326 Dr. R. D. Kleeman on Relations between the 



the nature of the liquid. The writer* has shown that this 

 equation can he deduced if <£ 2 ( r'T") * s I Jut ec L im ^ *° (~~) m 

 the genera] law of attraction between molecules. We then 

 obtain D= -fe(S V»h) 2 ^ where m denotes the molecular 



weight of the liquid, p c the critical density, and S a numerical 

 constant. This value of D agrees fairly well with the facts. 

 The latent heat is also given by the equation f 



where K 4 is a numerical constant equal to about 1'75 ; 

 which also corresponds to a particular case of the general 

 law of attraction between molecules. Equating these two 

 different equations for the lateni heat we obtain 



B( / >P- / )f)=Tlog(g), 



where 



Another expression for B which is convenient can be 

 obtained by determining B at the critical temperature from 

 the first of the above two equations. Writing p 2 = ,vp l we 

 have 



p l0 4 1 



L wi-.^)J 



3T C 



B=\ °X =- l7 3, 



13Q _„1,3 N ) jLtx=l 



and the above equation becomes 



^(Pl 3 -^ 5 ) = T10 8 (^). • • • • (1) 



pc W 



If the two different expressions obtained for B are equated 

 we get 



T ^3K^O ( J ^ 



an equation which has already been discussed in previous 



papers. 



Equation (1) has many useful applications, and it has 



therefore been tested over considerable ranges of temperature 



for a number of liquids in Table L, which contains the 



10 4 

 values of -p- calculated by means of this equation. The 



* Loc.cit. f Phil. Mag-. Oct. 1910 ; p. G88. 



