li Historical Sketch of the Physical Sciences, 1818. 
uelin on the same subject, of both which an account will be 
found in the Annals of Philosophy, xii. 290. 
12. Gallic Acid.—M. Braconnot, who has turned a great deal 
of his attention to vegetable substances, has published a method 
of procuring gallic acid, which promises to be more economical 
and much more effectual than any of the processes hitherto 
proposed. It is founded on the original process of Scheele, 
which, however, Braconnot has shortened, and considerably 
modified. His process, as he has described it, is as follows : 
Two hundred and fifty grammes of nutgalls were infused for 
four days in a litre of water (nearly half a pound avoirdupois of 
nutgalls in a wine-quart of water), taking care to agitate the 
mixture from time to time. The whole was then squeezed 
through a cloth, and the liquid passed through a filter. It was 
then left in an open glass caraf from July 22 to Sept. 22. No 
sensible quantity had diminished, but it had deposited a consi- 
derable quantity of crystals of gallic acid. These were separated 
by squeezing the liquid through a cloth. The liquid, when evapo- 
rated to the consistence of a syrup, deposited an additional 
quantity of crystals, which were separated in the same manner. 
The residual matter of nutgalls from which the infusion had been 
procured, when moistened with water, and left to spontaneous 
fermentation, yielded an additional crop of crystals when treated 
with hot water; so that nutgalls, when properly treated, yield 
the fifth part of their weight of gallic acid. 
By these different processes, M. Braconnot obtained 62 
grammes of gallic acid, still coloured, and mixed with an inso- 
luble powder. It was boiled with three decilitres (18 cubic 
inches) of water, and filtered while boiling hot. The liquid on 
cooling deposited 40 grammes of crystals of gallic acid of a yel- 
lowish-white colour. The mother-water was brown, and when 
properly evaporated yielded 10 grammes more of crystallized 
gallic acid, darker coloured than the first crystals. To free these 
crystals entirely from colouring matter, they were mixed with 
eight times their weight of water and about the fifth of their 
weight of ivory black, and the mixture was kept for about a 
uarter of an hour at the boiling temperature. It was then 
filtered while hot. On cooling, it concreted into a mass of 
perfectly white crystals of gallic acid, which were separated from 
the liquid by pressure in a cloth. 
The acid thus obtained is white, like snow, and quite pure. 
Its aqueous solution is not rendered muddy by a solution of glue. 
Its taste is weakly acid, and it leaves in the mouth an impression 
of sweetness.—(Ann. de Chim. et Phys. ix. 181.) 
13. Ellagie Actd.—By this very absurd name (the French 
term galle reversed), Braconnot has thought proper to distinguish 
an acid substance which he extracted from nutgalls at the same 
time with gallic acid. Chevreul, in a note published inthe Ann. 
de Chim. et Phys. ix. 329, informs us that he had given to the 
