1835.] Decolourizing Compounds of Chlorine. 435 



the paper becomes friable, but is not charred, while oxygen 

 is disengaged. 



The experiments of Soubeiran and Liebig shewed that 

 alcohol is converted by the decolourizing chlorides into a 

 peculiar chloride of carbon. The hypo-chlorites possess 

 the same property. The facts already stated justify the 

 following conclusions : 1. The hypo-chlorites enjoy a great 

 number of properties which characterize free hypo-chlorous 

 acid. 2. These properties are identically the same as those 

 which have been observed in the decolourizing chlorides, 

 which should be considered as consisting of 1 atom chlo- 

 ride 4-1 atom hypo-chlorite. 3. The presence of a metallic 

 chloride in the decolourizing chlorides does not alter the 

 properties of the hypo-chlorite itself. 



It may be asked, how do these compounds decolourize 

 and disinfect 1 The answer is easy. — When an acid is added 

 to them chlorine is disengaged, and it is this chlorine which 

 disinfects and decolourizes, by a mode of action not yet 

 understood, but which is generally considered to be an 

 oxidation produced in an indirect manner, at the expense 

 of the elements of water. If they act without the aid of 

 acids, it is only by the oxygen of the acid and of the base 

 of the hypo-chlorite that they can decolourize and disinfect, 

 and which transforms the latter into a chloride. 



A corresponding compound of bromine and oxygen, hypo- 

 hromous acid may be obtained by a similar proceeding. 



Article III. 



On Bleaching Powder.* By Thomas Thomson, M.D., 

 F.R.S., L. & E., Regius Professor of Chemistry in the 

 University of Glasgow. 



Bleaching powder has been in common use among the 

 bleachers and calico-printers of Great Britain for the 

 greatest part of the present century. The gradual diminu- 



* The experiments contained in this paper were made several years ago. I 

 puhlish them at present, because they serve to confirm the results of M. Balard's 

 analysis of chlorous acid, contained in the preceding memoir. 



2f2 



