W. F. Cooper and W. H. Nuttall 



233 



smeared with vaseline showed to be the case. The fact that the vasehne 

 is not wetted by soap sohition, however, in no way prechides its use as 

 a standard oil in the determination of wetting power. 



TABLE II. Wetting Power of Sodium oleate Solution 

 towards liquid Vaseline {at 20° C). 



* This concentration 'streamed' in our usual drop-pipette. The interfacial tension 

 was determined therefore in a pipette with a finer orifice. The number of drops is not 

 given, as it is not comparable with the other figures. 



80 



0-1 0-2 0-3 0-4 0-5 0-6 0-7 0-8 0-9 1-0 1-1 1-2 1-3 1-4 1-5 1-6 1-7 1-8 1-9 2-0 



Concentration of soap solution — % of fatty acid 

 Fig. 2. 



The values for the surface and interfacial tensions are plotted in 

 Fig. 2; the tensions as abscissae, the concentrations of fatty acid as 

 ordinates. The forms of the two curves are markedly different. With 

 concentrations of more than about 0-1 % of fatty acid, the surface 

 tension is only very sHghtly affected by rising concentration, the 



16—2 



