. Vol. ^5. No. 238. Dec. 189. 2 F . 



