Pressure and Latent Heat of Liquids. 63 



of values are obtained if one considers I to be the latent heat 

 of expansion of the liquid itself. A simple expression for I 

 having this signification may be obtained as follows. 



For the heterogeneous as well as homogeneous system we 

 have, on purely thermodynamic grounds, 



1 _ T bp 

 and on introducing the further expression 



i*i\ n^\ (¥\ = _i 



which holds only for a homogeneous system (say the liquid 

 form), one obtains 



Bp v \<yr ft 



7_m ur _ 



/p 



v \dp/T 



= -T 



P' 



where « is the coefficient of thermal expansion and j3 the 

 compressibility of the liquid. 



In the following table are given some values of I thus 

 calculated ; the a and {i data being taken from Landolt and 

 Bornstein's tables. 



Latent Heat of Expansion of non-associated 

 Liquids at 0° C. 



Substance. 



1 atmos./cm. 2 . 



/ cals./c.c. 



65 



88 



79 



91 

 103 

 316 



80 



84 



86 



82 



78 



Ethyl ether 



Chloroform 



2730 

 3700 

 3332 

 3822 

 4336 

 13280 

 3370 

 3547 

 3644 

 3430 

 3305 



Carbon disulphide 



Acetone 



Mercury 



Cymene 



Xylene 



Toluene , 



Benzene 



Ethyl acetate 





It will be observed that in general the latent heat of expan- 

 sion of the liquid is of quite the same order of magnitude as 

 its latent heat of vaporization. In the case of associated 



