Prof. Owens on Ihorium Radiation. 



381 



Table VIII e. 



Thorium Oxide. Thick layer. 



Conduction-current with Pressure. 



Plates 20 mm. apart. Lower plate 95 volts 4- , 



Pressure. 



Time of 100 div. in sec. 



Current. 



15 



27-6 



1000 



20 



28-6 



960 



25 



316 



87-0 



35 



37-4 



74 



45 



44-8 



62-0 



55 



552 



50-0 



Fig. 10. — Conduction-current with Pressure. 

 Thorium Oxide. Thick layer. I. Plates 2 - 5 mm. apart. 

 II. Plates 5-0 mm. apart. III. Plates 20 - mm. apart. 



30 35 40 45 50 



Pressure in lbs. per sq. inch. 



In Tables X a, X b, and X c, and fig. 12, the relations for 

 uranium oxide between current and pressure for different 

 distances between plates, with pressures above an atmosphere, 

 are given. Again we see, that as the plates are brought 

 closer together, the pressure must be increased to make the 

 curve slope to the #-axis. 



