2 BULLETIN OF THE UNIVERSITF OF WISCONSIN 



Preliminary Experiments. It is well known that when po- 

 tassium iodide, potassium chlorate, and hydrochloric acid 

 are mixed in solution, iodine is liberated according to this 

 reaction, 



K Cl O 3 + 6 H Cl + 6 K I = 7 K Cl + 3 H 2 O + I 6 . 



In order to ascertain the conditions favorable for study- 

 ing the speed of the liberation of iodine in such mixtures, 

 several preliminary experiments on the effects of tempera- 

 ture and concentration became necessary. 



It was found that in mixtures containing equivalents 1 of 

 the salts according to the foregoing reaction as deci -nor- 

 mal solutions at C., iodine is liberated very slowly, a 

 sample of twenty cubic centimeters of the mixture after 

 twenty-four hours requiring only one-tenth cubic centime- 

 ter of a deci -normal solution of " sodium thiosulphate to 

 destroy the blue color produced by the addition of starch 

 paste. 



The same mixture at 100 C. proved well adapted for 

 investigation, as the following table shows : 



Preparation of Solutions. The solutions used were pre- 

 pared as follows: A normal solution of potassium iodide 

 free from iodate served throughout the investigation. It 



1 Whenever this term is used it is understood to mean equivalents according to the reac- 

 tion already given. 



