PUCUS VESICULOSUS. 
that of soda ; when burut in close vessels it yields soda and charcoal, 
which last, has been named JEthiops Fegetabilis, Its medicinal 
properties are very slight, chiefly depending upon the portion of 
soda which it contains : when burnt, it is supposed to possess some 
deobstruent powers, as such, it has been exhibited in bronchocele 
and scrophulous affections. The mucus of the vesicles has long been 
a popular remedy as an external application to the joints in rickety 
children; and Dr. Russell found it an excellent resolvent when used 
as an embrocation to scrophulous swellings. But the principal use 
to which this plant has been applied is in the manufacture of kelp, 
as before noticed ; this latter substance has been found to contain 
a portion of that newly discovered elementary substance, named 
Iodine,* To this substance and the soda, the remedial efficacy of 
the fucus must be attributed. 
Iodine. This substance was discovered in 1813, by M. Courtois, 
a manufacturer of nitre in Paris, in the mother waters of soda, as 
it is obtained from sea-weed.+ Iodine is a simple substance, its 
name being derived from the Greek /wJvj?, on account of the violet 
colour of its vapour. Iodine (at the ordinary temperature) is a solid 
body, in the form of small greyish crystals with metallic lustre ; its 
odour is pungent, its taste acrid, and when applied to the skin stains 
it of a brownish yellow colour. It fuses at 338* Fahr. and volatilizes 
at 347'> Fahr. forming a very beautiful violet-coloured vapour. This 
vapour, when enclosed in a receiver, re-condenses into crystalline 
scales. Iodine is soluble in ether, and in spirit of wine ; water only- 
dissolves about YoVo*^h weight. Iodine is obtained, according 
to Dr. Ure, by the following formula : *' Take eight fluid ounces of the 
brown liquid which drains from the salt, which the soap-makers make 
use of who employ kelp, boil up, and evaporate to dryness ; heat it to 
230" Fahr. and add one fluid ounce of sulphuric acid, diluted with its 
own bulk of water; when the mixture cools, separate the crystals of 
the salts, which will form in it, by filtration through a woollen cloth, 
and add to the fluid poured into a matrass, 830 grains of black oxide 
of manganese in powder. A glass globe is then to be inverted over 
the mouth of the matrass, and the heat of a charcoal chauffer being 
applied, iodine will sublime in great abundance. It must be washed 
* Iodine has been obtained from many species of marine plants, via. Fucus Digitatns 
Fucu ScriaUis, Fucus Vesiculosus, Fucns Nodosus, Fucus Saccharinus, &c. Ulv; 
Pavonia, Umbilicalis, Linza, &c. 
t These waters are obtained bjr burning the different fuoi which grow on the sea- 
chores, ILxiviating the ashes, and concentrating the liquor. 
