in connexion with the Theory of Electro-statics, 467 



tricity can only exist at the surface of the conductor. Thus 

 as u within one of the conductors satisfies the equation 



dhi d?u d 2 u __ 



u must be a potential of masses which are situated externally 

 to this conductor. But u is a potential of all the free elec- 

 tricity ; hence no part can be situated in the interior of the 

 former conductor, nor in any part of the interior of any con- 

 ductor. 



The considerations we have laid down hold good whatever 

 the number, the form, and the arrangement of the conductors 

 may be which are placed in contact ; they also hold good in 

 that case in which one plate of a condenser is placed in con- 

 tact with a point of a closed circuit, and hence afford the 

 theory of experiments similar to those of M. Kohlrausch. 

 The results which they yield agree perfectly with those of this 

 experiment. 



The considerations we have laid down are based upon the 

 electro- static law of the action of electric particles. Neither 

 Ampere's electro-dynamic phenomena, nor the phenomena 

 of induction, can be explained by this law. Weber has dis- 

 covered a more general law, by which he has succeeded in 

 explaining these phaenomena; a law, in the expression of 

 which the relative velocity of the particles, whose action upon 

 each other is under consideration, is introduced, and which 

 passes into that of electro-statics, when this velocity disappears. 

 In bringing the various fields of the theory of electricity under 

 a single point of view, we must therefore aim at deducing the 

 laws of the currents in the closed circuit from Weber's law. 

 This deduction appears to be difficult ; still it is easy to prove, 

 a posteriori, that the idea regarding the currents, to which 

 the admission of the electro-static law has led, is also in confor- 

 mity with Weber's law, when a certain hypothesis is called in 

 aid, viz. that hypothesis, according to which, on calculating 

 the force which a separation of the two electricities produces 

 in the element of space v of one of the conductors, the elec- 

 tricities in v must be regarded as at rest. There is nothing 

 opposed to this view, when we bear in mind, that the motion 

 of the electricity in one conductor only passes from molecule 

 to molecule ; so that every particle of electricity finds a point 

 of rest in a molecule which it reaches. Adopting this view, it 

 may readily be granted that the quantity of electricity which 

 is transferred from one molecule to a neighbouring one is only 

 occasioned by the forces which are exerted upon the particles 

 of electricity, whilst they are still in a state of rest in the former 



2 H 2 



