﻿Methods for Separating Uranium X from Uranium. 395 



carbonate the ol rays constituted about one-third o£ the total 

 activity at the start. It apparently has been assumed that 

 this small amount of a. activity belongs to traces of uranium, 

 for Ur X is generally accredited with giving only (3 rays. 

 We found that in the Ur X separated by the above methods, 

 not only did the ft radiation decay according to an exponential 

 law, falling to half value in about 22 days, but the a radiation 

 also decayed and at the same rate. With acetone the pro- 

 portion of a activity was usually about 50 per cent, of the 

 total activity, although the amount depended to a certain 

 extent upon the sample of nitrate used, and the manner in 

 which the residue to be tested was spread upon the plate. 

 With the other solvents the ratio varied with the solvent and 

 a jso with the sample of nitrate used. 



Fie. 1. 



90 



































\ 

















70 





N^ 







































*\c 













ec 





























50 



\ 















\ X 



















V^A 







"^>^ 



30 













^^\^ 













^^^ 









B^-- 



"~"**-—^ 

 ^-^*l^-^ 



^^^^ 



20 









^^*^^ 



*~~~"~-~"-~--4- ^^-» 









i ^~ 



*^ — — ~— 



10 











^^"^■^-J ^ ' 













" " " 











T/ME ! /A/ DflrS 







6 12 18 24 30 36 42 48 54 



A = Decay curve of a radiation. 



B = n n & » 



C = „ „ total activity. 



The best curves showing the relation between the rates of 

 decay of the a and (3 radiations were obtained by first 

 filtering off from the insoluble residue and then stirring in 

 a little ferric hydroxide. By washing with the solvent the 

 hydroxide could be practically freed from uranium, the pre- 

 sence of which would affect the decay rate of the a radiation. 

 Fig. 1 represents the curves of decay obtained in this manner 



