The use of permselective membranes to determine the activity of the counterion in some polyelectrolyte solutions

Various cation‐selective membranes have been examined for sodium ion response in dilute solutions. The oxidized nitrocellulose membranes of Sollner have been used to determine cationic activities in solutions of Sky Blue FF, of cellulosic polyelectrolytes and of sodium polymethacrylate. The dyestuff behaves as a normal electrolyte of between 1:2 and 1:4 valence type, whereas the polyelectrolytes show the usual pronounced sequestering of the cation.