lately.--A.]
SECT. XXIX.--_Observations upon Pyro-lignous Acid, and its
Combinations._
The ancient chemists observed that most of the woods, especially the
more heavy and compact ones, gave out a particular acid spirit, by
distillation, in a naked fire; but, before Mr Goetling, who gives an
account of his experiments upon this subject in Crell's Chemical Journal
for 1779, no one had ever made any inquiry into its nature and
properties. This acid appears to be the same, whatever be the wood it is
procured from. When first distilled, it is of a brown colour, and
considerably impregnated with charcoal and oil; it is purified from
these by a second distillation. The pyro-lignous radical is chiefly
composed of hydrogen and charcoal.
SECT. XXX.--_Observations upon Pyro-tartarous Acid, and its Combinations
with the Salifiable Bases[46]._
The name of _Pyro-tartarous acid_ is given to a dilute empyreumatic acid
obtained from purified acidulous tartarite of potash by distillation in
a naked fire. To obtain it, let a retort be half filled with powdered
tartar, adapt a tubulated recipient, having a bent tube communicating
with a bell-glass in a pneumato-chemical apparatus; by gradually raising
the fire under the retort, we obtain the pyro-tartarous acid mixed with
oil, which is separated by means of a funnel. A vast quantity of
carbonic acid gas is disengaged during the distillation. The acid
obtained by the above process is much contaminated with oil, which ought
to be separated from it. Some authors advise to do this by a second
distillation; but the Dijon academicians inform us, that this is
attended with great danger from explosions which take place during the
process.
TABLE _of the Combinations of Pyro-mucous Acid, with the Salifiable
Bases, in the Order of Affinity(A)._
_Bases._ _Neutral Salts._
185