absorption of the oxide of carbon; and yet, for the lost fractions of
the latter, it is necessary to replace a part of the absorbing liquid
three or four times. The absorbing liquid is prepared by making a
saturated solution of chloride of copper in hydrochloric acid, and
adding thereto a small quantity of dissolved chloride of tin. Afterward,
there are added to the decanted mixture a few spirals of red copper, and
the mixture is then carefully kept from contact with the air.

To fill the burette with gas, the three-way cock, _a_, is so placed that
the axial aperture shall be in communication with the graduated part, A,
of the burette. After this, water is poured into the funnel, t, and the
burette is put in communication with the gas reservoir by means of a
rubber tube. The lower point of the burette is put in communication with
a rubber pump, V (Fig. 2), on an aspirator (the cock, _b_, being left
open), and the gas is sucked in until all the air that was in the
apparatus has been expelled from it. The cocks, _a_ and _b_, are turned
90 degrees. The water in the funnel prevents the gases communicating
with the top. The point of the three-way cock is afterward closed with a
rubber tube and glass rod.

If the gas happens to be in the reservoir of an aspirator, it is made
to pass into the apparatus in the following manner: The burette is
completely filled with water, and the point of the three-way cock is
put in communication with a reservoir. If the gas is under pressure, a
portion of it is allowed to escape through the capillary tube into the
water in the funnel, by turning the cock, _a_, properly, and thus all
the water in the conduit is entirely expelled. Afterward _a_ is turned
180 deg., and the lower cock, _b_, is opened. While the water is flowing
through _b_, the burette becomes filled with gas.