Manchester Memoirs, Vol. xli. (1897), ^ 7 °- 8. 7 



As Schonbein pointed out, the solutions are very 

 unstable. I have made a number of experiments upon 

 the rate at which the change occurs, estimating this by 

 the diminution in bleaching power. I find that the 

 presence of excess of alkali makes the solution more 

 stable ; but even then a solution loses half its bleaching 

 power on standing, in the dark, for four hours. In 24 

 hours 75 °/ Q of the bleaching power goes. If a much 

 smaller amount of alkali is used half the bleaching power 

 goes in an hour. On heating the solutions, they alter 

 very rapidly, and every bleaching liquid of this kind 

 which I have prepared loses its bleaching power entirely 

 if boiled for three or four minutes. As Schonbein 

 assumed, this loss of bleaching power is doubtless due 

 to a change of the hypoiodite into iodide and iodate — 



3 KOI=2 KI + KIO3. 



As mentioned above, Schwicker has recently investi- 

 gated the rate at which the above change occurs at the 

 ordinary temperature with different proportions of iodine 

 and potash present. The results do not appear to have 

 been altogether satisfactory. But he used iodine dissolved 

 in potassium iodide, and there is no doubt that the 

 latter would affect the results materially. Probably 

 better results would be obtained by the use of a solution 

 of hypoiodite made from hypoiodous acid (see page 16), 

 which would not contain any iodide at all. 



I may refer here to the fact that whether the liquid 

 contains iodide and hypoiodite or iodide and iodate, the 

 addition of an acid at once liberates the whole of the 

 iodine ; in the one case hypoiodous and hydriodic acids 

 are liberated, which at once decompose each other 

 (H O I + H I=H 2 + I 2 ) ; in the other hydriodic and iodic 

 acids are similarly liberated, and in the exact amounts 



