152 Messrs. A. S. Russell and F. Soddy on the 



a small initial thickness (0*36 cm. for zinc), but for lead the 

 curve is convex to the axis up to 0*8 cm., as in Disposition 5, 

 and then is straight. The results are tabulated below, the 

 results for lead referring to the straight part of the curve 

 beyond 0*8 cm. 



Disposition 5. 





Yalues of 



A (cm.) \ 



1 

 X ( Act.)/\ (Bad.). 



Actinium. 



Radium. 



Lead 



1-20 



0-547 



2 20 





Zinc 





0-521 



0-269 



1-94 







Zinc (hardened by 0'6 cm 



Pb).| 0-420 



0262 



1-60 



Aluminium 





0-217 



0115 



1-8'J 









Disp>osition \ 



2. 





Lead 



1-85 



0-517 



3-57 



Zinc 





0-618 



0-305 



202 







Zinc (hardened by - 6 cm 



Pb) J 0-495 



0-264 



1-87 



Aluminium 





0-234 



0-124 



190 







Copper 



0722 



0-377 



1*91 





The separate mean values of \ for different thicknesses of 

 lead are shown below. 



Disposition 5. 



Range (cm.). 



0-0-124 0-124-0-30 030-0 85 , 0-85-2-40 



X (cm.) 



3-31 



2-65 



i 



2-22 



1-20 



Disposition 2. 



Range (cm.). ... 



0-2-0-3 



0-3-0-5 



0-5-0-8 



0-8-1-7 



\ (cm.) . ... 



1 



4-24 



3-26 



2-50 



1-85 



