Films between two immiscible liquids

A methyl cellulose also spread in much the same manner as at a water-air surface. 

As a means of aiding in determining the constitution of unknown substances, the examination of surface films has also proved of considerable use. The first case was with batyl and chimyl alcohols, which are monoglyceryl ethers of long-chain alcohols. There was a question 

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Adsorbed films between two immiscible liquids. The question of the meaning of the term pn in the surface layer has been raised by Crax-ford, Gatty, and Teorell,2 without, however, coming to any very clear decision. Danielli s estimate was a very rough one, based on the application of the Donnan equilibrium between the surface layer and the interior, and suffers from the difficulties always attending an attempt to consider concentrations in the surface layer in a similar way to concentrations in a bulk phase the surface layer is not homogeneous. pH is closely related to, and is determined by, the electrochemical potential (see Chap. VIII, pp. 304 ff.), and this depends on the electrostatic potential, which varies rapidly at different levels near to the surface it appears possible that the only satisfactory definition of pa in the surface may be one which varies rapidly at different depths. The question appears one which would repay... 

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