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THE HONGKONG GOVERNMENT GAZETTE, 1ST APRIL, 1899.
513
If the flash takes place at any temperature below 77° Fahrenheit the temperature at which it occurs is to be recorded. The fresh portions of the sample are then to be successively tested in a similar manner and the results recorded. If no greater difference than 20 Fahrenheit exists between any two of the three recorded results, each result is to be corrected for atmos- pheric pressure, as hereafter described, and the average of the three corrected results is the flashing point of the sample. In the event of there being a greater difference than 2° Fahrenheit between any two of the results, the series of tests is to be rejected and a fresh series of three similarly obtained, and so on until a sufficiently concordant series is furnished, when the results are to be corrected and the average taken in the manner already described.
No flash which takes place within eight degrees of the temperature at which the testing is commenced shall be accepted as the true flashing point of the sample tested. In the event of a flash occurring at or below 64° when the test is applied in the manner above described, the next testing shall be commenced ten degrees lower than the temperature at which the flash had been previously obtained (that is to say, at 54° or thereunder) and this procedure shall be continued until the results of three consecutive tests do not show a greater difference than 2o.
If a temperature of 70° Fahrenheit has been reached without a flash occurring, the application of the test-flame is to be continued at every degree rise of temperature until a temperature of 95° Fahrenheit has been reached. If no flash has occurred up to this point, the tests shall not be continued, and the testing officer shall certify that the petroleum has a flashing point of over 95. But if the petroleum is petroleum tar or petroleum fuel, and is declared to liave its flashing point at or above 200°, the test shall be continued as follows:-The oil-cup is to be removed from the water-bath, and the temperature of the water in the water-bath is to be reduced to 95° Fahrenheit by pouring cold water into the funnel (the hot water escaping by the overflow-pipe). The air-chamber is then to be filled to a depth of 12 inches with water at a temperature of about 95° Fahrenheit, the oil-cup is to be replaced in the water-bath, and the spirit-lamp, attached to the water-bath, is to be lighted and placed underneath. The test-flame is then to be again applied, from 96° Fahrenheit, at every degree rise of temperature as indicated by the thermometer in the oil-cup until a flash takes place, or until a tempe- rature of 200° Fahrenheit has been reached. If during this operation the test-flame appears to diminish in size, the lamp is to be replenished in the manner prescribed (at 2) without interrupting the test.
If a flash occurs at any temperature between 76° and 200° Fahrenheit, the temperature at which it occurs, subject to correction for atmospheric pressure, is the flashing point of the sample.
In repeating a test, a fresh sample of oil must always be used, the tested sample being thrown away, and the cup must be wiped dry from any adhering oil, and cooled, as already described, before receiving the fresh sample.
5. CORRECTION FOR ATMOSPHERIC PRESSURE. AS the flashing point of an oil is influenced by changes in atmes- pheric pressure to an average extent of 10-6 Fahrenheit for every inch of the barometer, a correction of the observed flash- ing point may become necessary. The true height of the barometer must, therefore, be determined at the time of making the test for the flashing point. To facilitate the correction of a flashing point for pressure a table is appended, giving the flashing points of oils ranging from 65° to 80° Fahrenheit, under pressures ranging from 27 to 31 inches of mercury.
The table is used in the following manner :-
EXAMPLE. An oil has given a flashing point of 71°, the barometer being at 286; take the nearest number to 71° in the vertical column headed 28 6. This number is 70-8. Substitute for this the number in the same horizontal line in the column headed 30 (the normal height of barometer). The Substituted number, i.e., the true flashing point of the oil, is 73°.
TABLE for correction of FLASHING POINTS indicated by the Test for Variations in Barometric Pressure on either side of Thirty Inches.
27
27-2 27-4 27.6 27.8 28
BAROMETER IN INCHES.
28.2 284 286 288 29 29.2 294 296 29·8 | 30 | 30-230-4
FLASHING POINT IN DEGREES FAHRENHEIT,
|2306|30-1
30.8 31
60-2605 60.8 61.2 61.5 61-8] 62·1 62.4 62.8 63·1 | 63·4 687 64 644 647 6565,365⋅6 | 66 | 66.3 66.6 612 615 61.8 62.2 62.5 62.8 631 634 638 641 644 64-7 | 65 |65'4|65·7 | 66 | 66-366-6 | 67 | 67.3 67.6 62.2 62.5 628 63-2 63.5 63.8 641 644 648 651 | 65·4 65·7 6666.4 66·7 | 67 | 673 67.6 68 | 68.3 68.6 63.2 63.5 63.8 642 645 648| 65.1| 65·4 65·8 | 66·1 | 664 66·7 | 67 67-467·7 | 68 | 69.3 68.6 69 69.3 696 642 645 648 65-2 65·5| 65·8 | 66+1 | 66′4 66·8 67-1 674 67-7 68 68-468-7 | 69 69.3 69.6 70 | 70-370-6 65.2 65.5 65.8 66.2 66.5 66.8 671 674 67-8 68-1 | 68.4 68.7 69 69:4 69-7 | 70 | 70-370-6| 71 | 71-371-6 66-2 66.5 66.8 67.2 67.5 67.8 68.1 68.4 68.8 69.1 69.4 69-7 70 70-470-771 71-371-6 7272-372-6 67.2 67.5 67-8 68-2 68.5 68.8 69.1 69-4 69.8 70·1 70-470-7 71 71:4 71-7 72 72-372-6| 73 73.3 78.6 68.2 68.5 68.8 69.2 69.5| 69·8 | 70-1 | 70-4 70-8|71-171-471-7 | 72 724 72-7 7373-3 736 | 74 | 74-374-6 69.2 69.5 69-8 70-270-570-8 | 71·1 | 71-4] 718 72-172-472-7 73 73-4 73-7 7474-374-6 75 75-3 | 75.6 70-2 70.5 70.8 71.2 71-571-8 72-1 72-4 72-8 73-1734 73-7 74 74.4 74.7 7575-375-6 76 76-376*6 71-2 715 71·8 72-2 725 72-8 731 73-4 73-8 741744 74.7 75 75-475-7 76 76-3 76-6 77 77-877-6 72.2 72.5 72.8 78.2 73.5 73.8 74.1 74-4 748 75175-4757 76 |76-476·71 77 | 77-377-6 78 78.3 78.6 73.2 73.5 78.8 74.2 74-574-875-175-4 75·8 76·1764 767 77 | 77-4 777 78 78-378-67979-379-6 74-2 74.5 74.8 75.2 75-5 75-8 76-1 76-4 76.8 77.177-477-7 | 78 78-478-7 7979-379.6 80 80.3 80.6 75-275-5 75-876-2 765 76-877-1 774 778 78-178-478-779 79-479-78080-380-6 8181.3 81.6
COUNCIL CHAMBER,
HONGKONG.
J. G. T. BUCKLE, Clerk of Councils.