Friction, Lubrication and the Lubricants in HorologyLewis, W. T. (William T.)
Science
Friction, Lubrication and the Lubricants in Horology
Lewis, W. T. (William T.)
Clock and watch making; Friction; Lubrication and lubricants
AA represents an ordinary retort stand, with adjustable arms, BB, for
holding in position the thermometer C, and the funnel DD capable of
holding about one pint of water. EE is the viscosimeter proper, a glass
tube, swollen at the lower end, and terminating in a circular orifice of
1 millimeter (= .04 inch) in diameter;[25] being a "pipette" holding one
cubic centimeter of oil between the dotted lines U and O.
F is a flexible gum elastic tube fitting with an air-tight joint to the
upper end of the glass tube. The funnel is closed at its lower end by a
tightly-fitting cork H, in which an opening is made, through which
opening the pipette passes and projects slightly below. G is a small,
shallow vessel, preferably of glass, of sufficient capacity to receive
the contents of the pipette. S is a syphon composed of a glass tube in
two sections--united by a short piece of rubber tube on which the
device P pinches by the adjustment of the lever L--the bent section
beginning near the bottom of the funnel, while the straight section
terminates below the level of the table on which the retort stand is
placed.
In operating with this, the author proceeded as follows: The funnel was
partially filled with water, and hot water added until its temperature
reached 43° C. (= 110° F). A sufficient quantity of the oil to be tested
was placed in the glass vessel G, and drawn into the viscosimeter by
gentle suction of the mouth until it exactly reached the line U, where
it was retained, by a slight pressure with the thumb and finger, for
five minutes, the temperature of the water in the funnel being kept
constant. At the end of that time, after being sure that all the
conditions as to temperature and quantity of oil were satisfied, the
pressure of the thumb and finger was relaxed, when the oil began to drop
through the lower end of the pipette.
The time required for the upper surface of the oil to fall from U to O
was carefully ascertained by means of a "stop watch," and the number of
seconds noted. In case of doubt the test was repeated.
The temperature of the water in the funnel was then lowered by the
addition of ice, to 38° C. (= 100° F.), when the operation was again
performed as just described. This was repeated at regular intervals of
temperature down to 4° C. (= 40° F), when the water was again heated,
the pipette thoroughly cleansed by introducing benzine into the pipette
in a manner similar to that by which the oil was introduced. The surplus
water which accumulated in the funnel was allowed to escape through the
syphon by relaxing the lever of the pinching device. It is obvious that
the number of seconds, in each case, corresponds to the viscosity. Other
oils were put through the same course, the results obtained being shown
in table XI.
TABLE XI.
RELATIVE VARIATIONS OF VISCOSITY OF OILS IN VARYING TEMPERATURES.
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