Parizene gas
Parizene gas was a gaseous chemical stored on Federation starships.
When the USS Cerritos was being transformed by terraforming emulsion from an ancient generation ship in 2380, Ensign Beckett Mariner discovered that the affected areas were saturated by carbon polymer dust. Thus, she surmised she could flood the ship with parizene gas and trigger a reversion of the transformation with radiation from the main deflector. (LD: "Moist Vessel")