A review is given of the characteristics of the limiting current, reversible and irreversible waves, criterion of reversiblity of the wave form, the kinetic current and the adsorption waves (prewave and postwave) at the rotated dropping mercury electrode (RDME). The limiting current at the RDME in the presence of a suitable curl tce active substance is hardly affected by variation of the mercury pressure, while the etcct of drop time and hence of potential is much greater at the RDME (t^1/2) than at the DME (t^1/6). The large drop time effect is particularly important when a mixture of two or more electroactive species is analyzed. Reversible waves at the RDME cars be analyzed in the same way as those at the DME. The half-wave potential of reversible reduction waves at the RDME of simple ions of metals which are soluble in mercury is depcnclcrlt on characteristics of the electrode and is more negative than that at the DME. When oxidized and reduced species are both soluble in the solution, the half-wave potential at the RDME is independent of characteristics of the electrode. The half-wave potential of totally irreversible waves is much more negative at the RDME than at the DME. An expression for the difference in half wave potential at the two electrodes is derived and illustrated by comparing the waves of nickel ion in sodium perchlorate solution obtained at the DME and at the RDME. Criteria of reversibility of waves obtained with the RDME and with the DME are compared. Because of the greater rate of mass transfer at the RDME, the specific rate constant must be greater for the wave to be reversible at the RDME than at the DME. When the rate constant is not sufficiently large, a species yielding a reversible wave at the DME may give an irreversible wave at the RDME. This situation is illustrated by composite waves obtained with a mixture of vanadic and vanadous ions in sulfuric acid solution. Kinetic currents at the RDME are treated on the basis of the concept of reaction layer. When the current is entirely controlled by the rate of the chemical step involved, the expression for the kinetic current is the same at the DME and at the RDME. Since the kinetic current and the mass-transfer controlled limiting current are both practically independent of the mercury pressure, the dependence of current on the mercury pressure cannot be used to detect kinetic nature of the current at the RDME. On the other hand, the kinetic current at the RDME decreases with increasing speed of rotation of the electrode, the decrease corresponding to the decrease in drop time. Thus kinetic currents can be identified at the RDME by determining the effect of speed of rotation upon the value of the limiting current. The RDME is particularly useful in the study of polarograms involving adsorption owing to the fact that maxima of the second kind always appear in the absence of adsorption. This is demonstrated by the application of the RDME to the study of the potwave observed with copper (ll)-thiocyanate system and the anodic prewave observed with solutions containing iodide ions.

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The methods of determination of the rate constants of homogeneous reactions in solution by using kinetic current due to the reaction which foregoes the electrode reaction, are reviewed. The most commonly used basic equations for the kinetic current of the simple first order reaction are interpreted, in respect to the correlations between the equations. The methods of determination of the rate constants are explained with known examples : 1) dissociation and recombination of weak acids, 2) hydration and dehydration of aldehydes and ketones, and 3) formation and opening of the ring forms of aldoses and ketoses. The necessary conditions for the determination of the rate constants by using kinetic current and the common origins for the errors are discussed.

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It has been a usual method in the polarographic determination of vanadium to utilize the anodic wave produced by the oxidation of vanadyl ion (IV) to vanadate ion (V) in a supproting electrolyte composed of 1 M sodium hydroxide and 0.08 M sodium sulphite.1) Recently, Musha and Takao studied on the simultaneous determination of titanium and vanadium using a base solution of 0.1 M EDTA and 0.02 M sodium citrate.2) However, these supporting electrolytes can not be applied to the high sensitive determination with square wave polaroglaph, since the reactions of vanadium ions in these supporting solutions appear to proceed irreversibly, or to be accompanied by a chemical reaction. Only an available reversible reaction for this purpose in the consecutive reduction processes of vanadium ions is a reaction between vanadic (III) and vanadous (II). As the half wave potential of this reaction in 1 N sulphuric acid is -0.508±0.002 V. res. S.C.E. and that of the reaction between vanadyl (IV) and vanadous (II) in 0.1 N sulphuric acid is -0.85 V. res. S.C.E., it is impossible to reduce vanadyl (IV) ion direct-ly to vanadic (III) ion. Thus, for the high sensitive determination of total vanadium with square wave polarograph it is necessary to convert aII vanadium ions into the state of either vanadic (III) or vanadous (II). It is accepted in general that when a oxidation-reduction reaction invoIVes a process of formation or breaking of covalent metal-oxygen bond, the reversibility of the redox reaction becomes very poor. The irreversibility of the reaction between vanadyl (IV) and vanadous (II) may be caused from the formation of a metal-oxygen bond VO⁺⁺ which is invoIVed in the reaction process between vanadyl (IV) and vanadic (III). Therefore, it is expected that the reversibility of the reaction between vanadyl ion (IV) and vanadous ion (II) may be increased by preventing the formation of VO⁺⁺ ion, using a much higher concentrated sulphuric acid as a supportinng electrolyte, in which VO⁺⁺ ion is scarcely formed. The aim of the present study was to obtain informations for the determination of vanadium with square wave polarograph, utilising the reaction between vanadyl (IV) and vanadous (II) in a highly concentrated sulphuric acid on the basis of the abovementioned expectation.

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[in Japanese]

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Although bromate and iodate have been known to be electroreducible at the dropping mercury electrode, their reaction processes involve some uncertainties. Two kinds of the reduction waves, acidic and alkaline waves, were first discovered by Rylichl' in the polarography of potassium iodate and bromate in unbufered solutions which contain various rations as supporting electrolyte. Orlemann and Kolthoff performed a systematic study in which influences of various rations onthe irreversible reductions of iodate and bromate anions were both experimentally and theoretically investigated. More recently Cermak pointed out in his short publication that each of these polarographic waves consists of two separate parts in a certain pH range, and assumed the kinetic current phenomena rising between the free acid molecules and their dissociated anions. There have been known few examples for the kinetic current of inorganic acids, but those kinetic mechanisms are expected to be more comprehensible and more convenient to the theoretical treatment, compared with the complexities assumed in the cases of organic depolarizers.
The purpose of the present work is to study the reduction of bromate in detail with respect to its kinetic current phenomenon. On the reduction of iodate, it was hardly possible to make the reliable measurements on the first and the second waves separately, because the potential difference of the two waves was always small. The more detailed observation with iodate, therefore, was not made in spite of the expectation of its similar behaviour to bromate.

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