194 Transactions of the Canadian Institute. [vol. ix 



III. Since it has been shewn that gases occluded in such substances as 

 carbon contribute to the secondary radiation excited at the surface of 

 these substances by a rays, it follows that the procedure adopted in 

 this investigation constitutes a new method of studying the phenomena 

 of occlusion. 



IV. The results of the experiments described in this paper also go to 

 shew that with a metal like brass the amount of a gas retained in its 

 surface when it is placed in a vacuum is less at the temperature of liquid 

 air than at ordinary room temperature. 



In conclusion, I desire to thank Professor McLennan for the kindly 

 interest he has shewn throughout the course of this research. 



