hole apparatus is it
necessary to be more careful than with the couplings which connect the
various absorber systems with each other and with the valves; for these
couplings are opened and closed once every hour or two and hence are
subject to considerable strain at the different points. If they are not
tight the experiment is a failure so far as the determination of oxygen
is concerned. For the various parts of the absorber system we have
relied upon the original type of couplings used in the earlier
apparatus. A rubber gasket is placed between the male and female part of
the coupling and the closure can be made very tight. In fact, after the
absorbers are coupled in place they are invariably subjected to severe
tests to prove tightness.

For connecting the piping between the calorimeter and the absorption
system we use ordinary one-inch hose-couplings, firmly set up by means
of a wrench and disturbed only when necessary to change from one
calorimeter chamber to another.

ABSORBER TABLE.

The purifying apparatus for the air-current is compactly and
conveniently placed on a solidly constructed table which can be moved
about the laboratory at will. The special form of caster on the bottom
of the posts of the table permits its movement about the laboratory at
will and by screwing down the hand screws the table can be firmly fixed
to the floor.

The details of the table are shown in fig. 30. (See also fig. 4, page
4.) The air coming from the calorimeter passes in the direction of the
downward arrow through a 3/4-inch pipe into the blower, which is
immersed in oil in an iron box F. The blower is driven by an electric
motor fastened to a small shelf at the left of the table. The air
leaving the blower ascends in the direction of the arrow to the valve
system H, where it can be directed into one of the two parallel sets of
purifiers; after it passes through these purifiers (sulphuric-acid
vessel 2, potash-lime container K, and sulphuric-acid vessel 1) it goes
through the sodium-bicarbonate can G to a duplicate valve system on top
of the table. From there it passes through a pipe along the top of the
table and rises in the vertical pipe to the hose connection which is
coupled with the calorimeter chamber.

The electric motor is provided with a snap-switch on one of the posts of
the table and a regulating rheostat which permits variations in the
speed of the motor and consequently in the ventilation produced by the
blo