830 



Mr. G. N. Antonoff on Radium D 



Another portion of the same preparation was heated in a 

 blowpipe flame until its activity was reduced from 60 divi- 

 sions per minute to 5 divisions per minute. This was again 

 found to fall to half value in 5 days (see fig. 2, carve 4). 



Fig. 2. 

































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Tiaie in days. 



Finally, radium D was separated incompletely from another 

 preparation, and was divided into two parts. The /3-ray 

 activity of the one was measured until it had reached a final 

 constant value 6*5. Subtracting this value from the readings 

 and plotting on logarithmic paper we get a straight line 

 showing a period of 5 days. The results are given in 

 Table III. (see also fig. 2, curve 1). 



The other portion was heated on a platinum crucible lid in 

 a blowpipe flame, in order to get rid of the radium D f The 

 time period of the residue was found to be 5*l-5*2 days ; 

 the excess of *1- 2 day over previously found values being 

 probably due to a very small quantity of radium D left 

 behind after heating (see fig. 2, curve 3). Radium E 

 separated from old radium solution gave again the period of 

 5 days (see fig. 2, curve 5). The variation with time of the 

 /3-ray activity of the various preparations is thus consistent 

 with the view that only one product is present between 

 radium D and radium F. The absorption of the rays from 



