420 Prof. E. M. Wellisch : Experiments on 



We deduce 



n _ 9 



b 2 -a< 



and 



4D 'loo; b — log a 



p _ q a 2 log b — b 2 log a 

 2 ~W' logb-loga 



The concentration at any place r is then given by 



*-__£> + 1_ V-a* Wr , 9 g 8 loga-6 8 loga 

 4D + 4=D'log&-loga 10 ° r+ 4D' log 6 -log a 



riff. i. 



Inasmuch as the concentration is zero at r = a and r=b, it 

 is obvious that there must be a position r x where the concen- 

 tration is a maximum. 



By differentiating (3) with respect to r we find 



r{ 



21og- 



In the steady state the deposit particles may be regarded 

 as streaming towards the central rod or the case according as 

 they are situated within or without the cylinder r = r x (fig. 1). 



The relative distribution on central rod and case will then 

 be proportional to the volumes cut off by the cylinder r = rij 



activity on central rod tt^ 2 — - a 2 ) 

 total activity 



tt(6 2 - 



1 



2 log 



a 2 ) 



h b 2 -a 2 



(4> 



