émulsions d'halogénure d'argent ayant une plus grande sensibilité

1,57,938. Sensitizing silver halide emulsions. AGFA A.G. April 9, 1964 [April 13, 1963], No. 14755/64. Heading G2C. Photographic silver halide emulsions are sensitized by after-ripening a silver halide emulsion at a pH between 5 and 7 in the presence of at least one simple or complex salt which is soluble in water or solvents miscible with water of a noble metal selected from Ru, Rh, Pd, Os, Ir, Pt and Au and in the presence of an aliphatic hydroxy carboxylic acid having up to 10 carbon atoms and having the following formula:- wherein X is a hydrogen atom an alkali metal ion or an ammonium ion and n is 0-8. The emulsions may be further sensitized with sulphur compounds, polyalkylene oxides and onium compounds. Specified noble metal salts are AuCl3, KAuCl4, NaAuCl4, Au2(SO4)3; K and Na aurous thiosulphates and aurous sulphites; potassium chloroaurite, potassium bromoaurite, potassium iodoaurite and the corresponding Ca, Sr, Cd and Ga salts; ammonium or potassium chloropalladate; ammonium, sodium or potassium chloroplatinate, bromoplatinate, chloroplatinite and chloropalladite and ammonium chlororhodate, chlororuthenate and chlororidate.