432 M. R. Kohh-ausch's Theory of the 



has attained its maximum j)r. In a similar manner it may be 

 shown why, when a part of the charge is suddenly withdrawn, 

 the disposable charge either sinks more slowly than before, or 

 stands, or increases according to the proportion which the residue 

 already formed bears to the quantity of electricity which still 

 remains. 



Hitherto we have neglected all loss of electricity. In prac- 

 tice, where such a loss always occurs, the residue cannot, of 

 course, attain any fixed maximum, and the condition of the plate 

 at the time t will depend upon the proportion existing between 

 the velocity with which the residue is formed and that of the loss 

 of electricity in the air. From this point of view all the phae- 

 nomena may be explained, although, it is true, such explanations 

 will first acquire the requisite amount of certainty when the law 

 of the residue-curve in § 11 shall have been deduced. 



We have yet to discuss the cause which generates in the glass 

 a kind of resistance to the influence of the external electricity, or, 

 in other words, to the formation of the electric residue. For 

 this purpose we must dive still deeper into the sea of hypothesis; 

 and although this may appear hazardous when we reflect that 

 we know nothing either of the essential nature of electricity or 

 of the law of molecular forces, yet such an attempt may be per- 

 missible provided we confine ourselves to perfectly definite ideas, 

 and obtain a result from our speculations. 



Two essentially different suppositions may be made as to the 

 slow formation of the residue, or rather of the electric moment 

 which causes it : — 



1. Electricity actually passes from one particle of glass to 

 another, without, however, being able to break through the sur- 

 faces of the glass in order to combine with the opposite electri- 

 cities there situated ; so that a condition will ensue exactly the 

 opposite of that before assumed for the penetration of the glass 

 by the external electricities. After the discharge, the electricities 

 in the glass combine in the same manner in which they were 

 separated. Then the slowness of the formation of a residue may 

 be attributed to the great difficulty of motion for the electricity 

 in the interior of a bad conductor ; the limit of the moment, how- 

 ever, to the circumstance, that within the glass, and on the coat- 

 ings, such a distribution has at length taken ])lacc, that the 

 potential of the whole electricity, in reference to every point 

 within the glass, has become constant. The question, whether 

 the possibility of such a distribution can be proved or not, must 

 remain an open one. Although in this hypothesis the assump- 

 tion of a quite peculiar force opposed to the electricity in the 

 surface appears strange, it might still be admitted if everything 

 else fitted well, for the surface is quite diff"erent from the interior. 



