On the sensitiveness of photographic dry plates

Abstract

It is found by microscopic test that the occurrence of sensitive nuclei is a characteristic property of silver bromide, and silver bromide is accompanied by these nuclei at its precipitation even from aqueous solutions of precipitants. The nature of these sensitive nuclei in silver bromide crystals was presumed from the results of electrometric titration· to be silver chloride which was precipitated from a minute trace of soluble chloride contained as an impurity in potassium bromide. Further experiments have shown that silver bromide and silv.er iodide in photographic emulsions act. as both :Chemical accepter and optical sensitizer for silver chloride nuclei. The ripening of an emulsion at digestion is explained by the coming in direct contact of silver chloride nuclei with silver bromide or iodide within the grain by diffusion through a thin layer of gelatin which was occluded at precipitation and isolates the silver chloride nuclei from other silver halides. To sum up again, the sensitiveness of silver bromide plate is concluded to be due to the sensitiveness of silver chloride.