Page:Scientific Memoirs, Vol. 1 (1837).djvu/283

Rh On the first supposition it is admitted, that chlorine, in acting on some metallic oxides, combines with, without decomposing them, so as to form compounds which are not very permanent. The gas being thus but slightly retained, acts upon vegetable colours as if it were free; that is to say, it destroys them, either by dehydrogenating them in a direct manner, or occasioning their oxidation by means of the oxygen of the water. The chlorine, by taking away the hydrogen, either of the water or the colouring matter itself, is converted into hydrochloric acid, and subsequently into a hydrochlorate.

On the second supposition, on the contrary, it is supposed that the chlorine acts upon the metallic oxide employed, so as to decompose part of it; that one portion of this chlorine unites to the metal to form a chloride, and the other to its oxygen to become chlorous acid; and that this, saturating the portion of the base undecomposed, thus forms a true chlorite. In this manner of regarding the subject, the product obtained is complex, and contains a mixture of chloride and chlorite. It is thus supposed that chlorine and water act upon the metallic oxides like sulphur, which, under the same circumstances, produces a mixture of sulphuret and hyposulphite. It is also supposed that these chlorites, coming into contact with putrid organic or colouring matter, yield to them all the oxygen both of their acid and base, and are converted into chlorides; and that it is thus entirely by an oxidizing action that they serve as decolorants and disinfectants.

In attempting to resolve the question à priori, upon theoretical considerations, we are tempted to consider this last supposition as the most probable. In fact, the combinations of simple with compound bodies are not common; and although the hydrates of chlorine, bromine, and phosphorus are incontestible examples of the union of a simple body with an oxygenated compound, combinations of this nature are not numerous. It is therefore good logic to admit of the existence of similar compounds, only when the phænomena which are concerned in their production cannot be explained by other views more consistent with general facts. It appears, also, difficult to suppose, that a body which so readily combines with the metals as chlorine does, could unite with their oxides without decomposing them, as is the case with the other metalloids, and remain in contact with the metals, with which it forms very neutral and permanent compounds, without so doing.

The facts hitherto observed agree with theory, and seem to support in preference the hypothesis of the chlorites.

Chemists, indeed, considering that the compounds which we are now considering had the property of disinfecting and decolorizing, like chlorine itself, were at first induced to think that this body existed in them in some sort of ephemeral combination, which allowed of its exerting the same kind of action as if it were free. But it has been since