Lauric Acid → Silver laurate

1.9 g of sodium hydroxide was dissolved in 100 ml of water, to which 12 g of lauric acid in 100 ml of toluene was added and the mixture was emulsified (at 25° C.). Further, an aqueous solution of silver nitrate consisting of 8.5 g of silver nitrate and 50 ml of water was added to the above emulsion to result in a separation into a silver laurate-containing toluene phase and an aqueous phase. After removal of the aqueous phase, the toluene phase was dispersed in 200 ml of methanol, and silver laurate was collected by centrifuging. 12 g of spindle-like silver laurate crystals of about a length of about 3μ was obtained. A polymer dispersion of a silver salt was prepared by dispersing 6 g of the resulting silver laurate in 12 g of polyvinyl butyral and 70 ml of isopropyl alcohol using a mixer. The polymer dispersion of the silver salt was maintained at 50° C. with stirring, to which 0.02 g of cobalt nitrate was added, followed by stirring for 20 minutes. 0.15 g of N-bromosuccinimide (silver halide-forming component) was then added, and further the resultant mixture was stirred for 90 minutes. After chillsetting at a temperature of 30° C., a heat developable light-sensitive coating solution using the composition containing the components set forth, with the components being added in the order listed every 5 minutes to the dispersion with stirring, was prepared.