168 G. S. Jamieson — New Volumetric Method. 



The iodine monochloride reacts with the sulphite and prevents 

 any loss of sulphur dioxide. The liberated iodine is titrated 

 with potassium iodate solution in the usual manner. The use 

 of iodine monochloride does not change the sulphur dioxide 

 equivalent of the potassium iodate solution. 



Several experiments were made by adding weighed amounts 

 of calcium sulphite to hydrochloric acid solutions which con- 

 tained iodine monochloride as described above, and after 

 thorough shaking, the liberated iodine was titrated. 



\ T o. 



Wt. of CaS0 3 



KI0 3 used 



S0 2 found 



S0 2 present 



1 



•0890 



19-95 CC 



47-86$ 



47*98$* 



2 



•0553 



12-45 



48-06 



u 



3 



•0878 



19*70 



47-90 



a 



4 



•0751 



16-90 



48-04 



a 



Weighed portions of sodium bisulphite were titrated in the 

 same manner as the calcium sulphite. 



No. 



Wt. of HNaSOs 



KTO3 used 



SOo found 



S0 2 present 



1 



•0972 



26'35 cc 



57-88^ 



58-01$ 



2 



•1271 



34-56 



58-04 



u 



3 



•1392 



37-85 



58-05 



it 



4 



•1372 



37-25 



57-96 



a 



It is recommended that the sulphite should be weighed in a 

 short specimen tube and after dropping it into the titration 

 bottle, the stopper should be inserted quickly so as to avoid 

 any loss of sulphur dioxide. 



Furthermore it should be observed that the strength of the 

 hydrochloric acid in which the titration is made is of much 

 importance. If more than 20 cc of a solution is to be titrated 

 or if a large volume of the potassium iodate solution is required, 

 sufficient hydrochloric acid should be added to give the proper 

 strength, which is 15 to 20$ actual acid as previously stated. 



Sheffield Chemical Laboratory, Yale University, 

 New Haven, Conn., May 11, 1914. 



chloric acid, then add a globule of chloroform, in a glass stoppered bottle, 

 and adjust exactly to a faint iodine color by shaking and adding dilute 

 potassium iodide or potassium iodate, as the solution may require. 

 * Average of 2 determinations by the Giles- Shearer method. 



