Prof. Owens ori Thorium Radiatfdn. 



363 



maximum value. If some time was allowed to elapse between 

 placing the oxide in position and taking the observations the 

 conduction current showed no increase with time. A sample 



Fig-. 1. 



J 



Z 



Earth 



Earth 



set of observations for thorium oxide under the first conditions 

 is as follows : — 



Plates 5 cm. apart. Lower plate 95 volts + . 



Time of 800 div. in sec. 

 17*4 1st observation . 

 15*6 2nd ,, 

 12-6 3rd „ 



12*6 4th „ constant. 



