188 PROCEEDINGS OF THE AMERICAN ACADEMY 



Calculated for BaCiBrjOi . 2HsO. Found. 



Ba 30.78 30.91 



The amount of dibrommaleic acid tlius formed is about 1 5 per cent 

 of the mucobromic acid taken, and 30 per cent of the total weight of 

 the distillate. 



Action of Baric Hydrate. 



The action of baric hydrate upon mucobromic acid was first studied 

 by Schmelz and Beilstein, The results they obtained were extremely 

 interesting, but needed extension in several directions. More espe- 

 cially inviting was the muconic acid which they considered formed in 

 the reaction, and to which they gave the formula HjC^Og. In begin- 

 ning this investigation, Mr. O. R. Jackson and I thought it best at the 

 outset to test experimentally the truth of the equation, 



2CJl2^r,Os + HgO = C.HgOg + C^IIBr + 200^ + 3HBr 



which Schmelz and Beilstein had given as an expression of the reac- 

 tion, and at the same time to determine the conditions most favorable 

 to the formation of baric muconate. The qualitative results we 

 found to be precisely in accordance with their statements, and it was 

 only necessary to study the reaction quantitatively. A weighed quan- 

 tity of mucobromic acid was introduced into a flask fitted with reverse 

 cooler, and dissolved in a little warm water. The upper end of the 

 cooler was then connected with a series of wash-bottles which were 

 filled with an ammoniacal solution of cu-prous oxide, made by reduc- 

 ing an ammoniacal solution of pure cupric sulphate with metallic 

 copper. The air in the apparatus was then displaced by pure hydro- 

 gen, a measured quantity of a standard solution of baric hydrate 

 introduced into the flask, and heat applied. When the action appeared 

 to be finished, we determined the weight of the baric carbonate which 

 had been formed in the reaction, the weight of tlie baric carbonate 

 which could be precipitated from the filtered solution by carbonic 

 dioxide, and the weiglit of the baric muconate left on evaporation after 

 washing out the baric bromide with cold water. In order to deter- 

 mine the amount of bromacetylen, we filtered off the voliuninous pre- 

 cipitate of acetylen copper which had separated in the wash-bottles, 

 acidified the filtrate, and precipitated the bromine with argentic 

 nitrate. 



The results which we obtained are given in the following table ; in 

 each case 2 grm. of mucobromic acid were taken. 



