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.
The outer dry skins of the bulb of the onion, Allium cepa (Linn.), were formerly employed for dyeing purposes. According to Leuchs (Farben und Färbekunde, 1825, 1, 434), "the outer skins of onion bulbs which are of a brownish-orange colour have long been used in Germany for dyeing Easter eggs yellow, and in conjunction with alum for dyeing woollen, linen, and cotton materials. The colour is fast and particularly brilliant. From Kurrer's observations onion skins are very suitable for dyeing cotton, on which they give a cinnamon-brown with acetate of alumina, a fawn with alumina and iron, a grey with iron salts, and a variety of shades with other additions."
The colouring matter was extracted by boiling the skins with distilled water for one hour, and the yellow extract on keeping gradually deposited the impure dye as a pale olive precipitate. The average yield was 1.3 per cent. This was extracted with alcohol, the concentrated extract treated with ether and the ethereal solution washed, until a tarry precipitate no longer separated. On extracting the ethereal solution with dilute alkali the whole of the colouring matter was removed, and on neutralising the alkaline liquid a yellow precipitate was thrown down, which was purified by crystallisation from dilute alcohol. The acetyl compound melted at 190-191°, and there could be no doubt as to the identity of this colouring matter with quercetin (Perkin and Hummel, Chem. Soc. Trans., 1896, 69, 1295). Attempts to isolate a quercetin glucoside from onion skins have hitherto failed, and it seems that such a compound is absent at least in the outer dry material.
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