﻿Growth of Radium C from Radium B. 



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0*09 mm. thick. The experimental curve is given in figure 2 

 (J, and the curves A and B are the same theoretical curves 



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as those plotted in figure 1. It will be seen that the 

 activity immediately after the recoil is more than 90 percent, 

 of the maximum activity. This is due to the existence of soft 

 ft rays emitted by RaB. If, however, corrections are applied 

 to the experimental carve in a manner similar to that ex- 

 plained for the experiment on the hard radiation, a curve is 

 obtained which again agrees very closely with curve A. It 

 therefore appears that not only the hard radiation but also 

 the soft radiation from RaC 2 contributes too small an amount 

 to the ionization produced by RaC to be detected in these 

 experiments. Now since the ionizing powers of successive 

 products emitting ft rays are of the same order of magni- 

 tude *, and since it has been shown by Fajans that RaC 2 

 emits ft rays f, it follows from the above results, that the 

 ratio of the number of atoms of RaC 2 to the number of 

 atoms of RaC x in equilibrium is so small as to be incapable 

 of detection in these experiments. This result is in good 

 agreement with the conclusions arrived at by Fajans, that 

 Ra0 2 forms a side branch in the radium series and is not 

 intermediate between RaCi and RaD, and that RaD is 

 formed from RaC^ in much greater quantity than RaC 2 . 



* Geio-er and Kovaiik, Phil. Mag. Oct. 1911. 

 t Fajans, he. cit. 



