﻿332 Ionization in Gaseous Mixtures hy Rijntgen Radiation. 



The addition of ethyl bromide at fairly high pressures to 

 sulphur dioxide was not accompanied by nearly the same 

 increase of ionization as when it was added to air. It was 

 found, however, that a liquid was deposited on the sides of 

 the gas-chamber, and that the gaseous pressure decreased 

 owing to some chemical action. Small quantities of ethyl 

 bromide were subsequently used with the results given 

 below. 



[Ag X-rays] C 2 H.Br at 375 cm. pressure when with air gave additional ionization 1 



80 2 „ „ -97 



[in other experiments '96, "98] 



[Ag X-rays] C 2 H 5 Br at 16'G cm. pressure when with air gave additional ionization 1 



C0 2 „ „ -98 



SH 2 „ „ -945 



[Ag X-rays] CH 3 I at 13"3 cm. pressure when with air gave additional ionization 1 



SH 2 „ • „ -98 



It will be seen from the above results and those in Table VI. 

 column 6, that the additional ionization due to the addition 

 of ethyl bromide or methyl iodide to various gases did not 

 differ by more than 8 per cent, from that when mixed with 

 air, the extreme variation being with hydrogen. With this 

 exception the variations appear within the limits of experi- 

 mental error. When ethyl bromide was mixed with hydrogen 

 the mass of ethyl bromide was over fifty times that of 

 hydrogen, so we may conclude that practically all secondary 

 rays were absorbed in the ethyl bromide itself. When the 

 ethyl bromide was mixed with air, there w T ere approximately 

 equal masses of air and ethyl bromide to absorb the secondary 

 radiations. From our previous experiments, if all ionization 

 had been due to corpuscular radiation we should have 

 expected a difference much greater than the 8 per cent- 

 observed between the additional ionizations due to the ethyl 

 bromide. 



Again, according to the corpuscular ionization hypothesis, 

 the additional ionization due to mixing ethyl bromide with 

 sulphuretted hydrogen might have been expected to be con- 

 siderably greater than that due to mixing w 7 ith air. What 

 little difference w r as observed was in the wrong direction. 

 These experiments have not, however, been made under a 

 sufficient variety of conditions to justify definite conclusions. 

 We believe, however, that they will give a complete answer 

 to the question of primary and secondary ionization effects. 

 These, preliminary experiments already suggest much. 



