ACIDUM TANNICUM — TANNIN 261 



Vegetable Astringents. 



Tannic acid Geranium 



Gallic acid Hematoxylon 



Galls Ehois Glabra (Sumac) 



Kino Quercus (Oak bark) 



Krameria Hamamelidis 



Gambir Eubus 



Mineral Astringents. 



Alum Salts of Copper 



Salts of Iron Salts of Bismuth 



Salts of Lead Salts of Silver 



Salts of Zinc Calcium Carbonate 



ACIDUM TANNICUM — TANNIC ACID 



Synonyms. Tannin, Gallotannic acid, Digallic acid 

 Tannin is the active constituent of all vegetable astringents. It 

 is prepared from nutgalls, which contain from 30 to 60 per cent. It 

 occurs as a light yellov? amorphous powder, gradually turning darker 

 when exposed to light and air, usually adhering in the form of glis- 

 tening scales or spongy masses, odorless or of a feebly characteristic 

 odor and astringent taste. It is soluble in 0.34 parts of water, 0.23 

 of alcohol in 1 part of glycerin, and almost insoluble in absolute 

 ether, chloroform or benzine. 

 Preparations. 



* Collodium Stypticum 20 per cent. 



Olyceritum Acidi Tannici 20 per cent. 



Unguentum Acidi Tannici 20 per cent, in benz. lard. 



Trochisci Acidi Tannici, each 1 gr. of tannin. 



B. P. Suppositoria Acidi Tannici, each 3 gr. of tannin. 



Doses. 



Acidum Tannicum. H. 3j — vj ; 4. — 25. D. gr. ij — ^vij ; 

 0.13—0.5. 



Action. Since tannic acid is changed to other products which 

 do not have its characteristic action before absorption takes place, 

 its action may be described as purely local. It forms a white pre- 

 cipitate with neutral solutions of gelatin, or albumen, which are 

 entirely insoluble in water, but are soluble in an excess of gelatin 

 albumen, lactic or acetic acids. Solutions of peptone are also pre- 

 cipitated unless in an acid medium. But if a proteid tannate is 

 subjected to the action of the gastric juice, it is digested similarly to 

 any coagulated proteid, but the acid is set free during the process of 

 digestion and may precipitate other proteids, but this does not take 

 place in the acid gastric juice. 



* Unofficial. 



