G, (Pl. V. Fig. 5.), into which the sea-salt is introduced, well
dried[13], we then pour on some concentrated sulphuric acid, and
immediately introduce the beak of the retort under little jars or
bell-glasses A, (same Plate and Fig.), previously filled with
quicksilver. In proportion as the acid gas is disengaged, it passes into
the jar, and gets to the top of the quicksilver, which it displaces.
When the disengagement of the gas slackens, a gentle heat is applied to
the retort, and gradually increased till nothing more passes over. This
acid gas has a very strong affinity with water, which absorbs an
enormous quantity of it, as is proved by introducing a very thin layer
of water into the glass which contains the gas; for, in an instant, the
whole acid gas disappears, and combines with the water.
This latter circumstance is taken advantage of in laboratories and
manufactures, on purpose to obtain the acid of sea-salt in a liquid
form; and for this purpose the apparatus (Pl. IV. Fig. 1.) is employed.
It consists, 1st, of a tubulated retort A, into which the sea-salt, and
after it the sulphuric acid, are introduced through the opening H; 2d,
of the baloon or recipient c, b, intended for containing the small
quantity of liquid which passes over during the process; and, 3d, of a
set of bottles, with two mouths, L, L, L, L, half filled with water,
intended for absorbing the gas disengaged by the distillation. This
apparatus will be more amply described in the latter part of this work.
Although we have not yet been able, either to compose or to decompound
this acid of sea-salt, we cannot have the smallest doubt that it, like
all other acids, is composed by the union of oxygen with an acidifiable
base. We have therefore called this unknown substance the _muriatic
base_, or _muriatic radical_, deriving this name, after the example of
Mr Bergman and Mr de Morveau, from the Latin word _muria_, which was
anciently used to signify sea-salt. Thus, without being able exactly to
determine the component parts of _muriatic acid_, we design, by that
term, a volatile acid, which retains the form of gas in the common
temperature and pressure of our atmosphere, which combines with great
facility, and in great quantity, with water, and whose acidifiable base
adheres so very intimately with oxygen, that no method has hitherto been
devised for separating them. If ever this acidifiable base of the
muriatic acid is discovered to be a known substance, though now unknown
in that capacity, it will be requisite to change its present
denomination for one analogous with that of its base.
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