in Gases by the Motion of Negatively Charged Ions. 641 



moving with a fixed velocity through the gas. For this 

 purpose it would be necessary to find the equations of the 

 curves ; but we do not intend to investigate this point until 



Fig. 2. 



•d -h v 

 some other experiments are made at lower pressures, which 



may give the larger values of - more accurately. 



X P 



For values of — less than 800, the curve for carbonic 



. P. 

 acid almost coincides with the curve for air. We may 



conclude that for small velocities of the colliding ion the 



ratio of the number of new ions generated to the total number 



of collisions is nearly the same for carbonic acid as for air. 



