how fluorine was finally isolated

The Mechanism

Fluorine is the most reactive element there is — it attacks almost everything it touches, and the acid it forms with hydrogen, hydrofluoric acid, is savagely toxic and eats through glass and bone. For about seventy years after chemists recognized that a new element must lurk inside minerals like fluorspar, every attempt to isolate it failed, and the attempts maimed the people who made them. The list of casualties became known as the "fluorine martyrs": the Irish Knox brothers were left invalids by their experiments; the Belgian chemist Paulin Louyet and the Frenchman Jérôme Nicklès both died of hydrogen-fluoride poisoning; even Humphry Davy and Gay-Lussac were injured trying. The problem was that fluorine is so eager to react that the instant you free it, it grabs the nearest thing — including whatever container you made. The French chemist Henri Moissan solved it on 26 June 1886. He electrolyzed a solution of potassium bifluoride dissolved in liquid, anhydrous hydrogen fluoride, using platinum-iridium electrodes in a platinum vessel, and — crucially — cooled the whole apparatus to about −50 °C, cold enough to slow the freed gas's ferocious appetite for its own container. At the positive electrode a pale greenish-yellow gas collected: elemental fluorine at last. He announced it to the French Academy of Sciences. The work took a heavy toll on his own health — he is thought to have been poisoned repeatedly across the years of experiments — and it is widely suspected the fluorine exposure shortened his life. He received the Nobel Prize in Chemistry in 1906, and died in Paris on 20 February 1907, aged 54, only weeks after returning from Stockholm. The most dangerous element to ever sit in the periodic table cost a string of chemists their sight, their health, and in several cases their lives, before one of them finally trapped it in the cold — and it very likely killed him too.