Mordant dyes, dyeing with; regenerated celluloses, dyeing.--Natural or regenerated cellulosic textile material is dyed with a chrome dyestuff after treatment with an aqueous solution of a quaternary ammonium, quaternary phosphonium or ternary sulphonium salt of which the molecule contains a saturated, nonhydroxylated aliphatic chain of at least 10 carbon atoms and contains no acylamino group. The pre-treated material may be further treated with a reduced bichromate prior to the dyeing or the dyed material may be after-treated with a soluble bichromate. Specified salts are octadecyl- and cetyl - pyridinium bromides, cetyltrimethylammonium chloride or bromide, octadecyltrimethylammonium methosulphate, dimethyldicetylammonium bromide, dimethylcetylsulphonium methosulphate, benzylmethyldodecylsulphonium methosulphate and cetyltrimethylphosphonium bromide. The following examples are specified: (1) Viscose stockinette is immersed for \ba1/2\be hour in a 3 per cent solution at 90 DEG C. of cetyltrimethylammonium bromide, rinsed and placed in a warm dyebath containing Solochrome brown RH, acetic acid and Glauber's salt and the temperature is raised gradually to 90--95 DEG C. with an addition of formic acid after \ba1/2\be hour and of potassium bichromate after a further \ba1/4\be hour; the dyeing is of good fastness to light and washing. (2) Viscose stockinette is immersed for \ba1/2\be hour in a 3 per cent solution at 90--95 DEG C. of cetylpyridinium bromide, rinsed and placed in a dyebath at 50 DEG C., made slightly alkaline with ammonia, containing Solochrome brown MG, potassium bichromate and ammonium sulphate and the temperature is raised gradually to 95 DEG C.; a dyeing fast to washing and light is obtained after \ba3/4\be hour. (3) Viscose stockinette, pre-treated and rinsed as in (2), is treated for \ba1/2\be hour in a bath at 95 DEG C. containing potassium bichromate and cream of tartar, again rinsed and placed in a warm dyebath containing Solochrome orange GR and the temperature is raised gradually to 95 DEG C. with an addition of acetic acid after \ba1/2\be hour; the dyeing is fast to washing and light, (4) Viscose stockinette, pre-treated, rinsed, treated with reduced bichromate and again rinsed as in (3) is placed in a dyebath at 90 DEG C. containing Solochrome red ERS with an addition of acetic acid after \ba1/2\be hour and of potassium bichromate after a further \ba1/4\be hour and dyeing is continued for a further 20 minutes to obtain a full red dyeing, fast to washing. (5) Cotton goods are treated for \ba1/2\be hour in a 3 per cent solution at 90 DEG C. of dimethyldicetylammonium bromide, rinsed and placed in a dyebath at 50--60 DEG C. containing Solochrome brown MG and acetic acid and the temperature is raised to 95 DEG C. with an addition of acetic acid after \ba1/2\be hour and of bichromate after a further 10 minutes; the temperature is maintained for a further \ba1/2\be hour to obtain a dyeing fast to washing. (6) Viscose stockinette is treated for \ba1/2\be hour in a 3 per cent solution at 90 DEG C. of octadecyltrimethylammonium methosulphate, rinsed and dyed as in (5). (7) Viscose stockinette is immersed for \ba1/2\be hour in a 3 per cent solution at 90--95 DEG C. of dimethylcetylsulphonium methosulphate and placed in a dyebath containing Solochrome red 6B, acetic acid and Glauber's salt with an addition of formic acid after dyeing for \ba1/2\be hour at 90--95 DEG C. and a further addition of formic acid and potassium bichromate after a further \ba1/4\be hour, dyeing being then continued for a further \ba1/2\be hour. (8) Viscose stockinette is similarly pre-treated in a 3 per cent solution of benzylmethyldodecylsulphonium methosulphate and is dyed and after-chromed as in (4) to (6) above, the dyebath containing Solochrome yellow C, acetic acid and Glauber's salt with subsequent addition of formic acid. Specification 398,175 is referred to. Dimethyldicetylammonium bromide is obtained by interaction of dimethylamine (1 mol.) and cetyl bromide (2 mols.). Dimethylcetylsulphonium methosulphate is obtained by treating with dimethyl sulphate and caustic soda, the mercaptan resulting from treatment of cetyl bromide with sodium hydrosulphide in alcohol, and further treating the product with dimethyl sulphate. Benzylmethyldodecylsulphonium methosulphate is obtained by treating with sodium ethoxide and benzyl chloride the mercaptan from dodecyl bromide and further treating the product with dimethyl sulphate. Cetyltrimethylphosphonium bromide is obtained by interaction of trimethylphosphine with cetyl bromide.