132 ROYAL SOCIETY OF CANADA 



will be determined, therefore, partly by the ratio of the mimber of 

 particles leaving it to the number comiflg to it. An alteration in this 

 ratio would take place when both the thickness and the material of 

 the plates were varied, when the distance between the plates was altered, 

 and when thei distance of the radium was increased, and it was quite 

 conceivable, therefore, that this ratio could vary in such a manner as to 

 ffive rise to the results obtained. 



From the experiments which have been cited in this paper, it is 

 evident that the manner in which insulated metallic cylinders surrounded 

 by others joined to earth, or insulated plates of metal placed close to 

 others of the same or of different metals become electrically charged is 

 both complex and obscure. It is clear, too, that both the Volta effect 

 and secondary radiation are influences affecting the process of charging, 

 and, although the experiments of the present investigation throw con- 

 siderable light on the relative influence of these two factors, it will 

 bf necessary to take more extensive observations before a complete 

 explanation can be offered. 



In conclusion, the writer wishes to express his sincere thanks to 

 Prof. McLennan for his kindly interest and helpful suggestions during 

 the progress of the investigation. 



