fluorine.

Moreover, the hydrofluoric acid is found to contain a small quantity
of platinum fluoride in solution. The electrolytic reaction is
probably therefore much more complicated than was at first considered
to be the case. The mixture of acid and alkaline fluoride furnishes
fluorine at the positive terminal rod, but this intensely active gas,
in its nascent state, attacks the platinum and produces platinum
tetrafluoride, PtF_{4}; this probably unites with the potassium
fluoride to form a double salt, possibly 2Kl.PtF_{4}, analogous to the
well known platinochloride 2KCl.PtCl_{4}; and it is only when the
liquid contains this double salt that the electrolysis proceeds in a
regular manner, yielding free fluorine at the positive pole, and
hydrogen and the complex black compound at the negative pole.


PHYSICAL PROPERTIES OF FLUORINE.

Fluorine possesses an odor which M. Moissan compares to a mixture of
hypochlorous acid and nitrogen peroxide, but this odor is usually
masked by that of the ozone which it always produces in moist air,
owing to its decomposition of the water vapor. It produces most
serious irritation of the bronchial tubes and mucous membrane of the
nasal cavities, the effects of which are persistent for quite a
fortnight.

When examined in a thickness of one meter, it is seen to possess a
greenish yellow color, but paler, and containing more of yellow, than
that of chlorine. In such a layer, fluorine does not present any
absorption bands. Its spectrum exhibits thirteen bright, lines in the