484 



Prof. McLennan and Mr. Keys on the 



Wave-lengths in 



Relative Intensity. 



Angstrom Units. 



Arbitrary scale. 



X= 2124-4 



10 



2073-] 



2 



65-2 



1 



61-4 



2 



549 



2 



24-9 



1 



1990-1 



4 



86-2 



1 



21-7 



1 



09-3 



1 



01-0 



5 



1885-5 



10 



58-4 



Faint 



53-9 



1 



50-0 



Faint 



45-5 



2 



42-2 



I 



The Physical Laboratory, 





University of Toronto, 



■ 



May 1st, 1915. 





LI. On the Mobilities of Ions in Air at High Pressures. 

 By Professor J. C. McLenna^ F.E.S., and David A. 

 Keys, B.A., University of Toronto *. 



I. Introduction. 



IN a paper by the writers " On the Electrical Conductivity 

 imparted to Liquid Air by Alpha Rays," attention was 

 called to the exceedingly high insulating properties possessed 

 by liquid air. The paper also included some measurements 

 on the saturation currents in liquid air and in air at high 

 pressures when these were ionized by alpha rays. In the 

 discussion of some phenomena connected with these currents 

 attention was drawn to the necessity for making measure- 

 ments on the mobilities of ions, both in liquid air and in air 

 at very high pressures. Since the publication of that paper 

 we have on several occasions made attempts to measure the 

 mobilities of ions produced in liquid air, but up to the present 

 have not succeeded in getting any trustworthy results. 

 Convection currents due to the motion of air-bubbles formed 

 in the liquid air, and the contamination of the liquid air 



* Communicated bv the Authors. 

 Canada, May 26th, 1915. 



Read before the Royal Society of 



