Manchester Memoirs, Vol. xli. (1897), No. 8. 9 



contains some silver hypoiodite. If the liquid is poured 

 off or filtered off from the precipitate, it is found to have 

 completely lost its bleaching power. On the other hand, 

 if the precipitate is treated with a dilute acid, part of it 

 dissolves up, leaving the yellow iodide of silver, and at 

 the same time the solution acquires bleaching properties, 

 though not to anything like the extent that would corre- 

 spond to a complete transformation of the hypoiodite into 

 a silver salt, and then to hypoiodous acid. In the two 

 transformations a large amount of the hypoiodite is 

 evidently decomposed. 



I have already mentioned that Schonbein was greatly 

 puzzled to account for his bleaching solutions giving a 

 deep blue colour with starch alone. Lunge and Schoch, 

 in their paper, suggested that some iodine probably 

 existed in the liquid in combination with potassium 

 iodide. But a much more reasonable explanation had 

 already been supplied by the experiments of E. Lenssen 

 and J. Lowenthal (Journal fur praktische Chemie, 1862, 

 p. 245), who found that sodium iodide and hypoiodite 

 decompose each other, liberating iodine, and that the 

 amount of alkali required to react with free iodine 

 was greater when potassium iodide was present than 

 when there was no iodide. They practically stated that 

 the reaction 



2 K O H + 1 2 == K I + K O I + H 2 0 



is a balanced one, and that the addition of potassium 

 iodide reverses the action, which now produces potash 

 and free iodine. 



It follows that the amount of alkali required to 

 complete the above reaction must be greater than that 

 represented by the equation. I have added varying 

 amounts of a standard solution of soda to the same 

 amount of aqueous iodine. With one equivalent of 



