370 



Prof. Owens on Thorium Radiation. 



Fig. 3. — Screening effect of thin Aluminium foil. 

 Thorium Oxide. Thick layer. 



100 . 



5 6 7 



Layers of foil. 



foil over its surface was about 25 per cent, of the current with 

 thick layer, as may be seen from the tables. 



Table III. 



Thorium Oxide. Thin layer. 



Screening effect of thin Aluminium foil. 



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



u 



Layers of foil. 



Time of 100 div. in sec. 



Current. 







45-6 



100-0 



1 



84 2 



54-0 



2 



1600 



28-5 



3 



2700 



16-9 



4 



4760 



9-5 



5 



881-0 



5-2 



6 



15950 



2-8 



8 



56400 



0-8 



