Disazo dyes; regenerated celluloses, dyeing.-Secondary disazo dyes dyeing blue tints are obtained by coupling a diazo compound which does not carry hydroxyl in o- or p-position to the diazo group with a sulphonated or unsulphonated ether of 1 : 2-aminonaphthol, rediazotizing, and coupling (alkaline) with a 2 : 5 : 7-aminonaphtholsulphonic acid or an N-aryl derivative thereof containing no external amino group, the product, if necessary, being saponified. The dyeings on cotton and regenerated cellulose fibres, ranging from violet-blue to green-blue, are fast to light, and some of them give level dyeings on "stripey" viscose. They are convertible into dyestuffs containing metal by treatment with an agent yielding metal applied either to the disazo product or during the final coupling or applied in the dyebath or on the fibre. The following examples are specified: (1) The dyestuff aniline-2-sulphonic acid --> 1-amino-2-methoxynaphthalene-6-sulphonic acid --> (alkaline) phenyl-2 : 5 : 7-acid dyes regenerated cellulose silk level clear blue shades. (2) The dyestuff 2-aminonaphthalene-4 : 8-disulphonic acid --> 1-amino-2-ethoxynaphthalene --> (in aqueous pyridine solution) 2 : 5 : 7-acid dyes regenerated silk level blue shades; there may also be used as first components sulphanilic acid, metanilic acid, 4-aminoacetanilide, 4-aminoacetanilide-3-sulphonic acid, 4-chloraniline-2-sulphonic acid, 2-acetylamino-4-chloro-5-aminophenol methyl ether, xylidinesulphonic acid (CH3 : CH3 : NH2 : SO3H = 1 : 3 : 4 : 5), chlorotoluidinesulphonic acid (CH3 : NH2 : Cl : SO3H = 1 : 2 : 5 : 3), aniline-2 : 5-disulphonic acid, toluidine-2 : 5-disulphonic acid (CH3 : NH2 : SO3H = 1 : 4 : 2 : 5), 41-methyl-2-aminodiphenylsulphone-4-sulphonic acid, p-amino-salicylic acid, 3 - amino - 4 - sulphobenzoic acid, 41-methyl-4-aminodiphenylamine-2-sulphonic acid, 2 : 6- (or 2 : 7-)naphthylaminesulphonic acid, 2 : 4 : 8-naphthylaminedisulphonic acid, 1 : 5 : 7-aminonaphtholsulphonic acid, or H-acid (preferably as the O-ester); other suitable middle components are 1-amino-2-methoxynaphthalene, and 1-amino2-ethoxynaphthalene-6-(or 7-)sulphonic acid, and homologues thereof; other suitable end components are the various N-tolyl, N-xylyl, N-anisidyl, N-oxyphenyl, and N-oxycarboxyphenyl derivatives of 2 : 5 : 7-acid; specified dyestuffs are the saponified product from 2-acetylamino-4-chloro-5-aminophenol methyl ether --> 1-amino-2-methoxynaphthalene-6-sulphonic acid --> (alkaline) 2 : 5 : 7-acid, 41-methyl-4-aminodiphenylamine-2-sulphonic acid --> 1-amino-2-methoxynaphthalene-6-sulphonic acid --> (alkaline) 2 : 5 : 7-acid, and sulphanilic acid --> 1-amino - 2 - methoxynaphthalene - 6 - sulphonic acid --> (alkaline) phenyl-2 : 5 : 7-acid. (3) The dyestuff metanilic acid --> 1-amino-2-methoxynaphthalene-6-sulphonic acid --> (alkaline) phenyl-2 : 5 : 7-acid is boiled with a solution of copper sulphate or of a cuprammonium salt; the product gives from a feebly alkaline bath blue shades more greenish than those from the uncoppered dyestuff; the coppering may also be effected in the dyebath or on the fibre; the dyestuffs containing o-oxycarboxy groups are particularly suitable for conversion into metal compounds. Examples are also given of the dyeing processes for cotton and for viscose. Specifications 12119/98, 14248/07, [both in Class 2, Acids and salts, Organic &c.], 292,660, and 301,754, [both in Class 2 (iii), Dyes &c.], are referred to. Chlorotoluidinesulphonic acid (CH3 : NH2 : Cl : SO3H = 1 : 2 : 5 : 3) is obtained by baking the sulphate of 5-chloro-2-toluidine. 1-Amino-2-ethoxynaphthalene-7-sulphonic acid is obtained by ethylating 2 : 7-naphtholsulphonic acid, nitrating the product and reducing the nitro group. The Specification as open to inspection under Sect. 91 (3) (a) comprises also (1) the use of any diazotizable first component, (2) the use as end components of sulphonic acids of 2 : 5- and 2 : 8-aminonaphthols and their N-substitution products in general, containing no external amino group, additional specified components being N-acidyl, N-alkyl, and N-aralkyl derivatives of 2 : 5 : 7-acid, and the following acids and their N-acidyl, N-alkyl, N-aralkyl, and N-aryl derivatives, viz. 2 : 8 : 6-acid and 2 : 5 : 1 : 7- and 2 : 8 : 3 : 6-aminonaphtholdisulphonic acids. This subject-matter does not appear in the Specification as accepted.