marsh gas

American  

noun

1. a gaseous decomposition product of organic matter, consisting primarily of methane.

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marsh gas British  

noun

1. a hydrocarbon gas largely composed of methane formed when organic material decays in the absence of air

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Etymology

Origin of marsh gas

An Americanism dating back to 1775–85

Example Sentences

I don’t read Swedish, so I’m unsure how to apportion credit for beautiful sentences, but they abound: Snide comments are “tiny puffs of marsh gas.”

From New York Times

This ‘marsh gas’ is methane, a greenhouse gas that is some 20 times more potent than carbon dioxide.

From Nature

The simplest of these is methane, or marsh gas, which is formed in nature by the bacterial decomposition of organic matter under water.

From The New Yorker

It was subject to continual leaks and floods, and suffused with fetid marsh gases that would periodically combust, ignited by the gas lamps that lit the tunnel.

From The New Yorker

Air Force determined it was all related to “marsh gas” or “swamp gas.”

From Washington Times