G. S. Jamieson — New Volumetric Method. 



16' 



mixture of 30 cc of concentrated hydrochloric acid, 20 cc of 

 water, and 6 CC of chloroform. During the first part of the titra- 

 tion, the iodate is added rapidly while shaking the bottle so as 

 to give the contents a circular motion, until the iodine which 

 gradually appears and increases to a maximum amount has 

 largely disappeared from the solution. Then the stopper is 

 inserted and the solution is thoroughly shaken. The titration 

 is continued with very thorough shaking of the closed bottle 

 after each addition of potassium iodate solution until the end 

 point, which is the disappearance of the violet color of che chlo- 

 roform, is obtained. 



The following table contains the results of titrating measured 

 quantities (5-20 cc ) of sulphur dioxide solutions which had 

 recently been titrated by the Giles-Shearer method : 



No. 



S0 2 taken 



KI0 3 used 



S0 2 found 



Error 



1 



•0224 



10'53 



•0225 



+ •0001 



2 



•0290 



13-70 



•0292 



+ •0002 



3 



•0290 



13-72 



•0293 



+ •0003 



4 



•0315 



14-85 



•0317 



+ •0002 



5 



•0317 



14-95 



•03 1 8 



+ •0001 



6 



•0471 



22-20 



•0473 



+ -0002 



7 



•0628 



29-70 



•0634 



+ -0006 



8* 



•1146 



22-80 



•1145 



— •0001 



9 



•1699 



33-80 



•1697 



— •0002 



10 



•0426 



8-50 



•0427 



+ •0001 



11 



•1362 



27-10 



•1360 



— •0002 



These results show a very satisfactory agreement among 

 themselves and with the actual amounts present. 



The result sobtained by titrating measured quantities (6-15 cc ) 

 of a sodium bisulphite solution are as follows : 



No. 



S0 2 taken 



KI0 3 used 



SO a found 



Error 



1 



•0495 



23-40 



•0499 



+ •0004 



2 



•0492 



23-20 



•0495 



+ •0003 



3 



•0492 



23-15 



•0494 



+ •0002 



4 



•0328 



15-40 



•0329. 



+ •0001 



5 



•0336 



15-70 



•0335 



— •0001 



6 



•0224 



10-50 



•0224 



•0000 



It is important to cool the hydrochloric acid solution to 

 15°-18° C. before adding the sulphite solution. If it is desired 

 to titrate much larger amounts of sulphite, it is recommended 

 that the sulphite solution should be added to a titration bottle 

 which contains 10-15 cc of iodine monochloridef solution in 

 addition to the usual amounts of hydrochloric acid, etc. 



* Titrations 8-11 were made with a potassium iodate solution l cc = , 005020g. 

 S0 2 . 



f To prepare this solution, dissolve 10 grams of potassium iodide and 6*44 

 grams of potassium iodate in 75 cc of water, add 75 cc of concentrated hydro- 



