Subclass 1/22: Photosensitive materials (photosensitive materials for multicolour processes G03C 7/00; for diffusion transfer processes G03C 8/00; photosensitive glass C03C 4/04) Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein (catalytic amounts of silver halide in dry silver systems G03C 1/498) with non-macromolecular additives (G03C 1/04 takes precedence) Sensitivity-increasing substances Organic substances Methine or polymethine dyes with an even number of CH groups