128 



STATIC ELECTRICITY 



Connecting A again to the batteiy, its potential was once more 

 raised to V r But B being insulated, its potential was raised by 

 an amount proportional to the additional charge on A, for this 

 additional charge induced on B an equal and opposite charge con- 



HI 



FIG. 87. 



nected with itself and an equal like charge connected with the si 

 of the vessel. We may therefore put the potential of B as equal to 



- V a ) 



where m is a constant, 

 or 



Suppose the charge observed in the electrometer to be dri. 

 bv 8. The number of cells was now increased from n to n + 1, 



and the potential of A was consequently -raised to V x + - 1 , and 



V 



that of B was raised by m *. 



If the change observed in the electrometer was 3' 9 we have 



whence K 



<J 

 ? 



nS' 



K-l 

 K 



= n 



m> 



The following Table gives BoltzmaniTs results at C. and 

 760 mm., with the values of ^ as determined by Dulong for white 

 light. As the difference between this and p <x is probably 

 small for gases, these values may fairly be taken. 



