Process for preparing photographic emulsions

Claim 1

IN A PROCESS FOR PREPARING A PHOTOGRAPHIC GELATINO-SILVER-HALIDE EMULSION, THE STEPS WHICH CONSIST IN (1) ADDING TO A GELATINO-SILVER-HALIDE EMULSION WHICH CONTAINS THE WATER-SOLUBLE SALTS GENERATED DURING THE FORMATION OF THE SILVER HALIDE FROM A WATER-SOLUBLE SILVER SALT AND A WATER-SOLUBLE HALIDE, AFTER COMPLETION OF THE FIRST DIGESTION, AT LEAST ONE WATER-SOLUBLE, INORGANIC SALT SELECTED FROM THE GROUP CONSISTING OF AMMONIUM SALTS, SALTS OF THE ALKALI METALS HAVING AN ATOMIC WEIGHT LESS THAN 140 AND SALTS OF METALS OF GROUP II OF THE PERIODIC ARRANGEMENT OF ELEMENTS HAVING AN ATOMIC WEIGHT LESS THAN 140, IN QUANTITY SUFFICIENT TO COAGULATE THE SILVER HALIDE, AND ALSO ADDING TO THE EMULSION AT LEAST ONE WATER-SOLUBLE ACID HAVING AN IONIZATION CONSTANT AT LEAST THAT OF ACETIC ACID IN QUANTITY SUFFICIENT TO LOWER THE PH TO AT LEAST 6, (2) DECANTING THE SUPERNATANT LIQUOR, (3) ADDING WATER TO THE COAGULATED, SUBSTANTIALLY GELATIN-FREE SILVER HALIDE, (4) AGITATING THE MIXTURE THUS OBTAINED, (5) SETTLING THE MIXTURE, (6) DECANTING THE SUPERNATANT LIQUOR, SAID STEPS (2), (3), (4), (5) AND (6) BEING PERFORMED SUCCESSIVELY UNTIL THE CONCENTRATION OF THE WATER-SOLUBLE HALIDES IS REDUCED TO THE DESIRED LEVEL, AND (7) REDISPERSING THE WASHED SILVER HALIDE GRAINS IN AN AQUEOUS GELATIN SOLUTION.