S. E. Moody — Iodides and Iodates. 



381 



In another series of experiments, the apparatus was changed, 

 so that the distillate passed from the first Yoit flask, Y 1 , through 

 a second Yoit flask, Y 2 , containing an excess of standard acid to 

 take up the ammonia and then into the receiver containing 

 potassium iodide without acid. 



Table IY gives results of experiments thus modified. 













Table IV. 

















Iodine equivalent 

 monia absorbed 



of am- 

 in Yoit Iodine estimated 



in 













flask. 



A. 



Drexel flask. 





Ammo- 

 nium 

 sulphate 



. KI. 



KIO a 



Approx. 



N/10. 



. H 2 S0 4 . 



Time 

 in 



Approx. 



N/10 

 Na 2 S 2 3 . I. 



Approx. 

 N/10 

 Diff. Na 2 S 2 3 . I. 



Diff. 



cm 3 . 



grm. 



cm 3 . 



cm 3 . 



hours. 



cm 3 . grm. 



grm. cm 3 . grm. 



grm. 



25 



1-0 



20 



50 



3 



38-15 0-4757 



— 0-0016 38-23 0-4767 - 



-0-0006 



25 



1-0 



20 



50 



3 



38*20 0-4763 



— 0-0010 38-25 0-4769 - 



-00004 



25 



1-0 



20 



50 



H 



38-15 0-4757 



— 0-0016 38-20 0-4763, - 



-o-ooio 



25 



1-0 



20 



50 



3 



38-20 0-4763 



— 0-0010 38-27 0-4771 - 



-0-0002 



25 



1-0 



20 



50 



H 



38-17 0-4759 



— 0-0014 38-20 0-4763 - 



-o-ooio 



25 



1-0 



20 



50 



H 



38-15 0-4757 



— 00016 38-20 0-4763 - 



-o-ooio 



25 



1-0 



20 



50 



3 



38-20 0-4763 



-0-0010 38-25 0-4769 - 



-0-0004 



These experiments show that the sulphuric acid neutralized 

 in the Yoit flask is a measure of the ammonia while the iodine in 

 the Drexel flask corresponds to the 

 sulphuric acid of the ammonium 

 sulphate. 



Similar results were obtained with 

 ammonium chloride. The exact 

 value of a solution of 5 grms. of 

 this salt made up to 500 cm3 was 

 obtained by precipitating and weigh- 

 ing the silver chloride produced by 

 silver nitrate, 25 cm3 of the solution 

 containing of the salt the equivalent 

 of 0*5922 grm. of iodine. 



Portions of this solution were measured from a burette into 

 a flask, to which was added, in each experiment, the iodide- 

 iodate mixture and in the presence of a current of hydrogen 

 boiled until no further color, due to iodine, remained. The dis- 

 tillate was passed through a trap of standard sulphuric acid, 

 to absorb the ammonia, into the Drexel flask charged with an 

 aqueous solution of potassium iodide to dissolve the iodine, 

 which became known upon titration with standard sodium thio- 

 sulphate. The difference in amount of iodine which equivalent 

 volumes of the sulphuric acid used in the trap liberated from 



