Azo dyes, soluble metal compounds of; regenerated celluloses, dyeing.-Azo dyestuffs containing metal and capable of dyeing stripy viscose uniform fast grey tints are obtained by treating with one or more agents yielding metal disazo dyestuffs of the general formula <FORM:0357543/IV/1> in which R1 is an aryl residue carrying a hydroxyl group in o-position to the azo bridge and R2 is an aryl residue carrying a carboxyl group. The metallization may be effected in acid, neutral, or alkaline media, with or without application of pressure and with or without the presence of alkali metal salts such as sodium formate, acetate, phosphate or chloride. The dyeings of the products on cotton are stated to be faster than those obtainable with the dyestuffs containing chromium specifically referred to in Specification 271,897, [Class 2 (iii), Dyes &c.]. The following examples are specified. (1) The dyestuff, anthranilic acid --> (acid) 2 : 5 : 7-acid (alkaline) \sM 5-nitro-2-aminophenol, is boiled under reflux with a solution of chromium fluoride containing sodium acetate; the product dyes viscose uniform grey blue tints; when the o-oxydiazo component is replaced by 4-nitro-2-aminophenol-6-sulphonic acid and 4-chloro-5-nitro-2-aminophenol, the dyeings are blue grey and greenish grey respectively; the use as o-oxydiazo component of 4-chloro-2-aminophenol or of its 6-sulphonic acid yields similar dyeings. (2) The sodium salt of the dyestuff, anthranilic acid --> (acid) 2 : 5 : 7-acid (alkaline) \sM 6-nitro-2-aminophenol-4-sulphonic acid or 4-nitro-2-aminophenol-6-sulphonic acid, is boiled under reflux with a solution of chromium fluoride; the products dye viscose p uniform grey blue tints. (3) The sodium salt of the dyestuff, m-aminobenzoic acid --> (acid) 2 : 5 : 7-acid (alkaline) \sM 6-nitro-2-aminophenol-4-sulphonic acid or 4-nitro-2-aminophenol-6-sulphonic acid, is boiled under reflux with a solution of chromium fluoride; the products dye viscose neutral grey and red grey tints respectively; when the o-oxydiazo component is 4-chloro-2-aminophenol-6-sulphonic acid or 5-nitro-2-aminophneol the dyeings are grey to blue grey. (4) The sodium salt of the dyestuff, anthranilic acid --> (acid) 2 : 5 : 7-acid (alkaline) \sM 4-chloro-2-aminophneol-6-sulphonic acid, is boiled under reflux with a solution of nickel chloride (NiCl2) and boiling is continued with addition of chromium fluoride; the product dyes viscose uniform grey tints. (5) The sodium salt of the first dyestuff of (2) above is treated with an ammoniacal solution of copper oxide and the copper compound separated by addition of acetic acid is boiled under reflux with a solution of chromium fluoride; the product dyes viscose uniform grey violet tints. (6) The sodium salt of the dyestuff, anthranilic acid --> (acid) 2 : 5 : 7-acid (alkaline) \sM 4-chloro-2-aminophenol-5-sulphonic acid, is treated with an ammoniacal solution of copper oxide and the copper compound is chromed as in (5); the product dyes viscose grey tints. (7) The first dyestuff of (1) above is boiled under reflux with a solution of chromium fluoride containing sodium acetate and the resulting chromium compound is coppered by means of copper sulphate; the product dyes viscose grey tints; when the proportion of chromium to copper is increased a product yielding grey violet tints is obtained; alternatively the copper may be introduced before, instead of after, the chromium. (8) Cotton is dyed by boiling for 1/2 -\ba3/4 hr. in a bath containing the metalliferous dyestuff, Glauber's salt, and common salt, or a feebly alkaline or feebly acid bath may be used. (9) Regenerated cellulose artificial silk is dyed by treatment at 60-80 DEG C. for 1 hr. in a neutral, feebly alkaline, or feebly acid bath containing the metalliferous dyestuff with or without an addition of salt. The manufacture of the copper compounds by coupling to form the azo dyestuff in presence of a water-soluble complex nitrogenous copper compound and the subject-matter claimed in Specification 351,400 are disclaimed. Specifications 26460/12, 16803/15, 116,530, 271,897, 297,003, 300,916, and 306,908, [all in Class 2 (iii), Dyes &c.], also are referred to.