192 



Transactions of the Canadian Institute. [vol. ix 



to exhaust the air from the apparatus for three hours continuously before 

 a reading was taken of the rate of charging of the polonium. 



Table XIV. — Am in Apparatus. 

 Brass electrode at Temp. 20° C. Charge on brass = -8i volts. 



It will be seen from the above table that at the end of three hours 

 constant pumping by the Gaede pump the pressure of the air in the ap- 

 paratus had fallen very low and that the rate of charging of the polonium 

 had become constant before the magnetic field was applied. 



Immediately after the readings on the rate of charging of the pol- 

 onium with increasing magnetic fields were taken, another reading was 

 taken of the rate of charging of the polonium without the magnetic field. 

 After this the brass plate was cooled by pouring liquid air in the tube E, 

 and the readings on the rate of charging of the polonium were continued 

 once more. 



Table XV. — Air in Apparatus. 

 Brass Electrode. Charge on Brass = -81 v olts. 

 Pressure of air Time from initial Current through Current to 

 in apparatus reading of Table XIV magnet polonium 



Less than .001 mm. 



28 min. 



o amp. 



-238.5 



Cooled Brass With Liquid Air. 



