RICHARDS AND STULL. — BROMINE AND OXALIC ACID. 



327 



SERIES III. 



Thus both substances acted iu harmony with the hypothesis, the hy- 

 drochloric acid retarding the reaction and the sodic acetate hastening it. 

 It is worthy of note that the retarding effect of the acid increases at a 

 faster rate than its concentration, and taking into account the ionized 

 hydrogen already present, it seems quite possible that the relation may 

 be the quadratic one demanded by theory. Another possible disturb- 

 ing influence will be pointed out iu the sequel. 



These observations were verified by repeating the experiments with 

 more dilute solutions, but they need not be recorded, since they furnish 

 no further light upon the problem. Sulphuric acid was found to give 

 a result corresponding to hydrochloric acid. (Exps. 29 to 33.) 



It became now a matter of interest to determine if the original time- 

 curve might be corrected for the growing concentration of ionized hydro- 

 gen caused by the substitution of bromine as an anion instead of the 

 group 0204". Preliminary calculation led at once to the conclusion 

 that the slight increase in the ionized hydrogen could by no means ac- 

 count for the rapid loss of speed observed in the first series. It seemed 

 therefore possible that hydrobromic acid might possess some specific ef- 

 fect, and preliminary experiments showed that this was indeed the case 

 to a surprising degree. In two hours 0.0008 mole per litre of hydro- 

 bromic acid was found to produce as much depressing effect on the total 

 progress of the reaction as was caused by 0.01 mole of hydrochloric 

 acid. 



* It is not impossible that the acetate ion itself may be slightly attacked by 

 bromine, but considerable action is not likely at the low temperature employed. 



