Fuming \Fum"ing\, a. Producing fumes, or vapors. {Cadet's fuming liquid} (Chem.), alkarsin. {Fuming liquor of Libsvius} (Old Chem.), stannic chloride; the chloride of tin, {SnCl4}, forming a colorless, mobile liquid which fumes in the air. Mixed with water it solidifies to the so-called butter of tin. {Fuming sulphuric acid}. (Chem.) Same as {Disulphuric acid}, uder {Disulphuric}.