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On the Acid'ificat'ion of Iodine hj means of Nitric Acid. By 

 Arthuii Connell, Esq. A. M. Communicated by the 

 Author. 



The methods which have been hitherto followed for the oxida- 

 tion of iodine with a view to the formation of iodic acid, may 

 apparently be reduced to three : Jirst, The action of alkaline 

 solutions giving rise to the formation of a hydriodate and an 

 iodate, from the latter of which the iodic acid may be separated 

 by the original method of M. Gay-Lnssac, and more perfectly 

 by the recent processes of M. Serullas*; secondly'. The action 

 of cuchlorine, as suggested by Sir H. Davy ; and, thirdli/, The 

 action of water on the perchloride of iodine, and subsequent 

 separation of iodic acid by means of alcohol, as also proposed 

 by M. Serullas t. The agency of nitric acid, under certain 

 management, offers another method, which I have been unable 

 to observe noticed any where, and which, perhaps, will be 

 found to equal in facility of execution any of the preceding 

 processes. 



■ This agency mav be advantageously studied on the small 

 scale. If a little iodine be boiled with a small quantity of nitric 

 acid in a common test tube about five inches long, the iodine is 

 dissolved, and a red solution formed. If the liquid be now far- 

 ther boiled, and the orifice of the tube kept slighdy stopped 

 with a piece of cork, the iodine sublimes, and condenses on the 

 sides of the tube. Tlie iodine is then to be waslied back again 

 into the liquid by agitation ; the liquid again boiled, and the 

 sublimed iodine again washed back into the fluid; and this pro- 

 cess is to be continued until no iodine any longer appears, and 

 the liquid is colourless. If the boiling be then continued for a 

 litde, so as to increase the concentration of the liquid, it usually 

 becomes milky ; and if it be poured out and evaporated to dry- 

 ness, a white mass is left, which is iodic acid, retaining a little 

 nitric acid. 



Having made these observations on the small scale, I pro- 



• Annates dc Chimie ct tie Physique, xliii. 127 & 217. 

 f Ibiil. xlv. 63. 



