﻿278 



Mr. R. D. Kleernan on the Recombination 



uranium oxide was out) was found to be 10 divisions for 13 

 seconds, and practically independent of the potential applied ; 

 and 10 divisions have therefore been subtracted from each 

 leak. 



Table I. 



xr u Deflexion 

 Volts per / , -,. 

 cm ( each reading j 

 repeated). 



Volts per 

 cm. 



Deflexion 



(each reading 



repeated). 



• 



8 i 1647 1641 j T , , 

 1200 ! 2128 2158 i Lnck ™ 



8 1676 1663 j "t™*™ 

 1200 ! 2079 2145 22 l Der cent ' 



1200 

 20 



1200 

 20 



2121 2135 

 1844 3 829 

 2095 2117 

 1847 1855 



Lack of 

 saturation 

 lo per cent. 



It will now be shown that the lack of saturation obtained 

 when 8 or 20 volts per cm. were applied, was not due to the 

 existence of general recombination of the ions. 



Let us consider the case when 8 volts per cm. were applied. 

 The capacity o£ the uranium chamber could be calculated, 

 and by means of it, making nse of the method of mixtures, 

 the capacity of electrometer and chamber was found to be 

 about 230 E.S. Us. The deflexion of needle for one volt 

 was 4800 scale-divisions. The leak per second was about 

 130 scale-divisions. The area of the electrode upon which 

 the current was received was 324 cm. 2 The current per cm. 2 

 per second received on the plate was therefore equal to 



—^^1^-— E.S. Us., that is (r5xlO- 5 E.S.Us. The 

 4800x300x324 J 



number of ions received per cm. 2 is therefore 2 X 10° approxi- 



•5 



mately. The longest life of an ion was about ^ — r~R °f a 



J & ox l*o 



second, if the velocity of an ion under the action of one volt 



is taken to be 1'5 cm. per second. Let us assume that the 



air between the plates was uniformly ionized, and let n 



denote the number of ions per c.c. at any instant. Then 



n x 94 



— ~ = 2 x 10 5 , which gives n = l-7 x 10 4 . 



The number of ions lost by general recombination is 

 10~ 6 



therefore (1-7 x 10 4 ) 5 



, that is 1-4 x 10 2 . The ratio of 



the number of ions lost by recombination to the total number 

 received is therefore x4o~o- Thus only a small fraction of 

 the ions made are lost by recombination. 



Since the ionization is not uniform between the plates, let 

 us assume that it is equivalent to all the ionization taking 



