14 Taylor, Hypoiodous Acid and Hypoiodites. 



HYPOIODOUS ACID. 



So far as I have been able to ascertain, it has always 

 been stated that all attempts to obtain hypoiodous acid by 

 the action of iodine and water upon mercuric oxide have 

 failed, and that nothing but iodic acid was formed.* I 

 had tried the action once more with the aqueous solution 

 of iodine, and had apparently been as unsuccessful as 

 ever. I had succeeded, as I believe, in obtaining the acid 

 by other methods, to be presently described, and had 

 noticed the curious anomaly that the free acid, or what I 

 took to be the free acid, bleached indigo with far less 

 energy than the hypoiodites described in the first part of 

 this paper ; but I had failed, as others no doubt had 

 frequently failed, to obtain any bleaching solution by the 

 action of iodine and water upon mercuric oxide. 



In the paper already referred to by Walker and Kay, 

 the authors state that they " made a solution of hypo- 

 iodous acid by agitating pure aqueous solution of iodine 



* So long ago as 1845 Kone (Poggendorff's Ann., 66, p. 302) tried the 

 experiment of shaking up precipitated mercuric oxide with an alcoholic 

 solution of iodine, and, from the fact that he obtained an unstable solution 

 which gradually liberated iodine, and from analogy with the chlorine com- 

 pounds, he concluded that hypoiodous acid was formed. I have repeated 

 the experiment, and there certainly appears to be a hypoiodous compound 

 produced ; the alcohol which is present, however, interferes with the 

 reactions. The filtered liquid contains a considerable amount of mercury. 

 It gives a yellowish precipitate with water, and if a little alkali is added 

 to this it possesses very strong bleaching properties. The precipitate 

 produced with water dissolves up in sodium hydrate, but in a few seconds 

 another precipitate appears which is manifestly iodoform ; at the same 

 time the liquid loses it bleaching power. This appears to point to the 

 conclusion that the formation of a hypoiodite is the necessary prelude to 

 the formation of iodoform (see Van Dev enter and Van't Hoff, Chem. Central., 

 1888, p. 362). On account of this rapid change in presence of an alkali, the 

 solution does not give the cobalt reaction. If the precipitate produced by 

 water in the alcoholic solution is allowed to stand for some hours, scarlet 

 mercuric iodide separates out. The alcoholic solution is moderately stable, 

 but it gradually liberates iodine on standing. 



