﻿Intelligence and Miscellaneous Articles. 333 



Summary. 



Experiments on tlie ionization of gaseous mixtures by 

 homogeneous beams of X-rays have led to the following 

 conclusions : — 



Ionization by X-rays is not purely atomic. It depends to 

 a certain extent on the chemical combination of the elements. 



Equal absorptions of X-rays and of their secondary rays by 

 different gases are not always accompanied by equal ioniza- 

 tions, though as a rule the deviation from proportionality 

 is not great. 



Equal absorptions of corpuscular (electronic) radiation by 

 different gases are notalways accompanied by equal ionizations. 



The relative ionizations produced by equal absorptions of 

 X-rays in the gases experimented upon are, within small 

 errors of experiment, the same as those produced by the 

 corpuscular radiation excited by the X-rays. The results 

 thus point to the possibility of the relative ionizations in 

 different gases due to the total absorption of X-radiation 

 being identical with those due to corpuscular (electronic) 

 radiation and a radiation. 



Preliminary experiments appear to indicate — though we do 

 not accept the results as conclusive — that much of the 

 ionization by X-rays is not due to the secondary corpuscular 

 radiation. Further experiments on these lines will probably 

 give the most direct answer to the question as to the part 

 played by secondary rays in the process of ionization. 



XXIX. Intelligence and Miscellaneous Articles. 

 To the Editors of the Philosophical Magazine. 



Gentlemen, — 

 TN my paper in the December number of the Phil. Mag., there 

 was a footnote on page 875 referring to the work of Eutherford 

 and others which was done more recently than that utilized 

 in the paper. I feel that this footnote, which was hurriedly 

 attached while the paper was in proof, is very inadequate, and 

 wish to express my opinion that pages 875 and 876 of the paper 

 need considerable modification in view of more "recent work. 

 This applies, of course, only to the statements concerning the 

 possible varieties of a particle, which were developed only as 

 illustrations of the theory, so that their complete removal would 

 not alter the scope of the theory. 



Prof. Rutherford and Ins collaborators have shown, in so many 

 cases, that the a particle, at any rate soon after birth, is a Helium 

 atom, that these two pages should be read with caution. 



I shall be very glad if you can publish this letter, pending 

 a more detailed treatment on which 1 am at present engaged. 



Yours very truly, 



Trinity College, Cambridge. ,1. \\\ Nh'HOLSOX. 



