712 Mr. J. A. Cranston on the Growth of 



of thorium, will be adsorbed * in the barium sulphate, whilst 

 the uranium Y will be left in solution. If it exists it ought 

 to be obtained in a pure condition on reprecipitating the iron 

 as carbonate. When this was done, only a small residual 

 activity due to uranium X was obtained, and no trace 

 whatever was found of any substance producing either soft 

 ft or a. rays whose period was 1*5 days. 



These experiments were repeated many times under 

 varying conditions, but never was anything observed which 

 would lead to the conclusion that a short period body existed 

 whose parent was either uranium 1 or 2. 



Conclusion. 



All attempts to confirm the existence of the substance 

 called uranium Y were unsuccessful. 



I wish to take this opportunity of thanking Mr. F. Soddy, 

 F.R.S., for his interest and advice throughout the course of 

 the work. 



Physical Chemistry Department, 



Glasgow University. 



March, 1913. 



LXXIY. The Growth of Radiothorium from Mesothorium 2. 

 By John A. Cranston, B.Sc, Robert Donaldson Scholar f. 



THE object of this research was to establish whether or 

 not there exists an intermediate body between meso- 

 thorium 2 and radiothorium {. Additional interest is lent 

 by the fact that radiothorium corresponds with ionium, the 

 parent of which is experimentally unknown. The growth of 

 u activity from a quantity of pure mesothorium 2 was 

 observed. 



A theoretical curve for this was calculated, making the 

 following assumptions : — 



(1) That mesothorium 2 gives no a rays. 



(2) That mesothorium 2 disintegrates directly into radio- 



thorium. 



(3) That during the course of the experiment (1 month) 



the amount of radiothorium present does not de- 

 crease appreciably by its own disintegration. 



(4) That thorium X, thorium emanation, and thorium A 



disintegrate together. 



(5) That thorium B and thorium C disintegrate together. 



ft * Fleck, Journ. Chem. Soc. 103. p. 381 (1913). 

 t Communicated by F. Soddy, M.A., F.R.S. 

 | Hahn, Phys. Zeit. ix. p. 246 (1908). 



~v 



