Chem. [a. F. tanin, ‘le principe tannant’ (1798 Proust in Ann. de Chimie, XXV. 225), f. tan TAN sb.1 + -IN1.] Any member of a group of astringent vegetable substances, the tannins, which possess the property of combining with animal hide and converting it into leather.
The first member of this group isolated and so named was the tannin of gall-nuts, subsequently also called TANNIC acid; and to this the names tannin and tannic acid are still often specifically applied. But the discovery that the astringent principles of other vegetable substances were not chemically identical with that of gall-nuts made it needful to distinguish the various tannins. The original or ‘ordinary tannin’ became distinctively GALLOTANNIN, other members of the group being named caffetannin, catechutannin, kinotannin quercitannin, etc. (cf. TANNIC), or particularized as oak-bark tannin, alder, beech, hop, horse-chestnut, larch, rhatany tannin, according to their source.
1802. Nicholson’s Jrnl., II. 198. Abridgment of a Memoir of Mr. Proust on Tanin and its Specics.
1804. Phil. Trans., XCIV. 210. The effects which it produced on gelatin, also demonstrate the presence of tannin.
1836. Brande, Chem. (ed. 4), 928, note. The tannin of catechu is said to contain less oxygen than that of galls.
1838. T. Thomson, Chem. Org. Bodies, 109. Pure tannin is colourless.
1867. Baker, Nile Tribut., viii. (1872), 123. It is rich in a hard gum, which appears to be almost pure tannin.
1895. Muir & Morley, Watts’ Dict. Chem., V. 632/1. The origin of tannin in plants has given rise to much debate.
b. attrib. and Comb., as tannin drop, pill, treatment; tannin-like adj.; tannin-glycerol, glycerin of tannic acid; tannin-sac, a vessel in plants which secretes tannin.
1874. Garrod & Baxter, Mat. Med. (1880), 357. Tannin Lozenges.
1875. Bennett & Dyer, trans. Sachs’ Bot., 628. Tannin-like compounds are formed in particular cells.
1879. St. George’s Hosp. Rep., IX. 800. It soon passed off again with rest and the opium and digitalis and tannin pills.
1884. Bower & Scott, De Bary’s Phaner., 153. We may here introduce these organs as Tannin-sacs. They occur as elongated sacs, especially near to the vascular bundles, in the parenchyma of the stem and petiole of many Ferns (Marsilia, Polypodiaceæ, Cyatheaceæ, Marattiaceæ, &c.).
1898. P. Manson, Trop. Diseases, vi. 121. The tannin treatment … might also be tried.
Hence Tannined (-ind) a., charged or impregnated with tannin; Tanningenic a., in tanningenic acid, a synonym of CATECHUIC acid and CATECHIN.
1898. E. F. Spence, in Westm. Gaz., 6 Sept., 3/3. For breakfast we had undrinkable coffee, which we exchanged for tannined tea.
1852. Morfit, Tanning & Currying (1853), 69. Catechuine or tanningenic acid.
