92 Proceedings of the Royal Irish Academy. 



Summary. 



1. The composite character of ionization in air is shown by a third 

 method. 



2. An examination of the ionization in hydrogen not specially dried or 

 purified gives results closely related to those already found for air, and in 

 many respects identical with the results obtained by Haines for very pure 

 and freshly prepared hydrogen, j 



3. Ionization in moist hydrogen is examined. 



4. Criticisms of Blackwood in connexion with results obtained by the 

 author's air-stream method are considered. 



