THE VISCOMETER 79 f
efflux method has been worked out through the labors of Graham 5
(1846-1861), O. E. Meyer (1866-1873), Puluj (1876), E. Wiede- I
mann (1876), Breitenbach (1899), and Schultze (1901). We may 1
describe briefly the form used by Schultze as illustrating tihe |
modifications which are necessary in the apparatus used for \
liquids, In Fig. 31 the glass capillary, Z = 52.54 cm, R = \
0.007572 cm, is contained in the upper chamber of the hath /, ;•
which is maintained at constant temperature by water, water |
vapor, or aniline vapor. A condenser is shown at b and SS is a i
shield to protect the rest of the apparatus from the radiation.
On either side of the bath the apparatus is exactly similar, so that I
only the right side is shown in. the figure. The gas is contained I
in the bulbs P and Q (and J?r and Q' on tie left side) surrounded 'I
by a separate bath. The lower bulbs are each connected with
two stop cocks B and C (or B' and C'); from B (or 5') a rubber 1
tube leads to the mercury reservoir G (or (?'), aad from C (or C') ?
there is a glass tuhe drawn out into a capillary. Adj acent to both
the capillary and the bulbs, considerable lengths of glass tubing
are put in connection and immersed in the respective baths in
order that the gas in the capillary or bulbs may be at the desired
temperature at the time of measurement. In each tube leading
from the bulbs to the capillary there is a stop eock A (and A'} \ \
and a connection with a manometer K (and #')- By means of
stop cocks at E and E1 the two manometers may he connected
together or gas admitted to the apparatus from outside. Since
the presence of water vapor is objectionable and gases are
more or less soluble in water, the manometer contains both mer-
cury and water, and is calibrated before use.
In makin'g a measurement, enough, gas is admitted into
the evacuated apparatus so that at atmospheric pressure, the
surface of the mercury is in the lower part of the bulb Q and in
the middle part of the bulb Q'. The stop cock A is then closed
and the mercury reservoirs G and <?' raised, but the former
enough higher than the latter so that a pressure head is estab-
lished which is a few millimeters greater than is desired in the
measurement. The mercury fills the two bulbs Q and Q'. When
the temperature is constant the stop cock A is opened. The
pressure is immediately adjusted and thereafter maintained
constant by means of the screws F and Fr which serve to slowly