Objectives of this program are (1) to characterize mineral oxide surfaces and to relate these parameters to surfactant adsorption, (2) to study chromatographic effects resulting from use of surfactant blends, (3) to understand the properties of microemulsions as they relate to surfactant structure, and (4) to develop a thermodynamic theory of microemulsions which includes surfactant structure, cosolvents, and surfactant blends as well as the properties of the system oil and water. This quarter, we have completed collecting a comprehensive suite of adsorption data for two surfactants--decyl and dodecyl sodium sulfonate. Zeta potentials have been measured under conditions closely matching those which prevailed at points along the isotherm. Also, the free energy required to assemble a water-continuous microemulsion starting with molecularly-dispersed surfactant and excess solubilizate molecules is examined in some detail. In addition, the partitioning of alcohol between an aqueous and a micellar phase has been studied and the specific sites at which alcohols bind to micelles considered. Finally, to explain the unusual dielectric properties of microemulsions, a model which represents a microemulsion as a mosaic of water and oil-continuous regions has been adopted. 56 refs., 39 figs., 4 tabs.