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 wood of the Spanish chestnut, Castanea vesca, though it contains only 3-6 per cent, of tannin, is the source of the much-valued chestnut extract. The bark contains more tannin than the wood (17 per cent), but is not much used. The tree, which grows to from 60 to 80 feet in height, is abundant in Italy, the South of France, and Corsica, where it forms immense forests, and it is also very common in America.
Trimble ("The Tannins"), who very carefully examined the tannin, obtained analytical data and reactions which indicated that it was identical, or nearly so, with gallotannin, but it is probable that this wood also contains traces of a catechol tannin, for a certain quantity of a red colouring matter is also present, which resembles in character a phlobaphene. Some writers have suggested that chestnut tannin is a methyl ether of ordinary gallotannin, but there is apparently no definite evidence in support of this theory.
Chestnut is employed almost entirely in the form of extract, the strength of which varies, but usually contains from 26 to 32 per cent, of tannin. The extract is frequently decolorised, and some times mixed with quebracho extract and other materials. Chestnut tannin is the tannin which is most largely employed for the dyeing of silk. Castanea vesca appears to be frequently confused with the horse-chestnut, Æsculus hippocastanum. The tannin derived from this latter is, however, of little or no practical value.
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