Inorganic Stamp Corner
by
Daniel Rabinovich
Taming the Beast
The French chemist Henri Moissan (1852-1907) was awarded the 1906 Nobel Prize in
Chemistry for two rather different areas of scientific endeavor, namely the isolation of elemental
fluorine and the introduction of the electric furnace in the preparation of metal carbides and other
refractory materials. The selection committee of the Royal Swedish Academy of Sciences had a
particularly difficult task that year, and Moissan edged out by a single vote (5-4) no one less than
Dmitri Mendeleev, of periodic table fame. Unfortunately the renowned Russian chemist, who
was considered an eccentric genius but an outsider in the European establishment, never got a
chance to be nominated again since he died of influenza on February 2, 1907. As bad luck
would have it, Moissan himself died from acute appendicitis only 18 days later, shortly after
returning to Paris from his trip to Stockholm.
The isolation of fluorine in 1886 was a remarkable achievement given the extreme
reactivity of this element. Moissan succeeded by electrolyzing at -25 °C a solution of potassium
hydrogen fluoride (KHF2) dissolved in anhydrous hydrogen fluoride, using special platinum–
iridium electrodes in a platinum U-shaped vessel capped with fluorite (CaF2) stoppers. Not
exactly an experiment undergraduate students conduct today in a laboratory course! In any
event, Moissan’s electrolytic cell is depicted on the two French stamps shown herein.
Interestingly, the stamp on the left, released in 1986 to commemorate fluorine’s centennial,
displays the incorrect (reverse) chemical equation, i.e., hydrogen does react with fluorine to yield
hydrogen fluoride, but that is evidently not how the lightest halogen was isolated in the first
place!