646 BOTANY AND PHARMACOGNOSY. 



Mollc). Similar resins are found in other genera of the Ana- 

 cardiaceae, as Astronium and Semccarpiis. 



Chios Turpentine is a product resembling mastic which is 

 obtained from Pistachia terehinthinus (Fam. Anacardiacese) and 

 consists of 10 to 12 per cent, of a volatile oil (consisting chiefly of 

 pinene) and 80 to 90 per cent, of resin. 



GALLA. NUTGALL. An abnormal development on the 

 young twigs of Quercus infectoria (Fam. Cupuliferse), due to 

 the puncture and presence of the deposited ova of a Hymenop- 

 terous insect, Cynips tinctoria. The galls are collected before the 

 maturing of the insect, and are obtained principally from Aleppo, 

 in Asiatic Turkey (p. 252). 



Aleppo Galls. Somewhat spherical, i to 2 cm. in diameter; 

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

 tuberculate above, the basal portion nearly smooth, and con- 

 tracted 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 occa- 

 sionally 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. 



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 iodine and prevents the 

 latter from giving the characteristic reaction with starch. 



Two classes of tannic acid are recognized, depending on their 

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

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

 and also found in chestnut (Castanca), pomegranate (Piinica) 

 and sumac (Rhus) ; (2) tannic acid, giving a greenish color with 

 ferric chloride, as that contained in oak barks (Quercus), cate- 



