Current outputs of NaCl and K2SO4, were related to the membrane c.d. at fixed reactants concns. At less than 154-170 g NaCl/l., the NaCl current output was const. at ca. 90%; whereas upwards of 155-171, the output fell as NaCt concn. was raised. At K2SO4=100 g/l, the K2SO4 current output was const. at 93.7-94.9%. The solns. collected contained a free acid or a free hydroxide, on account of the different current outputs of the ions passing through the membrane from the diln. to the concn. chamber.