Precipitate impregnated membranes: I. Some properties of the BaSO4‐cellophane membrane

Abstract Washed‐out BaSO4‐cellophane membranes have been analysed. The number and strength of acid groups in them are the same as in the original cellophane. Membrane diffusion potentials arising with different electrolytes at washed BaSO4 membranes have been measured in the usual way and found to be the same as with original cellophane. Direct examination of the permeability of effective BaSO4 membranes to Ba and SO4 ions in a special case (viz. our “standard experiment”) confirmed that this permeability is extremely low, amounting practically to impermeability in this case. This property, as well as the characteristic membrane potentials at the effective BaSO4 membrane depend on the simultaneous presence of Ba and SO4 ions in the adjacent solutions. The special behaviour of the effective BaSO4 membrane is not due to “fixed charges” in the usual sense.