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ROYAL SOCIETY OF CANADA 



was removed, veiy considerable variations occurred in the magnitude of 

 the charge. Some readings were also taken of the potential acquired 

 by the free copper plate without the use of radium, when both zinc and 

 copper plates were placed at different distances above it. These results 

 are recorded in the first column of Table XVIIT. For the purpose 



TABLE XVL 

 Upper plate copper. Distance between plates, 2mm. 



of comparison, the final maximum values obtained in the cases illus- 

 trated by the curves 12, 13, and 14, are also recorded in the second 

 column of this table. From these results it will be seen that in every 

 case the values obtained without the radium were more positive than 

 those obtained with it. 



TABLE XVIL 

 Upper plate copper. Distance between plates, 2mm. 



