or resin called Benzoin: The means of procuring it, _via humida_, was
discovered by Mr Geoffroy, and perfected by Mr Scheele. Upon benzoin,
reduced to powder, pour strong lime-water, having rather an excess of
lime; keep the mixture continually stirring, and, after half an hour's
digestion, pour off the liquor, and use fresh portions of lime-water in
the same manner, so long as there is any appearance of neutralization.
Join all the decanted liquors, and evaporate, as far as possible,
without occasioning cristallization, and, when the liquor is cold, drop
in muriatic acid till no more precipitate is formed. By the former part
of the process a benzoat of lime is formed, and, by the latter, the
muriatic acid combines with the lime, forming muriat of lime, which
remains dissolved, while the benzoic acid, being insoluble,
precipitates in a concrete state.
SECT. XXXVII.--_Observations upon Camphoric Acid, and its Combinations
with Salifiable Bases[49]._
Camphor is a concrete essential oil, obtained, by sublimation, from a
species of laurus which grows in China and Japan. By distilling nitric
acid eight times from camphor, Mr Kosegarten converted it into an acid
analogous to the oxalic; but, as it differs from that acid in some
circumstances, we have thought necessary to give it a particular name,
till its nature be more completely ascertained by farther experiment.
As camphor is a carbono-hydrous or hydro-carbonous radical, it is easily
conceived, that, by oxygenation, it should form oxalic, malic, and
several other vegetable acids: This conjecture is rendered not
improbable by the experiments of Mr Kosegarten; and the principal
phenomena exhibited in the combinations of camphoric acid with the
salifiable bases, being very similar to those of the oxalic and malic
acids, lead me to believe that it consists of a mixture of these two
acids.
SECT. XXXVIII.--_Observations upon Gallic Acid, and its Combinations
with Salifiable Bases[50]._
The Gallic acid, formerly called Principle of Astringency, is obtained
from gall nuts, either by infusion or decoction with water, or by
195