6 ORD. II. Amentacex. QUERCUS INFECTORIA 
litmus, and forms precipitates with solutions of the following substances :— 
isinglass, lime-water, subcarbonate of potass, acetate of lead, sulphate of 
copper, nitrate of silver, sulphate of iron, nitrate of mercury, tartrate of anti- 
mony, and the infusions of Columbo root, Cusparia bark, and Cinchona 
bark. The muriate of mercury renders the infusion milky and opaque; but 
no precipitate is formed. Nitrous acid, sulphate of zinc, infusion of quassia, 
ammonia, and infusion of saffron, occasion no precipitate. A saturated de- 
coction of gall,.on cooling, deposits a copious pale yellow precipitate, which 
appears to be. purer tannin than can be got by any other process. Alcohol 
takes up nearly seven parts out of ten, and ether five. Newmann obtained 
from 960 grains of coarsely powdered galls, 840 watery extract, and after- 
wurds 4 alcoholic ; and inversely, 760 alcoholic, and 80 watery. The ethe- 
real tincture, when evaporated on water, leaves on the side of the glass an 
_opaque pellicle, and on the surface of the water small drops of an oily resin- 
ous-like matter, while the substratum of water becomes charged with tannin 
and gallic acid. The alcoholic tincture reddens litmus, and forms precipi- 
tates with the re-agents as the watery infusion. To what principles these 
precipitates are owing, remains to be ascertained. It is observed by Vauquelin, 
that the infusions of nut-galls and cinchona, agree in precipitating both ge- 
latine and tartrate of antimony, and that they precipitate each other. We 
are told by Dr, Duncan, that, in his experiments, “ a saturated mixture of 
the infusions of nut-galls and cinchona still precipitate gelatine; but infu- 
sions, separately saturated by gelatine, do not act on each other.” Hence 
it appears, that the action of the infusions on each other, depends on prin- 
ciples contained in each, compatible with the presence of tannin, but re-act 
ing on each other, and that gelatine precipitates the principles, along with 
the tannin. It has been generally asserted, that the precipitate of tannin - 
and gelatine is insoluble in water, either cold or hot; but I find, that in 
boiling water, it not only becomes soft and viscid, but a certain portion is 
dissolved, which separates again when the solution cools.”* M. Braconnot 
has discovered in nut-galls a new acid, which he has named Ellagic.t This 
acid is in the form of a white powder, with a slight tinge of red, itis insipid, 
inodorous, and insoluble in boiling water; combined with nitric acid, and 
gently heated, the mixture acquires a deep red colour. Galls also yield, by 
distillation with water, a small portion of a concrete, volatile oil.t . 
* Edin. New Dispensatory. + Ann. de Chim. et Phys. t. ix. p. 187. + Phil. Mag. 
