Recombination of Ions produced by Rontgen Rays. 

 Internal Pressure o£ Liquids at 0° C. 



65 



Substance. 



K in atmos. 



Ether 



1932 



2780 

 2518 

 2917 

 3188 



Chloroform 



Carbon tetrachloride 



Carbon disulphide 



Acetone 



Mercury 



12645 





2718 

 2815 

 2847 

 2639 

 2466 



Xylene 



Toluene 



Benzene 



Ethyl acetate 





It will be seen that the values of K obtained by this method 

 are approximately double of those previously given. This 

 in itself is not sufficient to discriminate between the two 

 possible meanings to be attached to /. In an associated liquid 

 I — in either of its significations — may be no measure of K 

 at all. 



It is still an open question, therefore, whether in calcu- 

 lating internal pressures from latent heats, one should employ 

 the latent heat of vaporization of 1 c.c. of the liquid or the 

 latent heat of expansion of the liquid itself. 



VII. The Recombination of Ions produced by Rontgen Rays. 

 By S. J. Plimpton, Ph.D., Yale University *. 



WHEN a gas is exposed to the continued action of 

 Rontgen rays the number of ions contained in a 

 unit volume of the gas does not go on increasing indefinitely 

 because of the electrostatic field associated with the ions. A 

 continuous diffusion takes place from the region of maximum 

 ionization, and in addition oppositely charged ions recombine 

 under their attractive forces. The process of diffusion is a 

 relatively slow one, and with properly designed apparatus 

 may be disregarded in measuring the changes in ionization 

 due to recombination. 



According to the accepted theory of ionization in gases, 

 the rate of change of the number of ions of either sign per 

 unit volume is proportional to the square of this number ; 

 that is, 



', (1) 



dt=-« 



where a is a constant known as the coefficient of recom- 

 bination and is independent of n. 



* Communicated by the Author. 

 Phil Mag. S. 6. Vol. 25. No 145. Jan. 1913. F 



