564 VEGETABLE DRUGS 



Cynips Gallse tinctoiiae Olivier (class Insecta ; order Hymen- 

 optera). 



Hohitat. — Levant. 



Description. — Subglobular, 1 or 2 Cm. in diameter, more 

 or less tuberculated above, otherwise smooth, heavy, hard ; 

 often with a circular hole near the middle communicating 

 with the central cavity; blackish olive-green or blackish- 

 gray ; fracture granuhir, grayish ; iu the centre a cavity con- 

 taining either the partly developed insect, or pulverulent 

 remains left by it ; nearly inodorous ; taste strongly astrin- 

 gent. Light, spongy, and whitish-colored nutgall should be 

 rejected. 



Constituents. — 1, (gallo) tannic acid, 60 per cent.; 2, gallic 

 acid, 2-3 per cent.; 3, sugar ; 4, resin. 



PREPARATION. 



Unguentum Oallce. Nutgall Ointment. (U. S. & B. P.) 

 Nutgall, 20; benzoinated lard, 80. (U. S. P.) 



AciDUM TA.NNICUM. Tannic Acid. HC14H9O9. 

 (U. S. & B. P.) 



Synonym. — Acidum gallo-tannicum, tanninum, tannin, 

 digallic acid, E.; acid tannique, tannin, Fr.; gerbsaure, 

 tannin, G. 



An organic acid obtained from nutgall. 



Derivation. — Powdered nutgall is exposed to damp air 

 for 48 hours. It is then treated with water and ether. The 

 water dissolves tannic acid ; the ether removes gallic acid, 

 coloring matters and impurities. The mixture is filtered and 

 allowed to stand, when the lower aqueous layer yields tannic 

 acid on evaporation. 



Properties. — A light yellowish, amorphous powder, 

 usually in the form of glistening scales or spongy masses ; 

 odorless, or having a faint, characteristic odor, and a strongly 

 astringent taste ; gradually turning darker when exposed to 

 air and light. Soluble in about 1 part of water, and in 0.6 



