Abstract: The present invention relates to a process for dyeing leather by the exhaust method, characterized in that water-insoluble sulphur dyes in dispersed form are used.

Abstract: Encapsulated salts of organic or inorganic acid particles having sparing solubility in water wherein the salt particles are surrounded by a pressure-resistant, elastic, abrasion-resistant polyurethane/polyurea casing, the ratio by weight of salt to the polyurethane component of the casing material being 1:0.2 to 1:2.5, are produced by emulsifying a mixture of 83 to 28% by weight of the salt to be encapsulated and 17 to 72% by weight of a polyurethane prepolymer containing free isocyanate groups in water in the presence of a protective colloid and reacting the emulsified prepolymer with the equivalent amount of polyamine at temperatures from 0.degree. to 80.degree. C., with vigorous mixing.