532 Dr. F. A. Liiidemami and Dr. F. W. Aston on the 

 designed contrifuge, so that ~- might be made as great as 



-O^CMi-Ma) 



or even .-own,-*^ 



I£ Mi — M 2 is taken as 2 a single operation would therefore 

 give fractions with a change of K of 065. Thus again, if 

 neon is supposed to consist of 90 per cent, of gas of atomic 

 weight 20 and 10 per cent, of a gas of atomic weight 22, the 

 concentration of the heavier component at the edge would be 

 2*36 times that at the centre. The apparent atomic weight 

 of the gas from the edge, however, w r ould only be about 

 1*0065 greater than that of gas from the centre after one 

 operation. By centrifuging several times, however, or by 

 lowering the temperature the enrichment might be increased 

 exponentially. 



Centrifuging a liquid, e. g. liquid lead, would not appear to 

 be so favourable, though it is difficult to form an accurate 

 idea of the quantities without a knowledge of the equation of 

 state. If compression is neglected and the one lead treated 

 as a solution in the other, a similar formula to that given 

 above holds. Provided the atoms occupy equal spaces, as 

 they appear to do in the solid, the centrifugal force on the 



v 2 

 heavier component is (M^ — M 2 W, and, as above, its concen- 

 tration should increase from the centre to the edge in the 

 ratio 



Again, putting Mi — M 2 = 2 (e. g. thorium lead and 

 uranium lead), u=10 5 and T = 600, one finds that the con- 

 centration of the thorium lead would be nearly 50 per cent, 

 greater at the edge than at the centre, after one operation. 

 Separation by this method therefore seems possible though 

 difficult and costly. 



Positive Rays, 



This method consists in allowing the parabolas corre- 

 sponding to the isotopes generated by the use of electric 

 and magnetic fields in the usual way, to fall through two 

 parabolic slits into separate vessels containing e. g. charcoal 

 cooled in liquid hydrogen. In this manner theoretically 



