Journal of the Chemical Society Abstracts
Compare t h i s vol., i i , 557).-The action of hydrogen peroxide on halogen acids has been further studied. The affinity of the halogen hydrides for hydrogen peroxide varies as the affinity of the halogen for oxygen, hydrogen iodide being easily decomposed. 'The reaction depends on the order in which the substances are brought together. When hydrogen iodide is added to hydrogen peroxide, the reaction is so violent that the solid iodine which is first liberated volatllises. leaving a colourless
... eaving a colourless liquid, but when hydrogen peroxide is added to an excess of the acid, although the reaction is vigorous, %he iodine does not disappear. Exactly the reverse is the case with the other acids. The reaction is more energetic when hydrogen peroxide is added t o the acid. The haloid salts behave in the same way, from which it appears that hydrogen peroxide' first liberates the free acid and then decomposes it. This view is supported by the fact that ammonium peroxide (D'Ans and Wedig, A., 1913, ii, 1051) precipitates the peroxides from solutions of the alkaline earth haloids. J. C. W. The System Ammonia-Water, A. SM~TS and S. POSTMA (Proc. K. Akccd. Wetmsch. Amsterdam, 1914, 17, 182--194).-Further cooling-curve observations have enabled the authors t o give a more complete description of t;he freezing-point diagram. The two compounds 2NH"H,O and N€€"H,O melt at' -78'9O and 79*0° respectively. The eutectic point at which ammonia and 2NH"H,O coexist as solid phases lies a t 81.4 mols. % of ammonia and -92.5O. The point atl which 2NH"H20 and NH"H,O co-exist lies at 58.5% ammonia and -86*0°, and that corresponding with the co-existence of NH"H,O and ice at 34.7% of ammonia and -100.3O. Except in the interval f o r mixtures containing 30-40 mols. % of ammonia, the authors' data agree satisfactoriIy with those of Rupert (A ., 1909, ii, 726; 1910, ii, 605).