Elements of chemistry : including the applications of the science in the arts . ximatively by precipitation by the ammonio-nitrateof silver. Properties.—Iodine is generally in crystalline scales of a bluish black colour andmetallic lustre. It is obtained, from solution, in modifications of an elongated octa-hedron with rhomboidal base (fig. 161.) The density of iodine is 4-948; it fusesat 225°, and boils at 347°; but it evaporates at the usual temperature, and morerapidly when damp than when dry, diffusing an odour having considerable resem-blance to chlorine, but easily distinguished from it.
Elements of chemistry : including the applications of the science in the arts . ximatively by precipitation by the ammonio-nitrateof silver. Properties.—Iodine is generally in crystalline scales of a bluish black colour andmetallic lustre. It is obtained, from solution, in modifications of an elongated octa-hedron with rhomboidal base (fig. 161.) The density of iodine is 4-948; it fusesat 225°, and boils at 347°; but it evaporates at the usual temperature, and morerapidly when damp than when dry, diffusing an odour having considerable resem-blance to chlorine, but easily distinguished from it. Iodine stains the skin of ayellow colour, which however disappears in a few hours. Its vapour is of a splendidviolet colour, which is seen to great advantage when a scruple or two of iodine isthrown at once upon a hot brick. Hence its name, from Iw^s, vapour of iodine is one of the heaviest of gaseous bodies, its density beino- 871623 354 IODINE according to the experiment of Dumas, and according to calculation from itsatomic weight. Fia. Pure water dissolves about 1-7000th of its weight of iodine, and acquires a browncolour; but when charged with salt, particularly the nitrate or hydrochloratc ofammonia, water dissolves a considerably greater quantity of iodine. The solutionof iodine does not disengage oxygen in the light of the sun, and does not destroyvegetable colours, but after a time it becomes colourless, and then contains hydriodicand iodic acids. In other respects, iodine generally comports itself like chlorine,but its affinities are much less powerful. Iodine is soluble in alcohol and ether,with which it forms dark reddish-brown liquids. Solutions of iodides, too, all dis-solve much iodine, and become of a deep red colour. A liquid containing 20 grainsof iodine and 30 grains of iodide of potassium in 1 ounce of water, is known asLugols solution, and preferred to the tincture in medicine, because the iodine is notprecipitated from
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