Manchester Memoirs, Vol. xli. (1897), No. 8. 



3 



of iodine upon the alkalies was similar to the action 

 of chlorine and bromine, and might be represented as 

 follows : — 



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



He also concluded that, as the liquids lost their bleaching 

 power, they gradually changed into iodide and iodate, 

 according to the following equation : — 



3KOI = 2 KI+KI0 3 . 



One thing which seemed to puzzle him very much 

 was that the liquids gave a blue colour with starch 

 alone, even when he added potash in the proportion of 

 two equivalents to one of iodine. He thus made the 

 liquid strongly alkaline, and capable, as he said, of 

 taking up more iodine ; and he argued, therefore, that 

 there could not be any free iodine present in the excess 

 of potash, and that hence the blue colour could not be 

 due to iodine. In addition he pointed out that the 

 liquid was almost, if not quite, colourless. He found, 

 however, that the addition of potassium iodide turned 

 the liquid brown again, manifestly owing to the libera- 

 tion of iodine. I shall show further on that these results 

 are easily explained. 



I may mention that in all my experiments the iodine 

 used was carefully purified by Stas' method, and that 

 the indigo was a solution of indigo carmine in water. 



As has been already mentioned, the liquids produced 

 by the action of alkalies upon aqueous iodine have a 

 most energetic bleaching action upon indigo ; they also 

 bleach cochineal and logwood, but not litmus. In 

 bleaching indigo they are much more active than either 

 a solution of chlorine or of bleaching powder of 

 anything like the same strength ; in fact, compared 

 with Schonbein's solutions, chlorine and hypochlorites 

 may be described as very sluggish. 



