292 Gooch and Blake — Estimation of Bromic Acid. 



Table V — Continued. 







Arsenious Acid Method. 











(Volume not exceeding 100"= 



mZ\ 









AS2O3 



AS2O3 



Error in 



KBr03 



AS2O3 



H2SO4 Time un- 



oxi- 



terms of 



taken. 



taken. 



(1 : 1) in changed. 



dized. 



KBr03 



grm. 



grm, 



grm. minutes. grm. 



On the steam bath,— 80° 



grm. 



grm. 



0-0704 



0-2475 



5 30 0-1241 



0-1229 



0-0013- 



0-0704 



0-2475 



5 30 0-1246 



0-1234 



0-0010- 







At atmospheric temperature. 





0-0704 



0-2475 



5 10 0-2066 



0-0409 



0-0474 — 



0-0704 



0-2475 



5 10 0-1991 



0-0488 



0-0426 — 



0-0704 



0-2475 



5 30 01533 



0-0922 



0-0185 — 



0-0704 



0-2475 



5 60 0-1231 



0-1244 



0-0004- 



0-0704 



0-2475 



5 120 0-1242 



0-1233 



0-0011 — 



0-0704 



0-2475 



5 120 0-1238 



B. 

 Arseniate-Iodide Method 



0-1237 



0-0009 — 



(H,S04) (1 : 



1) 20="^3 . initial volume 110^^3 . 



final volume 



35cm3 







Iodine corre- 











sponding to 



Iodine corre- 



Error in 



KBrOa 



H2KASO4 



I value of AS2O3 pro- 



sponding to 



terms of 



taken. 



taken. 



KI taken. duced. 



KBrOs. 



KBrOa. 



grm. 



grm. 



grm. grm. 



grm. 



grm. 



0-0704 



2 



0-8812 0-0607 



0-3205 



0-0001 - 



0-0704 



2 



0-3812 0-0588 



0-3224 



0-0003 + 



0-0704 



2 



0-3812 0-0595 



0-3217 



0-0001-f- 



0-0704 



2 



0-3842 0-0590 



0-3222 



0-0002+ 



0-0704 



2 



0-3812 0-0615 



0-3197 



0-0003- 



0-0647 



2 



0-3812 0-0839 



0-2973 



0-0004 + 



The mean erj-or of the arseniate-iodide process applied to 

 this particular sample of bromate is 0-0001+ grm. in terms of 

 bromate ; the arsenious acid method shows a mean deficiency 

 of about 0-0009 grm. for the smaller amount of bromate 

 employed, if, as is obviously reasonable, those results are 

 omitted from tlie averages which were obtained by standing 

 at the ordinary temperature for periods less than one hour. 



It appears, therefore, that the deficiency in the indications 

 of the iodide process and the arsenious acid process are 

 satisfactorily accounted for by the presence in the bromate of 

 traces of chlorate ; and that the oxidizing power of a bromate 

 may be determined by boiling it in solution with a known 

 excess of arsenious oxide and an excess of sulphuric acid, 

 and determining the amount of arsenious oxide remaining 

 unchanged. A chlorate, as we have found by direct experi- 

 ment, is scarcely affected by this treatment. 



