184      Prof.  McCoy  on  the  Relation  between.  Radioactivity 
Table  VI. — Carnotite,  No.  5, 
w. 
a. 
w 
a 
1 
•3704 
•2634 
•0949 
•0477 
•0423 
•0172 
1-829 
1765 
1094 
•644 
•574 
•272 
•2025 
•1493 
•0868 
0741 
•0736 
•0631 
2 
3 
4  
5  
6  ... 
In  Table  VII.,  k^  represents  the  total  activity  of  unit  mass 
of  the  mineral  as  calculated  from 
\a  fo 
The  area,  s,  was  equal  to  39*82  sq.  cm.     P  is  the  weight  of 
uranium  in  1  g.  of  ore. 
Table  VII. 
0. 
*r 
P. 
P 
1 
2  
3  '.'.'.'.'.'. 
4  
5  
•0472 
•0594 
•0400 
•0446 
•0612 
1687 
1341 
1990 
1786 
1301 
•511 
•403 
•611 
•547 
•399 
330 
332 
326 
327 
326 
Mean  328 
The  value  of   p  is  very  nearly  constant  and  is  equal  to 
3280  for  uranium  minerals.  The  corresponding  constant  for 
pure  uranium  compounds  is  791.  The  ratio  of  these  two 
quantities  is  4*15.  That  is,  for  equal  uranium  content  the 
ores  are  4' 15  times  as  active  as  the  pure  compounds. 
If  radium  and  all  of  the  other  radioactive  substances  in 
uranium  ores  are  genetically  related  to  uranium,  it  should  be 
found  that  the  amounts  of  each  such  substance  in  the  ore, 
and  therefore  also  the  total  radioactivity,  should  be  directly 
proportional  to  the  uranium  content,  provided  the  mineral  is 
sufficiently  old  to  have  reached  the  equilibrium  condition. 
The  results  just  described   seem,   therefore,  to   confirm  the 
