﻿108 Mr. D. Tyrer on the 



Combining the equation 



c c-cf— - 



Lyx (V + AV)- 



with equation (3) we get 



Cp — \j v L — E 



fJL_ i I SA i\ 



~\ n-l rT n-l \ I n— 1 w— 1 I 



lyr (Y + AY / )-3~ j L v L ir "V v -t j 



Neglecting for low temperatures the term — ^ as small 

 1 V v~r 



compared with — ^z\, we can write 



lo g (l-%^A 

 n = 3 V L - Jlj / +1. ... (4) 



1o -(yTav) 



In Table II. are given the values of n calculated by aid of 

 this equation. The values of L— E are taken from tables 

 calculated by Mills * by aid of the Clapeyron-Clausius 

 equation. 



Though the values of n appear to approximate to the 

 value 4, they cannot be regarded as constant as the diver- 

 gencies are greater than errors in the data. Moreover, the 

 relation 



L-E = C{A_^} 



obtained by putting n = 4 in equation (3) does not hold. We 

 must conclude that either (1) the equation representing the 

 law of attraction between molecules includes some other 

 function besides the simple function of the distance of sepa- 

 ration of the molecules, or (2) the assumptions regarding the 

 ] potential energy of a liquid on which the above equations 

 are based are not true. Let us first consider the second 

 possibility. One assumption which certainly requires a 

 closer study than has hitherto been accorded to it, is that 

 the total energy of a liquid or gas, minus the potential 

 energy of molecular attraction and potential energy due to 



* Journ. of Phys. Chem. viii. p. 405 (1904). 



