What is the X in X-mas?
gaseous hydrocarbon, 1864, from French acétylène, coined by French chemist Marcelin-Pierre-Eugène Berthelot (1823-1907) from chemical ending -ene + acetyl, which was coined from acetic in 1839 by German chemist Justus von Liebig; see acetic. Liebig's coinage was in reference to a different radical; acetyl was transferred to its current sense in 1850s, but Berthelot's coinage was based on the original use of acetyl.
The name acetylene is an unfortunate one as the hydrocarbon is not directly related to the modern acetyl radical and the molecule ... contains a triple bond, not a double bond which the suffix -ene (q.v.) implies. [Flood, "Origins of Chemical Names," 1963]
acetylene a·cet·y·lene (ə-sět'l-ēn', -ən)
A colorless, highly flammable, and explosive gas used for metal welding and cutting and as an illuminant.
A colorless, highly flammable or explosive gas with a characteristic sweet odor. It is used in welding torches and in the manufacture of organic chemicals such as vinyl chloride. Acetylene is the simplest alkyne, consisting of two carbon atoms joined by a triple bond and each attached to a single hydrogen atom. Also called ethyne. Chemical formula: C2H2.