RADIO-ACTIVITY 



189 



junction of several constituent curves, of the usual 

 typical form shown by uranium-X. At least three 

 successive changes in the radio-active matter 

 are indicated : the actual curve is the resultant 

 of these three processes, which are going on 



'^O 60 80 100 



Time in MunjjZes 



Fig. 34. 



simultaneously. If the measurements be confined 

 to the /5 and 7 rays, it is found that the activity 

 rises from zero to a maximum before it begins 

 to decay. Radium, radium emanation and its 

 first product emit a rays only, the second product 

 gives P and 7 rays, and the third product all three 

 types of radiation. 



