Zinc Amalgam reference electrode

Reductant equivalent weights of, 847 Reduction 409 by chromium(II) salts, 409 by hydrogen sulphide, 416 by Jones reductor (zinc amalgam), 410 by liquid amalgams, 412 by silver reductor, 414 by sulphurous acid, 416 by tin(II) chloride, 415 by titanium(II[), 410 by vanadium(II), 410 see also Iron(III), reduction of Reduction potentials 66 Reference electrodes potentials, (T) 554 Relative atomic masses (T) 819 Relative error 134 mean deviation, 134... 

A zinc amalgam electrode has been employed as reference electrode in dimethyl sulfoxide (DMSO) [205] and ammonia [206]. The saturated zinc amalgam was prepared [207] by electrolytic deposition of zinc into a layer of pure mercury from an aqueous ZnS04 solution. The solution in equilibrium with the Zn(Hg) consisted of a saturated solution of Zn(C104)2, 4DMSO or ZnCF, 6NH3. 

The use of cadmium and zinc bars as reference electrodes ) had become an established practice in the storage battery industry by the time that Nernst was concerning himself with the problem of a standard. Ostwald ( ) also mentions that in earlier times amalgamated zinc in a concentrated zinc sulfate solution was used as a constant electrode and occasionally as a reference electrode but that its use posed some serious problems. 

Ostwald antedated Nernst by several years in his proposal of a reference electrode for the electromotive series. He was, of course, aware of the early attempts to prepare reference electrodes. He specifically mentions that in earlier times amalgamated zinc in concentrated zinc sulfate solution had been used as a reference electrode, that this combination when used as a reference electrode Q) gave liquid junction potentials with other electrolytes which could not be calculated, and that the electrode also contaminated the experiments. 

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