This paper is not intended as a scientific discussion of the combustion ofoil but is written from the standpoint of an operator who has the experienceand qualifications necessary to guide others in producing the most economicalresults in the use of liquid fuels. Oil, in this paper, usually means petroleumor its products but incidental reference is made to other liquid and gaseousfuels, so that the term may be considered as referring to all liquid andgaseous hydrocarbons in comparison with solid fuels, as coal and wood. However, only a few of the principal factors in the use of oil as a fuel can begiven. The present, and prospective, high price of coal is causing users of fuel torenew inquiry as to the merits of other forms of fuel for industrial purposes.Crude oil (petroleum) is proving to be one of the world's most valuable mineralresources. The recent discovery that oil underlies a considerable area of theUnited States, Mexico, and other parts of the world to a greater extent thanwas formerly believed and the large production of some of the wells in theseareas shows the probable quantity of fuel oil that may now be available.Through the energy of Lord Cowdrey, who was one of the pioneers of the oilindustry in Mexico, oil has been discovered in England; some prominentgeologists believe that it may be found in quantity in Great Britain. For years, oil has been known to be of great value in the manufacture ofmetals. It has proved incomparable in forge shops, steel foundries, heat-treating furnaces, and wherever accuracy of temperatures is essential, orwhere a maximum output is desired as well as quality of metal. In some types ofequipment, the output produced with oil as fuel is double that obtained withcoal and at a reduction of 50 per cent. in the cost of the fuel. For example, in drop-forging plants, the metal is always waiting for the man when oil isused as fuel, whereas with coal, the man must wait for the metal to becomesufficiently heated. It has only been since January, 1919, that the oil supply could be relied onfor boiler service, owing to the war conditions and the inability to get oiltankers for the delivery of the oil from Mexico to Atlantic ports; but now aconstant supply is assured, and many manufacturers are installing it in theirpower plants. AIME 065–48