“…Production.-Moissan originally prepared gaseous fluorine by the electrolysis of solutions of potassium fluoride in liquid hydrogen fluoride, and this inconvenient method, requiring cooling of the solution to prevent evaporation of the liquid, was used until 1919. In that year Argo, Mathers, Humiston, and Anderson (7) introduced the use of molten potassium hydrofluoride, KHF2, as an electrolyte, and their method, or its modification using KF(HF)3 as suggested by Lebeau and Damiens (8), is in most general use today. The hydrofluoride method, which is largely responsible for the present rapid development of the chemistry of fluorine, will be the one described here.…”