THE POTENTIALS OF GALVANIC CELLS WITH LIQUID JUNCTIONS

Though it is not possible to assign definite differences of potential to any portion of a galvanic cell, a source of electromotive force may be looked for whenever an electric conductor is non-homogeneous. Such a source of potential may be (a) the junction of two metals, (b) a metal-electrolyte boundary, (c) the junction between two solutions, of different compositions, but with the same solvent, (d) the junction of two solutions with different solvents, (e) a solution with a solvent of graded composition, and there are other possibilities. The simplest galvanic cell involves at least three of these boundaries. A “set-up” for observing potentials originating in biological material necessarily includes more than this number of sources of potential, frequently many more. Since only one electromotive force arises from any given galvanic cell with its various sources of potential it is evident that in this field we are always dealing with more...