New electrocapillary phenomena

Abstract

In the present communication the mechanism of certain phenomena connected with the presence of a double layer at a metal-solution interface is discussed. The forces acting on a completely polarizable metal particle placed in an electric field in electrolyte solutions are considered. It is shown that the same action of an external field on the charges of the double layer which in the case of a dielectric gives rise to the usual electrokinetic movement, induces electrocapillary movement in a liquid metal drop. The theory of these movements has been developed by B. Levich and the author. Quantitative expressions are given for the velocity of the electrocapillary movement. In highly conducting solutions or at low values of the charge this velocity approaches the velocity of a particle bearing a free charge equal to that of the inner sheet of the double layer. The nature of the damping effect exercised by the charges of the double layer on the movement of the liquid metal surface is considered. This effect brings a decrease in the mobility with increasing dilution, and the appearance of a maximum on the curve representing the velocity of movement as a function of the surface charge. The values of the potentials corresponding to zero surface charge, as determined by Rehbinder and Wenstrem, from the relation between the hardness of metals and polarization are compared with the values of the potentials at the maxima of the electrocapillary curves of molten metals according to Karpachev. It is shown that there is a satisfactory agreement between the results of the measurements by the two methods.