So that it is very probable that when Gallic acid is taken into the blood, it acts as an Astringent by co-operating or uniting with the elements of grape-sugar in that fluid. But when Tannic acid is received into the organism, and has done its work there, it is finally decomposed, Gallic acid passing out into the secretions, and the sugar being retained in the body for combustion into carbonic acid and water. (p. 116.) The principal vegetable substances that are employed as Astringents are said to contain Tannic acid in the following proportions:-- Kino 70 per cent. Krameria 43 " Catechu 40 " Uvæ Ursi 36 " Oak-galls 26 " Pomegranate-bark 19 " Tormentil 18 " Oak-bark 16 " These numbers are a tolerably fair measure of the astringent power of the substances named. But it must not be supposed that the astringent principle is in all cases strictly identical with Tannic acid, properly so called; for there appear to be various modifications of this substance contained in the different plants, many of which have peculiar chemical characters of their own, but all of which agree in possessing the power of tanning, or combining with animal gelatine, and in the medicinal property of astringency. GENERAL INDEX. Absorption, action of medicines by, 61, 68, 87. Acids, 120. Aconite, 352. Aconitina, symptoms of action of, 353. Ague, remedies used for, 129, 207. Alcohol, 339. Aliments, 115. Alkalies, 126. Aloes, absorption and action of, 80, 96, 289. Alteratives, 35, 157, 165. Alum, as an Astringent, 263. Ammonia, 334. Anæmia, treatment of, 148, 320. Anthelmintics, 97. Antidotes, action of, 92. Antimony, 321. Arsenic, 333. Astringents, 256, 358. Belladonna, 240. Benzoic acid in lithic deposits, 156. Bile, relation of remedies to the, 137. Billing, Dr., on action of medicines, 132, 163, 216. Bismuth, nitrate of, 87, 94, 97. Blood, medicinal actions in the, 103, 106, 167. Borax, actions of, 155, 232. Brodie, Sir B., his experiments, 63. Calomel, not a sedative, 328. Cantharides, its uses, 67, 214, 307. Castor oil, 291. Catechu, 358. Cathartics, 95, 286. Chalk, not astringent, 264. Charcoal, said to become absorbed, 88. Chemical theories of medicinal actions, 47. Chlorine, an Antiscrofulic, 193. Chloroform, 342. Cholagogues, 295. Cinchona, 129. Citric acid, its actions, 123, 202, 205. Cod-liver oil, 310. Colchicum, 331. Conium, its actions, 246. Copaiba, action of, 267. Copper, Sulphate of, 93, 211, 264. Counter-irritants, action of, 67, 91. Creosote, actions of, 94, 245, 265. Diabetes, treatment of, 119, 194. Diaphoretics, 298. Diarrh[oe]a, treatment of, 294. Diet, rules of, 118.