FUCUS VESICULOSUS. ORD. LIV. Alge. 113 
covered with a saline efflorescence: but if the fresh plant be immersed in 
boiling water before drying it, the colour remains as vivid as in the fresh 
plant. 
Qualities. Its taste is nauseous and somewhat like that of soda; its 
odour peculiar but slight. When fused, it yields charcoal, soda, and iodine. 
Medical Properties and Uses. The'burnt plant is considered deobstruent ; 
and has been exhibited in diseases of the glands (particularly goitre and 
scrofula) with much success. Dr. Russell found the mucus in the vesicles 
of the plant to be an excellent resolvent when externally applied, in dis- 
persing scrofulous swellings. He recommends the patient to rub the tu- 
mout with these vesicles bruised in the hand, and afterwards to wash the 
part with sea-water. It appears that: the beneficial effects produced by the 
external exhibition of this plant, may be chiefly attributed to the iodine it 
contains. 
Iodine is a simple body, discovered by M. Curtois in the mother-waters 
formed in the preparation of soda from sea-weed.* These waters are ob- 
tained by burning the different fuci which grow on the sea-shores, lixiviating 
the ashes and concentrating the liquor. The name iodine is derived from 
the Greek word ‘wénc, on account of the blue colour of its vapour. At the 
ordinary temperature, iodine is a solid substance, inthe form of small greyish 
crystals, which have but a weak tenacity, and the aspect of plumbago. It 
fuses at 170° c. (838 Fah.) and volatilizes at 175° (347° Fah.) forming a very 
beautiful violet-coloured vapour. This vapour, when enclosed in a receiver, 
re-condenses into crystalline scales. It has a pungent odour, an acrid taste, 
and stains the skin of a brownish-yellow colour. It is soluble in alcohol 
and ether (the latter taking up more or less, according to its degree of rec- 
tification) but sparingly so in water: its solutions have an orange-brown 
tint, destroying the vegetable colours. Iodine forms, with oxygen, the todic 
acid, and with chlorine the chloriodic acid. It has much affinity for hy- 
drogen, and takes it from a great number of bodies. It absorbs it in a 
gaseous state when the temperature is elevated ; and forms with this gas the 
hydriodic acid, which is composed exclusively of iodine and hydrogen. 
* Jodine has ben obtained from a great variety of marine plants; as the Fucus 
saccharinus, serratus, vesiculosus, Filum, nodosus, palmatus, digitatus ; Ulva umbili- 
calis, Pavonia, §c. It has also been procured from sponge, by Dr. Fyfe, and M. Straub 
of Hofwyl 
Vou. V. Q 
