Sulfur group sensitized emulsions

Claim 1

A SILVER BROMOIODIDE-GELATIN PHOTOGRAPHIC EMULSION IN WHICH THE IODIDE COMPRISES 1-10 MOLE PERCENT OF THE HALIDE, SAID EMULSION BEING SENSITIZED WITH A SULFUR, SELENIUM OR TELLURIUM SENSITIZER, SAID EMULSION WHEN COATED ON A SUPPORT AT A SILVER COVERAGE OF BETWEEN 300 AND 1000 MG. PER SQUARE FOOT AND EXPOSED ON AN INTENSITY SCALE SENSITOMETER AND PROCESS FOR FIVE MINUTES IN KODAK DEVELOPER DK-50 AT 68*F. HAS A LOG SPEED OF 280-400 AND A REMAINDER RESULTING FROM SUBSTRACTING ITS GRANULARITY VALUE FROM ITS LOG SPEED OF BETWEEN 180 AND 220.

Claim 3

A METHOD OF PREPARING WASHED SILVER BROMOIODIDE PHOTOGRAPHIC EMULSIONS, THE SILVER HALIIDE GRAINS OF WHICH HAVE A HIGH RATIO OF SURFACE TO INTERNAL SENSITIVITY, WHICH COMPRISES: (A) SIMULTANEOUSLY INTRODUCING A SOLUTION OF SILVER NITRATE AND A SOLUTION OF AN ALKALI METAL HALIDE INTO A NONAMMONIACAL SOLUTION OF PROTEIN PEPTIZER, THE HALIDE WHICH IS 99-90 MOLE PERCENT OF BROMIDE AND 1-10 MOLE PRESENT OF IODIDE BEING KEPT IN 4-20 MOLE PERCENT EXCESS THEREIN PER MOLE OF SILVER PRESENT; (B) CONTACTING THE SILVER HALIDE GRAINS THUS FORMED WITH 5-50 GRAMS PER MOLE OF SILVER OF A WATER-SOLUBLE THIOCYANATE WHICH DOES NOT HAVE A DELETERIOUS EFFECT ON THE EMULSION; (C) SUBSEQUENTLY WASHING THE SOLUBLE SALTS FROM THE SILVER HALIDE GRAINS; (D) DIGESTING THE GRAINS BY SUBJECTING A DISPERSION THEREOF TO AN ELEVATED TEMPERATURE; AND (E) SENSITIZING THE SILVER HALIDE SUSPENSION WITH A SULFUR, SELENIUM OR TELLURIUM SENSITIZER.

Claim 4

A METHOD OF PREPARING WASHED SILVER BROMOIODIDE PHOTOGRAPHIC EMULSIONS, THE SILVER HALIIDE GRAINS OF WHICH HAVE A HIGH RATIO OF SURFACE TO INTERNAL SENSITIVITY, WHICH COMPRISES: (A) SIMULTANEOUSLY INTRODUCING A SOLUTION OF SILVER NITRATE AND A SOLUTION OF AN ALKALI METAL HALIDE INTO A NONAMMONIACAL SOLUTION OF PROTEIN PEPTIZER, THE HALIDE WHICH IS 99-90 MOLE PERCENT OF BROMIDE AND 1-10 MOLE PRESENT OF IODIDE BEING KEPT IN 4-20 MOLE PERCENT EXCESS THEREIN PER MOLE OF SILVER PRESENT; (B) CONTACTING THE SILVER HALIDE GRAINS THUS FORMED WITH 5-50 GRAMS PER MOLE OF SILVER OF A WATER-SOLUBLE THIOCYANATE WHICH DOES NOT HAVE A DELETERIOUS EFFECT ON THE EMULSION; (C) SUBSEQUENTLY WASHING THE SOLUBLE SALTS FROM THE SILVER HALIDE GRAINS; (D) DIGESTING THE GRAINS BY SUBJECTING A DISPERSION THEREOF TO AN ELEVATED TEMPERATURE; AND (E) SENSITIZING THE SILVER HALIDE SUSPENSION WITH A SULFUR, SELENIUM OR TELLURIUM SENSITIZER.