702 Transformations in the Active Deposit of Actinium. 



Table I. 



Product : - 



Emanation. 



A. 



I 





1 Radium 



A (sec. -1 ). Range a 



i 



X. 



Range a . 



X. 



PjS. 



Uy. 



2-085 xlO- 6 4-16 



;3-85 X10~ S 



4-75 



13 ! 230 



4-33X10" 4 91 40 



i Ool 



Thorium 



1-28 XlO- 2 ! 5-0 



4-95 



5*7 



1 i 160 



1-82x10-° 110 32 



j 0-36 



Actinium ... 



1-8 XlO" 1 



5-7 



350 



6-5 



3-18x10" 



, 120 

 4 very soft, qq 



' 0-45 



! 



Product : — 



C«. 



Op. 



2 (RaC). 



D (RaC 2 ). 



Radium 





Range a . 



v 



P*. 



*,- 



Range a . 



X. 



Pf*- 



*v 



l-8xl0~ 7 



? 



5-93 XlO" 4 



13 



53 



0115 



694 



8-25X10- 3 



u 



9 

 0-096 



, Thorium ... 



6-7X10" 5 



4-8 



1-23 XlO" 4 



13-5 



None 



8-60 



3-73X10- 3 



21-5 



Actinium ... 



5-4X10" 3 



5-40 



8 xlO" 6 



? 



None 



6-4 



2-45x10-3 



28-5 



0-198 



empirical relations, predicted that, if actinium C 2 exists, it 

 ought to have a range of 9*3 cm. and not 6*4 cm. as found 

 in these experiments. 



With regard to the supposed a radiation of radium C a ; 

 these « particles have not yet been observed owing to the 

 very small number to be expected. In some experiments en 

 the magnetic deflexion of a particles by one of us, a search 

 was made by assuming them to possess the velocity predicted 

 by Geiger's formula for a period of 19*5 mins. The results 

 were negative; but a fraction of less than about O005 of the 

 main beam of a. particles would have escaped detection. 



