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° 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