THE STRUCTURE OF T H E COLLODION MEMBRANE AND ITS ELECTRICAL BEHAVIOR XII. THE PP~PARATION AND PROPERTIES OF "MEGAPERMSELECTIVE" PROTAMnCE COLLODION MEMBRANES

The preceding paper 1 of this series describes the preparation of "megapermselective" collodion membranes which are extremely impermeable to anions, but at the same time are very permeable to univalent cations. The purpose of the present paper is to describe the preparation and the properties of analogous electropositive "megapermselecfive" membranes which are very impermeable to cations, but at the same time very permeable to univalent anions. Abrams and Sollner ~ have recently shown that electropositive membranes similar to the activated dried collodion membranes 8 can be prepared by the adsorption of protamine on highly porous collodion membranes and their subsequent drying in air. Such membranes show considerable electroposifive activity in solutions ranging from pH 2-10. The "characteristic concentration potential" (0.1 ~ KC1/0.01 ~ KC1) of these membranes varied with different specimens from --47 to --52 Inv.;4 the membranes retained their electromotive properties on prolonged contact with water and electrolyte solutions. Their resistance was high and correspondingly their absolute permeability was low, having approximately the same magnitude as that of "activated" collodion membranes. 3 The dried protamine collodion membranes of Abrams and Sollher were of irregular shape and quite wrinkled in appearance; they were fragile and liable to easy destruction. I t was also impossible with these membranes to measure accurately the surface area which should be known for many experiments. The present paper describes membranes which are free of these enumerated shortcomings. They are designated "permselective" or "megapermselective" protamine collodion membranes.