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Additional Observations on the Relation of Nitric aiid Nitrotis 

 Acids to Bromine and Iodine. By Arthur Connell, Esq. 

 F. R.S. E., &c. Communicated by the Author. 



In a late notice, mention was made of some unsuccessful at- 

 tempts to oxidate bromine by means of nitric acid, by a process 

 similar to that which effected the conversion of iodine into iodic 

 acid *. It was farther stated, that when a small quantity of 

 bromine was boiled with nitric acid for a considerable time in a 

 long tube, the upper and open extremity of which was bent and 

 terminated in water, and the intermediate part kept cool by 

 moistened bibulous paper, so as to condense the bromine as 

 it sublimed, and cause it to fall back into the acid, the water, 

 after the free bromine which had passed over was expelled by 

 heat, gave with nitrate of silver a pretty plentiful precipitate of 

 bromide of silver. This precipitate I have since found, from 

 an examination of the liquid in a variety of ways, was caused by 

 the presence of hydrobromic acid ; and the question arose, to 

 what cause the occurrence of that acid could be attributed. To 

 ascertain whether bromine was capable of decomposing pure 

 water by similar treatment, and of so giving rise to the forma- 

 tion of hydrobromic acid, a little bromine was boiled with water, 

 under the same circumstances; but after the liquids employed 

 had been deprived of colour by a gentle heat, no hydrobromic 

 acid could be discovered by the agency of chlorine, and subse^ 

 quent agitation with ether. It became necessary, therefore, to 

 look for some third body, which, by its affinity for oxygen, might 

 contribute to the decomposition of water ; and as a coloured and 

 fuming nitric acid had been employed, it appeared probable 

 that nitrous acid might have that effect Accordingly, on ma- 

 king the experiment with colourless nitric acid and bromine, 

 and afterwards driving off free bromine from the water,, ia 

 which the extremity of the apparatus terminated, by a gentle 

 heat, no hydrobromic acid could be observed in it, when ex- 

 amined by means of chlorine and ether. On the other hand, 

 when the experiment was repeated with a red and highly fum- 

 ing nitric acid, the presence of hydrobromic acid in the water 



• This Journalj April 1682; 



