6 Taylor, Hypoiodous Acid and Hypoioditcs. 



whole of the iodine. The solutions used are extremely 

 dilute, but there is really no difficulty in making estima- 

 tions which will be accurate to within two or three per 

 cent. The general result of these experiments is that 

 95 % of the iodine in Schonbein's solutions undergoes the 

 reaction represented by the equation 



2 K O H + I 2 =K I+K O I + H 2 0. 



These results are amply confirmed by an altogether 

 different method— one which was used by A. Schwicker 

 {Zeit. physikal. Chem., 16, 303-314) in an investigation 

 which he has recently made on the reaction velocity of 

 potassium hypoiodite. He takes advantage of the fact 

 that potassium bicarbonate will decompose a mixture of 

 hypoiodite and iodide, with liberation of iodine. He also 

 uses a little soda-water, the carbonic acid in which is 

 intended to convert any liberated potash into the bicar- 

 bonate. The bicarbonate apparently decomposes the 

 mixture of hypoiodite and iodide, with formation of 

 normal carbonate and liberation of iodine, according to 

 the following equation : — 



K O I + K 1+2 K H C 3 =2 K 2 C 3 +H 2 + I 2 . 



With my dilute solutions, I find that it answers just as 

 well to run into the liquid, which is always sufficiently 

 alkaline, a small quantity of soda-water. This imme- 

 diately liberates the iodine, which can now be estimated 

 by means of a centi-normal solution of sodium arsenite. 

 Carbonic acid does not decompose potassium iodate, so 

 that this method may be employed in all mixtures of 

 hypoiodites, iodates, and iodides. In one determination 

 by this method 97 % of the iodine originally used was 

 liberated on the addition of the soda-water. We may, 

 therefore, conclude that when potash acts upon iodine- 

 water there is practically no iodate formed. 



