sis 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
red, between wave lengths 744 and 623. Their positions and relative
intensities are as follows:

[lambda] = 744 very feeble. | [lambda] = 685.5 feeble
740 " | 683.5 "
734 " | 677 strong
714 feeble. | 640.5 "
704 " | 634 "
691 " | 623 "
687.5 " |

At a temperature of -95 deg. at ordinary atmospheric pressure, fluorine
remains gaseous, no sign of liquefaction having been observed.

METHODS OF EXPERIMENTING WITH FLUORINE.

When it is desired to determine the action of fluorine upon a solid
substance, the following method of procedure is adopted. A preliminary
experiment is first made, in order to obtain some idea as to the
degree of energy of the reaction, by bringing a little of the solid,
placed upon the lid of a platinum crucible held in a pair of tongs,
near the mouth of the delivery tube of the preparation apparatus. If a
gaseous or liquid product results, and it is desirable to collect it
for examination, small fragments of the solid are placed in a platinum
tube connected to the delivery tube by flexible platinum tubing or by
a screw joint, and the resulting gas may be collected over water or
mercury, or the liquid condensed in a cooled cylinder of platinum. In
this manner the action of fluorine upon sulphur and iodine has been
studied. If the solid, phosphorus for instance, attacks platinum, or
the temperature of th