THE BLEACHING COMPOUNDS OF CHLORINE. 273 



question, which is not only of itself of considerable importance, but the 

 solution of which might also throw some light on the true mode of 

 action possessed by these decolorizing compounds, the uses of which 

 are daily multiplied in medicine and the arts. 



I think that I have succeeded in proving that these compounds are 

 really saline combinations of a peculiar acid formed of chlorine and oxy- 

 gen. It is this acid, which I have isolated, that forms the subject of this 

 essay, in which I shall treat successively of the manner of obtaining it, 

 of the properties by which it is distinguished, the proofs of its composi- 

 tion, and the generic charactei's of the combinations which it forms. 



Until a knowledge of the proportion of its elements, of which I shall 

 treat in a following paragraph, allows of my stating the true name 

 which the rules of chemical nomenclature assign to this acid, I shall 

 continue to call it chlorous acid, and designate its compounds by the 

 name of chlorites. 



§ 2. On the Processes by which Chhrous Acid may he prepared. 



When reflecting on the best mode of proceeding in these researches, 

 it will be soon perceived in reasoning on the hypothesis of the exis- 

 tence of chlorites, that the question would be on the point of being 

 determined, if the supposed chlorite could be separated from the chlo- 

 ride with M'hich it is considered as mixed in the decolorizing compound. 

 Nothing would be easier to perform, if there existed a metal which 

 would form with chlorine a compound soluble in water, and the ox- 

 ide of wliich could at the same time form with the chlorous acid a 

 compound insoluble in this liquid. But, unfortunately, all the known 

 decolorizing compounds are soluble in water, and therefore nothing is 

 to be hoped for in this respect. 



This separation would also be very easy if, on the contrary, a metal 

 was known which would form an insoluble compound with chlorine, and 

 the oxide of which, by uniting with chlorous acid, would form a soluble 

 and stable compound, up to a certain point. But the metallic chlo- 

 rides are all soluble in water, except chloride of silver, lead, and proto- 

 chloride of mercury ; these three metals are therefore evidently those 

 only M'hich afford a choice. 



Economical motives made me at first think of the salts of protoxide 

 of mercury and of lead ; but I soon found that no good result could be 

 obtained by employing them. 



When a solution of chloride of lime or of soda is treated with proto- 

 nitrate of mercury, there is immediately precipitated a great quantity 

 of protochloride of mercury, and the supernatant liquid is strongly de- 

 colorizing ; but this property soon disappears, and the liquor then con- 

 tains a notable quantity of deutochloride of mercury : the precipitate soon 

 becomes red, and changes to an oxichloride. 



