“It is desirable that a gasoline should contain a certain percentage of very low-boiling constituents, so that engines may start more readily, especially in unfavorable conditions of weather or climate; but a large proportion would be undesirable because of loss through evaporation and the liability of accidental ignition and explosion. A reasonable amount of light volatile material would probably be about 3½ per cent. Again a reasonably low percentage of the very less volatile constituents is desirable to insure complete vaporization at a not too high temperature, say not more than 10 per cent.; but such a gasoline would be expensive. The producers and refiners claim that the present immense demand necessitates the mixture of low-boiling kerosene constituents with the true gasoline fraction.
“Kerosene.
—The character of this fuel is best understood by comparing it with gasoline, which it in general resembles, except that it is much less volatile. It is obtained from crude petroleum at a temperature just above that (300°F.) at which gasoline passes off. Its chief use is as an illuminant in lamps. It is also increasingly used as a fuel in cooking stoves, small portable heaters, and as a motor fuel for engines and tractors.
“The laws of most States stipulate certain tests which kerosene must meet in order to be approved for general sale. These tests include color, flash point, fire test, sulphur determination, and candlepower tests. The North Dakota Oil Inspection Law (1917) specifies that the color shall be water-white when viewed by transmitted light through a layer of oil 4 inches deep. It shall not give a flash test below 100°F. and shall not have a fire test below 125°F. Such illuminating oils shall not contain water or tar-like matter, nor shall they contain more than a trace of any sulphur compound. The photometric test, when burning under normal conditions, shall not show a fall of more than 25 per cent. in candlepower in a burning test of not less than 6 hours nor more than 8 hours’ duration, consuming 95 per cent. of the oil.
“The flash point of an oil is the lowest temperature at which vapors arising therefrom ignite, without setting fire to the oil itself, when a small test flame is quickly approached near the surface in a test cup and quickly removed.
“The fire test of an oil is the lowest temperature at which the oil itself ignites from its vapors and continues to burn when a test flame is quickly approached near its surface and quickly removed.
“When oils containing sulphur are burned, the sulphur is thrown off in the form of gaseous sulphur compounds. Because of their poisonous nature and their bleaching and disintegrating action on clothing, hangings, wall coverings, etc., it is obvious that to safeguard the health and preserve the furnishings of the home, illuminating oils should contain not more than a trace of sulphur compounds, and that their flash and fire limits should be high enough to insure safety in ordinary use in lamps and stoves.
“The law further specifies as to the boiling limits of kerosene: ‘It shall be the duty of the State Oil Inspector ... to have chemical tests made ... demonstrating whether or no such oils contain more than 4 per cent. residue after being distilled at a temperature of 570°F., and shall not contain more than 6 per cent. of oil distilling at 310°F., when one hundred cubic centimeters of the oil is distilled from a side-neck distilling flask’ of certain specified dimensions.
“This is to insure the kerosene against an excess of easily inflammable material of the gasoline range and thus render it dangerous to the user. In addition it is to insure against an undue proportion of heavy constituent of lubricating oil distillate, which would clog the wick and reduce the efficiency, heating and illuminating value of the oil.”