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34
Uniting gas bubbles
Viscosity standards
down 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.
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.
CANNON
®
Instrument Company recommends that laboratories check
their kinematic viscosity measurements with viscosity standards. If the
laboratory is using CANNON
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.
®
TE-1500 Thermoelectric Constant Temperature Bath
CANNON
Revision 1.1b—January, 2007; CANNON
2139 High Tech Road • State College, PA 16803 • USA
®
calibrated viscometers and has developed
®
Instrument Company
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