Potassium iodide, KI, is obtained by dissolving iodine in potash, the deoxidation of the iodate being facilitated by the addition of charcoal before ignition, proceeding as with the bromide.
The third most valuable indication which molecular structure gives about these isomers is how to prepare them, for instance, that normal hexane, represented by CH 3 CH 2 CH 2 CH 2 CH 2 CH3, may be obtained by action of sodium on propyl iodide, CH 3 CH 2 CH 2 I, the atoms of iodine being removed from two molecules of propyl iodide, with the resulting fusion.
On shaking up iodine with a solution of sulphuretted hydrogen in water, a solution of hydriodic acid is obtained, sulphur being at the same time precipitated.
By adding an alcoholic solution of iodine to a solution of the sulphate in acetic acid a compound known as herapathite, 4Qu 3H 2 SO 4.2HI Ie6H 2 O, is obtained, which possesses optical properties similar to those of tourmaline; it is soluble in Iwo parts of boiling water; and its sparing solubility in cold alcohol has been utilized for estimating quinine quantitatively.
In 1830 he published in the Philosophical Transactions a paper on the iodine and bromine of mineral waters.
In medicine iodine is frequently applied externally as a counterirritant, having powerful antiseptic properties.
On the Bade Insel is the Kurhaus (1872) and also the chief spring, the Elisabethquelle, impregnated with iodine and bromine, and prescribed for scrofulous, bronchial and rheumatic disorders.
Iodine in the presence of water frequently acts as an oxidizing agent; thus arsenious acid and the arsenites, on the addition of iodine solution, are converted into arsenic acid and arsenates.
They are more easily reduced than the corresponding chlorates; an aqueous solution of hydriodic acid giving free iodine and a metallic oxide, whilst aqueous hydrochloric acid gives iodine trichloride, chlorine, water and a chloride.
Although hypoiodous acid is not known, it is extremely probable that on adding iodine or iodine monochloride to a dilute solution of a caustic alkali, hypoiodites are formed, the solution obtained having a characteristic smell of iodoform, and being of a pale yellow colour.