Mr Kleeman, The Work done in the Formation, etc. 409 
_ The Work done in the Formation of a Surface Transition Layer 
of a Liquid Mixture of Substances. By R. D. KiEEMAN, D.Sc. 
_ B.A., Emmanuel College. 
[Received 16 March 1914.] 
In a previous paper* I have shown that the surface tension 
which a pure substance would have if no surface transition layer 
were formed would be given by 
14+ 949+... Bee 
l+@qt+e,t... 
where U denotes the energy expended in overcoming molecular 
attraction on separating the molecules of a gram of the substance 
an infinite distance from one another, p denotes the density of the 
substance, and mq the absolute molecular weight of a molecule. 
This equation is based on Laplace’s definition of surface tension 
according to which it is the work done against molecular attraction 
per unit increase of surface on cutting a slab of a substance into 
two slabs and separating them an infinite distance from one another. 
Besides the assumption is made that the attraction between two 
molecules separated by a distance z is given by a law of the form 
< 
, Where k and r are constants or functions of 7’, the temperature. 
The constants ¢,, 3, C,, ... C, in the expression 
14 g+3+... 
1l+o+e,+.. 
are then functions of r. Since the molecular attraction is approxi- 
‘mately given by a law of the above form, and the foregoing 
expression is not sensitive to variations in the values of the 
jconstants C2, C3, C4,...€n, the value of the expression may be 
‘calculated with fair accuracy by means of a law of attraction 
which has been found to fit approximately the facts. In this 
manner I obtained ‘876 for the value of the expression putting 
r=5, and equation (1) accordingly became 
* Phil. Mag., Dec. 1912, pp. 876—885. 
