2 Taylor, Reaction of Iodine with Mercuric Oxide. 



Some time after the publication of tlic paper above 

 referred to, Messrs. K. J. P. Orton and VV. L. Blackman 

 described some experiments { Jonrn. Chevi. Soc, Vol. jj 

 (1900), p. 835) which led them to the conclusion that "the 

 solutions obtained from iodine and mercuric oxide con- 

 tain only a small quantity of hypoiodite, and that the 

 iodine is chiefly present as iodate." The experiments by 

 which the authors arrived at this conclusion were of such 

 a character as to make it evident that they were not aware 

 of the extremely unstable nature of hypoiodous acid, 

 and that they were not acquainted with the results of my 

 experiments. They do not mention the quantities of 

 iodine (in proportion to the water employed) which they 

 used, although that would have much to do with the 

 results of the experiments. They do state, however, that 

 they used iodine which had been finely powdered, that 

 they shook up with water and mercuric oxide for " a few 

 minutes" (in one case "for 15 minutes"), and that the 

 filtering of the liquid usually took 10 minutes. Experi- 

 ments extending over such a long time were not likely to 

 be successful where a highly unstable body like hypo- 

 iodous acid was concerned. As the results thus described 

 by Orton and Blackman were so very different from m)' 

 own, I decided to make some further experiments, this 

 time using considerably larger amounts of iodine (in 

 proportion to the water) than I had formerly used. 



In these further experiments I always used precipitated 

 iodine, which is much more finely divided than that 

 obtained by powdering, no matter how long, in a mortar. 

 Some of the iodine used was precipitated by pouring a 

 very strong solution of iodine in potassium iodide into 

 excess of water, and some by adding bromine water to a 

 solution of potassium iodide In both cases, it is needless 

 to say, the iodine was well washed, and that portion which 



