The electrochemical adsorption of four aliphatic compounds, i.e., n-butanol, isopentanol, n-pentanoic acid, and n-hexanoic acid has been investigated by employing a capillary electrometer of greatly improved sensitivity. As observed by previous workers from this laboratory, for each adsorbate, π versus In α curves at different polarizations were found to be superimposable by abscissa translation implying thereby that the adsorbate-adsorbate interactions in the surface layer are independent of the electrical nature of the interface and that the surface charge density varies linearly with surface excess at fixed polarization. The improved precision attained in the measurements of interfacial tension permitted construction of well-documented ln(π/α) versus π curves; such plots do not appear to have been published before. These curves resemble parabolas and for a given adsorbate, the family of these curves obtained at different polarizations were superimposable by ordinate translation. The Frumkin equation was used to fit the data for each absorbate. Three further methods that can be used to determine the parameters of the Frumkin equations are discussed. These are based on the analysis of In (π/α)-π, In α-θ, and π-In α data. The free energies of adsorption referred to specified standard states have been calculated on the basis of the Frumkin equation. The model evolved in the previous work correlating the standard free energies of adsorption with polarizabilities of the adsorbate molecules has been successfully tested.