32
CANNON
®
CT-1000 Constant Temperature Bath
Revision 3.1a—February, 1998;
CANNON
®
Instrument Company
P.O . Box 16 • State College, PA • USA
the capillary. Another method consists of gently tapping the stem above
the separation against the palm of the hand, forcing the organic fluid to
break away from the wall of the capillary and flow down the bore to join
the main column.
Uniting gas bubbles
Minute gas bubbles, which are sometimes found along the surface of the
mercury in the thermometer bulb, may be collected by “washing” the bulb
with a large gas bubble. Bring all of the mercury into the bulb as outlined
in section (A). Hold the thermometer in a horizontal position and gently
tap it against the hand to form a large gas bubble. Force the bubble to
travel around the walls of the bulb by rotating the thermometer and
tapping it against the palm of the hand. When the entire surface has been
“washed” rotate the bubble to the top of the bulb and reunite the mercury
as described above.
All of these manipulations require patience, and experience is helpful, but
they will yield results if care is used. Results can be verified by checking
the ice point or some other reference point on the scale.
Viscosity standards
CANNON
®
Instrument Company recommends that laboratories check
their kinematic viscosity measurements with viscosity standards. If the
laboratory is using
CANNON
®
calibrated viscometers and has developed
a good measuring technique, kinematic viscosity determination using a
standard will often point to temperature errors.
Viscosity standards should
not
be used to establish the correct tempera-
ture of the bath, however. Bath temperature should be checked and
corrected by applying the reliable thermometric techniques outlined
above.