The extraction of an acidic solute RH from the solution in a hydrocarbon type liquid by means of an aqueous base solution, can be formulated by the following equilibria: (l) (2) RH RH RB hydrocarbon aqueous phase phase This formula,l in which R is an organic acid radical and B is a base radical indicates that there are at least two main equilibria, marked (1) and (2) respectively, which control th