Chem. Combining base of tann-ic, tann-in, used in forming names of tannin compounds, etc., and also in compound substantives, e.g., tannometer for tannin-meter. Tannocaffeic acid, CAFFETANNIC acid. Tannoform, C29H20O18, a product of gallotannic acid and formaldehyde; a reddish white, light powder, insoluble in water, but soluble in alkaline solutions. Tannogallate, Tannogallic a. = GALLOTANNATE, -TANNIC. Tannogelatin, a mixture of gelatin with a solution of tannin.
c. 1865. in Circ. Sc., I. 351/1. *Tanno-caffeic acid, when roasted, develops the agreeable smell of coffee.
1899. Allbutt’s Syst. Med., VIII. 726. Powders of *tannoform, salicylic acid, talc, bismuth, or lycopodium may be employed.
1819. Brande, Chem., 394. The *tannogallate of iron is of the utmost importance, as forming the basis of writing ink, and of black dyes. Ibid. (1836), Chem. (ed. 4), 928. Tannin forms a white precipitate in solution of gelatin (*tannogelatin), which, when carefully dried, becomes hard and tough.
1877. Knight, Dict. Mech., *Tannometer, a hydrometer for determining the proportion of tannin in tanning liquor.
