THEORY OF ELECTRIC DISCHARGES 85 



With regard to the factor y,the experimental determina- 

 tions of currents between parallel plates show that the 

 supposed effect which it is intended to represent either 

 does not exist or else is so small as to be inappreciable. 

 For let it be supposed that a certain number in of the 

 negative ions in going through the gas become attached 

 to molecules and lose the property of ionizing the gas ; 

 then if the conductivity be produced by ultra-violet light, 

 as described in section 2 above, the equations for the 

 determination of the quantity of electricity q arriving at 



,, .,.1-1 dn , dm 



the positive electrode are -r-=anyn and =yn, 



where n is the number of corpuscles which cross a plane 

 at a distance x from the negative electrode, andx the 

 number of new ions generated in the distance dx, and yndx 

 the number of corpuscles that become attached to 

 molecules in the distance dx. When x=l, the distance 

 between the electrodes, (m+ri)e is the total charge q 

 arriving at the positive electrode, e being the atomic 

 charge. 



The above equations give 



(a-y)l , y 



n=w e ' and m=n Q - 



when n Q corpuscles start from the negative electrode. 

 Hence the quantity q for the distance I between the plates 

 is given by the equation. 



q , x <* ( a ~ y)Z n y 

 v ^- 



e "a y a y 



Now it has been found experimentally that the values of 



q are given accurately by the formula q=qoe a even 

 for the higher pressures and small electric forces where 



