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.

SYMBOLS ACCORDING TO TABLE III.SECONDS REQUIRED FOR 1 C. C. OF OIL TO FLOW THROUGH AN ORIFICE OF 1 MM. (= .04 IN.)
Temp.{A} CENT. 4.5 10 15.5 21 26.5 32 37.5 43
FAHR. 40 50 60 70 80 90 100 110
E. K. w. 25 20 17 15 10 8.5 7 6
W. F. N. w. 27 20 14 11 9 8 7 6
D. C. S. w. 32 23.5 19 15 12.5 11.5 9.5 8
D. C. S. ch. 28 23 17 14 11.5 9 7 6
D. C. S. cl. 29 20 17 14.5 11 8.5 7 6.5
W. C. w. 24 20 18 13 11.5 10 8 7
B & K. w. 46 35 25 20 17 15 11.510
S. B. & Co. w. c. 21 16 11.5 10 9 8 7 6.5
C. L. Co. w. 14 10 9 6.5 5 4.5 4 3.5
C. L. Co. No. 1. 32 28 12.5 10 8.5 7.5 6.5 6
Glyc. 19 13 10 9.5 7.5 6.5 5.5 5
Alb. f. 25 19 16 13 10 8 6.5 5.5

[Note A: The readings of the Centigrade and Fahrenheit scales given here are not exactly equivalent; but they are near enough for all practical purposes.]

85. Mixed Oils have been tried by many who have been desirous of obtaining a better lubricant. A mixture of different kinds of animal or vegetable oils—or a combination of both—has usually proved worse than any single one of the components; as, when it is known that "alterations[26] of composition occur in the animal and vegetable oils with exposure to air and light and with advancing age" (74-2), it is obvious that this chemical action is accelerated by a mixture.

The mineral oils are not subject to such alterations to any serious extent; and, when they are compounded with animal or vegetable oils, the resulting mixture partakes of the good qualities of both, according to experiments which the author has made. It would make this paper[27] too lengthy to insert the results; however, a future opportunity may not be wanting.

86. Various Manufacturers of watches, chronometers and clocks, have favored the writer with more or less valuable information in answer to queries on the subject, which has been tabulated and which is shown in table XII.

It is necessary to know just what kind of oil has been used by the manufacturer of a time piece for three reasons:—

(1.) If some of the bearings need a small quantity of oil, being otherwise in such good condition—because of never having been used, in fact "new"—that it is unnecessary to take all the mechanism apart and clean it, it is very important that the operator know what kind, or variety, of lubricant has been previously used, in order not to "mix oils;" or, if a mixture is thus made, to make it intelligently. (85.)