SURFACE TENSION OF SERUM : XII. A TECHNIQUE FOR THE ACCURATE STUDY OF THE DROP IN FUNCTION OF THE TIME.

A technique is described for the study of the adsorption in function of the time of molecules of colloidal substances in the surface layer of water. This technique eliminates previous causes of error, in particular the individual coefficient. The curves obtained by plotting the data for serum at various dilutions give a clear picture of the phenomenon, and show that the low values of the initial surface tension of pure serum and serum at low dilutions are due to the extreme rapidity of adsorption of the molecules in the surface layer, owing to their high concentration. Evidence is given that colloidal substances in solution substantially lower the surface tension of the solvent, even when they are in too small a number to form an homogeneous monolayer.