Contribution to T H E Theory of Permeability of Membranes for Electrolytes. by L. Michaelis

Investigation of the permeability of membranes is most important for biology. The complicated and variable permeability of biological membranes cannot be understood before the simpler conditions in artificial membranes of different qualities have been satisfactorily explained. After M. Traube in 1867 had developed the copper ferrocyanide membrane and Pfeffer published his investigations, the prevalent interest of physicochemists was directed to the phenomenon of the osmotic pressure for many years. The problem of the permeability of the membrane has been neglected for a long time. In the last 20 years several authors have taken up this problem. R. Collander 1 has given a good review, of this subject as an introduction to his experimental work on the permeability of the Traube membrane for non-electrolytes. I am referring, in this paper, to some experiments on the permeability of several membranes for electrolytes which will be published from this laboratory in a series of papers. 2 The essential contents of these are as follows. A. 1. The starting point of the investigation was a confirmation of the experiments of Jacques Loeb and R. Beutner 3 on the electric phenomena of the apple skin. The potential difference of the apple skin against an electrolyte solution depends on the nature and the concentration of the dissolved electrolytes. The anions have no influence at all, the cations exert an effect which depends on their