History of the Physical Chemistry of Charged Membranes

Abstract

One has to look for the roots of what now has been called membranology far back in time and search into many different fields of human activity. My task in this chapter must necessarily be more limited as indicated by the title “Charged Membranes.”* Seen in retrospect, the primary problems and speculations were concerned with the riddle of many life processes. The search began with experiments on frog muscle contractions by Galvani about 1780 (Fig. 1). Incidentally, it can be said that the ensuing controversy between Galvani and Volta and others, about the actual nature of “animal electricity” also led to the development of electromagnetism, which gave rise to our first electrical measuring instruments (galvanometers and voltmeters). The debates on muscle electricity and muscle contractions enhanced old speculations on the mechanism of bodily excretions and secretions, such as urine, bile, and gastric juice. These are more “visible” problems, which inspired “model making” with pig bladder, parchment, and other “diaphragms.” Dialysis and osmosis were discovered, and this was the beginning of colloid chemistry. It is of particular interest to recall that the “electrified osmosis” called electroendosmosis was discovered already in 1803 by Reuss. Later, Dutrochet, Quincke, and particularly Wiedemann (1893) were able to set up the quantitative laws for electroosmosis which are valid even today, notwithstanding the advent of a new powerful tool, irreversible thermodynamics. The author’s own work on excitability models rests on “Wiedemann’s law” and on the important “hydrodiffusion” law of A. Fick (Figs. 2 and 3). Fick (1866) has an excellent chapter on diffusion in his book Medizinische Physik, probably the first text on this subject.

An important principle in any department of knowledge is to find the approach from which a problem appears in its greatest simplicity.

Quotation attributed to J. Willard Gibbs (1839–1903)