8 RUSS, Note on Radio-active Recoil. 



The variation of this activity with time may be calcu- 

 lated from the expressions R,-\-R'. 



If Radium A and Radium B are projected up the 

 tube ill equal quantities, the deca\' curve of the active 

 matter on the disc would be that obtained by adding the 

 activities due to (i) and (2) in the ratio in which they 

 stand, namely : — 



r = I 7 "O 



where \^= 3'85 x 10"'^ and \.,- 5*93 x 10^*. 



This has been done and the results tabulated in 

 Table I. and reproduced graphically in the full line curve 

 in Fig. 2. It will be seen that the experimental points, 



/}>. 2. 



which are represented by small circles, do not lie exactly 



