Gaseous Mixtures by Rontc/en and Corjmscular Radiations. 855 



given evidence in this paper which strongly supports as- 

 sumptions (1) and (2) in the particular case tested. There 

 seems no reason to doubt the validity of the assumption (2). 

 Again, we see no reason to suspect an inaccuracy of the 

 necessary order in the determination of the relative ionizations 

 produced in C 2 H 5 Br and in air by the complete absorption 

 of a corpuscular radiation. (Many experiments were per- 

 formed showing that the value 1*5 given in Table II. for 

 2 H 5 Br is correct within two or three per cent.) Nor, as 

 we have seen, is there reason to doubt the applicability of 

 the ratio to the somewhat slower corpuscles excited by 

 Cu X-radiation (series K). We must therefore leave this 

 result for further investigation. 



These experiments, however, show that the deviation of 

 the ionization in a mixture of gases from the sum of the 

 ionizations in the separate constituents is of the kind and of 

 the order of magnitude that would be expected if most of the 

 X-ray ionization were due to the secondary corpuscular 

 radiation. For some reason which we have not isolated, our 

 experiments have not, on the assumptions made 5 indicated 

 the entire absence of direct X-ray ionization. 



Summary. 



The relative ionizations produced in various gases and 

 vapours by the complete absorption of corpuscular radia- 

 tions set free by homogeneous X-radiations have been 

 determined. 



No change of relative ionization with velocity of the 

 ionizing corpuscles has been observed. 



The relative ionizations due to complete absorption of 

 corpuscular radiation have been found to agree closely with 

 the relative ionizations due to complete absorption of a 

 Rontgen radiation and all its secondary radiations. The 

 results indicate that the complete absorption of a given 

 X-radiation by different gases results in the emission of the 

 same number of corpuscles. [The case in which there is 

 a large transformation of energy of primary X-radiation into 

 fluorescent X-radiation has not yet been fully investigated.] 



The ionization coefficients for homogeneous X-radiations 

 in a number of gases and vapours have been determined, 

 and the generality of the laws given by one of us further 

 verified. 



The ionizations in gaseous mixtures due to the complete 

 absorption of corpuscular radiation have been determined. 

 On the most obvious and most probable interpretation of the 



3 M2 



