removed, it crystallizes and carbonizes on the tubes and is difficult to scrape off. The frequent use of steam jets will result in clean tubes, the soot being easily removed in the early stages of its deposition.

Since the soot deposits which result from the combustion of oil are in the nature of pure carbon and are very adhesive their insulating effects are much increased over those from coal. With coal, the deposits settle on the top of the tube, leaving the balance of the circumference comparatively free. Oil burning causes deposits which are more evenly distributed, covering rather uniformly the entire firing areas.

The following table gives the fuel oil consumption of railroads of the United States from 1909 to 1920, figures prior to 1919 being those of the U. S. Geological Survey:

Barrels

31,093,266

33,004,815

33,605,598

29,748,845

23,187,346

19,905,335

Miscellaneous Facts Concerning Heating By Oil. Good practice in the atomization of fuel oil requires an average of 0.3 pound of steam per pound of oil burned.

One pound of fuel oil requires 14 to 15 pounds or 200 cubic feet of air for complete combustion; 225 cubic feet is good practice. The stack gases from an oil furnace for the highest efficiency should not contain less than 15% of carbon dioxide (over 13% is good).

The temperature of an oil flame with complete combustion and without an excess of air is about 3,750° F. (Natural gas flame, 3,250° F.)

One pound of oil will yield on combustion 16 to 17 pounds of gases of combustion or 400-500 cubic feet at a temperature of 400° F.

Oil is successfully used in melting iron and steel scrap. For this purpose it is much superior to coal on account of the absence of mineral matter and the very much smaller amount of sulphur.

One barrel of oil will melt one ton of steel in the reverberatory furnace, with the furnace walls already hot.

A typical malleable iron foundry by the changing of the furnaces from coal to oil fuel increased the strength of their castings 100% and increased the output 20%.

Diesel engines consume from .45 to 7 pound of heavy oil per brake H. P. per hour.

Oil requires 60% of stack area needed for coal firing.

Oil gives a fuel efficiency at least 10% greater than coal.

The advantages of oil fuel installations for locomotives and boats have been found to be as follows:

(a) Economy of space reserved for carrying fuel; 50% more fuel value per unit space.

(b) Ease in filling tanks.

(c) Rapidity of time in meeting a varying load on boiler. Fires may be instantly lighted.

(d) Ability to force boiler to extreme duty in case of emergency. (e) Short height of stack.

(g) Superior personnel available for the operation of the burners. h) Ability to secure and maintain higher speed with oil fuel than with coal. No deterioration in storage.

In the distillation of crude oil in which 50% of the crude is distilled off as benzine and kerosene, in good practice, 2.8 barrels of fuel oil are used per 100 barrels of crude oil treated.

Theoretical draft with various flue gas and air temperatures, for a chimney 100 feet high and assuming an area ficient that friction in the chimney may be neglected. For a chimney of any other height, multiply the tabular figure by where H is the height of the chimney in feet

H 100.

Fig. 68-Influence of Temperatures of Stack on Drafts in Oil Furnaces Based Upon 100-Foot Stack.

For all refining purposes in the production of gasoline, naphtha and kerosene only, from 6 to 7 barrels of fuel oil are required for each 100 barrels of crude treated, assuming that 50% of the lighter hydrocarbons are distilled from the crude.

One-fourth of a gallon of fuel oil is required to produce one gallon of 58° Baume' gasoline by cracking according to a pressure distillation process now extensively used.

The specific heat of petroleum is about 0.5 (.49-.53), the heat of vaporization averages about 130 B. T. U. per pound and the heat of fusion 63 B. T. U. per pound (Paraffin).

For Natural Dry Petroleum of Paraffin or Semi-Paraffin Base the following relation of gravity (Baume'-U. S.) and heating value holds:

B. T. U. per pound = 18700 +40 (Be'-10).

Of the world's total tonnage of vessels of 100 tons and upward on Lloyd's Register, an approximate division as to the fuel motive power is as follows, according to Westgarth Brown, president of the South Wales Institute of Engineers:

34 bbls. oil (42 gallons per bbl.) is the equivalent of 5,000 pounds hickory or 4,550 pounds white oak.

6 gallons oil equals 1,000 cubic feet of natural gas of calorific value of 1,000 B.T.U. per cubic foot.

32 gallons oil equals 1,000 cubic feet of commercial or water gas of calorific value of 620 B.T.U. per cubic foot.

24 gallons oil equals 1,000 cubic feet by-product coke-oven gas at 440 BT.U. per cubic foot.

0.42 gallons oil equals 1,000 cubic feet blast-furnace gas at 90 B.T.U. per cubic feet.

SAMPLING FUEL OIL.

The accuracy of tests depends upon the care with which an average representative sample of fuel oil delivery has been taken and the importance of obtaining such a sample cannot be over-estimated. Top, middle and bottom samples should be taken with a standard "car thief" and these samples should be combined and thoroughly mixed to form one sample for car deliveries. Where oil is received in tanks or reservoirs the swing pipe should first be locked at a position well above the level of the water and sediment usually found in the bottom of such tanks. Tanks should be sampled every foot for the first five feet above the bottom of the swing pipe, and at five-foot intervals from there to the surface of the oil. This sampling should be done with a standard tank thief, the samples tested individually, and deductions for impurities made on the separate volumes which these samples represent. If the tank is a large one, it should be sampled through at least two hatches. In receiving large deliveries of the more viscous oils it is necessary to take many samples in order to insure fair and average impurity (M. & B. S) deductions. This is because water and sediment do not readily settle out of such oils.