AbstractEs wird das Gel‐Modell für die Grenzfläche Oxid‐Lösung betrachtet und zwar werden die Oxide TiO" Fe2O3, SiO2 und Al2O3 in Gegenwart eines 1:2 ‐ 2: l‐Elektrolyten behandelt.

A model of the oxide water interface postulating the existence of a finite layer of hydrolyzed material at the surface is considered. A modified Poisson-Boltzmann equation is obtained for the distribution of ions and potential in this region. Values of the titratable charge and zeta potential are calculated and found to be in good agreement with experimental values reported for these systems.

An analysis is given of the van der Waals attraction between two flat plates of infinite extent but of finite thickness, taking account of the retardation correction. Four cases are recognized and the four distinct equations are shown to be mutually consistent. A table of correction factors is given for various values of the particle thickness and separation.

The solution of a number of problems which arise in the measurement of ζ-potentials, by the microelectrophoretic and streaming potential methods, is discussed.