suction in the washers and from thence in the generator and causes the
acid in the vessel, C, to flow into the generator through the leaden
siphon tubes, c. Coming in contact with the chalk in suspension, the
acid produces a disengagement of gas which soon establishes sufficient
pressure to stop the flow of the acid and drive it back into the siphon
tube. The play of the pump continuing, a new suction takes place and
consequently a momentary flow of acid and a new disengagement of gas.
Thus the production of the latter is continuous, and is regulated by the
very action of the pump, without the operator having to maneuver an
acid-cock. The latter he only has to open when he sets the apparatus in
operation, and to close it when he stops it.

The arrangement of the washer is the same as in the preceding apparatus,
save that a larger cylindrical copper reservoir, G', is substituted for
the lower flask. The pump and saturator offer nothing peculiar.

A bent tube, u, which communicates with the generator, D, on one side,
and with a cylindrical tube, V, ending in a glass vessel on the other,
serves as a safety-valve for both the generator and the acid vessel.

The consumption of chalk is about 2.5 kilogrammes, and the same of acid,
for charging 100 siphons or 150 bottles. The apparatus shown in the
figure is capable of charging 600 siphons or 900 bottles per day.

_An Apparatus Completely Mechanical in Operation_ (Fig. 11).--This
apparatus consists of two very distinct parts. The saturator, pump, and
driving shaft are supported by a hollow base, in whose interior are
placed a copper washer and the water-inlet controlled by a float-cock.
This part of the apparatus is not shown in the plate. The generator,
partially shown in Fig. 11, is placed on a base of its own, and is