Electricity through Gases by Charged Ions. 261 



equations are 



— = 4:7r{n 1 -n 2 )e, 



^{k 2 n 2 X)=-q. 



If q is constant, we have 



A: 1 ?z 1 X = got, 



# 2 ?2 2 X= go:, 



the constant has been determined so as to make ni~0 when 

 x=0 ; substituting these values for n 1? n 2 , in the equation 

 giving dUL/dx we get 



or 



,2 



x --Kf(H,)-f>^ 



the constant may be determined from the condition that 

 when x = \ 



^~qe\k 1 + k 2 ) 2J 

 from this we find 



~ OC L 2 f , 47T6 £. ._ _ . 1 



Since C is the value of X 2 when w=0, it is the value of X 2 

 at the positive plate; if we call Xj the value of X at the positive 

 plate and X the value of X between the layers we have 



w{it^(M*>}'. 



thus X x is always greater than X , the value of X between the 

 layers. 



If X 2 is the value of X at the negative plate we have 



Thus, if k 2 , the velocity of the negative ion, is very large 



