﻿720 Profs. Welliscli and Bronson on the Distribution of 



and is exhibited as a curve in fig. 2, which refers to air at 

 1 atmosphere ; the method of procedure for determining the 

 points has already been given in section 2. 



100 





/> 



,„,,., 







X 



y * 



c60 7nm. 









"/ 



















/ 













750 



1500 



2?50 3000 3750 



Potential in Volts . 



450Q 



It will be seen from an inspection of this curve that the 

 percentage cathode activity always increased with the applied 

 potential, a result which indicates that there are practically 

 no negative carriers of activity ; all the so-called anode 

 activity to which reference is made by many investigators is 

 due to the diffusion to the walls of the vessel of uncharged 

 restatoms. A slight correction has on this account to be 

 made for the amount of uncharged activity that diffuses to 

 the cathode during the exposure ; this correction w T as made 

 by estimating the relative areas of the exposed surfaces of 

 cathode and case, which were found to be in the ratio 1 : 50, 

 and assuming that the uncharged restatoms were distributed. 

 in this proportion. The true percentage cathode activity, 

 that is, the number of positive carriers expressed as a per- 

 centage of the total number of carriers, is obtained from the 

 percentage cathode activity (p), as determined experimental! v, 



51 r 

 by evaluating the expression 1— /-_2. All values given in 



this paper for the percentage cathode activity denote the true 

 percentage obtained by correcting in this manner. 

 A typical set of measurements is given below: — 



Emanation passed through P 2 5 and glass-wool into 

 vessel containing air at 1 atmosphere. +975 volts 

 on case. Exposure about 2 hours. 

 Equilibrium rate with added capacity: 6*17. 

 Activity on case measured at 10 and 15 minutes after 

 removal of emanation ; rates with added capacity : 

 •19 and *17 respectively. 

 Activity on cathode measured at 20 and 25 minutes 

 after removal of emanation; rates with added capacity; 

 1*05 and '98 respectively. 



