Fuel
2 of the 6 encyclopedias on this shelf carry an entry for Fuel. Both are reproduced below, so you can see where they agree and where they differ.
Collier's New Encyclopedia (1921)
any combustible which is used for the production of heat. substance In this extended sense of the term, alcohol, wax , tallow, coal-gas, oil, and other inflammable bodies which are used, especially in the chemical laboraoccasionally tory, as sources of heat as well as light, might be included under it. But the term fuel is more properly limited to coal, coke, charcoal, wood, and a few other substances, which are our common sources of heat , and as such are burnt grates, stoves, fireplaces, and furnaces. in In this country , as in England, coal, from its abundance and cheapness, is the fuel commonly employed; but in other countries , as France, Germany, etc., wood is chiefly used, either in its original state or in the form of charcoal. But whatever substance be used, the essential ultimate elements of fuel are carbon and hydrogen; and the heat which is evolved by their combustion is derived from their combination at high temperatures with the oxygen of the air; the principal results or products of this combustion are carbonic acid and water, these escaping into the atmosphere by the flue or chimney generally attached to furnaces and fireplaces. The different kinds of pit-coal give out variable quantities of heat during their combustion; upon an average, one pound of coal should raise 60 pounds of water from the freezing to its boiling point. The heating power of coke as compared with coal is nearly in the ratio of 75 to 69: a pound of good coke, heating from 64 to 66 pounds of water from 32° to 212°. A pound of turf will heat about 26 pounds of water from 32° to 212°, and a about 30 pounds; by compressing and pound of dense peat drying peat, its value as a fuel is greatly increased. The following table, by Dr. Ure, shows the from 32 to 212 by one pound weight quantity of water raised of the different combustibles enumerated in the first column; it also shows the number of pounds of boiling water which the same weight of fuel will evaporate and the quantity of atmospheric air absolutely consumed during combustion: Pounds of Pounds of Weight of water which a boiling atmospheric air Combustible. pound can water raise from evaporated at 32° required to by one 32° to burn one pound 212° pound. Dry wood..... 35.00 common wood. 6.36 5.96 26.00 4.72 4.47 Charcoal 73.00 13.27 11.46 Pit coal.. 60.00 10.90 9.26 Coke 65.00 11.81 11.46 Turf 30.00 5.45 4.60 Coal-gas 76.00 13.81 14.58 Oil, wax, tallow 78.00 14.18 15.00 Alcohol 52.00 9.56 11.60
The Encyclopedia of Founding (1892)
Fuel is a term of general application to all combustibles employed for producing heat. The two elementary bodies which produce the heating power of fuels, both natural and artificial, are hydrogen and carbon; and as there is little or none of the former element contained in anthracite, peat charcoal, wood charcoal, or coke, we may therefore regard these as carbonaceous fuels. But wood, peat, and most varieties of coal contain hydrogen as well as carbon, and in their combustion these two substances combine to produce volatile and combustible hydrocarbons, which are volatilized previous to being consumed; while a purely carbonaceous fuel evolves no volatile matter until combustion has been effected. See COMBUSTION; COAL; COKE; PETROLEUM; PRESSED FUEL; LIQUID FUEL.
What Has Changed in the Last Century
When Collier's wrote this in 1921 it could state flatly that "the essential ultimate elements of fuel are carbon and hydrogen" and list coal, coke, charcoal, wood, turf and tallow as the practical choices. Within a generation that was no longer true: petroleum and natural gas overtook coal as the world's leading energy sources, and nuclear fission — unknown until Hahn and Strassmann's 1938 experiment and the first sustained chain reaction in 1942 — added a fuel with no combustion at all, while wind and solar now generate electricity with no fuel whatsoever. The heating values in Dr. Ure's table are straightforward calorimetry and still hold, but the entry's calm note that the products "escape into the atmosphere by the flue or chimney" reads very differently now: that "carbonic acid" is carbon dioxide, and its accumulation is the central problem of twenty-first-century energy policy. Coal, described here as the fuel of choice for its "abundance and cheapness," is now being deliberately retired across much of Europe and North America.
Written for this edition, 2026.