Proceedings of the Royal Irish Academy. 



less than would be calculated from the percentage present in the 

 mixture, on the supposition that the surface-tension "was proportional 

 to the composition. The following liquids were used : — benzene, 

 dhloroform, turpentine, paraffin, alcohol, benzolene, and ether. These 

 were examined, two and two, in nearly all those cases where mutual 



JO- 



liO 



Z- 10 







Fig.U. 







(- — r; " 





J 









£ 



cS 



- 





f. 



j; 









s. 







. V. 



§ 







$ 



H 







5 









^ 



1. 







1 



^ 







v. 



Parafftrut 100 % 

 ChlorofoTm. % 



0% 



m % 



Fig. 2. 



Fiffffl 



solution occurs. In addition, water and alcohol, water and glycerine, 

 aniline and chloroform, olire oil and benzene, were examined, all 

 with like results. 



The curve shown, as in fig. 3, typically exhibits the results 

 obtained in general for mixtures of liquids. The dotted line gives 

 the value the surface-tension would 

 have for all percentage-mixtures if the 

 surface-tension were proportional to 

 the composition. The ordinates to the 

 full line represent the observed values. 



"When the surface-tensions of the 

 pure liquids are the same or not very 

 different from each other, the surface- 

 tension of mixtures in all or in some 

 proportions may be less than either of 

 the given substances. 



The depression of the surface-ten- 

 sion of mixtures of liquids below the calculated value seems to be 

 but a particular case of a general principle which underlies the 

 character of the effect produced on physical properties by admixture 

 or solution, and which ranges from things so far asunder as melting 

 points and electrical conductivities. 



WOVoA 



50% A 



0%A 



(l%B 



SOW 

 Fig. 3. 



WO%B 



