NUCLEATED HIGH CONTRAST PHOTOGRAPHIC ELEMENTS CONTAINING SUBSTITUTED THIOUREAS WHICH ENHANCE SPEED AND INCREASE CONTRAST

Silver halide photographic elements which are capable of high-contrast development and are especially useful in the field of graphic arts comprise surface latent image forming high-chloride silver halide grains and have incorporated therein a hydrazine compound which functions as a nucleator, an amino compound which functions as an incorporated booster, and a combination of a gold compound and a thiourea compound which functions as a chemical sensitizer. Thiourea compounds effective for this purpose are substituted thioureas having one or two acyl substituents or having three alkyl substituents or having one aryl substituent and two alkyl substituents.