32 



BULLETIN OF THE UNIVERSITY OF WISCONSIN 



(7) Formic acid being a good reducing agent retards 

 the speed of iodine liberation to a remarkable degree, as 

 the following results show: 



Duration of reac- 

 in minutes. 



10 



20 



80 



120 



Cubic centimeters 

 of solution taken. 



10 

 10 

 10 

 10 



Cubic centimeters 



of ^ Na„ So O3 



used in each 

 titration. 



3.7 



5.6 



8.35 



8.7 



Per cent, of 

 Iodine liberated. 



9.3 



14.0 

 20.9 

 21.8 



