OF ARTS AND SCIENCES. 165 



(1 14-115°), were shown to be dibrommaleic anhydride. In confirma- 

 tion we prepared from the aqueous solution obtained by washing the 

 crude product with cold water considerable quantities of baric dibrom- 

 maleate, wliicli was identified by analysis. 



0.5423 grm. of the air-dried salt gave on ignition with HgSO^ 0.2853 

 grm. BaSO^. 



Calculated for BaC^BrjO^ . 2 H2O. Found. 



Ba 30.78 ' 30.93 



Since the most volatile portions of the oil gave with water 8-mono- 

 brompyromucic acid, it contained doubtless the corresponding mono- 

 brompyromucyl bromide. Tlie quantity, however, appeared to be so 

 small that we made no attempt to isolate it. 



P^-Dibrompyromucamide, C^HBrgOoNH.,. — Concentrated aqueous 

 ammonia acts but slowly upon the ethyl ether of /?S-dibrompyromucic 

 acid, and even after long standing the decomposition is imperfect. 

 The amide may readily be made from the bromide just described by 

 the action of aqueous ammonia, and may be purified by recrystalliza- 

 tion from hot water. Thus prepared, it forms long silky needles which 

 melt at 175-176°. It is readily soluble in alcohol, quite readily solu- 

 ble in ether, chloroform, or hot benzol, and almost insoluble in car- 

 bonic disulphide or ligroin. It is sparingly soluble in cold water, but 

 freely soluble in hot water. 



0.9102 grm. substance gave 44.5 c.c. moist nitrogen at 14.5° and under 

 a pressure of 722 ram. 



Calculated for Cr,UBr202NH2. Found. 



N 5.20 5.31 



Action of Bromine and Water. 



We found that the /38-dibrompyromucic acid was rather slowly 

 attacked by bromine in aqueous solution, and the reaction aftpeared 

 to be essentially the same whether tiie bromine was added rajiidly or 

 slowly. We therefore suspended the acid in water, and added at 

 once rather more than two molecules of bromine, taking care to pre- 

 vent any decided rise of temperature. Carbonic dioxide was slowly 

 evolved, and the red oil which was at fir.-*t formed gradually solidi- 

 fied. The product was then pressed with filter-paper, and recrystal- 

 lized from boiling ligroin. Treatment with bone-black was usually 

 necessary in order to obtain a colorless product. The substance thus 



