The course of the operation in the saturator may be followed by an
inspection of the water level, n, seen at the front and side in Figs.
2 and 3. This apparatus, in which the pressure reaches 4 to 6
atmospheres in the manufacture of Seltzer water or gaseous lemonade in
bottles, and from 10 to 12 atmospheres in that of Seltzer water in
siphons, is provided also with a pressure gauge, m, and a safety
valve, both screwed, as is also the tube, n², into a sphere, S, on
the top of the saturator.

_Apparatus for Using Carbonate of Lime_ (Figs 2, 3, and 10)--When chalk
is acted upon by sulphuric acid, there is formed an insoluble sulphate
which, by covering the chalk, prevents the action of the acid from
continuing if care be not taken to constantly agitate the materials.
This has led to a change in the arrangement of the generator in the
apparatus designed for the use of chalk.

It consists in this case of a leaden vessel, D, having a hemispherical
bottom set into a cylindrical cast iron base, K, and of an agitator
similar to that shown in Fig. 11, for keeping the chalk in suspension in
the water. These latter materials are introduced through the mouth, B
(Fig. 3). Then a special receptacle, C, of lead, shown in detail in Fig.
10, and the cock, c, of which is kept closed, is filled with sulphuric
acid. The acid is not introduced directly into the vessel, C, but is
poured into the cylinder, C, whose sides contain numerous apertures
which prevent foreign materials from passing into the siphon tube c,
and obstructing it.

To put the apparatus in operation, the acid cock, c, is opened and the
wheel, A, is turned, thus setting in motion both the pump piston, P, and
the agitator, within S and D. Then the play of the pump produces a