Gradually heat 100 cubic centimeters of the oil in a distillation flask to a temperature of 150 degrees centigrade; collect the distillate in a graduated tube and measure the resulting water. Such a method insures complete removal of water and reduces the error arising from the slight solubility of the water in [Pg 213] gasolene. Two samples checked by the two methods for the amount of moisture present gave,
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Calorific Value—A pound of petroleum usually has a calorific value of from 18,000 to 22,000 B. t. u. If an ultimate analysis of an average sample be, carbon 84 per cent, hydrogen 14 per cent, oxygen 2 per cent, and assuming that the oxygen is [Pg 214] combined with its equivalent of hydrogen as water, the analysis would become, carbon 84 per cent, hydrogen 13.75 per cent, water 2.25 per cent, and the heat value per pound including its contained water would be,
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The nitrogen in petroleum varies from 0.008 to 1.0 per cent, while the sulphur varies from 0.07 to 3.0 per cent.
[Table 46], compiled from various sources, gives the composition, calorific value and other data relative to oil from different localities.
The flash point of crude oil is the temperature at which it gives off inflammable gases. While information on the actual flash points of the various oils is meager, it is, nevertheless, a question of importance in determining their availability as fuels. In general it may be stated that the light oils have a low, and the heavy oils a much higher flash point. A division is sometimes made at oils having a specific gravity of 0.85, with a statement that where the specific gravity is below this point the flash point is below 60 degrees Fahrenheit, and where it is above, the flash point is above 60 degrees Fahrenheit. There are, however, many exceptions to this rule. As the flash point is lower the danger of ignition or explosion becomes greater, and the utmost care should be taken in handling the oils with a low flash point to avoid this danger. On the other hand, because the flash point is high is no justification for carelessness in handling those fuels. With proper precautions taken, in general, the use of oil as fuel is practically as safe as the use of coal.
Gravity of Oils—Oils are frequently classified according to their gravity as indicated by the Beaume hydrometer scale. Such a classification is by no means an accurate measure of their relative calorific values.
Petroleum as Compared with Coal—The advantages of the use of oil fuel over coal may be summarized as follows:
1st. The cost of handling is much lower, the oil being fed by simple mechanical means, resulting in,