Steam:
Its Generation and Use

 value under a steam boiler, assuming that the < gases pass off at 320°, the temperature of steam < at 75 lbs. pressure, and the incoming draft to be : at 6o°; also that with chimney draft twice and with blast only the theoretical amount of air is • required for combustion. The relative value of different fuels is largely a question of locality and transportation. For in- stance, in some parts of Central America they burn rosewood under their boilers, because it is cheaper than coal; while a few years ago in the West it was found, during a coal famine, that In- dian corn was the cheapest fuel they could burn. In some places they burn manure only. The Babcock & Wilcox boilers of Chicago cable rail- ways are run regularly 011 the offal from the stables of the horse roads, a very small propor- tion of coal being used to keep it alight. “Slack” or the screenings from coal, when properly mixed — anthracite and bituminous,— and burned by means of a blower on a grate adapted to it, is nearly equal in value of com- bustible to coal, but its percentage of refuse is greater. A number of firms are using slack with decided economy, under Babcock & Wilcox boilers, in which there is ample space below the tubes for the dust to accumulate without covering heating surface or impairing the draft. Much is said nowadays about the wonderful saving which is to be expected from the use of petroleum for fuel. This is all a myth, and a moment’s attention to facts is sufficient to con- vince any one that no such possibility exists. Petroleum has a heating capacity, when fully burned, equal to from 21,000 to 22,000 B. T. U. per pound, or say 50 per cent, more than coal. But owing to the ability to burn it with less losses, it has been found through extended ex- periments by the pipe lines that under the same boilers, and doing the same work, a pound of petroleum is equal to 1 ‘8 pounds of coal. The experiments on locomotives in Russia have shown practically the same value, or 177. Now, a gallon of petroleum weighs 67 pounds (though the standard buying and selling weight is 6’5 pounds), and therefore an actual gallon of petro- leum is equivalent under a boiler to twelve pounds of coal, and 190 standard gallons are equal to a gross ton of coal. It is very easy with these data to determine the relative cost. At the wells, if the oil is worth say two cents a gallon, the cost is equivalent to $3.80 per ton for coal at the same place, while at say three cents per gdl Ion, the lowest price at which it can be delivered in the vicinity of New York, it costs the same as coal at |5-7o per ton. The Standard Oil Co. estimate that 173 gallons are equal to a gross ton of coal, allowing for incidential savings, as in grate bars, carting ashes, attendance, &c. & Saw dust can be utilized for fuel to good ad- vantage by a special furnace and automatic feed- ing devices.' Spent tan bark is also used, mixed with some coal, or it may be burned without the coal in a proper furnace. Its value'is about one- fourth that of the same weight of wood, as it comes from the press, but when dried its value is about 85 per cent, of the same weight of wood in same state of dryness. Bagasse, the refuse of sugar cane, after being dried in the sun, is largely employed in Cuba. Its value is about equal to the same weight of pine wood, in the same state of dryness. As it conies from the mill it contains from 50 to 80 per cent, of water, in which state it may be burnt in Cook’s Bagasse Furnace, under Babcock & Wilcox Boilers, with a result nearly or quite equal to that of the dried bagasse under ordinary boilers, thus saving the large expense of drying it. It has been estimated that on an average one pound of coal is equal, for steam-making pur- poses, to 2 lbs. dry peat, 2(4 to 2% lbs. dry wood, 2^4 to 3 lbs. dried tanbark, 2^ to 3 lbs. sun- dried bagasse, 2% to 3 lbs. cotton stalks, 3 '-i 3^ lbs. wheat or barley straw, 5 to 6 lbs. wet bagasse, and 6 to 8 pounds wet tan-bark. Natural gas varies in quality, but is usually worth 2 to 2^ times the same weight of coal, or about 30,000 cubic feet are equal to a ton of coal. TEMPERATURE OF FIRE. By reference to the table of combustibles, it will be seen that the temperature of the fire is nearly the same for all kinds of combustibles, under similar conditions. If the temperature is known, the conditions of combustion may be in- ferred. The following table, from M. Pouillet, will enable the temperature to be judged by the appearance of the fire : Temp. Fah.jj Appearance. Appearance. Red, just visible . “ dull......... “ Cherry, dull “ “ full.. “ “ clear Temp. Fall. 977 1290 147° 1650 183° Orange, deep.. “ clear. White heat .. “ bright .. “ dazzling 2010 2190 2370 2550 2730 To determine temperature by fusion of met- als, etc.— Sub- stance. Tallow. .... Spermaceti . Wax, white. Sulphur .... Tin........ Temp. Fah. Metal. Temp. Fah. Metal. Temp. Fah. Q2° Bismuth.. 518 Silver, pure... 1830 120 Lead 630 Gold Coin .... 2156 T54 Zinc 793 Iron Cast, med 2010 239 Antimony 810 Steel 2550 455 Brass... 1650 Wrought Iron 2910 55