_Bases._ _Neutral Salts._
Barytes Citrat of barytes.
Lime lime.
Magnesia magnesia.
Potash potash.
Soda soda.
Ammoniac ammoniac.
Oxyd of
zinc zinc.
manganese manganese.
iron iron.
lead lead.
cobalt cobalt.
copper 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 to 23 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
183