PURPOSE: To provide production of a carboxylic acid useful as a dry type silver salt sensitlzed material having high concentration of exposure part, low concentration of nonexposure part and excellent contrast, forming a picture image by carrying out a development process by a heat treatment method, produced in the presence of an indium compound.
CONSTITUTION: A solution obtained by dissolving a carboxylic acid in a solvent which can dissolve a carboxylic acid but hardly dissolves a silver carboxylate and silver nitrate is mixed with an aqueous solution of silver nitrate and/or an aqueous solution of silver complex, the carboxylic acid is reacted with silver ion in the presence of an indium compound to provide production of the silver carboxylate. This dry type silver salt sensitized material contains heat development elements comprising at least the silver carboxylate, a reducing agent, a photosensitive silver halide and/or a photosensitive silver halide-forming component and a binder on a substrate.
OI TAKEHIKO
SANTO TAKESHI
UENO KAZUNORI
FUKUI TETSURO
