678 Dr. R. D. Kleeman on the Equation of Continuity 



matter whether we consider K a function of the temperature 

 or of the density, as the density is thus a function of the 

 temperature. Since P n =L'/o it will be most convenient to 

 develop first a formula for the latent heat along the same 

 lines. We have seen * that in general, according to the law 

 of attraction between molecules, 



^{©"MM-er-^F 



V^iV 



where 



0a(j,j8) and hQ, $) 



have each the same values for all liquids at corresponding 

 states. If K is to be independent of the temperature, 



*»&*) a " d *»Q>e) 



must be functions of p l and p 2 respectively, or rather of 

 — and — , since they must have the same values at corre- 



Pc Pc 



spohding states. A fairly good agreement with the facts is 

 obtained by writing for these functions 



c( , r .,„„ D( , r 



respectively, whore U is a numerical constant. The equa- 

 tion for the latent heat then becomes 



L=U0>?-^)W (9) 



y m ' p c ' 



This is the same equation as was obtained in a previous 

 paper from surface-tension considerations f ; it was there 

 applied only to liquids considerably below their critical 

 temperatures, and therefore written 



m ir6 pl 



h = Vpl 



The above equation is tested for a number of liquids over 

 considerable ranges of temperature in Table II. The values 



of -= s contained in the fifth and twelfth columns of the 



A- A 



* O) p. 746. 



t Phil. Mag. Oct. 1909, pp. 499-505. 



