374 



Prof. Owens on Thorium Radiation. 



Table V. 



Thorium Sulphate. Thick layer. 



Screening effect of thin Aluminium foil. 



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



Layers of foil. 



Time of 100 div. in sec. 



Current. 







72-6 



100-0 



1 



130-8 



55-0 



2 



220-0 



330 



3 



3430 



210 



4 



518-0 



14-4 



5 



767-0 



9-5 



6 



1000-0 



73 



8 



1420-0 



51 



12 



1850-0 



3-9 



Fig. 6. — Screening effect of thin Aluminium foil. 

 Thorium Sulphate. Thick layer. 



5 6 7 



Layers of foil. 



11 12 13 



