24 



THE THEORY OF IONIZATION OF GASES 



centimetre in the gas at 1 millimetre pressure, and 

 the constant V represents the potential difference 

 between the ends of a path along which an ion 

 acquires sufficient velocity to generate others by 

 collisions. 



12. Comparison of the values of a with the 



__NV 



expression Ne x . 



The following tables give values of a for the gases 

 at 1 millimetre pressure, the forces X being expressed 

 in volts per centimetre, and also the values of the 



__NV 



quantity Ne x , the constants N and V having been 

 chosen so that the formula should agree with the 

 experimental results for the larger forces. 



The values of a corresponding to any other pressure 

 may be obtained by taking the numbers to indicate X/p 

 and a/p instead of X and a respectively. 



TABLE I. 

 AIB. N=14-6; V=25-0. 



