There is no doubt, however, that the first successful application was made in 1838, as the discovery was reported to the world early in January, 1839.
Preparation .-- Iodine is mostly prepared from kelp, or the half vitrified ashes of seaweed, prepared by the inhabitants of the western islands, and the northern shores of Scotland and Ireland.

It is treated with water, which washes out all the soluble salts, and the filtered solution is evaporated until nearly all the carbonate of soda and other saline matters have crystallized out.

The remaining liquor, which contains the iodine, is mixed with successive portions of sulphuric acid in a leaden retort, and after standing 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.