Produced by Bontgen Bays. 51 



unit volume. If the ions are distributed non-uniformly as in- 

 dicated by these experiments the rate of recombination at any 

 instant would not be uniform throughout the volume, but 

 would vary according to the density of the ions. If the dis- 

 tribution of the ions were known so that an average density for 

 the total volume of the gas ionized could be computed by inte- 

 gration, it might be proved that a does not vary with the 

 time. Since these data are not available the true absolute value 

 of a cannot be computed. In the following table, the effect of 

 a non-uniform distribution of the ions is disregarded and a is 

 computed as if the ions were distributed uniformly by using 

 the equation, 



It is obvious that the values of i\ and n x obtained in this way 

 will be too small since when the ions are segregated they do 

 not properly occupy the entire volume between the electrodes, 

 but only a small part of that volume. The absolute values 

 of a given in this way are therefore much too large, but 

 diminish with the time during which the ions are allowed to 

 recombine and diffuse since the tendency of diffusion is toward 

 a uniform distribution. 



The values given were obtained as follows : 



a =z the charge which causes electrometer deflection of V 

 e = the charge carried by the electron 

 D=the electrometer deflections 

 n = the number of ions per unit volume 

 Y= the total volume of the gas ionized ; 



then 



mm 



n v- 1 V« 



q D = n\ e or — = — p: 

 * n qD 



by equation (2) 



__n^ n 1 _ Ye / 1 1 \ _ 4-Q7 X (10) 5 / 1 J_\ 



a ~ ~^^~ " ?(«,-«,) V "D, - D; ; - («, - tj \D~D~J 



In computing the volume Y a correction was made for the 

 distortion of the field between the electrodes due to the charge 

 induced by the field on the insulated electrodes. This was 

 obtained by first applying the usual field while the electrom- 

 eter electrode was earthed. The earthing key was then 

 opened and a flash of X-rays applied giving a reading of the 

 electrometer D'. The process was then repeated in the same 



