Hydrogen Fluoride Gas from Fluorspar and Sulphuric Acid

Hydrogen fluoride is the gas that fluorspar gives off when it is warmed with strong sulphuric acid; in water it is hydrofluoric acid. Thorpe (1912): one part of powdered fluorspar and about twice its weight of strong sulphuric acid in a lead retort on a sand bath. Here the gas is led off through lead to where it is used. It eats glass, so only lead or copper touches it. Hydrogen fluoride is a deadly poison and its burns go deep: full protection, outdoors, never alone. The picture: our diagram.