1. Strongly electropositive porous membranes were prepared by the adsorption of protamine (salmine) on porous collodion membranes. These membranes retain their electrochemical chracteristics for at least 12 months without change.
2. They are distinctly electropositive between pH 1 and 10, the range of most pronounced electropositive behavior occurring in solutions between pH 3 and pH 8. The filtration rates and ohmic resistance of these membranes do not differ significantly from similar uncoated membranes.
3. The porous protamine-collodion membranes show very pronounced positive anomalous osmosis, the observed effects with proper electrolytes being similar to those obtained with oxidized collodion membranes. They also show very conspicuous negative osmosis with strong acids.
4. Protamine-collodion membranes which correspond in their properties to the activated dried collodion membranes were prepared by the adsorption of protamine on porous collodion membranes followed by drying in air. The concentration potentials across such dried protamine-collodion membranes closely approach the thermodynamically possible maximum.