Chemistry. An orange-red substance, 1,2-dihydroxyanthraquinone, originally extracted from madder root (genus Rubia) and subsequently synthesized…

The colouring principle of red sanders.

A red dye that is a constituent of orchil, consists of a number of substituted phenoxazine derivatives of orcinol, and can be obtained from orcinol…

Chemistry. A red dye extracted from the root of the madder and also prepared artificially by the oxidation of alizarin.

A rose-coloured crystalline substance obtained by the alkaline hydrolysis of a sulphonated derivative of indigo.

A crystalline, reddish-orange substance (C8H5NO2), of brilliant lustre, obtained from indigo by oxidation.

Any of certain red dyes which are derivatives of rosaniline, spec. the hydrochloride (fuchsin).

A red colouring matter produced (by Kolbe and Schmidt in 1861) by heating phenol with oxalic acid and strong sulphuric acid.

sulphonated castor oil, principally used with alizarin to produce the colour Turkey red.

A synthetic red azo dye, used in photography as a desensitizer; 3,7-diamino-5-phenylphenazinium chloride, C18H15N4Cl. Also: a substituted…

Any of a class of synthetic xanthene dyes, chiefly pinks and reds, which are obtained by condensation of phthalic anhydride with m-aminophenols…

= rosaniline, n.

Either of two red dyes that are chlorinated derivatives of eosin and are used as biological stains; dichlorotetrabromofluorescein, C20H6Br4Cl2O5…

Any of a class of synthetic red xanthene dyes employed chiefly as microscopic stains; (in later use) esp. either of two such dyes (in full pyronin…

a red dyestuff obtained from primuline base by diazotization followed by coupling with β-naphthol.