﻿394 Profs. Moore and Schlundt on some New 



a small amount of basic nitrate. This residue was filtered oft', 

 washed three times with acetone, and tested by the photo- 

 graphic method. It was found to be exceedingly active, an 

 excellent radiograph being obtained in sixty hours. On 

 testing the uranium nitrate in the filtrate it proved to be 

 only slightly active to a photographic plate. Several samples 

 of uranium nitrate of different degrees of purity were tested 

 in the same way. Generally speaking, the larger the amount 

 of insoluble residue the better the separation. If, after the 

 insoluble residue is filtered off, a small amount of moist 

 freshly precipitated ferric hydroxide be stirred into the clear 

 filtrate, the uranium nitrate is practically freed from UrX. 

 The ratio of the amounts of UrX contained in the insoluble 

 residue and in the ferric hydroxide varies to a certain extent 

 with the sample of uranium nitrate used. In one experiment 

 the ratio between the activities, as measured by a Dolezalek 

 quadrant-electrometer and the usual testing vessel, in the 

 insoluble residue and in the ferric hydroxide, was as 9 to 11. 

 In a similar experiment the insoluble residue was more active, 

 the ratio being almost 2 to 1. 



Another 5 gram sample of the nitrate was dissolved in 

 acetone, and, without filtering, moist ferric hydroxide was 

 stirred into the liquid. On filtering the solution and washing 

 the residue with acetone, the latter was found to contain all 

 of the ft activity of the original sample, the uranium obtained 

 from the filtrate giving no effect on a photographic plate after 

 an exposure of five days. 



Ur X can be separated from uranium in the same manner 

 by using the following solvents instead of acetone : — Methyl 

 acetate, ethyl acetate, methyl, ethyl, and amyl alcohols, and 

 aceto-acetic-ether. In all cases the separated UrX was not 

 only recognized by the photographic method, but the curves 

 of decay were also taken by the electrical method, the ft 

 activity decaying to half value in about 22 days. The same 

 variation in the amount of activity removed, with the sample 

 of nitrate used, noticed in the case of acetone, was also found 

 to hold good with these solvents. In no case was all of the 

 UrX removed by filtering off the small residue which re- 

 mained insoluble in each liquid. The addition of moist ferric 

 hydroxide, or in the case of a liquid immiscible with water, 

 dry barium sulphate, completes the separation. The barium 

 sulphate, however, does not answer as well as the ferric 

 hydroxide. 



The UrX, no matter which solvent was used to make the 

 . separation, always gave off a as well as ft rays. Rutherford* 

 and Grier found that in the separation by means of ammonium 

 * Phil. Mag. Sept. 1902. 



