| 摘要 |
PURPOSE:To prepare the entitled emulsion capable of forming an image superior in conrast and graininess, by reducing divalent cupric ions under a specified condition to form fine cuprous halide crystals. CONSTITUTION:A photographic sensitive emulsion containing photosentive cuprous halide having 0.1-1mum average grain diameter is prepared by reducing divalent cupric ions, e.g. formed by dissolving cupric bitrate, etc., using a reductant, e.g. sulfite in presence of (a) colloidal particles of a metal or its salt lower in solubility than cuprous halide, e.g. zinc sulfide of <=0.1mum particle diameter, and (b) halogen ions in an acidic aqueous solution containing a hydrophilic polymer, e.g. gelatin, and growing the cuprous halide crystals on the speed nuclei of zinc sulfide. |
