228 Mr. Williamson on the 



tion from the precipitate, was boiled until all free hypochlorous 

 acid had disappeared. It now contained no traces of a hypo- 

 chlorous acid salt, as proved by the fact that tincture of litmus 

 was not bleached by it, though an excess of sulphuric acid 

 was added, proving that the barytes salt was completely de- 

 composed by carbonic acid. 



A solution of barytes was saturated with chlorine in the man- 

 ner above described, and being freed from superfluous chlo- 

 rine, was now treated in a similar manner with carbonic acid. 

 No precipitate whatever was formed, which must have been the 

 case had any hypochlorous acid been combined with barytes. 

 The hypochlorous acid salt, formed by the action of the first 

 equivalent of chlorine with the base, had thus been entirely 

 decomposed by the second equivalent. 



When I further state, that on this liquid being subjected to 

 distillation, hypochlorous acid passed over, while the residue 

 consisted of chloride of barium with a small quantity of chlo- 

 rate of barytes, then I think it will be beyond a doubt, that of 

 the two equivalents of chlorine which the barytes took up, 

 one combined with the barium, the other with its oxygen. 



The following is the formula explaining the decomposition : 



Aq + 2BaO + 2C1 = BaCl + BaOClO 

 Aq + 2BaO + 4C1 = 2BaCl + 2C10 



In endeavouring to purify this mixture, of chloride of barium 

 and hypochlorous acid, from all free chlorine contained in it, 

 I noticed a remarkable circumstance, which I will relate. By 

 agitating the solution with repeatedly renewed portions of atmo- 

 spheric air, I was able to obtain a colourless liquid, which 

 possessed but a very slight smell of chlorine. But when this 

 was allowed to stand for a few minutes, especially in a strong 

 light, the colour and smell of chlorine re- appeared. Now, 

 as no chlorine had access to it from without, this must have 

 been caused by a decomposition of the hypochlorous acid. 

 This decomposition takes place in common daylight, more 

 rapidly in direct sunshine, and most rapidly when the liquid 

 is heated in a water-bath. The solution, after decomposition 

 had ceased, and no more chlorine was given off, contained a 

 considerable quantity of chlorate of barytes. The liquid 

 now contained no hypochlorous acid, either free or combined. 

 The following analysis was made in order to determine the 

 proportion of chlorine remaining in it. The barytes was first 

 precipitated by sulphate of soda. The chloric acid was then 

 deoxidized by means of sulphurous acid, and after separation 

 from the sulphate of barytes, the whole of the chlorine was 

 determined by means of nitrate of silver, thus: — 



