copper.
arsenic arsenic.
mercury mercury.
antimony antimony.
silver silver.
gold gold.
platina platina.
Argill argill.

[Note A: These combinations were unknown to the ancient chemists. The
order of affinity of the salifiable bases with this acid was determined
by Mr Bergman and by Mr de Breney of the Dijon Academy.--A.]

SECT. XXVIII.--_Observations upon Citric Acid, and its Combinations._

The citric acid is procured by expression from lemons, and is found in
the juices of many other fruits mixed with malic acid. To obtain it pure
and concentrated, it is first allowed to depurate from the mucous part
of the fruit by long rest in a cool cellar, and is afterwards
concentrated by exposing it to the temperature of 4 or 5 degrees below
Zero, from 21 deg. to 23 deg. of Fahrenheit, the water is frozen, and
the acid remains liquid, reduced to about an eighth part of its original
bulk. A lower degree of cold would occasion the acid to be engaged
amongst the ice, and render it difficultly separable. This process was
pointed out by Mr Georgius.

It is more easily obtained by saturating the lemon-juice with lime, so
as to form a citrat of lime, which is insoluble in water; wash this
salt, and pour on a proper quantity of sulphuric acid; this forms a
sulphat of lime, which precipitates and leaves the citric acid free in
the liquor.

TABLE _of the Combinations of Pyro-lignous Acid with the Salifiable
Bases, in the Order of Affinity(A)._

_Bases._ _Neutral Salts._

Lime Pyro-mucite of lime.
Barytes barytes.
Potash potash.
Soda soda.
Magnesia magnesia.
Ammoniac ammoniac.
Oxyd of
zinc zinc.
manganese manganese.
iron iron.
lead lead.
tin tin.
cobalt cobalt.
copper copper.
nickel nickel.
arsenic arsenic.
bismuth bismuth.
mercury mercury.
antimony