874 Heterogeneity of fi Rays from Thick Layer of Radium E. 



That the type of absorption curve obtained for homo- 

 geneous rays was not due to the arrangement of apparatus 

 was shown as follows. The radium E was placed 6 cms. 

 below the hole P and an absorption curve of the whole 

 bundle of rays taken. The result obtained is shown in 

 fig. 3 curve c. The curve is exponential, showing that the 



1-000 



-500 



Fiff. 3. 





\b ^ 









\ x 







r HICKN£SS Or /IL //V MMS. 



apparatus used has no effect on the absorption curves and 

 the absorption coefficient found 42'8 cm. -1 is in very good 

 agreement with the results obtained by other observers. 

 The initial drop is due to scattering of the rays and not to 

 the presence of any soft radiation, since the same percentage 

 drop is obtained if various thicknesses of aluminium are 

 placed directly over the radium E and the absorption curve 



again taken. 



