1) Photographic properties of blue print were discussed using H & D curves which were obtained following the example of silver halide emulsions. Formation of Turnbull's Blue and its bleaching was observed and the existence of reciprocity law failure was demonstrated.
2) Compositions of blue print sensitive solutions were discussed and optimal concentration was shown. Then, the role of sodium ferricyanide was discussed and the influence of its content upon sensitivity of blue print was clarified.
3) Addition agents were discussed and suitableness of sodium oxalate, formate was pointed out.
4) Redox potentials of sensitive solutions of ferric ammonium oxalate and ferric ammonium citrate were measured and the effect of addition of some organic acids or their salts were discussed.

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Among the seventeen compounds employed, the eleven had the stabilizing effects for the second digestions, the strengthes of them are compared and decided these orders, and these effects were conserved if another type of gelatine or period added was taken. The effects in the developers are somewhat different, and these tend to accelarate the development especially in the regions of the high intensity of light.

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