﻿444 



Ranges of a. Particles from Uranium. 



a curve was obtained which agreed completely with the 

 experimental curve for uranium. 



Uranium consists, therefore, of two a-ray products whose 

 ranges are 2'9 and 2\5 cm. in air at atmospheric pressure 

 and at a temperature of 15° C. The value of the range of 

 the a particles from uranium obtained by other observers and 

 also previously by us (2*72 cm.), was obviously an average 

 value of the two figures given above. No evidence has been 

 obtained in these experiments of a particles of range 1*6 cm. 

 as suggested recently by Friedmann *. 



The above figure for the range of uranium, viz. 2*5 cm., 

 is in much better agreement with the straight-line relation 

 mentioned above between transformation constant and range, 

 and fixes the straight line with a much higher degree of 

 accuracy (see fig. 3). This is of special interest, since it 



Fig. 3. 



1 



U 



I 



10 







RaEm 4 



RaA^ 







My 







Roy 



UrlL/ 







Url/ 











•3 -4 -5 <6 



Logarithms of Rances (0°C) 



enables us to calculate the period of ionium and of the second 

 product in uranium (uranium II.) with greater certainty than 

 has hitherto b.een possible. 



* F. Friedmann, Wien. Ber. cxx. p. 1361 (1911). 



