182      Prof.  McCoy  on  the  Relation  between  Radioactivity 
The  results  are  given  in  Tables  II.  to  VI.  Column  two 
gives  the  weight,  w,  of  the  film  ;  column  three  gives  the 
ratio,  a,  of  the  activity  of  the  film  of  the  mineral  to  that  of 
the  standard  film  of  pure  U3Q8  of  equal  area.     The  fourth 
w 
column  contains  the  values  of  —      The  accompanying  curve 
represents  Table  II.  and  illustrates  the  method  of  determining 
g)o  graphically. 
W 
a 
15 
^ 
•1? 
jf 
il 
jy 
08 
■07 
^ 
06 
J* 
jst 
•05 
^r~- 
•03 
•0° 
•01 
o-i 
0-3 
Table  II.— Pitchblende,  No.  1. 
w. 
a. 
w 
a 
1 
2 
•3922 
•3443 
•2458 
•1640 
•1135 
•0943 
•0741 
•0523 
•0466 
2-827 
2-813 
2-504 
2-140 
1-730 
1533 
1-276 
•976 
•860 
•1387 
•1224 
•0982 
•0766 
•0656 
•0615 
•0581 
3  
4  
5  
6  
8  
9  
•0536 
•0542 
