This order of salts, entirely unknown to the ancient chemists, was
discovered in 1786 by Mr Berthollet.--A.
SECT. XIX.--_Observations upon Muriatic and Oxygenated Muriatic Acids,
and their Combinations._
Muriatic acid is very abundant in the mineral kingdom naturally combined
with different salifiable bases, especially with soda, lime, and
magnesia. In sea-water, and the water of several lakes, it is combined
with these three bases, and in mines of rock-salt it is chiefly united
to soda. This acid does not appear to have been hitherto decomposed in
any chemical experiment; so that we have no idea whatever of the nature
of its radical, and only conclude, from analogy with the other acids,
that it contains oxygen as its acidifying principle. Mr Berthollet
suspects the radical to be of a metallic nature; but, as Nature appears
to form this acid daily, in inhabited places, by combining miasmata with
aeriform fluids, this must necessarily suppose a metallic gas to exist
in the atmosphere, which is certainly not impossible, but cannot be
admitted without proof.
The muriatic acid has only a moderate adherence to the salifiable bases,
and can readily be driven from its combination with these by sulphuric
acid. Other acids, as the nitric, for instance, may answer the same
purpose; but nitric acid being volatile, would mix, during
distillation, with the muriatic. About one part of sulphuric acid is
sufficient to decompose two parts of decrepitated sea-salt. This
operation is performed in a tubulated retort, having Woulfe's apparatus,
(Pl. IV. Fig. 1.), adapted to it. When all the junctures are properly
lured, the sea-salt is put into the retort through the tube, the
sulphuric acid is poured on, and the opening immediately closed with its
ground crystal stopper. As the muriatic acid can only subsist in the
gaseous form in the ordinary temperature, we could not condense it
without the presence of water. Hence the use of the water with which the
bottles in Woulfe's apparatus are half filled; the muriatic acid gas,
driven off from the sea-salt in the retort, combines with the water, and
forms what the old chemists called _smoaking spirit of salt_, or
_Glauber's spirit of sea-salt_, which we now name _muriatic acid_.
170