Disintegration Products of Uranium. 



421 



total activity, and the second the activity due to the hard 

 rays. 



UrX separated from uranium by the barium method gives 

 for both types of rays exponential decay curves with practi- 

 cally identical periods. Also the absorption curves of such 

 preparations taken at different intervals after separation are 

 always of the same shape, indicating that the UrX contains 

 no other active product. 



When UrX is separated by the ferric method, a rapid 

 initial drop in the decay curve is always observed, if the 

 preparation is uncovered. The activity of the UrX thus 

 prepared, when measured through O'Ol cm. or more of 

 aluminium, decays exponentially with the same period as the 

 preparations obtained by the barium method. The absorp- 

 tion curves of the ferric preparations show the presence of a 

 much larger quantity of soft ft rays than is found in the 

 barium preparations. 



Fiar. 1. 













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i i 













1 

























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Time in days. 



The experimental results for the barium preparations are 

 given in fig. 1, and plotted as curves L and 2. Curve 1 

 gives the activities of an uncovered preparation, and curve 2 

 those through O'Ol cm. of aluminium. 



Phil. Mag. S. 6. Vol. 22. No. 129, Sept 1911. 2 F 



