Alchemist's fire was a viscous, Alchemical liquid that stuck to most everything it touched. Upon contact with air, it burst into flames and burns until consumed or put out. Because of this, it was frequently stored in breakable flasks and used as a thrown weapon and in traps.
A creature with alchemist's fire adhered to its body could avoid additional injury if they managed to extinguish the flames before they dissipated naturally. Rolling on the ground improved the chances, while immersion in water put the flames out immediately.