Page:Proceedings of the Royal Society of London Vol 1.djvu/528

Rh A solution of the triple compound, in sulphurous acid, when distilled, yields iodine, and leaves sulphate of potash; but the phenoemena are variously modiﬁed, by a greater or less proportion of either ingredient.

From such experiments as the author has made on the proportional weights. of the constituents of this salt, he considers it perfectly analogous to hyperoxymuriate of potash; and its constitution will be represented by one of potassium '75, six of oxygen 90, and one of iodine 165.

The author also made triple compounds with iodine and alkaline earths, which, like oxyiode of potash, contain a redundance of oxygen, separable by heat, and gave hopes that a compound of iodine and oxygen, similar to euchlorine, might be obtained from some of them; but these salts are not decomposable by acids; for even the oxyiode of barytes is not decomposed by sulphuric acid, and hence no compound of iodine and oxygen has yet been obtained in a sepa- rate state.

From hydriodic gas, or from the acid formed by union of this gas with water, iodine may be obtained by union with oxygen, by nitric acid, by hyperoxymuriate of potash, or even by absorption of oxygen from the atmosphere.

This acid unites with the alkalies and common earths into compounds very analogous to the corresponding compounds with muriatic acid, but decomposable, in a. certain degree, by heat when oxygen is present, which occasions most of these compounds to be- come alkaline when long heated.

Although chlorine and iodine unite in all proportions, there is one compound nearly colourless that appears to be deﬁnite, having strongly acid properties, and the author terms this chloriodic acid. When any of these compounds are mixed with alkaline solutions, the tendency appears to be, in the ﬁrst instance, to form oxyiodes with the alkali or earth present; but the phenomena necessarily vary according to the proportion of the several ingredients present.

In the next set of experiments, which the author made with gases, the results appear to be regulated by the presence of hydrogen, form- ing hydriodic acid With the iodine, as in the instances of oleﬁant gas and sulphuretted hydrogen.

No change was produced in nitrous gas, nor in carbonic oxide, to which iodine was exposed in common day-light, nor even when it was sublimed in it; but it appeared doubtful whether there might not be some tendency to combine when the violet vapour was formed by heat in full sunshine. -

In conclusion, the author reports various unsuccessful attempts to obtain iodine from different species of sea-weeds, and from sea-water, on the shores of the Mediterranean; and he recommends silver as a test of its presence, since water containing only Tenth part of its weight of any salt of iodine tarnishes polished silver, even after boiling with muriatic acid, although this property is destroyed in sulphurets by similar treatment. -