AppearanceCyclopropane is a colorless gas with a petroleum-like odor. It is shipped as a liquid at 4-6 atms. It is easily ignited. The vapors are heavier than air. Contact with the liquid may cause frostbite. It can asphyxiate by the displacement of air and has a narcotic effect in high concentration (formerly used as an anesthetic gas). Under prolonged exposure to fire or intense heat the containers may rupture violently and rocket.