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ROYAL SOCIETY OF CANADA 



In carrying out the experiment it was found that when the earth connec- 

 tion to the free quadrants was broken, the needle moved out in the posi- 

 tive direction on the scale for a distance which represented approximately 

 1/40 of a volt, and came to rest in this position. This deflection was 

 taken to represent the deviation arising from the volta effect. The cham- 

 ber was then slowly evacuated, but as the exhaustion proceeded no addi- 

 tional deflection of the needle was observed. An attempt was then made 

 );o reduce the pressure as low as possible, but although a pressure of .3 

 mm. was reached no indication was obtained of any additional charge 

 being acquired by the insulated tray which carried the uranium nitrate. 

 As it is known that both alpha and beta rays are emitted by the 

 salts, this result pointed to the conclusion that these rays carried away 

 from the salt equal amounts of positive and negative electrical charges. 

 In order to test this matter still further a second form of exposing 

 chamber was constructed. 



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Its design is shown in Fig. IV. The salt was spread out in thlin. 

 layers some 3 or 4 mm. thick on a set of 13 brass trays A A whose dia- 

 meters were about 9 cms. These were all fastened to a central brass rod 

 C which was suspended in the outer brass cylinder by an insulating 

 support of ebonite. This vessel carried a small tray of P^Og in the 

 bottom and it was also provided with a set of plates, DD, so arranged 

 between the trays as to intercept the rays issuing from the salt. The 

 apparatus was provided with a cover as shown in the figure, and all the 

 joints were again made air-tight with solder and sealing wax. 



With this form of apparatus the volta effect was again in the posi- 

 tive direction, but the corresponding displacement was greater in this 

 case, and represented approximately one quarter of a volt. After the 

 deflection resulting from the volta effect had become steady, the air was 

 rapidly exhausted from the receiver, and although the pressure was re- 

 duced to .02 mm., no indication of any charging action was obtained. 



