- 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.