Etymology
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carbon monoxide (n.)
1869, so called because it consists of one carbon and one oxygen atom (as opposed to carbon dioxide, which has two of the latter). An older name for it was carbonic oxide gas.
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carbon dioxide (n.)
1869, so called because it consists of one carbon and two oxygen atoms. The chemical was known since mid-18c. under the name fixed air; later as carbonic acid gas (1791). "The term dioxide for an oxide containing two atoms of oxygen came into use in the middle of the 19th century." [Flood].
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