Cabot, of Boston, Mass., and is only one of a chain of factories scattered over the state of West Virginia. Other plants owned by Mr. Cabot are at Creston, 16 miles below Grantsville, at Spencer, at Bristol, and at Cabot, Pa. The plant at Creston is being enlarged; it was started in 1910. In the plant at Grantsville the open-ring method is used, though the waste is greater in the use of this method than any other.

"The rings in which the black is produced are 60 feet in circumference, and near the top of the ring is a flat, smooth iron plate entirely covering the ring. The black is made by impinging the burning natural-gas jet upon the surface of the plate, which is kept constantly revolving. Against the plate is arranged an automatic scraper which removes the black produced. By means of screw conveyors the black is conveyed from the scraper to a large bin, where it is ground, sifted, and bolted, and all foreign matter eliminated. The better part is elevated to a packer bin, while the waste is carried off. From the packing bin it is run into bags containing 12 lbs. each and into barrels containing 100 lbs. of black. The capacity of this plant is nearly 8000 lbs. daily. Each ring contains 1265 burners, or tips. In all, 142,945 tips are employed, consuming 9,143,560 cubic feet of natural gas daily. At least onefourth of the gas burned, and probably one-third, is wasted, in the form of lamp-black carried through the vents in the rings by the heat. A dense cloud of black smoke arises from the plant and hovers over it."

PETROLEUM AS FUEL.1

Crude petroleum is commonly employed as fuel for steam-raising in the various oil-fields, but the usual presence in the oil as it comes from the wells of the more volatile hydrocarbons introduces an element of risk in storage and handling, and for general industrial purposes the petroleum is deprived of these hydrocarbons by distillation, the liquid fuel thus being obtained of a specified minimum flash-point.

The characters which a fuel oil should possess are high calorific value, fluidity at moderately low temperatures, freedom from solid matter which may choke the jets of atomisers or cause trouble through abrasion, and a satisfactorily high flash-point. Some authorities lay stress on a low sulphur content, and a maximum figure is quoted in many specifications, but the harm resulting from sulphur has probably been overestimated.

The British Admiralty Fuel Oil Specification states that the oil fuel supplied shall consist of liquid hydrocarbons, and may be either (a) shale oil; or (b) petroleum as may be required; or (c) a distillate or a residual product of petroleum.

The flash-point shall not be lower than 175° F., close test, Abel or PenskyMarten.

In the case of oils of exceptionally low viscosity, such as distillates from shale, the flash-point must be not less than 200° F.

Sulphur shall not exceed 0-75 per cent.

1 The use of liquid fuel has been described by Aydon, Proc. Inst. Civ. Engineers, lii, 177 (1878); Urquhart, Proc. Inst. Mech. Engineers (1884, 1888, and 1889); Mills and Rowan, Fuel and its Applications, London (1889); Veitch, Das Erdöl (1892); Robinson, Journ. Soc. Arts, April 29 (1891), and Cantor Lectures (1892); and the author (Journ. Soc. Chem. Ind., iv, 70, and Cantor Lectures, 1886). More recent works on the subjects are: Liquid Fuel and its Combustion, by Wm. H. Booth (1903), Liquid and Gaseous Fuels, by Vivian B. Lewes (1907), and Oil Fuel, by Sydney H. North, 2nd ed., revised by Edward Butler (1911); Fuels: Solid, Liquid, and Gaseous, by J. S. S. Brame (1917); J. S. S. Brame, Journ. Inst. Pet. Techs., iii, 194 (1917), on Liquid Fuel and its Combustion.'

The oil fuel supplied shall be as free as possible from acid, and in any case. the quantity of acid must not exceed 0.05 per cent. calculated as oleic acid when tested by shaking up the oil with distilled water, and determining by titration with decinormal alkali the amount of acid extracted by the water, methyl orange being used as indicator.

The quantity of water delivered with the oil shall not exceed 0-5 per cent. The viscosity of the oil supplied shall not exceed 1000 seconds for an outflow of 50 cubic centimetres at a temperature of 32° F., as determined by Sir Boverton Redwood's Standard Viscometer (Admiralty type for testing oil fuel).

The oil supplied shall be free from earthy, carbonaceous, or fibrous matter, or other impurities which are likely to choke the burners.

In the British Mercantile Marine the minimum flash-point is 150° F. The United States Specifications for Navy fuel oil, gas oil, and bunker oil state that (a) fuel oil shall be a hydrocarbon oil free from grit, acid, and fibrous or other foreign matter likely to clog or injure the burners or valves. If required by the Navy Department, it shall be strained by being drawn through filters of wire gauze having 16 meshes to the inch. The clearance through the strainer shall be at least twice the area of the suction pipe and strainers shall be in duplicate.

(b) The unit of quantity to be the barrel of 42 gallons of 231 cubic inches at a standard temperature of 60° F. For every decrease or increase of temperature of 10° F. (or proportion thereof) from the standard, 0.4 of 1 per cent. (or prorated percentage) shall be added or deducted from the measured or gauged quantity for correction.

(c) The flash-point shall not be lower than 150° F. as a minimum (Abel or Pensky-Marten's closed cup), or 175° F. Tagliabue open cup. In case of oils having a viscosity greater than 8 Engler at 150° F. the flash-point (closed cup) shall not be below the temperature at which the oil has a viscosity of 8 Engler.

(d) Viscosity shall not be greater than 40 Engler at 70° F.

If the Engler viscometer is not available, the Saybolt standard universal viscometer may be used. Equivalent viscosities:

(e) Water and sediment not over 1 per cent. If in excess of 1 per cent., the excess to be subtracted from the volume; or the oil may be rejected. Water and sediment will be taken by the distillation method. When oil in small lots is consigned to Naval vessels or to Navy Yards the centrifuge test will be used in order to obviate delay. In this test 30 c.c. of oil and an equal quantity of best commercial benzol, 30 per cent. white, will be used, and the mixture heated to 100° F.

(f) Sulphur not over 1.5 per cent.

For many years Russia was the only country producing and consuming liquid fuel on a scale of commercial magnitude, the crude petroleum from the prolific oil-fields of Baku yielding a large proportion of a suitable product, but for some time past there has been in the United States a rapid growth in the general employment of liquid fuel, large supplies being obtained in California, Texas, and elsewhere. The Kutei district of Borneo has also become an important factor in the industry, the petroleum found there yielding an excellent fuel oil and being apparently obtainable in very large quantities. Among

other present and prospective sources of supply to which the now general recognition of the advantages of liquid fuel, especially for marine purposes, has caused attention to be directed, are those of Burma, Persia, Egypt, Trinidad, Mexico, Galicia, and Rumania, and there can be no doubt that the efforts now being made to develop fresh sources of supply will result in a very considerable increase in the quantity at present available. It would, however, be misleading to suggest that there is any prospect of a general substitution of oil for coal as fuel in steam-raising and for other purposes. The author pointed out in giving evidence before the Royal Commission on Coal Supplies in 1903, that if the then aggregate output of petroleum in the world were doubled, and the whole of the surplus thus created were used as fuel, this surplus would, taking into account the relative thermal efficiencies, only be equivalent to about 5 per cent. of the world's output of coal.

It has also to be taken into account that with the development of most oil-fields there is a progressive decrease in the proportion of fuel oil yielded by the crude petroleum, the oil obtained at greater depth usually containing a larger proportion of the more volatile hydrocarbons. Lastly, the exhaustion of the older oil-fields, which is proceeding pari passu with the opening up of new fields, must not be lost sight of in forming an estimate of the extent to which the world's supplies may be augmented. In this connection, attention should be drawn to a report in which Dr. David T. Day, the expert of the United States Geological Survey, in charge of petroleum investigation, gave the data on which he arrived at the somewhat startling conclusion that at the rate of increase of the output of petroleum the known oil-fields of that country would, on the basis of the estimated minimum quantity of oil obtainable, be exhausted by the year 1935, whilst if the output at that time were only maintained, the supply would on the same basis only last for ninety years. In these circumstances it is fortunate that, through the success which has attended the introduction of the Diesel engine, to which reference will be made subsequently, every attention is now being given to the extended use of the internal-combustion engine, for with the Diesel type of engine it is possible to obtain about three times as much power from a given quantity of oil as is usually yielded when the oil is used for steam-raising in conjunction with the best types of steam-engine, though, as is hereafter pointed out, modern improvements in the raising and use of steam may be held to necessitate a revision of this comparison.

In their final report, dated 7th January 1905, the Commissioners express themselves on the subject of the substitution of oil for coal in the following

terms

There has been much disposition in recent years to speak of oil fuel as if it were a serious competitor of coal, and a real substitute for it. The facts before us do not bear out that view. Dr. Boverton Redwood in his evidence has given us a valuable account of the present and prospective sources of supply of petroleum and its allied products, and while he thought there was ample scope for energy and capital in searching for and opening up fresh sources of supply, he expressed himself very strongly against the possibility of any largely extended use of petroleum as a substitute for coal. He pointed out that the world's production of coal in 1901 was 777 million tons, and that in the same year the work production of petroleum was 22 million tons, or only 2-8 per cent. of the weight of the coal.

"The conclusion we have arrived at as regards the use of oil fuel in this country is that which is expressed by Dr. Boverton Redwood in answer to Question 13,559, when he said: 'I think there will be certain selected appli

cations of liquid fuel where the advantages of employing such a fuel are especially obvious; but for anything like general employment, I cannot see where we are to look for adequate supplies.""

For Naval purposes the many advantages liquid fuel offers make its use almost indispensable; here cost cannot be allowed to outweigh the advantages gained by its adoption. As is well known, it has been widely adopted by all the great Powers, and the large oil-fired turbine-propelled battleships and battle-cruisers of the British Navy fully proved the capabilities of oil, as was the case also with the smaller units, light cruisers, destroyers and even submarines.

The author has on many occasions pointed out the advantages presented by the use of liquid fuel. On shipboard these are especially marked. Not only can a supply of liquid fuel be taken on board far more easily, more quickly, and at less cost than a supply of solid fuel, and in the case of a passenger steamer without occasioning the discomfort attendant upon "coaling," but it occupies, for an equal value in steam-raising, only about half the space; the vessel can therefore either make a far longer voyage without the necessity arising for replenishing the bunkers, or a certain amount of space, which, if coal were used, would be occupied by the fuel, can be devoted to cargo. The labour of stoking and coal-trimming, which is most exhausting in a tropical climate, is completely done away with, and there are no ashes and clinkers to be removed. The combustion is smokeless under natural draught-and may be made so under forced draught a point of no small importance in the belligerent marine; no soot or dust is deposited in the boiler-tubes; the fire can be instantly extinguished or as quickly relighted, and is under complete control, waste of steam at the safety-valve on the one hand, or a short supply on the other, being easily avoided. If the flame should be extinguished in stormy weather, there is no delay in kindling it again, and the risk of scalding is diminished. The oil may be carried in bunkers where coal could not be put, and these may be filled with water as the oil is used, so that the trim of the vessel need not be altered during the voyage, and, if suitable oil is used, there is no danger of explosion or fire, such as attaches to the carriage of coal. The chief practical difficulty formerly encountered in the use of liquid fuel on shipboard was the provision of a supply of steam for atomising the oil. The steam used in the engines is, of course, condensed, and the water returned to the boilers; but in respect of that which is employed for spraying the oil, an equivalent amount of fresh water must be replaced in the boilers, and to obtain this it is usually necessary to have an independent distilling apparatus. This objection obviously does not attach to those burners in which the atomising is effected mechanically, the type now almost universally employed.

During recent years oil fuel has firmly established its position as the best fuel for steam-raising in the Mercantile Marine and Naval Service, but although it was found fairly easy to obtain smokeless combustion in the furnaces of cargo boats, where there was plenty of grate space to allow completion of the combustion, the problem presented much difficulty in ships where the restricted space available for the boilers necessitated a much larger consumption of fuel per foot of combustion space, and under these conditions most of the burners which had given good results when used to inject comparatively small quantities of the fuel, gave dense black smoke when the consumption was largely

increased.

This arose partly from the fact that the furnaces were designed to burn steam coal, about 75 per cent. of which is consumed upon the furnace bars, yielding chiefly carbon monoxide, which needs only a comparatively small

proportion of air to complete its combustion in the furnace and combustionchamber, and partly from the fact that when a substance like oil is injected into the furnace, the impetus imparted by the injector is aided by the draught of the funnel, with the result that the oil vapour is hurried through the furnace, combustion-chamber, and tubes too fast to allow anything like complete combustion to take place, and dense smoke is produced.

It was also found that steam injection added to the trouble when the area was small, and the fact that 0-2 lb. of steam per I.H.P. is used in atomising and injecting, threw an extra strain upon the boilers.

Such burners as most of the modern "pressure" type not only possess the advantage of operating without the use of steam, but as they cause the stream of injected atomised oil to follow a spiral, instead of a direct, course through the furnace, the length of travel of the oil spray is increased and more time is given for the chemical action essential to the attainment of smokeless combustion.

It will be apparent that many of the advantages which have been pointed out, attach to the substitution of liquid fuel for coal on locomotives and in stationary boilers. At electric generating-stations in large cities, where the delivery and storage of coal and the removal of ashes are not easy, and where in consequence of fog there may be a sudden and unexpected demand for steam, it would appear to be exceptionally desirable to employ liquid fuel, and there can be but little doubt that, if adequate supplies of suitable oil become available for the purpose, this description of heating agent will be more largely employed.

For industrial operations oil fuel has also been extensively adopted. Here, as a general rule, low-pressure air-spraying is the most satisfactory system and the least costly. For metal melting, and reheating of billets for forgings and stampings; for rivet heating and heat treatment of tool steels, many efficient patterns of oil-fired furnaces are constructed. An increased number of heats is possible in the working day and loss of metal in melting operations is reduced. For glass-melting furnaces and even cement furnaces, where oil is cheap, it has also been successfully used.

In a method patented in 1883 (No. 1157) by Mr. J. Riley, for application of oil fuel to regenerative furnaces, the oil is supplied from a tank through a stop-cock, to a series of nozzles which are automatically turned to project the oil into either side of the furnace according to which of the regenerators is in action. A method of burning oil in open trays for furnaces in which iron and steel were melted in an open hearth or in crucibles, was introduced by Nordenfelt.

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In the Eames process, introduced for the purpose of melting down scrap iron and rolling the product into boiler-plates, the oil ran downwards over a series of shelves projecting alternately from opposite sides of a cast-iron generator, and in passing from shelf to shelf was gasified by a slow current of highly superheated steam. The mixture of vapour and steam passed into a mixing chamber," occupying the position of the former fire-space, where it met the air-blast, and was driven through an opening in the furnace bridgewall and over the furnace-bed.

According to a communication from Mr. A. von der Ropp to the California Miners' Association, crude petroleum is used in the works of the Selby Smelter in four roasting-furnaces with eleven burners, one matting-furnace with three burners, one copper-furnace with one burner, fourteen lead-furnaces with fourteen burners, thirteen zinc-retorts with thirteen burners, three cupelfurnaces with three burners, one antimony-furnace with one burner, and one furnace for smelting fine silver with one burner. For all these purposes the