380 



Prof. Owens on Thorium Radiation. 



decrease as the pressure increases, and this also was to be 

 anticipated from what has been said. Using a thick layer of 

 uranium oxide covered with one layer of aluminium foil, and 

 varying the pressure from 50 mm. to 2780 mm. of mercury, 

 the results as given in Table IX. and on fig. 11 were obtained. 

 The plates were 4 cm. apart, and the lower plate charged to 

 95 volts. 

 The curve is similar to the corresponding one for thorium. 



Table VIII a. 



Thorium Oxide. Thick layer. 



Conduction-current with Pressure. 



Plates 2*5 mm. apart. Lower plate 95 volts + 



Pressure. 



Time of 100 cliv. in sec. 



Current. 



15 



88-0 



1000 



20 



810 



105-0 



25 



80-4 



109-0 



30 



80-8 



1090 



45 



78-6 



1120 



55 



810 



109 



Table VIII b. 



Thorium Oxide. Thick layer. 



Conduction-current with Pressure. 



Plates 5 mm. apart. Lower plate 95 volts + 



Pressure. 



Time of 100 div. in sec. Current. 



15 

 45 



64-5 100-0 

 1510 105-0 

 700 92-0 



