In a binary mixture of surface-active sodium salts of dodecylsulfate, benzenesulfonate and dodecylbenzenesulfonate, each substance appeared to act independently over the range of concentrations examined. There was no evidence of competition like that reported earlier for a system that involved ion-pairing. In cases such as those in the present study, degradation of the separation may result when the less surface-active species is initially much lower in concentration. Measurements of the volume of solution in the flask during a foaming experiment confirmed the expectation that faster gas flows and higher concentrations of surface-active species lead to higher holdup and longer time to reach a steady state.