Reference Work Entry

Environmental Geology

Part of the series Encyclopedia of Earth Science pp 400-401

Marsh gas (methane)

  • Günay Kocasoy

Marsh gas, which is also called methane, is produced by the anaerobic bacterial decomposition of vegetable matter and the rumen of herbivorous animals under water. For a very long time it was considered as having supernatural properties due to its ability to self-ignite, which occurred in marshes and was visible, especially at night. From the viewpoint of chemistry it is the simplest member of the aliphatic or paraffin series of hydrocarbons which is shown by the type of formula CnH2n+2. Its chemical formula is CH4. It can be found abundantly in nature as the chief component of natural gas. The methane content of marsh gas varies between 50 and 80 per cent, but mostly it is around 60 per cent.

Marsh gas has no color or odor. It is lighter than air and has a specific gravity of 0.554. It is only slightly soluble in water but is more soluble in ethyl alcohol and ethyl ether. It is generally very stable. It burns readily in air and produces carbon dioxide and water vapor. Its flame is pal ...

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