594 



Dr. G. Hevesy on the Diffusion and 





The number of charges on the radio-ions, 

 calculated from their diffusion constants. 



Diffusion constant 

 in sq. cm. per day. 



Uranium X ++++ 



0-4 



0-33 



0-67 



0-76 



0-65 



0-45 



Ionium ++++ 



Radiuin + + 



Radium F ++ (radium A ++ ) 



Eadium D ++ (radium B ++ ) 



Eadiuin E+++ (radium C/++) 





Thorium ++++ 



0-33 

 0-66 

 0-46 

 0-33 

 0-66 

 0-76 

 0-67 

 0-5 



Thorium X + + (mesothorium I ++ ) 



Actinium +++ (mesothorium 11+ + + ) 



Radiothorium ++ + + 



Thorium X 



Radium F ++ (thorium A ++ ) 



Thorium B++ 



Thorium C +++ 





Actinium + + + 



0-46 

 0-33 

 0-66 



Radiothorium ++ + + (radioactimum ++++ ). . 

 Actinium X ++ 







The Diffusion of Colloidal Radio-elements. 

 (In collaboration with F. Paneth, Ph.D.) 

 Eecently the question of: diffusion has been approached 

 from a different standpoint, namely, that under certain con- 

 ditions the radio - elements are present in solution in a 

 colloidal state. Paneth * sought to separate radium D, E, 

 and F from lead by means of dialysis, and found that 

 radium D, just like lead, can pass through a membrane, 

 but that in the cases of radium E and especially radium E 

 only the smallest quantities could pass through. Paneth's t 

 experiment points to the fact that radium E and F are 

 present in a lead nitrate solution in a colloidal form. 



* F. Paneth, Wiener Ber. cxxi. p. 2193 (1912). 

 t F. Paneth, Kolloid. Zeit. xii. p. 1 (1913). 



