[m'lennan] on electric CHARGES 99 



The effect observed in all cases was small and it will be noted that it 

 required exceptional conditions to bring it into evidence. 



From the results obtained so far it has not been found possible to 

 decide whether any radiation of the alpha type is emitted by the potas- 

 sium salts or not. It is the intention of the writer, however, to examine 

 the charging effect with the potassium salts covered with thin layers of 

 aluminium. The use of such layers while preventing the emission of any 

 alpha rays which might be present would probably not diminish to any 

 great extent the intensity of the beta radiations. 



The measurements made in this investigation demanded consider- 

 able patience and care, and T am indebted to Mr. M. E. Liezert and Mr. 

 B. L, Cooke for kind assistance rendered on occasions during the pro- 

 gress of the observations. 



Physical Laboratory, Toronto, May 20, 1909. 



