Cadet's fuming liquid was a red-brown oily liquid prepared in 1760 by the French chemist Louis Claude Cadet de Gassicourt (1731-1799) by the reaction of potassium acetate with arsenic trioxide. It consisted mostly of dicacodyl (((CH<sub>3</sub>)<sub>2</sub>As)<sub>2</sub>) and cacodyl oxide (((CH<sub>3</sub>)<sub>2</sub>As)<sub>2</sub>O).
The global reaction (mass balance) corresponding to the oxide formation is the following:
These were the first organometallic substances prepared; as such, Cadet has been regarded as the father of organometallic chemistry.
This liquid develops white fumes when exposed to air, resulting in a pale flame producing carbon dioxide, water, and arsenic trioxide. It has a nauseating and very disagreeable garlic-like odor.
Around 1840, Robert Bunsen did much work on characterizing the compounds in the liquid and its derivatives. His research was important in the development of radical theory.