168 SCIENTIFIC AND APPLIED PHARMACOGNOSY 



when the tannic acid is changed into an insoluble oxidation product 

 and the gall becomes more porous, constituting the so-called white gall 

 of commerce (Kraemer, Bot. Gaz., 1900, p. 275). 



Aleppo Galls. Somewhat spheroidal, 1 to 2 cm. in diameter; 

 externally grayish-brown or dark grayish-green, more or less tuber- 

 culate above, the basal portion nearly smooth, and contracted into 

 a short stalk, sometimes with a perforation on one side; heavy; 

 fracture horny; internally yellowish or dark brown, consisting of a 

 central portion which contains starch, and occasionally the partly 

 developed insect, and an outer zone which is porous, lustrous and 

 occasionally traversed by a radial canal, these two zones being 

 separated by a layer of nearly isodiametric stone cells or parenchyma 

 cells with thick cellulose walls; odor slight; taste strongly astringent. 



Powder. Yellowish-brown; starch grains numerous, more or 

 less free in the powder and varying in shape from spheroidal or 

 ellipsoidal to polygonal, and from 0.005 to 0.030 mm. in diameter; 

 numerous fragments of thick-walled, starch-bearing parenchyma; 

 stone cells few, resembling those found in fruits and seeds, vary- 

 ing considerably in shape and size, from 0.025 to 0.300 mm. in length ; 

 occasional fragments with spiral or reticulate tracheae; fragments 

 mounted in very dilute ferric chloride solution should become of a 

 deep blue or greenish-blue color. 



A rough method of obtaining an idea of the value of powdered 

 nutgalls is as follows: Macerate 0.5 gm. of powdered nutgall with 

 2 c.c. of alcohol for a few minutes, add 500 c.c. of water, stir the 

 mixture well for five minutes and filter. On adding a drop of ferric 

 chloride solution to 1 c.c. of this filtrate, diluted with 10 c.c. of dis- 

 tilled water, a distinct blue or violet-blue color should develop. 



Constituents. The principal constituent is tannic acid, which is 

 found to the extent of 50 to 70 per cent; the drug also contains gallic 

 acid 2 to 4 per cent, starch and resin. 



Tannic Acid (gallotannic acid or digallic acid) is a yellowish-white 

 amorphous substance, with a characteristic odor and astringent taste. 

 It is soluble in cold water and alcohol; forms amorphous salts; gives 

 a blue color and precipitate with ferric chloride; forms a soluble 

 compound with iodin and prevents the latter from giving the char- 

 acteristic reaction with starch. 



Two classes of tannic acid are recognized, depending on their 

 behavior with iron salts and other reagents: (1) Tannic acid, giving 

 a bluish color with ferric chloride, as that of Aleppo galls, and also 

 found in chestnut (Castanea), pomegranate (Punica) and sumac 

 (Rhus) ; (2) tannic acid, giving a greenish color with ferric chloride, 



