some other Constants of the Inactive Gases. 



811 



Taking N=2'75 x 10 19 as in Part L, we get ^=13*8 and 

 ^ = 1*55. Obviously this value of q mast be the same as the 



ratio of a obtained from V= - No- 3 , V beino- obtained from the 



density of the liquid, to a obtained from the viscosity co- 

 efficient. These two values are (cf. Part I.) 4*43 and 2*85, 

 and their ratio is 1*56. 



Part V. — Ax Estimate of the Density of Liquid Neon. 



In Part I. we calculated the values of a for the inactive 



gases from the formula V=-rN<7 3 , deriving V from the 



densities of the liquids and also from the refractive index. 

 The results were as follows : — 



I 



I7X10\ 



He. 



Ne. 



A. 



Kr. 



1 



X. 



V from d ... 



V from ju ... 

 Ratio 



4-34 

 1-17 

 372 



? 



1-47 



? 



4-43 

 235 

 1-89 



493 



2-G9 



j 1-83 



4-88 

 316 

 1-54 





The last line in the table gives the ratio of the two values 

 corresponding to q in Part IV. If we plot the ratios against 

 the atomic weights and draw a smooth curve through the 

 points thus obtained, we find for neon a ratio of about 25. 

 This would give for a from d a value of about 3*68. Hence 



^ 080 = ;.2-75xl0»x(3-68)3xl0- 



whence 



d=l'2L 



This atomic volume would thus be about 16, which is not 

 very different from the value — 202 — deduced by Ramsay 

 and Travers (Phil. Trans. /. c.) from the periodic curve of 

 the atomic volumes of all the elements. 



London, Jan. 1909. 



Added April 19th. To Part I. — Whilst the above was in the 

 press, two papers dealing with the same subject have appeared, 

 the one, by Sutherland (Phil. Mag. [6] xvii. p, 320), 

 criticising the cr-values deduced by Jeans (I. c), and the 

 other, by Reinganum (Ann, d. Plvjs. xxviii. p. 142), criticising 



