The sorption of the blue dye into the foam matrix was found to be fast reflecting the excellent hydrodynamic properties [10] of the foam phase arising from its membrane-like structure. Expectedly, a
shaking time of 10 min easily allowed maximum absorbance to be reached, compared to the 35 min necessary for complete equilibration using the ion-exchange
colorimetry method [14]. Immersion of the foam parallelepipeds into the measuring cell filled once with
water and once with benzene showed a real improvement of the absorbance of the azo dye sorbed into the
foam in the latter medium. Benzene, which is known