A comprehensive discussion is provided for the complex system obtained on equilibrating an aqueous solution of a salt with an acid-base couple (ABC) extractant. These extractants were analyzed as a combination of a liquid cation exchanger and a liquid anion exchanger operating concurrently. The effect of the amine on the organic acid activity and the effect of the acid on the amine activity were compared to those of mineral bases and acids on single active component extractants. The available distribution and spectroscopic data, summarized in the previous article, are discussed.