878 



Dr. R. D. Kleeman on the Effect of the 



Let a mass of liquid represented by AB in the figure be 

 cut into two slabs by an imaginary plane ah. Let the 



a 



B 



O O O O* O O O 



A 



i 



attraction of the slab A on a molecule c at a distance x from 

 the plane ah be denoted by F^. The amount of surface 

 tension \ x contributed by the molecule on separation of the 

 slabs, supposing no transition layer formed, is given by 



2X 





dx. 



Since the attraction between two molecules decreases with 

 their distance of separation 



[jV^-o, 



and hence 



2X t 



-J"'- 



dx, or 2 -y- = ¥ x 

 dx 



The amount of intrinsic pressure P# contributed by the mole- 

 cule is equal to F , and hence the foregoing equation may 

 also be written 



2^=Px (3) 



dx 



In order to be able to deal with all the molecules in the 

 slab B in this manner, and to compare the results with one 

 another, it is necessary to know the relative distribution of 

 the mean positions of the molecules in a liquid. In a 

 previous paper * it was shown that we may suppose that the 

 molecules in a pure liquid are situated at the points of 

 intersection of three systems of parallel equidistant planes 

 which intersect each other at right angles. Let us suppose 

 that one of the planes coincides with the plane ah. Let us 

 take one of the molecules in ah as zero of coordinates. 

 Consider the molecules lying on a line at right angles to ab 



* Phil. Mag. April 1911, pp. 537-538. 



