190 Striated Muscle Contraction [Jan. 



mined. The following results are typical of many others obtained 

 by Whatmough (p. 181).® 



Phenol and Water 



100 gm. water layer contain 8.5 gm. phenol 42.5 dynes/cm. 



100 gm. water layer contain 9.6 gm. phenol 41. i dynes/cm. 



100 gm. phenol layer contain 72.1 gm. phenol 42.4 dynes/cm. 



100 gm. phenol layer contain 66.9 gm. phenol 40.6 dynes/cm. 



Anilin and Water 



100 gm. water layer contain 3.4 gm. anilin 57.0 dynes/cm. 



IOC gm. aniHn layer contain 95.1 gm. anilin 51.6 dynes/cm. 



Isobutyric Acid and Water 



6.5° C. IOC gm. water layer contain 16.4 gm. isobutyric acid 29.9 dynes/cm. 



25.2° C. 100 gm. water layer contain 36.3 gm. isobutyric acid 28.4 dynes/cm. 



6.0° C. IOC gm. acid layer contain 73.4 gm. isobutyric acid 29.6 dynes/cm. 



25.2° C. 100 gm. acid layer contain 36.3 gm. isobutyric acid 28.4 dynes/cm. 



From the above data it is evident that two aqueous Solutions in 

 contact with one another may differ greatly in their concentration 

 of a common solute, with a very small surface tension between them. 

 In the above cases, the surface tension between the phenol and water 

 Solutions is practically zero and the same is true of the isobutyric 

 acid Solutions. Between the water Solution of anilin and the anilin 

 Solution of water there is a surface tension of but 5.4 dynes per cm., 

 altho the two layers differ in the fact that one contains 3.4 per cent. 

 of anilin ; the other, 95 per cent. In all of the above cases the layers 

 are in equilibrium insofar as the layers can remain in contact indefi- 

 nitely, without changing their concentrations, so long as the tem- 

 perature and other conditions remain constant. 



Whatmough did not measure the surface tension of one layer 

 against the other; this was done by Antonow''^ shortly after. Ac- 

 cording to Antonow, the two layers obtained, for example, by 

 thoroly mixing isobutyric acid and water, and then allowing the 

 layers to separate, have exactly the same surface tension against 

 air (p. 370). The surface tension between these layers would be 

 zero. The slight differences between the surface tensions of the 



Data on solubilities taken from Seidell : Solubilities of Inorganic and 

 Organic Substances (New York, 1911). 



7 Antonow : Journal de chimie physique, 1907, v, pp. 362-385. 



