Acetylene is a compound of carbon and hydrogen with the chemical formula C₂H₂. Acetylene is the only common dissolved gas. It is chemically very unstable and, even at atmospheric pressure, acetylene gas can explode. In order to safely store acetylene, cylinders are filled with a porous mass. In this mass there is a solution of acetylene in acetone or DMF (dimethylformamide) under pressure, typically 15 bar. Acetylene in solution is stable.

Acetylene is a colorless gas which is slightly lighter than air. Pure acetylene is odorless, but acetylene of ordinary commercial purity has a distinctive, garlic-like smell. Acetylene burns in air with an intensely hot, luminous and smoky flame. Mixtures of acetylene with air or oxygen in certain proportions can explode if ignited. Acetylene under pressure without the presence of air or oxygen can decompose with explosive force. Dissolved acetylene in a cylinder is safe.

Welding
Oxyacetylene gas welding

Cutting
Oxyacetylene gas cutting