Abstract: A solid composition which in aqueous solution liberates ammonia or a primary amine, containing either a) an ammonium salt of a water-soluble polymeric acid and at least one equivalent quantity, in relation to the acid value of the polymeric acid, of a basic compound, or b) a salt of a water-soluble polymeric acid and at least one equivalent quantity of a water-soluble ammonium salt of ammonia or primary amines and an essentially anhydrous inorganic and basic compound, or c) at least one ammonium salt of ammonia or primary amines with inorganic or organic acids and an equivalent quantity of a solid and essentially anhydrous inorganic and basic compound, containing basic compound selected from the group of alkaline earth metal and alkali metal hydroxides or oxides, borax and basic phosphate salts.

Abstract: Dye mixtures comprising at least two metal-free dyes of different colors having in each case two sulfo or carboxyl groups and a molecular weight of between 790 and 1100 are used for dyeing leather. A trichromatic dye mixture comprising at least one yellow dye of the formula (1), at least one red dye of the formula (2) and at least one blue dye of the formula (3) according to claim 2 is preferably used. Leather can be dyed in brilliant shades using these dye mixtures.