Ions produced by JRontgen Rays. 79 



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 : — 



n 



<2 = the charge which causes electrometer deflexion 

 of I mm.; 



£ = the charge carried by the electron; 

 D = the electrometer deflexions; 



?i = the number of ions per unit volume; 

 V = the total volume of the gas ionized; 



then t^ \t 1 V<? 



q\j = n\e or - — ■ -=rc'» 

 1 n qu 



therefore by equation (2) 



1 1 



n 2 " n, Ye /_1 1\_ 4-Q7xl0 5 / 1 1_\ 



5x)\D f IV (*i-*i) \D 2 DlA 



h—h ( lih- 



In computing the volume V 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 

 electrometer 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 way except that 

 the electrometer electrode was insulated before the field was 

 applied, thus receiving an induced charge which distorts the 

 field. In this instance, therefore, a smaller reading J)" was 

 obtained owing to the distortion of the field. The corrected 

 value of Y was obtained by measuring the volume subtended 



D" 



between the electrodes and multiplying this by the ratio jy . 



The following table gives the average values of - (where 



e is the charge carried by the electron) between the successive 

 pairs of points A, B, C, D, E of fig. 5. 



In the case of the gases air and carbon dioxide, the curves, 

 were extended to a point F where £ = 1*06 seconds. 



