NATURE OF THE BLEACHING COMPOUNDS OF CHLORINE. 279 



fused in water, the chlorous acid, which would seem to be pure, is 

 nevertheless mixed with a large quantity of chloric acid. 



Indeed, when chlorine is agitated with oxide of silver, it is an ope- 

 ration which, whatever be the rapidity with which it is conducted, 

 requires a minute or two that the absorption of the chlorine may be 

 complete ; even in this case a portion of the chlorite is decomposed, 

 and converted, as usually happens, into chloride and chlorate, and the 

 latter decomposed in its turn by the chlorine produces chloric acid. 

 Thus, in whatever manner the operation is conducted, a notable por- 

 tion of the chlorous acid is changed into this new compound. 



But this chlorous acid is fortunately possessed of a volatility which 

 allows of its separation from the bodies with which it is mixed, and it 

 may be obtained diluted with water by distilling the liquid prepared 

 by employing one of these three methods. However, as a high tem- 

 perature may decompose it in part, and as at the heat of boiling water 

 some of the substances with which it is mixed, as hydrochloric and 

 nitric acid, maj^ come over in distillation, it is better to operate in 

 vacuo, or at least under low pressure, at a temperature below 212" 

 Fahrenheit. A solution of chlorous acid is thus obtained, but diluted 

 Mith much water. The first product is the richest in chlorous acid ; if 

 this be kept apart and be again distilled, chlorous acid may be obtained 

 in a concentrated state. 



These methods supply, it is true, but very small quantities, and I 

 should have renounced the study of the properties of this new oxigen- 

 ated compound of chlorine, if I had not discovered a more economical 

 and productive process. This method consists in treating chlorine with 

 red oxide of mercuiy suspended in Avater. 



The action of chlorine upon this compound has been already studied 

 by M. Grouvelle. This chemist has stated that oxichloride of mer- 

 cury, very slightly soluble in cold water, was formed. M. Thenard, 

 on the other hand, has observed that the liquid contained chloride and 

 chlorate of mercury also in solution ; but I am at libei'ty to suppose 

 that these bodies are only formed consecutively, and that their exist- 

 ence had been preceded by that of a mercurial chlorite, as takes place 

 with the salts of silver. 



Certain theoretical considerations made me conceive some hope in 

 employing oxide of mercury. In fact, if we reflect on the conditions 

 wliich appear the most favourable for producing and isolating chlorous 

 acid, it will be seen that they are reducible to the four following; 1st, 

 • the action of chlorine on a strongly alkaline oxide; 2ndly, that this 

 oxide should form a chlorite possessing a certain degree of stability ; 

 3rdly, that the metallic chloride formed may, on account of its insolu- 

 bility, easily separate from the chlorite ; 4thly, and lastly, that it 

 should rc-act but feebly on the chlorous acid Avhen it is separated by 



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