On the coasts of certain islands belonging to the Duke of Argyll, vast quantities of sea-weed are occasionally torn up from their ocean beds and deposited on the shores. This weed, after being partially dried by exposure to the sun and air, is burnt in a shallow pit; the ashes are then collected, and form the commercial raw material called kelp, from which iodine is procured by a gradual series of processes.
EXPERIMENTS.
Iodine has a beautiful metallic lustre, with a bluish black colour, and should be kept in a well-stoppered bottle. A small quantity placed in a clear flask and heated, affords a magnificent violet vapour, which may be poured from the flask into another glass vessel, when it condenses again into crystalline plates. The colour of the vapour originates the name of this element, so called from the Greek ὶώδης, violet-coloured. If a little iodine be placed in contact with a thin slice of phosphorus, the latter takes fire almost immediately.
BROMINE.
So called from the Greek βρόμος, a bad odour, is most intimately allied with chlorine and iodine; like these elements it belongs to the sea, and is a constituent of sea-water. Bromine is a very heavy fluid, and should be preserved by keeping it covered with water in a stoppered-bottle.
Experiments with liquid bromine are not recommended, as all the most interesting ones can be performed with the vapour, which is easily procured by letting fall a few drops of bromine into a warm dry bottle.
EXPERIMENTS.
Pounded antimony sprinkled into the vapour takes fire immediately.
A thin slice of phosphorus placed in a deflagrating ladle and placed into the vapour of bromine ignites very quickly.
A solution of sulphate of indigo, or an infusion of red cabbage, are easily bleached by being shaken violently with the vapour of bromine.