THORIUM IN AN ELECTRIC FIELD. — HENDERSON. 



.ti o 



S o 



r 



r 



""a " 





[ 







— — • 1 





{/ 



^ 















\ 

















f 





A = 

 - B = 



DRV A 

 MOIST 



IR 









' 

















40 



80 



120 



160 

 Volts. 

 Fig. 4. 



Table 1. 



200 



240 



280 



320 



Volts. 



Percentage cathode 

 activity. 



6.4 



82.9 



14.1 



91.4 



14.0 



92.0 



14.1 



91.0 



20.4 



94.7 



32.0 



95.9 



40.4 



96.5 



120.0 



98.6 



12,000.0 



99.8 



It will be seen that this curve has the general shape of the 

 ionization saturation curve. The percentage cathode act- 

 ivity at 12,000 volts is the mean of three observations, in one 

 of which the activity of the anode measured less than the nat- 

 ural leak. As this value differs from 100 by less than the 

 observational error, there is no evidence to show that initial- 

 ly any fraction of the rest atoms is neutral. It must be under- 

 stood that the use of the word initially, as in this instance, 



