The bark of the yellow oak, used in dyeing.
Word of the Day: Catachrestical
1. The yellow inner bark of the Quercus tinctoria, the American black oak, yellow oak, dyer's oak, or quercitron oak, a large forest tree growing from Maine to eastern Texas.
2. Quercitrin, used as a pigment. See Quercitrin.
Quercitron
Encyclopedia Britannica
QUERCITRON is a yellow dye-stuff obtained from the bark of the quercitron oak, Quercus tinctoria (see vol. xvii. p. 693). The tree is a native of the United States, but is now also cultivated in France and South Germany. The dye-stuff is prepared by grinding the bark in mills after it has been freed from its black epidermal layer, and sifting the product to separate the fibrous matter, the fine yellow powder which remains forming the quercitron of commerce. The ruddy-orange decoction of quercitron contains quercitannic acid (vol. xvii. p. 692) and an active dyeing principle, quercitrin, C 33 H 30 O 17 . The latter substance is a glucoside, and in aqueous solution under the influence of sulphuric acid it splits up into a rich tinctorial principle, quercetin, C 27 H 18 O 12 , and a variety of sugar called isodulcite, C 6 H 14 O 6 . The reaction may be thus formulated...
C33H 3 0O 17 + ∏ 2 O = ^27^18θl2 ÷ C 6 H14O 6 . Quercetin precipitates in the form of a crystalline powder of a brilliant citron yellow colour, entirely insoluble in cold and dissolving only sparingly in hot water, but quite soluble in alcohol. Either by itself or in some form of its glucoside quercitrin, quercetin is found in several vegetable substances, among others in cutch, in Persian berries (Rhamnus catharticus ∖ buckwheat leaves (Polygonum Fagopyrum), Zante fustic wood (Rhus Cotinus), and in rose petals, &c. Quercitron was first introduced as a yellow dye in 1775. For many years it has been used principally in the form of Flavin (q.v. ∖ Flavin is prepared by boiling quercitron in water and precipitating the tinctorial principle by sulphuric acid. By one method soda crystals are added in preparing the solution. The yellow precipitate is washed to free it from acid, pressed, and dried. From 100 parts of quercitron about 85 of flavin are obtained, having a tinctorial power more than twice that of the original bark. Quercitron and its industrial derivatives are principally employed in calico-printing. With alumina (red liquor mordant) they yield a bright canary colour, with tin salt a fine clear yellow, with iron liquor grey, olive, or black according to the strength of the mordant, and with mixed alumina and iron liquor an orange tint.
9th ed. Encyclopædia Britannica, vol. 20, p. 175
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[382 words — estimated reading time: 3 minutes]
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