THE BLEACHING COMPOUNDS OF CHLORINE. 305 



the name of chlorous acid would be reserved for the j'et unknown com- 

 bination of tAvo volumes of chlorine and three of oxygen, and that of 

 hypochloric would signify, as M. Thenard has proposed, the compound 

 now called deutoxide of chlorine. 



§ 6. — Of the Hypochlorites. 



The hypochlorous acid, which is obtained, with difficulty it is true, 

 from the decolorizing compounds of chlorine, by employing the pro- 

 cesses which I have described, presents the same characters as that fur- 

 nished by the action of this gas on the red oxide of mercury. It is 

 therefore extremely probable that these compounds contain hypochlo- 

 rites mixed with chlorides. But as it is not impossible that the hypo- 

 chlorous acid obtained from them, instead of being really formed in 

 these bodies, is merely a product of their decomposition, it appeared to 

 me proper, in order to render the demonstration more complete, to study 

 the general properties of the compounds of this acid with bases, and, by 

 showing that they are the same as those which have been ascertained in 

 the decolorizing compounds, to confirm by synthesis the results obtained 

 by analysis. 



Pure hypochlorites may be obtained in two different modes, one di- 

 rect and the other by double decomposition. 



The direct combination of concentrated hypochlorous acid with pow- 

 erful bases, M-hether solid or in concentrated solutions, is accompanied 

 with the disengagement of intense heat. This heat, when it is a little 

 too great, changes the hypochlorite into chlorate and chloride. 



The presence of a certain excess of base prevents this conversion, 

 whereas it is very rapidly effected when the chlorous acid is in excess. 

 It is therefore necessary to add the alkaline substance to the acid, in 

 quantity insufficient for saturation, and constantly to agitate the bottle, 

 immersed in cold water ; and not to reverse the operation, by gradually 

 saturating the acid with the base. By taking these precautions, con- 

 centrated solutions of hypochlorous acid and potash may be used with- 

 out precipitating chlorate of potash, notwithstanding the sparing solu- 

 bility of this salt ; this proves, that if any is formed the quantity is very 

 small. If either of these precautions be neglected, chlorate is abun- 

 dantly precipitated ; when both are observed, the hypochlorous acid 

 combines simply with the base, and no gas is disengaged ; but when a 

 high temperature or an excess of chlorous acid occasion the decompo- 

 sition of the hypochlorite, a gaseous disengagement occurs. This gas 

 is pure oxygen if the base is in excess ; when on the contrary the hy- 

 pochlorous acid predominates, it is oxygen mixed with chlorine. 



It is easy to explain this double phsenomenon. The experiments of 

 M. Morin have proved, on the one hand, that the decolorizing compounds 

 of chlorine lose part of their oxygen when they are converted into chlo- 



