114 ORD. LIV. Algez. FUCUS VESICULOSUS. 
* 
This acid presents itself under the form of a colourless gas, which has a 
very strong taste, a very penetrating odour, powerfully reddens the tincture 
of turnsol, and extinguishes burning bodies. This gas is very rapidly ab- 
sorbed by water, and is very largely dissolved in it. It gives out white 
fumes in the air by uniting with the aqueous vapour contained in the 
atmosphere. 
Starch is the most delicate test of iodine, forming a compound of a rich 
blue colour, when added to any solution which contains it in an uncom- 
bined state. The specific gravity of iodine is 4,941, and that of its vapour 
8,678 ; 100 cubic inches weighing about 270 grains. 
Preparations of Iodine. Wollaston was the first who gave a precise for- 
mula for preparing it; he dissolved the soluble part of kelp in water, and 
after evaporating it as long as it continued to afford crystals, he added a 
little more sulphuric acid to the remaining liquid than was necessary to 
neutralize the free soda which it contained, and after all action had ceased, 
he added as much black oxide of manganese to the clear liquor which re- 
mained, and on the application of heat, iodine was disengaged. Dr. Ure 
recommends the following formula to beadopted. “Take eight fluid ounces 
of the brown liquid which drains from the salt which the soapmakers use, who 
‘employ kelp, boil up and evaporate to dryness; heat it to 230° Fah. 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 char- 
coal-chaffern being applied, iodine will sublime in great abundance. 
“Tt must be washed out of the globe with alcohol, then drained and dried 
on plates of glass, and purified by a second sublimation from dry quick-lime.” 
Medical Properties and Uses of Iodine. M.Coindet, a physician of Ge- 
neva, was the first who used iodine in medicine ; suspecting, from analogy, 
that this substance was the active principle in sponge, he was induced to 
try it in those cases for which burnt sponge was administered, and his treat- _ 
ment of goitre was remarkably successful. These trials were repeated by 
several practitioners in France, Italy, and in our own country, with undi- 
minished benefit; and their observations would seem to prove that we now 
possess a powerful remedy for the removal of a disease which has been 
