Verification of Gibbs formula

To compare the directly measured adsorption of phenol in aqueous solution with that calculated from surface tension. 

In the experiments of McBain and Swain (Proc. Roy. Soc. A 1936, 154, 608) a uniform layer less than 0.1 mm thick was cut off from a known area of the surface of a dilute solution by a small microtome blade travelling at about 35 ft sr. This thin layer was collected in a small silver-lined cylinder on which the microtome blade was mounted. The solution so obtained was weighed and its concentration compared with that of the bulk solution by means of an interferometer. 

Some of the measurements on solutions of phenol are given in table 1. At the top of the table are given the bulk compositions. Here w denotes the mass collected and A the number of divisions on the interferometer, each division corresponding to a concentration difference of 2.10 x 10 g/g HaO. The area A sliced was 310 cm . 

The values of F the adsorption per unit area obtained from the measurements of surface tension by Goard and Rideal (see problem 136) are given in table 2. 

For such dilute solutions we need not distinguish between mass of solution and mass of water. The adsorption F per unit area is then given by 

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