Decomposition of Oxides and Salts by Chlorine. 231 



The following is an experiment showing the nature of this 

 decomposition : — Treat a concentrated solution of simple car- 

 bonate of soda with chlorine until a considerable quantity of 

 bicarbonate is precipitated, but not until this precipitate com- 

 mences to be decomposed. The liquid on being now left to 

 itself in the light continues for several hours to give off car- 

 bonic acid with slight effervescence. We here have carbonate 

 of soda mixed with chloride of sodium and free hypochlorous 

 acid. These two latter, by gradually acting on each other, in 

 the manner above described, set chlorine free, which decom- 

 poses the carbonate. 



Now, as by treating carbonates with chlorine hypochlorous 

 acid is obtained free, and can be distilled over quickly, it ap- 

 peared to me that this might be an easy method of obtaining 

 this acid for use. It is desirable for this purpose to choose a 

 base which has not too powerful an affinity for chloric acid, and 

 consequently from the chloride of which, hypochlorous acid 

 can be quickly distilled off without decomposition. I chose, 

 with this view, carbonate of lime. 



This salt, prepared for the purpose by precipitation, was 

 mixed up with about 40 parts of water, and dissolved in chlo- 

 rine. When quickly heated to the boiling-point, this liquid 

 gave off' its hypochlorous acid, while the residue in the retort 

 consisted of a solution of chloride of calcium with a small 

 quantity of chlorate of lime. 



This is a cheap and easy method of preparing this most in- 

 teresting compound. It is well if a slight excess of carbonate 

 of lime be left in the liquid when subjected to distillation ; it 

 speedily dissolves as the liquid becomes hot, and the acid is 

 thus obtained free from chlorine, which is not the case with- 

 out this precaution. 



I was induced from this to try the action of chlorine upon 

 other salts with stronger acids, and discovered a series of in- 

 teresting decompositions, of which I will here state the outline; 

 and hope, after further investigation, to be soon able to com- 

 municate the details. 



A solution of tribasic phosphate of soda was treated with 

 chlorine, which it absorbed with great avidity. This solution, 

 after saturation, possessed a strong smell of hypochlorous 

 acid, which I distilled over from it. The residue gave a 

 sti'ongly acid reaction, proving that the chlorine had taken 2 

 atoms of soda from the phosphate, forming with the metal 

 chloride of sodium, and with the oxygen hypochlorous acid. 



Common phosphate of soda gave a similar result. The re- 

 sidue after distillation consisted of the same phosphate as the 

 preceding, with 1 atom chloride of sodium. 



