740 



Prof. E. Rutherford on the 



In column Y. is given the value of qt, the amount of radium 

 present in the solution at the time of testing. 



Growth of Radium in Actinium I. 



I. 



II. 



III. 



IV. 



V. 



Time in 

 days. 



Time of collection 

 in days. 



Observed movement 

 of electroscope. 



2- 



qt. 



4 



4 



2-13 



•56 



•32 



11 



7 



3-33 



•58 



•91 



18 



7 



3-74 



•58 



1-49 



25 



7 



4-12 



•56 



2-00 



32 



7 



4-53 



•56 



2-56 



38 



6 



465 



•60 



3-26 



53 



15 



7-25 



•55 



416 



82 



29 



104 



•56 



6-56 



121 



7 



9-36 

 Mean value 



•54 



9-33 



-566 



The amount of radium initially present corresponded to 

 3' 95 divisions per minute. 



Fig. I- 

 /o 



20 



40 6o SO 



T/M€ IN DfiYS 



too 



120 



The results are shown graphically in fig. 1 in the curve 

 marked actinium I. The ordinates represent the amount of 



