water gas

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A fuel gas containing approximately equal amounts of carbon monoxide and hydrogen, and varying smaller amounts of methane, carbon dioxide, and nitrogen, made by passing steam and air over heated coke or coal.

from The Century Dictionary.

• noun Two reaction s may occur, represented by the formulæ) C + 2H₂O = CO₂ + 2H₂ and C + H₂O = CO + H₂ — the former of these chiefly at a temperature of about 500° C. and the latter at about 1000° C. Hence the product usually consists of both the oxids of carbon, mixed with hydrogen. If the incandescence of the carbon is maintained by the continuous combustion of a part of it, requiring the continuous supply of air, the nitrogen of this air is also found in the product, thus diluting it with incombustible matter. Such a mixture is used as fuel in gas-fired furnaces. If, however, the intermittent process is adopted, the supply of air being cut off as soon as the mass of coke or anthracite is glowing brightly, and steam already at a high temperature introduced, the presence of nitrogen is avoided, until by the gradual cooling down of the mass it again becomes necessary to cut off the steam and turn on the air. Water-gas made by this intermittent process is largely used as a source of artificial light, especially in cities of the United States, but, having of itself but poor illuminating power, it requires to be “carbureted” by mixture with the vapor from hydrocarbon oils and strongly heating the mixture.
• noun A gas, non-luminous in its pure form, derived in part from the decomposition of steam.

from the GNU version of the Collaborative International Dictionary of English.

• (Chem.) See under gas.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A mixture of hydrogen and carbon monoxide produced by passing steam over hot coke; used as a domestic fuel

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a mixture of hydrogen and carbon monoxide with small amounts of other gases; made by blowing steam over hot coke or coal