x] RADIO-ACTIVE PROCESSES 301 
reduced to 25 per cent., and further aspiration for three weeks 
did not produce any further diminution. The radium was then 
evaporated to dryness, and the rise of its activity with time 
determined. The results are shown in the following table. The 
final activity in the second column is taken as one hundred. In 
column 3 is given the percentage proportion of the activity re- 
covered. 



| Time in days | Activity | y pean vod 
0 25:0 0 
0:70 33°7 11:7 
1:77 42:7 237 
4°75 68°5 58:0 
7:83 83°5 78:0 
16-0 96:0 95-0 
21:0 100-0 100-0 | 


















°/, of Normal Activity 

















Days. 
Fig. 58. 
The decay curve of the radium emanation is shown in the 
same figure. The curve of recovery of the lost activity of radium 
