90 



ROYAL SOCIETY OF CANADA 



From the following calculations it will be seen how the different 

 constants of the instnunent were used in making a determination of the 

 value of " q" for the air contained in a certain lead receiver: 



From Table II, the charge annulled per volt on the compensator 

 tube = .00501. 



. ■ . total charge annulled in 489" was 



.06513 e.s. units 

 Thus .06513 = 3 .4 X lO" 10 x q x 489 x 26700 



or q = 14.67 assuming the charge on an ion to be 

 3.4x10-10 E.S.U.'s. 



As a check on the values for " q " obtained with the instrmuent 

 for the ionization in the metallic receivers, detenninations were alter- 

 nately made in the laboratory with the Wilson electroscope and with a 

 sensitive Dolazelek electrometer. The method of using the latter is 

 fihown in Fig. 3. With this arrangement it was possible by simply 

 removing the receiver, unscrewing the electrode and slipping a metal 

 cap over the earthed tube E, to allow for any charge acquired by the 

 electrodes and the free quardrants through possible defective insulation 

 of supports, or by conduction through the air in any part of the appara- 

 tus, other than through that' in the metal receiver. 



The capacity of the instrument was found by measuring in each 

 determination of the conductivity, the rate of motion of the needle, 



