te
powder precipitates, which is the saccholactic acid discovered by
Scheele. It is susceptible of combining with the alkalies, ammoniac, the
earths, and even with the metals: Its action upon the latter is hitherto
but little known, except that, with them, it forms difficultly soluble
salts. The order of affinity in the table is taken from Bergman.

TABLE _of the Combinations of Formic Acid, with the Salifiable Bases, in
the Order of Affinity._

_Bases._ _Neutral Salts._

Barytes Formiat of barytes.
Potash potash.
Soda soda.
Lime lime.
Magnesia magnesia.
Ammoniac ammoniac.
Oxyd of
zinc zinc.
manganese manganese.
iron iron.
lead lead.
tin tin.
cobalt cobalt.
copper copper.
nickel nickel.
bismuth bismuth.
silver silver.
Argill argill.

_Note._--All unknown to the ancient chemists.--A.

SECT. XLI.--_Observations upon Formic Acid, and its Combinations._

This acid was first obtained by distillation from ants, in the last
century, by Samuel Fisher. The subject was treated of by Margraff in
1749, and by Messrs Ardwisson and Ochrn of Leipsic in 1777. The formic
acid is drawn from a large species of red ants, _formica rufa, Lin._
which form large ant hills in woody places. It is procured, either by
distilling the ants with a gentle heat in a glass retort or an alembic;
or, after having washed the ants in cold water, and dried them upon a
cloth, by pouring on boiling water, which dissolves the acid; or the
acid may be procured by gentle expression from the insects, in which
case it is stronger than in any of the former ways. To obtain it pure,
we must rectify, by means of distillation, which separates it from the
uncombined oily and charry matter; and it may be concentrated by
freezing, in the manner recommended for treating the acetous acid.

SECT. XLII.--_Observations upon Bombic Acid, and its Combinations with
Acidifiable Bases[52]._

The juices of the silk worm seem to assume an acid quality when that
insect changes from a larva to a chrysalis. At the moment of its escape
from the latter to the butterfly form, it emits a reddish liquor which
reddens blue paper, and which was first attentively observed by Mr
Chaussier of the Dijon academy, who obtains the acid by infus