Note 51 — Chapter XI · THE HALOGENS: CHLORINE, BROMINE, IODINE, AND FLUORINE
George Kamensky translation
According to Gore. Fremy obtained anhydrous hydrofluoric acid by decomposing lead fluoride at a red heat, by hydrogen, or by beating the double salt HKF2, which easily crystallises (in cubes) from a solution of hydrofluoric acid, half of which has been saturated with potassium hydroxide. Its vapour density corresponds to the formula HF.