Electricity through Gases by Charged Ions. 207 



cl 



dx 



(k^i^X) =q — an 1 n 2) 



- X. (^ 2 X) =^-«??in 2 , 



we get if k 1 and &o are independent of x 

 cf~X 2 



(/*'"' 



S7re{q-a ni n 2 )(^ + j-J. 



Thus q — a.n Y n. 2 is of the same sign as d 2 X. 2 /dx 2 . Tims when 

 ^ — a/^/^2 is positive, that is when the ionization exceeds the 

 recombination, the curve for X 2 will be convex to the axis 

 of x, and this curve will be concave to the axis of x when the 

 recombination exceeds the ionization. Places of sharp cur- 

 vature will be regions either of great ionization or recom- 

 bination. Fig. 4 is a curve for X 2 calculated from Graham's 









Fig. 4. 

















































Hi 











results. It will be seen that there arc two places of specially 

 sharp curvature with the curvature in the direction denoting 

 ionization, one, the most powerful one, just outside the 

 negative dark space, the other near the anode, while in the 

 positive light the curvature indicates recombination. It 

 would seem as if the positive ions formed at the centre of 



