Reviw of the author's researches, with his private opinions, is presented. The problems are claimed to be classified into two groups ; i.e. that of electrode reaction and that of polarographic active pathological substance. Confining to the former, 23 questions are taken out. Along the potential axis, the three regions are coined to facilitate discussion ; capillarity region 0--1.0V., cobalt region -1.0--1.4V., and catalytic region -1.4--2.0V. The sweep velocity of applied voltage for any kind of polarographic methods is requested to be defined and controlled caring for adsorption, dcsorption, change of orientation, transformation, transformation of complex, reformation of different metal complex, and other kind of kinetic factors. The involvement of faradaic current and capacity current are discussed. The complicated behaviors of CoIII the capillarity region which were originally pointed out by Kalous is discussed contrasting the results of A.C. polarographic and oscil-lographic polarographic methods. Current in the catalytic region is understood being much involved accompaning with generation and adhesion of hydrogen gas on the electrode surface and the desorpion of surface active substance, no matter what itself is the depolarizer at the same time or not. From tensammetric consideration, desorption of a surface active substance seems to play a great roll for the doubling of the catalytic wave of hydrogen. The “crossing” of the double peaks was discussed from this point. Redioactivity-potential curve discriminates faradaie current from capacity current, ion-ion redox current, or other kind of current which does not accompany cobalt amalgamation on the electrode surface. It's results (1) show the no disturbance of cobalt reduction even at the potential of the catalytic phenomena, and (2) suggest the reduction of Co^II→Co ^I corresponding the first wave of the splitted cobalt wave at cobalt region. The 3d orbital hydrid complex of Co^III is reduced to the outer orbital (N-shell) Co^II complex, after passing through the several transient steps ; disturbance of coordination field by electric field near the working electrode, ligand field theoretical transformation of an activated electron and final acception of reducive electron, followed by reformation of ligand arrangement. The affairs of such complex chemical phenoma is still more complicated by possible mercury complex, π bonded cobalt complex, and desorption from the electrode surface etc.. Morphology of the catalytic wave has been considered in several ways, to explain the mechanism involved. “Chemical differential mechanism” has been taken out for the explanation of the catalytic wave of hydrogenhaving symmetric peak form. The positive current, due to sum of cobalt reduction and catalytic hydrogen reduction, may compensated by the one of following negative current or factors. (1) Atomic hydrogen on the electrode surface is oxidized and the produced H⁺ is fed to CoSR reforming CoSHR. (2) Hydrogen gas accumulated on the electrode surface protects a part of mass transfer of CoSHR. (3) Due to the desorption and molecular up-set reorientation of CoSHR the chance of H⁺ reduction is decreased.

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The a. c. polarographic method of analysis established by B. Breyer is very widely employed especially in Japan. The present article describes its history, instrumentation, method of experiment and several applications. The instrument which appears in Japanese market is constructed according to the circuitry by Takahashi and Niki shown in Fig. 2. It is emphasized that in the application of the a.c, polarography one should take into account of the reversibility of the electrode process concerned. The periodical concentration polarization was schematically llustrated in Fig. 5. The mechnism by which the polarographic reduction of dissolved oxygen to hydrogen peroxide proceeds reversibly in alkaline media and irreversibly in acidic solution was cleared up according to the theory proposed by Bagotskii and Yablokova. The a.c. polarography also offers us a very simple and rapid method of easuring the differential capacity of electrode resulting in the automatic registration of the ten sammetric wave named by Breyer. The reason for this non-faradaic wave is explained as the competitive adsorption-desorption process of the indifferent cations and anions and the surface-active molecules, as shown in Figures 6 and 7. Some advantage of a.c. polarography such as the high sensitivity, high resolution power and others is summarized as well as some important caution that must be paid in, the analytical application

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Since Brdicka discovered the catalytic double wave of hydrogen to be caused by a protein containing sulf hydryl or disulfide group in a solution of ammonia and ammonium chloride containing hexammine cobaltic chloride or cobaltous chloride, much has been studied on the mechanism. The reactions which are responsible for the catalytic waves of proteins, cystine, cysteine and other mercaptans are not well understood, but cobalt and ammonia are seemed to be necessary constituents in the appearance of the catalytic wave.
The author considered the binding effects of active disulfide group in protein on cobalt and the effect of surface active character of protein on the cobalt reduction wave, and selected the following materials ; 1) Bovine Serum Albumin : the solution has both surface active character and disulfide group in it. 2) Gelatin : the solution has only surface active character and no disulfide group. 3) LEO (Polyoxyethylene laurylether) and Tween 80 (Polyoxyethylene sorbitan monooleate) as non-ionic surface active substance. These solutions have only surface active character and no disulfide group. Parameters studied with respect to their effect on the reduction wave of hexammine cobaltic chloride in ammoniacal ammonium chloride solution were the concentration of the proteins or surface active substances, electrocapillary curve at the constant concentration of these substances, and the evaluation of electron transfer coefficient times electron number, an, of the first step of cobalt reduction wave in the presence of these substances. The influence of bovine serum albumin (BSA) on the reduction wave of hexammine cobaltic chloride in ammoniacal ammonium chloride solution were compared with the influences of other substances. The influence of BSA upon cobalt reduction wave was equal to the ones of the other surface active substances on the consideration of the surface active effect, but the character that is shifting the half-wave potential of the first or second step of cobalt reduction wave is different from gelatin, LEO and Tween 80. It is considered that this may depend upon active disulfide group in BSA.

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It was reported by Shinagawa, et al. that some onium compounds and miscellaneous compounds have also shown similar catalytic waves to that by cysteine in ammoniacal cobalt solution, but a consideration for this effect brings more complicate relation on studying the mechanism of Brdicka's catalytic hydrogen-wave. In the series of this study, therefore, a compound containing sulf hydryl or disulfide group and the related compound are discussed mainly. The catalytically acting part of the compound lowering the hydrogen overvoltage in the ammoniacal cobalt solution is, in most instances, the sulfhydryl group, which is either present in solution or is formed by the reduction of disulfide group at more positive potential before the catalytic process gives rise. The relations between the structure of the compound given a catalytic wave and the catalytic effect in ammoniacal Co(II) or Co(II) solution are summarized as follows:
1) The compounds containing amino, sulf hydryl or disulfide, and carboxyl groups in a molecule ; such as cysteine, cystine, glutathione, cystinylglycine, penicillamine (dimethylcysteine), ergothioneine and thiolhistidine are amino acids and peptides, and give a similar wave to the catalytic wave shown by cysteine in ammoniacal cobaltous solution . In the ammoniacal cobaltic solution, cystine or homocystine at high concentration give a catalytic wave, but other compounds stated above were not tested in cobaltic solution .
2) The compounds containing amino and sulfhydryl group in a molecule; such as β-aminoethylmercaptan, diethylaminoethylmercaptan, vitamin B1, thiothiamine, ethylthiamine', benzothiamine give catalytic wave in both cobaltous and cobaltic ammoniacal ammonium chloride solution.
3) The compound containing sulf hydryl or disulfide and carboxyl group in a molecule; such as thioglycolic acid, thiomasalate1 or dithiodiglycolic acid give a catalytic wave in ammoniacal cobaltous solution. Thioglycolic acid in cobaltic solution is inactive (10^-3-10^-4M).
4) The compounds containing sulf hydryl or disulfide and other group e.g ., hydroxyl, aldehyde etc., such as ethylendithiol, or 2, 3-dimercaptopropanol (BAL) give a catalytic wave in ammoniacal cobaltous solution, BAL gave catayltic waves in both cobaltic and cobaltous ammoniacal ammonium chloride solution,

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