24° Mr. Davy’s Experiments and Observations 
Fahrenheit, by repeatedly pouring distilled water upon the 
best Aleppo galls broken into small pieces, and suffering it to 
remain in contact with them till the saturation was complete, 
was of the specific gravity 1.068. Four hundred grains of it pro- 
duced, by evaporation at a temperature below 200°, fifty- three 
grains of solid matter ; which, as well as I could estimate, by the 
methods of analysis that have been just described, consisted of 
about JL of tannin, or matter precipitable by gelatine, and JL 
of gallic acid, united to a minute portion of extractive matter. 
100 grains of the solid matter obtained from the infusion, 
left, after incineration, nearly 4-| grains of ashes ; which were 
chiefly calcareous matter, mixed with a small portion of fixed 
alkali. The infusion strongly reddened paper tinged with litmus. 
It was semitransparent, and of a yellowish-brown colour. 
Its taste was highly astringent. 
When sulphuric acid was poured into the infusion, a dense 
whitish precipitate was produced ; and this effect was constant, 
whatever quantity of the acid was used. The residual liquor, 
when passed through the filtre, was found of a shade of colour 
deeper than before. It precipitated gelatine, and gave a dark 
colour with the oxygenated sulphate of iron. 
The solid matter remaining on the filtre, slightly reddened 
vegetable blues ; and, when dissolved in warm water, copiously 
precipitated the solutions of isinglass. M. Proust,* who first 
paid attention to its properties, supposes that it is a compound 
of the acid with tannin : but I suspect that it also contains 
gallic acid, and probably a small portion of extractive matter. 
* The fact of the precipitation of solution of galls by acids, was noticed by M- 
Dize'. See Annales de Chimie, Tome XXXV. p. 37. 
