Tension and Complex Molecules. 389 



particles per unit volume (Avogadro's Law). That is, 

 however, only possible if there are phenomena of associa- 

 tion in the solutions. This will be further discussed and a 

 definite proof given in the subsequent paragraph. 



We shall now show that the relation (4) is in agreement 

 with the experimental evidence. This can be illustrated by 

 the following table, where the figures are given for a state 

 of complete equilibrium *. 



Table I. 



22-5 



1-4 



1-76 



21-1 



4-6 



4-4 



17-3 



9-4 



9'1 



40-0 



4-4 



5-1 



26-6 



27-4 



27-7 



28-2 



31-8 



32-6 



Water-isobutyl alcohol 23'9 



,, isoamylic alcohol 25"7 



„ ether ,. 267 



„ aniline 44'4 



„ chloroform 54'0 



,, benzene GO'O 



It is not easy to extend the above table for the following 

 reasons. The pairs of liquids with considerable mutual 

 solubility give saturated solutions with nearly equal surface 

 tension, e. g. aniline-amylene (trimethylethylene), isobutyric 

 acid- water, carbon disulphide-methyl alcohol, whose critical 

 points of separation into two layers are not far from the 

 ordinary temperature. In the proximity of that point the 

 tensions of: both layers are nearly equal, and a 12 is nearly 

 zaro |. No accurate results can be obtained under such 



* G. N. AntonofT, J. Ch. Phys. v. p. 372 (1907). 



t In such a case the meniscus of the separation of two layers is nearly 

 flat. As a rule the meniscus is curved according to the values ot esi and 

 a 2 , the liquid with higher tension wets the glass at the interface and forms 

 a concave surface. The explanation of these phenomena can be given 

 by means of the above theoiy. The theory of the doublets can also 

 permit of the explanation of the phenomena of humectation and of 

 adsorption that both result in molecular attraction. We have seen 

 that the attraction between two doublets of the same nature is 

 expressed hj 



3e 2 P 



Here d is the distance between the molecules. For a liquid of which 

 the doublets l x l 2 are of a different size, the attraction between the particles 

 will be expressed by 



SeHJ 2 



