Photographic film with fine grain silver chloride underlayer

Claim 1

A LIGHT-SENSITIVE MATERIAL CARRYING ON A PLASTIC TRANSPARENT SUPPORT IN THE FOLLOWING ORDER, A SUBBING LAYER, A SLOW SPEED GELATINOUS SILVER CHLORIDE EMULSION LAYER IN WHICH THE SILVER CHLORIDE PARTICLES ARE OF SUBMICROSCOPIC SIZE AND HAVE A MEDIAN PARTICLE SIZE ON THE ORDER OF 50 MILLIMICRONS, AND IN DIRECT CONTACT WITH SAID SILVER CHLORIDE EMULSION LAYER, APERMANENT HIGH-SPEED GELATINOUS SILVER HALIDE EMULSION LAYER IN WHICH THE SILVER HALIDE EMULSION IS SELECTED FROM THE GROUP CONSISTING OF SILVER BROMIDE AND SILVER BROMOIODIDE EMULSIONS AND HAS A RELATIVE SPEED RANGING FROM 45 TO 138, THE RELATIVE SPEED OF SAID HIGH-SPEED SILVER HALIDE EMULSION EXCEEDING THAT OF SAID SILVER CHLORIDE EMULSION BY A FACTOR RANGING FROM 50 TO 2000, THE SPEED OF SAID LOWER SILVER CHLORIDE LAYER BEING SO SLOW THAT NO SILVER IMAGE IS FORMED THEREIN UNDER CONDITIONS OF EXPOSURE BLACK AND WHITE DEVELOPMENT AND FIXING WHICH GIVE A HIGH DENSITY SILVER IMAGE IN THE TOP LAYER, SAID RELATIVE SPEED BEING EXPRESSED IN TERMS OF RECIPROCAL CANDLE SECONDS TO DEVELOP A DENSITY OF 0.2.