Parallelism ofRMvs. composition and logCsvs. composition relationships has been found (Cs=solubility, moles per liter), in spite of the strong molecular interactions involved, for three alkaloids chromatographed in solvent systems of the type (m-xylene +n-pentanol)/buffer solution and (tetralin + cyclohexanone)/buffer solution. Some correlation has also been found between the solubility of two naphthols in nonpolar and weakly polar solvents (hydrocarbons, chlorinated hydrocarbons) and theRMvalues in the corresponding solvent systems of the type organic solvent-formamide. The differences ofRMcoefficients and logCsvalues were found to be individual for a given solute and solvent system, even for closely related solutes (e.g., 1-naphthol and 2-naphthol) for which the ΔRMvalues and Δ logCsvalues tend to be constant for various systems (in other words, ΔRM≠ Δ logCs).