THE GENERAL conclusion of the paper1 is, that the diffusion potential between aqueous and non-aqueous electrolyte solutions of equal concentration will be small. The authors arrive at this result by measuring the emfs of a number of cells, which values, after some algebraic manipulations, are thought to give twice the value of this diffusion potential.
There is much confusion on the subject of diffusion potentials between electrolyte solutions in different solvents, which potentials in principle cannot be measured2, and we think that the conclusion of Schwabe and Geisler is based on an incorrect interpretation of the measured emfs.
From the description of their cells we conclude that, according to the IUPAC convention, U, is negative and U, and U, are positive. (We suppose that the + andsigns indicate the polarity of an electrode with respect to its counterpart.) However, from Tables and it follows that a positive value is assigned to U, (which gives the result U, M U, -UC).
Following the IUPAC convention gives U, w UC -U,, and further, D, M D, -D,. Therefore, instead of Schwabe and Geisler's equation ( ) we have