n. 气体

Gas \Gas\ (g[a^]s), n.; pl. {Gases} (g[a^]s"[e^]z). [Invented by
the chemist Van Helmont of Brussels, who died in 1644.]
1. An a["e]riform fluid; -- a term used at first by chemists
as synonymous with air, but since restricted to fluids
supposed to be permanently elastic, as oxygen, hydrogen,
etc., in distinction from vapors, as steam, which become
liquid on a reduction of temperature. In present usage,
since all of the supposed permanent gases have been
liquified by cold and pressure, the term has resumed
nearly its original signification, and is applied to any
substance in the elastic or a["e]riform state.

2. (Popular Usage)
(a) A complex mixture of gases, of which the most
important constituents are marsh gas, olefiant gas,
and hydrogen, artificially produced by the destructive
distillation of gas coal, or sometimes of peat, wood,
oil, resin, etc. It gives a brilliant light when
burned, and is the common gas used for illuminating
purposes.
(b) Laughing gas.
(c) Any irrespirable a["e]riform fluid.

3. same as {gasoline}; -- a shortened form. Also, the
accelerator pedal of a motor vehicle; used in the term ``
step on the gas''.
[PJC]

4. the accelerator pedal of a motor vehicle; used in the term
`` step on the gas''.
[PJC]

5. Same as {natural gas}.
[PJC]

6. an exceptionally enjoyable event; a good time; as, The
concert was a gas. [slang]
[PJC]

Note: Gas is often used adjectively or in combination; as,
gas fitter or gasfitter; gas meter or gas-meter, etc.

{Air gas} (Chem.), a kind of gas made by forcing air through
some volatile hydrocarbon, as the lighter petroleums. The
air is so saturated with combustible vapor as to be a
convenient illuminating and heating agent.

{Gas battery} (Elec.), a form of voltaic battery, in which
gases, especially hydrogen and oxygen, are the active
agents.

{Gas carbon}, {Gas coke}, etc. See under {Carbon}, {Coke},
etc.

{Gas coal}, a bituminous or hydrogenous coal yielding a high
percentage of volatile matters, and therefore available
for the manufacture of illuminating gas. --R. W. Raymond.

{Gas engine}, an engine in which the motion of the piston is
produced by the combustion or sudden production or
expansion of gas; -- especially, an engine in which an
explosive mixture of gas and air is forced into the
working cylinder and ignited there by a gas flame or an
electric spark.