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Mr. R. D. Kleeman on the Recombination 



I also tried whether there there is any abnormal initial 

 recombination effect when air is ionized by a and 7 rays at 

 the same time. 



The result is given in Table VIII. 



Table VIII. 



Air. 



Volts 

 per cm. 



Deflexion. 



Time 

 of leak. 



y leak. 



a rays. 



6 

 286 



1135 

 1478 



20 sec. 



1215-^=648 



1387- X ip =648 

 A 



a and y rays. 



6 



286 



1215 



1387 



10 sec. 



A plate covered with a thin layer of uranium oxide was 

 put into the chamber and a set of readings taken. The 

 radium bromide was then placed near the chamber, and 

 another set of readings taken, the air being now ionized by 

 a and 7 rays. 



If we take the value of an a ray leak for 10 seconds, and 

 subtract it from the a and 7 leak corresponding to the same 

 time and voltage, we ought to get the same remainder in 

 each case if the ionizing effects of a and 7 rays are simply 

 additive. 



This, as shown in the table, is the case. 



The electrons ejected from the molecules of a gas ionized 

 by /3, 7, or X rays have very likely themselves ionizing 

 power, and these electrons may cause the ejection of others 

 which also have ionizing power. But the number of electrons 

 ejected ultimately with a velocity so small that only a partial 

 separation of electron from molecule takes place, would be a 

 fraction of the whole number of ions made, and the effect of 

 initial recombination therefore small. 



Some experiments were also carried out to test whether 

 there is any connexion between the velocity of an a, particle 

 and the initial recombination of the ions made. 



The apparatus used is shown diagrammatically in fig. 4. 



A is a flat ebonite ring to which is attached a piece of wire 

 gauze a, which is connected with a battery. The ebonite 

 ring supports a metal case B, in which an electrode b is sus- 

 pended by a central rod which is connected with an electro- 

 meter but insulated from the case, the case being connected 



