Fermented liquors contain iodine; wine, cider, and perry
are more iodureted than the average of fresh waters.
Milk is richer in iodine than wine; independently of the soil,
with which it varies, the proportion of iodine in milk is
in the inverse ratio of the abundance of that secretion.
Eggs (not the shell) contain much iodine. A fowl's egg weighing
50 gr. contains more iodine than a quart of cow's milk.
Iodine exists in arable land. It is abundant in sulphur,
iron, and manganese ores, and sulphuret of mercury:
but rare in gypsum, chalk, calcareous and silicious earths.
Any attempt to extract iodine economically should be made
with the plants of the ferro-iodureted fresh waters.
Most of the bodies regarded by the therapeutists as pectoral
and anti-scrofulous are rich in iodine.

It is probably to the application of this body that we owe the discovery
of the daguerreotype. There is no record of thep recise date when Daguerre
commenced experimenting with iodine, but by the published correspondence
between him and M. Neipce, his partner, it was previous to 1833.
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