'30 Mr. D. L. Hammick on Surface Energy, 



If v Q is the specific volume at the absolute zero, we have 

 approximately v = v (l + aT), where ^^coefficient of expan- 

 sion and T = absolute temperature. 



Hence 



v (l + aT)_ „, 

 /3J "~ i,Al ' 



or 



01' 



t>(l + «T)-_ ,. i) 



Now the ratio o£ critical volume to volume at absolute 

 zero, — c , is a constant and approximately 4. Putting the 



,- V c i 



ratio — =n } we nave 



v v v c v _ 4 



v a'v„ n' 



and from above : 



H> - 



v 

 The ratio n— - has been evaluated for 21 liquids (using 



Young's data, for v c ). Excluding chlor-benzene (n = 2'0) 

 and acetonitrile (n = 3*4), the values of n range between 

 3'1 and 2*8, the mean value being 3*0. We have, therefore, 

 in (ix.) above : 



But we have found — = — 3^^ approximately (at 0° (J.). 

 Hence 



j.qT=—\ 1 s approximately at 0° C. . (x.) 



