202 Phelps — Estimation of Chlorates and Bromates. 



Table II records similarly experiments made upon a sample 

 of thrice crystallized potassium bromate which was prepared by 

 acting on potassium hydroxide with bromine evolved from pure 

 potassium bromide by sulphuric acid and manganese dioxide. 

 The experiments were performed like those with the chlorate, 

 described above, except that the excess of ferrous salt used in 

 the reduction was determined by decinormal iodine in alkaline 

 solution instead of by permanganate in acid solution. The 

 solution was cooled after boiling, was nearly neutralized with 

 a concentrated solution of sodium carbonate, and was then 

 treated with 2-3 grms. of Rochelle salt in solution and an. 

 excess of decinormal iodine solution. The mixture was made 

 alkaline with an excess of potassium bicarbonate solution, starch 

 paste added, the starch blue bleached with decinormal arsenious 

 acid, and, finally, the excess of this last titrated to color with 

 iodine. 





Table 



II. 



• 





Oxygen value 



Oxygen value 





KBrp 3 



of ferrous salt 



of ferrous salt 



Error on 



taken. 



taken. 



found. 



KBr0 3 . 



grm. 



grm. 



grm. 



grm. 



0-0500- 



o-oi776 



0-00357 



0-0006 — 



0-0500 



o-omo 



0-00336 



o-oooi — 



o-iooo 



0-03792 



0-00942 



0*0008 — 



o-iooo 



0-03792 



0-00922 



o-oooi — 



0-2000 



006321 



0-00576 



o-oooo± 



0-2000 



0-06321 



0-00580 



0-0002 — 



0-5000 



0-15670 



0-01342 



0-0013 — 



0-5000 



0-16212 



0-01870 



0-0008 — 



An inspection of the results shows that the processes may 

 be justly considered as accurate for analytical purposes — espe- 

 cially so when one considers that they measure only the oxygen 

 in the salt analyzed, which is 39 per cent for potassium chlo- 

 rate and 28 per cent for potassium bromate. 



