some other Constants of the Inactive Gases, 809 



Lord Kelvin deduced the relation * 



Ncr 2 =0-1629^ 



V 



from the two equations for the diffusivity 



1 G 



D= 



2 V3VJNV 2 ' 



and D =■ - , 

 P 



and putting /0 = 0'001781, y = 0*0002083, and G = 41400, he 

 found N<7 2 = 57700. 



If we take the simple equations 



V=^ P LG and L=y|^j, ^ 



we get N ,. = i * 5* =0-075^. 



The cause of the discrepancy is now obvious. Lord Kelvin, 



by a slip, used as the numerical factor /; im-tead of 

 ^ 2vo7r 



o 7| , which makes all the figures given by him subject to 



correction, and gives an entirely different value for N from 

 the one deduced by him: N = 10 20 . 



We will repeat his calculations, and compare them 

 side by side with those deduced from the more correct 

 equations. 



In Part I. of this paper the relation 77=: 0*30907 hilp 

 given by Meyer was used. Substituting in this 



L = —7-. , T „ and H = \ / -— (x, 



we get No- 2 = 0'0643 ?—-. 



V 



This formula we must also use in order to get the results 



* I have altered Lord Kelvin's symbols to make them agree with 

 those used in this paper. 



