Two merocarbocyanine dyes confaining benzoylallylidene groups-which were soluble in mixed medium ether and alcohol, -and two β-phenylpentamethine cyanine dyes which were insoluble in the above medium-were obtained from Na salt of formylacetophenone and ethiodide of quinaldine and 2-methylbenzothiazole.
Merocarbocyanine dyes were produced when orthoformate, ketomethylene compounds and the mother components of the dyes were heated together.; mother components-alkyl halide of α-picoline, 2, 6-lutidine, quinaldine and 2-methylbenzothiazole. ketomethylene compounds 1, 2-diphenyl-3, 5-dioxopyrazolidine, 1, 2-ditolyl-3, 5-dioxopyrazolidine and thiobarbituric acid.
Aminovinyl compounds were produced when orthoformate, primary aromatic amines and the mother components of the dyes-above mentioned-were heated together. But sulfamine, p-bromoaniline and p-aminosalicylic acid did not gave the aminovinyls when they were reacted with methiodide of α-picoline and 2, 6-lutidlne. And p-nitroanitine. o-nitro-p-toluidine and p-nitro-o-phenetidine gave carbocyanine dyes when they were reacted with alkyl halide of quinaldine of 2-methylbenzothiazole.

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In Vogel's reaction which is a chemical test of photographic gelatine, ammoniac silver nitrate solution and gelatin solution, both at a fixed concentration, are mixed at a fixed temperature, and their color only are compared after the fixed duration of reaction. When the concentration of gelatin solution was fixed on 2%, 3, 6 and 10% ammoniac solutions of silver nitrate were used, and when the concentration of ammoniac silver nitrate solution was fixed on 6%, 0.1, 1, 2, 5 and 10% gelatin solutions were used. The increases of the color of the solution in Vogel's reaction within 100 hours were measured as the optical densities by Pulfrich's photometer. The density generally increased with time and made an S curve. When either the concentration of gelatin or that of silver nitrate decomed high, the density at every hour increased and the tangent of the straight part in the S curve becomed large. But in the case of the gelatin with strong retarding-action, the higher the concentration of gelatin becomed, the less becomed the density after 30 hour or more. When the concentration of gelatin was very small, or 0.1%, the tangent of the straight part of the S curve was larger than when 1%. These results explain that the creation and growth of colloidal particles in Vogel's reaction undergo almost the same action as the retarding and the sensitizing action in the ripening of photgraphic emulsion.

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There are various explanations for the mechaniism of desensitization by dyes. Most of these theories insist the desensitizing agents act as an oxidizing agent for sensitivity specks or latent silver image. These ideas are not practical. Alternatively, the author now prescuts a hypothesis that, the desensitizing dyes (not necessarily dyes) adsorbed on the surface of the crystal, absorb or accept the photoelectron. The potential relation between the crystal and dye is faborable for this idea. From these idea, the optical sensitizing action of desensitizing dye is properly explained. Many experimental results are presented such as spectral sensitivity, polarographic determination of redox potential of dyes, and reciprocity law failure curve, etc.

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