NOTE. To find the latent heat of steam, or vapor of water, at any degree of temperature subtract the sensible heat from the constant quantity, 1212, and the remainder is the latent heat. One pound of steam will raise 3657 cubic feet of air 100, and cause it to expand from 320 to 420, about 3733 cubic feet. The heat that would raise 1 pound of water 10, would raise a pound of air 307; 1 pound of air about 11 cubic feet. Expansion of Liquids in Volume, from 32° to 212° Fahrenheit. The annexed table, by Mr. Gilbert, shows at one view those data which may be more implicitly relied upon. TABLE, Showing the Quantity of Heat producable from different kinds of Fuel. According to Mr. Gilbert, who experimented largely on this subject in the mining districts of Cornwall, seven pounds of coal will convert one cubic foot of water into steam; or, what amounts to the same thing, one bushel of coals will convert fourteen cubic feet of water from the ordinary temperature into steam. COMBUSTION. Combustion denotes the combination of a body with any of the substances termed supporters of combustion. With reference to the generation of steam, we are restricted to but one of these combinations, and that is oxygen. With equal weights of fuel, that which contains most hydrogen ought, in its combustion, to produce the greatest quantity of heat, where each kind is exposed under the most advantageous circumstances. For instance, pine wood is preferable to hard wood, and bituminous coal to anthracite coal. Dr. Ure gives the subjoined numbers as representing, in degrees of Fahrenheit's thermometer, the insensible heats of the corresponding vapors. The following Table shows the Power of various Species of Fuel. Peat compact, of or 2.8 3250 22.5 25.0 |