The initial evaporation path was calculated for an emulsion of water and a multicomponent oil phase under the following conditions. The computations were based on the phase diagram of the emulsion system combined with an algebraic system to extract information from phase diagrams to facilitate the mathematical treatment. An inherent consequence of the use of the phase diagram as a basis to calculate an evaporation path is the condition of equilibrium between the phases in the emulsion as well as between the vapor and the condensed phases. In addition to this fundamental limitation, the features of the phase diagram of the actual emulsion were restricted as follows. There is no solubility of significance in the water of either the oil or of the surfactant. The nonaqueous compounds display extensive mutual solubility with the solutions being close to ideal. This solution of the nonaqueous compounds does not dissolve nor solubilize water to a degree to affect the calculations in the stage of evaporation treated; an emulsion in the two-phase region of lowest surfactant content.