Existence of Uranium Y. 711 



possible. It was not possible to repeat his experiments by 

 what he called the " ferric method/'' which consisted in 

 boiling a uranium solution which contained a small quantity 

 of an iron salt. According to Antonoff the iron should be 

 precipitated as hydroxide and should contain uranium X and 

 the new substance, uranium Y. 



If, however, uranium X was removed with iron * by 

 boiling a solution, in excess of ammonium carbonate, of 

 uranium containing iron, the product when measured in an 

 electroscope with a 0'0034 mm. thick aluminium base gave 

 an effect very similar to the one described by An ton off. 

 When measured in an electroscope with a 0"1 mm. thick 

 aluminium base, ihe activity of this product decayed normally 

 with the period of uranium X. Attempts were now directed 

 to obtaining this quickly decaying substance free from 

 uranium X, and it w r as found that by precipitating lead as 

 lead sulphide in an acid solution of the active product of the 

 ammonium carbonate treatment, the precipitate contained 

 active material which, on examination, was shown to be 

 thorium B. When the iron in the filtrate was reprecipitated 

 as carbonate, it contained uranium X which decayed 

 normally. 



Efforts were made to purify the uranium salt from thorium 

 (a) by shaking the uranium containing water of crystallization 

 with ether and separating the aqueous from the ethereal 

 layer, (6) by precipitating with dilute oxalic acid and 

 allowing to stand overnight, and (c) by precipitating with 

 ammonium sulphide and shaking the precipitate with dilute 

 hydrochloric acid. After these various methods of treatment 

 and allowing time for any quantity of thorium X which had 

 collected to decay, the presence of thorium B could still be 

 detected, although of course in much smaller amount. 



After this, uranyl nitrate which had been separated by 

 Soddy t from uranium X, and therefore from any thorium 

 initially present, and which had been through the ammonium 

 carbonate treatment many times, was used, and no rapid 

 initial decay in the uranium X preparation was observed. 



An attempt was then made to concentrate the substance 

 by an experiment which does not seem to have been made 

 by Antonoff. According to him, uranium Y is precipitated 

 in ferric carbonate but not in barium sulphate. If, then, 

 we have uranium X and Y in ferric carbonate, dissolve both 

 in dilute acid, add a trace of barium and precipitate that 

 with sulphuric acid, then, all the uranium X, in the absence 



* Crookes, Proc. Roy. Soc. Ixvi. p. 409 (1900). 

 f Soddy, Phil. Mag-.~[6] xviii. p. 858 (1909). 



3C2 



