The Natural Organic Colouring Matters
By
Arthur George Perkin, F.R.S., F.R.S.E., F.I.C., professor of colour chemistry and dyeing in the University of Leeds
and
Arthur Ernest Everest, D.Sc., Ph.D., F.I.C., of the Wilton Research Laboratories; Late head of the Department of Coal-tar Colour Chemistry; Technical College, Huddersfield
Longmans, Green and Co.
39 Paternoster Row, London
Fourth Avenue & 30th Street, New York
Bombay, Calcutta, and Madras
1918
Kaikki kuvat (kemialliset kaavat) puuttuvat // None of the illustrations (of chemical formulas) included.
Saffron consists of the dried petals of the Crocus sativus (Linn.), a plant which flowers in September and October, and is distinct from the ordinary spring crocus (Crocus vernus, All.). It is a native of the East, but is cultivated in Spain, the South of France, and Austria, and is employed for flavouring purposes, for the staining of articles of diet, and to a very limited extent as a dyestuff. Saffron contains the aromatic oil known as saffron oil, picrocrocin, a bitter compound, and crocin, or poylchroit, the glucoside of the colouring matter. Pfyl and Scheitz (Zeit. Nahr. Genussm., 1908, 16, 337) failed, however, to obtain Kayser's "picrocrocin" (Ber., 17, 2228) though using the methods employed by him. These authors state that by extraction of saffron with chloroform they isolated three products: (i) a colourless crystalline substance, melting-point 280°C., which does not reduce Fehling's solution; (ii) a yellow crystalline substance, melting-point 164°C., readily soluble in water or alcohol, which when boiled with acid developed the odour of saffron oil, and gave a sugar, probably laevulose; and (iii) a crystalline hydrocarbon, melting-point 118°C. (cf. Schiller, Diss. Munich, 1899, and Hilger), apparently similar to the hydrocarbon found in marigold petals, arnica flowers, etc. According to these authors, the second substance referred to above somewhat resembles the "picrocrocin" described by Kayser. From alcoholic extraction of saffron the same authors obtained (i) the colouring matter; (ii) a sugar (possibly laevulose); and (iii) a glucoside, which on hydrolysis yields saffron oil and a sugar (possibly lævulose).
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Dyeing Properties.
Crocetin dyes aluminium and tin mordanted fabrics dull orange and yellow shades respectively.
According to Rochleder, the Chinese dyestuff "Wongsky" (q.v.), which consists of the fruit of the Gardenia grandiflora (Lour.), also contains crocin (Jour. Chem. Soc., 1858, 475).
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