SO Recombination of Ions produced by Rontgen Rays. 



Absolute Values of - . 



Graa or 

 Vapour. 



Pressure. 



A-B. 



B-O. 



C-D. 



D-E. 



E-F. 



Air 



768 



411 



760 



382 



355 



100 



37 



28 



100 



28 



95 



11540 

 7150 



10000 

 7500 



12500 

 4400 

 1560 

 3440 

 4100 

 2380 

 4400 



6100 

 4580 

 7100 

 6100 

 7640 

 3560 

 1270 

 2540 

 4070 

 2200 

 4070 



4680 

 3280 

 6700 

 5610 

 5150 

 2900 

 1160 

 1210 

 2870 

 1850 

 3700 



4600 

 2820 

 6500 

 5310 

 4600 

 2830 

 1060 

 1170 

 2830 

 1440 

 3180 



3960 



4880 





oo 2 



s'6 2 





c'k s i 



C H 5 C1 ... 

 o H,Br ... 



(C 2 H 5 ) 2 0... 



Effect of a Field on the Ionization. 



In order to ascertain the effect of an impressed field upon 

 the ionization, a potential of sixteen volts was applied to the 

 gas during the flash of X-rays and removed immediately after 

 the cessation o£ the flash, the recombination then being 

 measured in the usual way. 



The result is shown in curve X o£ fig. 5 for the case of 

 air at 760 millimetres pressure. Comparing this with the 

 corresponding curve for air without the application of this 

 field during the flash, it will be seen that the final slope is not 

 changed noticeably but that the initial slope is lessened. 

 This result is in accord with the explanation of initial 

 recombination given above. The positive and negative ions 

 in the initial pairs would be separated more widely by the 

 field and the probabilities of collisions between them would 

 be reduced, giving a lower value of a. 



Conclusions. 



(1) The recombination of ions takes place approximately 

 in accordance with the law 



dn 

 dt 



provided that sufficient time has elapsed to enable an effectively 

 uniform distribution of the ions to be established in the gas. 



(2) When a is determined by considering a certain volume 

 of ionized gas as a whole without regard to the distribution 

 of the ions, a as given in the above expression is not a 

 constant but has an initial maximum value, and approaches 

 its final constant value at first rapidly and then more slowly. 



- — em 2 



