Previous investigations conducted with porous plates have shown that some organic substances present, in minute quantities, in an aerated mixture increase the interfacial surface area (A) to such an extent that despite the reduced mass transfer coefficient (K sub L) the total rate of oxygen transfer (K sub L) can be considerably increased. The report deals with a preliminary investigation of three different models of aerators in which the organic agent was introduced at different rates of flow and concentrations. The objective of the tests was to obtain some information about the effects of these variables on quantities such as the bubble diameter, the interfacial area, the mass transfer coefficient, and the total rate of oxygen transfer. (Author Modified Abstract)