Antifoggants for photographic emulsions

摘要

Water sol. azodicarbonamide cpds. in which at least one of the amide nitrogen atoms is covalently linked to a group having a positive charged centre and a negatively charged portion to impart electrical neutrality. Pref. groupings are quaternary ammonium, sulphonium and phosphonium salts, as anti-foggants in silver halide emulsions at 0.1-1.5 m mole per mole silver.