OHM ON THE GALVANIC CIRCUIT. 403 



body was engaged in its entire expanse in the process of di- 

 spersion in the atmosphere ; while in the galvanic circuit the 

 electricity almost constantly passes through the interior of the 

 bodies, and consequently only the smallest portion can enter into 

 mutual action with the air ; so that, in this case, the disper- 

 sion can comparatively be but very inconsiderable. This con- 

 sequence, deduced from the nature of the circumstances, is 

 confirmed by experiment ; in it lies the reason why the second 

 law seldom comes into consideration. 



The mode in which electricity makes its appearance at the 

 place of contact of two different bodies, or the electrical tension 

 of these bodies, I have thus expressed : when dissimilar bodies 

 touch one another, they constantly maintain at the point 

 of contact the same difference between their electroscopic 

 forces. 



With the help of these three fundamental positions, the con- 

 ditions to which the propagation of electricity in bodies of any 

 kind and form is subjected may be stated. The form and 

 treatment of the differential equations thus obtained are so 

 similar to those given for the propagation of heat by Fourier and 

 Poisson, that even if there existed no other reasons, we might 

 with perfect justice draw the conclusion that there exists an 

 intimate connexion between both natural phaenomena ; and this 

 relation of identity increases, the further we pursue it. These 

 researches belong to the most difficult in mathematics, and on 

 that account can only gradually obtain general admission ; it 

 is therefore a fortunate chance, that in a not unimportant part 

 of the propagation of electricity, in consequence of its peculiar 

 nature, those difficulties almost entirely disappear. To place 

 this portion before the public is the object of the present 

 memoir, and therefore so many only of the complex cases have 

 been admitted as seemed requisite to render the transition ap- 

 parent. 



The nature and form commonly given to galvanic apparatus 

 favours the propagation of the electricity only in one dimension ; 

 and the velocity of its diffusion combined with the constantly 

 acting source of galvanic electricity is the cause of the galvanic 

 phenomena assuming, for the most part, a character which does 

 not vaiy with time. These two conditions, to which most fre- 

 quently galvanic pha;nomena are subjected, viz. change of the 

 ' lectric state in a single dimension, and its independency of time. 



