88 



tannic acid). To obtain it, extract pulverised nutgalls with common 

 father of 0-740 to 0'750; evaporate the tincture to dryness, and 

 remove I'esin, fat, and gallic acid with anhydrous ethei\ — White, 

 or slightly yellowish, loose, amorphous, resinous, easily friable 

 mass of faint, mostly a little ethereous odoiir, of highly adsti-ingent 

 taste, and of sti-ongly acid reaction; fuses incom])letely with heat, 

 swells up, and becomes carbonised, yielding a sublimate of pyro- 

 gallic acid (C12H6O6). Dissolves most readily in water, more 

 readily in hydrated than in anhydrous alcohol, slightly in anhy- 

 drous ether, readily in hydrated ether, which solution soon 

 separates into two portions, the lower of which contains most of 

 the acid with water and a little ethei-, and the ujiper stratum 

 a little of the acid only, water, and most of the ether. It secedes 

 on boiling with diluted sulphuric acid into gallic acid and glucose, 

 likewise with alkalies ; but then the sugar is instantly changed 

 into humus-like products. It throws down the glue in grey elastic 

 flocks, which re-dissolve in an excess of the glue. It does not 

 alter the salts of suboxyd of iron, but precipitates the solutions of 

 the oxyd blue or bhie-black, even when very much diluted; this 

 precipitate is in appearance quite similar to the one obtained by 

 gallic acid, but difiers from it by its behaviour towards alkalies 

 and acetic acid (see Gallic acid). Only the tannates of the alkalies 

 are soluble in water, but decompose easily when exposed to the 

 air. Even the aqueous solution of the pure acid becojnes soon 

 decomposed, turns mouldy, and deposes gallic acid. 



drill llboit'O. Exudation of the stem of Garcinia Cochinchinensis, 

 (G. pictoria and G. Morella), more or less brown yellow, yields a 

 bright yellow powder, has a faint odour and an acrid, rancid, 

 afterwards sweetish taste. Contains about 80% resin and 18% 

 gum. The resin, also called Gambogic acid, obtained by 

 extracting with ether, is cherry-red, almost opaque, yields a beau- 

 tiful yellow powder, is inodorous and tasteless, dissolves readily in 

 alcohol and ether, in alkalies, in concentrated sulphuric acid with 

 red colour, and precipitable by water without change, has an acid 

 reaction, and is composed according to the formula C40 H24 s • 



Gardenia Tsnillic Acids. In the Chinese wongshy (the fruits of 

 Gardenia grandifloi'a) . 



First Acid=C4s H.28 O26 + 8 HO. Exhaust the fruits with alco- 

 hol, evaporate the extracts in a current of carbonic acid gas, remove 

 by means of a moistened filter the oil, which separates on cooling 

 and on addition of water, and precipitate the red-yellow filtrate 

 with acetate of lead, which throws doA\ai pigment and the First 

 acid (the filti'ate serves for the pi'eparation of clilorrubiu). De- 

 compose the precipitate under water with sulphuret of hydrogen, 

 filter, again jn-ecipitate the filtrate with acetate of lead, decompose 

 again with suljihuret of hydrogen, whereby the whole of the 



