208 



SCIENCE PROGRESS 



means of estimating the change in concentration of the solute. 

 The following table shows the surface tension as a function of 

 concentration : 



Table 2 



Concentration (c) grams in ioo grams 

 of solution. 



O'OOO 



0-000977 



0*00243 



o 00500 

 o "00759 

 o '00806 



Surface tension, in dynes 

 per cm. 



72-91 



7I-83 

 67-97 



S7'33 

 50-24 



49*09 



Fig. 2. 



[From the paper by Donnan and Barker.] 



The adsorption process was brought about by allowing a 

 steady stream of air bubbles to pass up through a vertical 

 tube containing the solution into an overhead reservoir. 

 Mechanical stirring or mixing of the solution was avoided by 

 the use of a large number of diaphragms through which the 



