140 



CUPULIFEILE 



aggregate and prismatic crystals of calcium oxalate (10 to 20 /* in diam.); cork 

 cells, pentagonal or hexagonal (20 to 30 p in diam.). 



CONSTITUENTS. Quercitannic acid 6 to n per cent., a coloring matter, a bitter 

 principle (quercin), sugar (quercite), resin, etc. The active principles are 

 soluble in water and alcohol. The amount of tannin varies with the species, 

 the part of the tree, and the season of the year when gathered ; the young bark 

 contains a greater proportion than the old. 



Quercitannic Acid. Two forms of this principle exist, according to Lowe 

 one soluble in water, of the formula C^sH^Ou, and the other scarcely soluble, 

 CjgHnOij. Both are changed by the loss of water into oak red, CjgHjjOn. 



FIG. 58. Quercus alba Branch. 



Quercitron. Under this name large quantities of black oak (Quercus 

 tinctoria) bark deprived of its epidermis and reduced to a coarse powder 

 are sent from the United States to Europe as a dye. The coloring principle 

 is called quercitron, CssHssOso. This glucoside splits up by hydrolysis into 

 quercetin and isodulcite, or rhammose, CeHuOsCCsHgOsCHs). Quercetron 

 (Xantho rhamnin) forms yellowish crystals, odorless and tasteless, but in hot 

 aqueous or alcoholic solution has a bitter taste. 



Preparation of Quercin. Boil bark in acidulated (H 2 SO4) water; add milk 

 of lime to neutralize; filter; add K 2 CO 3 . Yellow needles slowly form on evapora- 

 tion of alcoholic solution of above precipitate. 



ACTION AND USES. Astringent and tonic, generally used externally in infusion or 

 decoction as an astringent and tonic bath, injection, etc. Dose: 15 to 60 gr. 

 (i to 4 Gm.). Fluidextractum Quercus, average dose 2 mils. 



