some days to allow the sulphureted hydrogen, etc., to escape,
peroxide of manganese is added, and the whole gently heated.
Iodine distills over in a purple vapor, and is condensed in a receiver,
or in a series of two-necked globes.

Properties.--Iodine is solid at the ordinary temperature,
presenting the appearance of dark-grey or purple spangles, possessing a
high degree of metallic lustre. It somewhat resembles plumbago,
with which it is sometimes diluted, particularly when it is fine.
Operators should endeavor to secure the larger crystals.
It melts at 224.6 deg., forming a brown or nearly black liquid.
It boils at about 356 deg., and emits a very deep violet colored vapor.
It gives off a very appreciable vapor, sufficient for all purposes
of forming the iodide of silver on the daguerreotype plate, at a
temperature of 45 deg. or even lower. Iodine crystallizes readily.
Every operator has found upon the side of the jar in his coating-box,
perfectly regular crystals, deposited there by sublimation.

Water dissolves but a small proportion of iodine, requiring 7000
parts of water to dissolve one of iodine,

[page 85]

or one grain to the gallon of water. Alcohol and ether dissolve it freely,
as does a solution of nitrate or hydrochlorate of ammonia and of iodides.

The density of solid iodine is 4.95; that of its vapor 8.716. It greatly
resembles chlorine and bromine in its combinations, but its affinities
are weaker. It does not destroy the majority of organic substances,
and vegetable colors generally resist its action. It combines