Page:Scientific Memoirs, Vol. 1 (1837).djvu/286

 274 chloric acid. Although this fact may be consistently explained by supposing that the presence of a chloride of an oxide in the saturated solution of chloride of potassium has diminished, in this case, the solvent power of the liquid with respect to this compound, and that the salt which is obtained is only a portion of that which previously existed in the liquor, and thus is not produced by the action of the chlorine, as supposed by Berzelius, the first explanation is yet the most probable, and induces the belief that metallic chlorides exist ready formed in the decolorizing compounds.

M. Soubeiran has confirmed this fact by an experiment which appears to me to be at present the only one not liable to objections. After having determined, by a preliminary trial, the intensity of the decolorizing power of a given volume of chloride of soda, he evaporated it in vacuo to dryness. He has stated that during the evaporation cubic crystals of chloride of sodium are formed, which may be separated in a state of perfect purity; and that the remaining solid residue dissolved in water and tested with a coloured but not acid liquor, possessed absolutely the same decolorizing power as the liquid from which it was procured. This decolorizing power not having suffered any diminution, it cannot be admitted that the chloride of sodium obtained was the product of the decomposition of the decolorizing compound. This chloride of sodium, therefore, existed in the solution of the alkaline chloride before its evaporation. If, then, in acting upon an alkali, the chlorine had formed chloride of sodium, without the production of a corresponding quantity of chlorate, of oxygenated water, or of gaseous oxygen, it necessarily follows that an oxygenated compound was formed, different from chloric acid.

The crystallization of chlorite of soda in vacuo, led M. Soubeiran to hope that he should succeed in isolating chlorous acid. But the continuation of his researches, although announced three years since, has not yet been published.

It will be observed, from what has preceded, that there may still exist among chemists some indecision as to the choice which may be made between the two hypotheses proposed as to the nature of the decolorizing compounds of chlorine. Although the hypothesis of chlorites is by much the most probable, it is nevertheless true, that not only chlorous acid has not been obtained in a free state, but even chlorites also; they not having been yet procured, but in a state of mixture with the metallic chlorides.

Thus, although very probable, the existence of these salts is far from being demonstrated, and the composition of chlorous acid, which was supposed to be formed of two volumes of chlorine and three volumes of oxygen, remains undecided.

It appeared, therefore, to me desirable to attempt some fresh experiments, with the endeavour of elucidating a theoretical chemical