Section 5. The test-lamp is then placed in position upon the lid of the cup, the lead line or pendulum,* which

5. 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°, 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. Note.—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 1½ inches, and the heating vessel or 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°, instead of with cold water. *This pendulum is two (2) feet in length from the point of suspension to the centre of gravity of the weight.