The test is applied in the following manner:- The apparatus is placed where it is not exposed to draughts. The water-bath is filled by pouring water into the funnel d until it begins to flow out at the spout of the vessel. The temperature of the water at the commencement of the test is to be 130°; F. (54$° C), attained in the first instance either by mixing hot and cold water in the bath, or in a vessel from which the bath is filled, until the thermometer which is provided for testing the temperature of the water gives the proper indication; or by heating the water with the spirit-lamp (which is attached to the stand of the apparatus) until the required temperature is indicated.

When a test has been completed, this water-bath is again raised to 130° F. (54 1/2° C.) by placing the lamp underneath, and is readily achieved while the petroleum-cup Is being emptied, cooled, and refilled with a fresh sample to be tested. The lamp is then turned on its swivel from under the apparatus, and the next test is proceeded with.

The test-lamp is prepared for use by fitting it with a piece of flat plaited candle-wick, and filling it with colza- or rape-oil up to the lower edge of the opening of the wick-tube. The lamp is trimmed so that, when lighted, it gives a flame of about 0.15 in. diameter, and this size of flame, which is represented by the projecting white bead i on the cover of the oil-cup, is readily maintained by simple manipulation from time to time with a small wire trimmer.

When gas is available, it may be conveniently used in place of the little oil-lamp, and for this purpose a test-flame arrangement for use with gas may be substituted for the lamp.

The bath having been raised to the proper temperature, the oil to be tested is introduced into the petroleum-cup, being poured in slowly until the level of the liquid just reaches the point of the gauge which is fixed in the cup. In warm weather, the temperature of the room in which the samples to be tested have been kept should be observed in the first instance, and if it exceeds 65° F. (18° C), the samples should be cooled down to about 60° F. (15 1/2° C), by immersing the bottles containing them in cold water, or by any other convenient method. The lid of the cup, with the slide closed, is then put on, and the cup is placed in the bath. The thermometer in the lid of the cup has been adjusted so as to have its bulb just immersed in the liquid, and its position is not under any circumstances to be altered. When the cup has been placed in the proper position, the scale of the thermometer faces the operator.

The test-lamp is then placed in position upon the lid of the cup, the lead-line or pendulum, which has been fixed in a convenient position in front of the operator, is set in motion, and the rise of the thermometer in the petroleum-cup is watched. When the temperature has reached about 66° F. (19° C), the operation of testing is to be commenced, the test-flame being applied once for every rise of one degree, in the following manner:-The slide is slowly drawn open while the pendulum performs three oscillations, and is closed during the fourth oscillation.

If it is desired to employ the test apparatus to determine the flashing-points of oils of very low volatility, the mode of proceeding is to be modified as follows:-The air chamber which surrounds the cup is filled with cold water to a depth of 1} in., and the water-bath is filled as usual, but also with cold water. The lamp is then placed under the apparatus, and kept there during the entire operation. If a very heavy oil is being dealt with, the operation may be commenced with water previously heated to 120° F. (49° C), instead of with cold water.

The schedule omits to state that the length of the pendulum to be used shall be 2 ft. from the point of suspension to the centre of gravity of the weight.

The " flashing-point" of an oil is understood to mean the temperature at which the escaping vapour will momentarily ignite; the "burning-point" is that at which the oil takes Are and burns. Lubricating oils should always flash above 250° F. (120° C), and take fire at a considerably higher temperature. Animal and vegetable oils do not vaporize, but decompose at high temperatures, beyond the range of a water-bath. A comparison of petroleum, sperm-oil, and lard-oil showed the following respective figures:-Flashing-point: 245° F. (118° C), 425° F. (219° C), 475° F. (246° C); igniting-poiut: 290° F. (143° C), 485° F. (252° C), 525° F. (274° C.); burning-point: 300° F. (149° C), 500° F. (260° C), 525° F. (274° C.). The standard animal and vegetable lubricating oils, and all mineral oils of good body and high sp. gr., decompose or vaporize only at temperatures exceeding that of steam in ordinary engines, the former usually and latter sometimes bearing steam at locomotive pressure.

The precise value of any lubricating material is best ascertained by one of the many forms o lfapparatus devised for this purpose, such as McNaught's, Napier's, Ingham and Stapper's, Bailey's, Ashcrofta, Cross-ley's, Van Cleve's, Hodgson's, etc, fully described and figured in Thurston's work on Friction.

The suitability of a lubricating medium depends upon the character of the work being done, and is not constant. In order to procure the nearest possible approach to what is required for special purposes, many compounds are now in the market, being mainly mixtures of mineral and animal or vegetable oils in proportions calculated to develop the particular characteristics required. The general experience gained of various oils used for lubricating tends to the following results:-(1) A mineral oil flashing below 300° F. (149° C.) is unsafe, on account of causing fire; (2) a mineral oil evaporating more than 5 Per cent. in 10 hours at 140° F. (60° C.) is inadmissible, as the evaporation creates a viscous residue, or leaves the bearing dry; (3) the most fluid oil that will remain in its place, fulfilling other conditions, is the best for all light bearings at high speeds; (4) the best oil is that which has the greatest adhesion to metallic surfaces, and the least cohesion in its own particles: in this respect, fine mineral oils are 1st, sperm-oil 2nd, neatsfoot-oil 3rd, lard-oil 4th; (5) consequently the finest mineral oils are best for light bearings and high velocities; (6) the best animal oil to give body to fine mineral oils is sperm-oil; (7) lard- and neatsfoot-oils may replace sperm-oil when greater tenacity is required; (8) the best mineral oil for cylinders is one having sp. gr. 0.893 at 60° F. (15 1/2° C), evaporating-point 550° F. (288° C), and flashing-point 680° F. (360° C.); (9) the best mineral oil for heavy machinery has sp. gr. 0-880 at 60° F. (15. 1/2° C.) evaporating-point 443° F. (229° C), and flashing-point 518° F. (269° C); (10) the best mineral oil for light bearings and high velocities has sp. gr. 0.871 at 60° F. (15 1/2° C), evaporating-point 424° F. (218° C), and flashing-point 505° F.