APPLICATION OF THE PRECEDING RESULTS TO 

 THE THEORY OF ELECTRICITY. 



(8.) THE first application we shall make of the foregoing 

 principles, will be to the theory of the Leyden phial. For this, 

 we will call the inner surface of the phial A, and suppose it to be 

 of any form whatever, plane or curved, then, B being its outer 

 surface, and 6 the thickness of the glass measured along a nor- 

 mal to A ; 6 will be a very small quantity, which, for greater 

 generality, we will suppose to vary in any way, in passing from 

 one point of the surface A to another. If now the inner coating 

 of the phial be put in communication with a conductor C, 

 charged with any quantity of electricity, and the outer one be 

 also made to communicate with another conducting body (7', 

 containing any other quantity of electricity, it is evident, in 

 consequence of the communications here established, that the 

 total potential function, arising from the whole system, will 

 be constant throughout the interior of the inner metallic coating, 

 and of the body (7. We shall here represent this constant 

 quantity by 



#. 



Moreover, the same potential function within the substance of 

 the outer coating, and in the interior of the conductor (?', will 

 be equal to another constant quantity 



ff. 



Then designating by F, the value of this function, for the whole 

 of the space exterior to the conducting bodies of the system, 



