OIL-FUEL. A great incentive has been given by the discovery of copious wells of 'petroleum (See OIL-WELLS AND OIL-TRADE) to the invention of some mode of using oil as a fuel for furnaces and stoves. Such attempts had often been made before; but they assume a new aspect now that oil has become so much cheapened. Nearly half the carry 'lug capacity of European steamships, and more than half in those which make long voy ages, is taken up with the stowage of coal. Petroleum (q.v.) gives out nearly twice as much heat as an equal weight of anthracite or steam coal.
- As respects the use of petroleum for raising steam, several reports have been made public, stating that it has been so employed with success; brit a careful examination of the most reliable experiments plainly shows that as yet, at any rate, this cannot he done economically, except in rare instances, such as in the oil regions of the United States. In a full and apparently very reliable report, on petroleum in all its bearings by Mr. J. Lawrence Smith, published in the general report of the judges of group. III., Phila delphia exhibition of 1876, it is stated that the average price of anthracite coal in Amer ica is eight dollars per ton, and at this rate petroleum for equal heating-power would cost three times as much. In Great Britain, where paralline oil is as cheap as petroleum, the advantage iu the use of coal is much greater. The reports of Mr. '1'. Lloyd to the 'English admiralty, and by Mr. Isherwood, chief of the bureau of engineering in the U. navy, agree in stating that, although mineral oils can be burned without difficulty for raising steam, it has yet to be pi.oved whether they can be used successfully and safely at sea. The eminent French chemist, St. Claire DeviIle, has perhaps made what are as yet the most trustworthy experiments respecting the burning of mineral oils for raising steam in locomotives. He considers that only the heavy and thick-flowing kinds can be used to advantage in heating these engines; that with heavy oil steam can be got up in the same time as with coal; and that, as compared with the latter, the oil required is only about one-half the weight. On one of the railways in the s. of Russia, the
petroleum found at Baku, on the Caspian sea, was burned for a time in the locomotives; but although a success from an engineering point of view, it was found to be too costly a fuel. For a drawing of the furnace used, see Engmecring for Jan. 5, 1877.
The chief advantages of petroleum compared with coal as a fuel in raising steam are its greater heating-power, the smaller storage space it requires, and its freedom from ash. Its disadvantages are greater cost, difficulty iu burning without much smoke or tarry deposits, and the danger attending its use.
More success has attended the use of petroleum in metallurgical processes. Its free dom as a fuel from deleterious ingredients gives it at once a great advantage here. One of the best petroleum furnaces for working iron is that designed by Dr. C. J. Eames, now at work in Jersey City. U. S. The petroleum is made to drip over a series of shelves in an iron vessel, and is there converted into vapor and carried forward by superheated steam to be mixed with air, and is then immediately burned in the "corn bristion-chamber" at the end of the furnace, close to where the iron is piled. Steam in one condition or another is used to convert the petroleum into vapor in most furnaces it is used. In furnaces for bending armor-plates. and also for working thinner iron plates, mineral oil has been found to have the advantage over coal of raising the heat required in a much shorter time. It also produces less scale on the iron, and with it the heat is more easily concentrated on a portion of the plate.
OtLLE'TS, or (EILLETs, small openings. often circular, used in mediwval buildings for discharging arrows, etc., through.