The electrical double layer has been dealt with in countless papers and in a number of reviews, including those published in previous volumes of the Modern Aspects of Electrochemistry series. [1][2][3][4][5][6][7][8][9] The experimental double layer data have been reported and commented on in several important works in which various theories of the structure of the double layer have been postulated. Nevertheless, many double layer-related problems have not been solved yet, mainly because certain important parameters describing the interface cannot be measured. This applies to the electric permittivity, dipole moments, surface density, and other physical quantities that are influenced by the electric field at the interface. It is also often difficult to separate the electrostatic and specific interactions of the solvent and the adsorbate with the electrode. To acquire necessary knowledge about the metal/solution interface, different metals, solvents, and adsorbates have been studied.In the earlier concepts of the interface structure, the metal was treated as a reservoir of electrons, uniformly distributed in the bulk of the phase. Spatial distribution of charges was considered mainly on the solution side. No such considerations were made for the solid electrodes, except for the Modern Aspects of Electrochemistry, Number 31, edited by John O'M. Bockris et al.