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The influence of single and mixed solvents on the rate of electrode reactions is discussed.

The adsorption of o-phthalic acid (H2Pht) on mercury electrodes was studied in the pH range 0.5–11.5 using surface tension, double layer capacity, and zero charge potential measurements. The calculated adsorption isotherms indicate a reorientation of H2Pht molecules from flat to vertical orientation with increase of H2Pht concentration in the solution. These results combined with the change of the zero charge potentials suggest that in the vertical position —COOH groups are directed to the surface of the metal. The change in the adsorption of phthalic acid at different pH's was explained by the different adsorbability of free acid H2Pht and its ions HPht− and Pht2−.

MERCURY electrodes used in electrochemistry are often prepared by plating mercury on solid electrodes. The formation of amalgams in these conditions has been in general disregarded. We have already shown1 that when gold or gold-plated electrodes are covered with mercury, there are electrode reactions different from those on pure mercury, owing to formation of intermetallic compounds.

IN the application of the hanging mercury drop electrode to analytical determination of trace metals we have used very dilute solutions1 in which no mutual interaction of metals was observed, even in the presence of more than one metallic species. We wish to report an investigation of the conditions in which such interaction effect cannot be neglected.

IT is usual to study electrode processes using hanging-mercury microelectrodes. Some authors prepare these electrodes by hanging a small mercury drop on a gold wire or a gold-plated platinum wire1,2, deliberately neglecting the presence of the gold for its electropositive potential. Such an electrode is however an amalgam electrode, and, as we have shown3, gold can influence the electrode processes of those metals which combine with it to form intermediate compounds.