[m'lennan] 



ON ELECTRIC CHARGES 



91 



From the fact that no charging action was obtained in either of the 

 experiments with the two forms of apparatus, it seems clear that the 

 alpha and beta rays from the nitrate of uranium carried away with them 

 from the salt equal amounts of positive and negative electricity. 



In order to test the accuracy of this conclusion an additional set of 

 experiments was made with uranium nitrate when using this second 

 form of apparatus. The salt on each tray was covered with two layers 



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To ELECTBro/^tîf. 



f\ù. IV 



of aluminium leaf, each about .007 mms. in thickness. As this thickness 

 was sufficient to cut off all the alpha rays,i but only a small proportion 

 of the beta rays, it was evident that a charging action should occur, and 

 some experiments were made to see at what pressure it could be observed. 

 As aluminium in the volta series is positive to brass, the charge ac- 

 quired in this case through the annulling of the volta effect was a nega- 

 tive one. When the pressure was reduced it was found that the electro- 



iPhys. Zelt. 8, p. 773, Oct. 24, 1907. 



