58 Gooch and Blumenthal — Use of Selenic Acid. 









Table 



II. 









The Determination c 



/ Bromine liberated by Selenic Acid. 



Br 





H 2 Se0 4 









Error in 



taken as 



NaCl 



(40-66$) 



Initial 



Final 



Br 



terms of 



KBr 



taken 



taken 



volume 



volume 



found 



Br 



grm. 



grm. 



cm 3 . 



cm 3 . 



cm 3 . 



grm. 



grm. 



0-0749 







5 



40 



15 



0-0721 



— 0-0028* 



0*0671 







5 



50 



13 



0-0762 



— 0-0009* 



0-0671 







5 



55-60 



6-7 



0-0760 



—o-ooii* 



0-0671 



---- 



5 



50 



15 



0-0758 



— 0-0013* 



0-0673 





5 



50 



16 



0-0765 



— 0-0008f 



0-0671 



. _ _ . 



5 



.. 



12 



0-0758 



— 0-0013f 



0-0685 







5 



50 



24 



00672 



— 0-0013f 



0-2364 



0-1757 



5 



40 



11 



0-2332 



— 0-0032J 



0-2026 



0-1507 



5 



40 



7-8 



0-2016 



— o-ooio;; 



0-1688 



0-1255 



5 



40 



7-8 



0-1677 



— o-ooi];: 



0-1.350 



0-1003 



5 



30 



7 



0-1340 



—o-ooio]; 



0-1350 



0-1003 



5 



30 



9 



0-1345 



-0-0005J 



0-1350 



0-1003 



5 



30 



12 



0-1348 



— 0-0002 1 



0-1350 



0-1003 



5 



30 



12-13 



0-1346 



— 0-0004 { 



0-1013 



0-0753 



5 



25 



11 



0-1006 



— 000071 



* The bromide, made from the bromate, was fused and weighed out in 

 each case. 



f The bromide, made from the bromate, was fused, recrystallized, dried, 

 and weighed out in each case. 



JThe bromide, made from the bromate, was made up with sodium chloride 

 in a solution from which aliquot portions were measured. 



As in the preliminary tests of Table I, these results run low 

 for bromine, with considerable fluctuations. 



An experiment showed that the flask residues of selenic acid, 

 selenious acid, and the potassium salts of these acids were 

 capable of reducing minute amounts of bromate, and of liberat- 

 ing bromine at the boiling temperature. Therefore, the larger 

 of the deficiencies observed cannot be wholly attributed to the 

 retention of bromine in the form of bromic acid or a bromate. 

 Apart from the possibility of trifling losses of liberated iodine 

 due to mechanical transfer in the current of carbon dioxide, 

 the most reasonable explanation of irregularity in results would 

 seem to be the escape of some hydrobromic acid from the 

 reaction flask, without undergoing oxidation. In the subse- 

 quent work, therefore, the apparatus was modified to the form 

 shown in fig. 2, so that the vapors escaping from the reaction 

 flask (I) might be forced through another portion of selenic 

 acid, kept hot in a relay flask (II), before passing to the 

 receiver. The selenic acid in the relay flask was kept at 100° 



