218 



LORD KELVIN, DR. M. MACLEAN, AND MR, A. GALT, ON THE 



electrified air was drawn from a point half-way down the can to the insulated 

 standard filter connected to the electrometer, and the deflection noted. The experi- 

 ment was repeated with a uranium plate suspended three-quarters of the way down 

 in the can by wires metallically connected with the can. The following results were 

 noted : 



Without uranium, 50 strokes of the pump were required before the electrometer 

 ceased to give a deflection, the total deflection being 271 divisions. 



Fig. 9- 







The uranium was now placed in position in the can, and the air was then 

 charged for one minute. It was kept in position till all the electrified air was 

 drawn off to the filter, the total deflection being 61 divisions. When the uranium 

 was inserted after the electric machine was stopped, and before the air in the can was 

 drawn to the filter, little more than 10 strokes were required before the electrometer 

 ceased to give a deflection, and the deflection was now 121 divisions. 



Using a very small lighted candle instead of the uranium plate, we found the 

 following results : 



