OF ARTS AND SCIENCES. 137 



usually allowed the addition to proceed at this higher temperature, 

 since the reaction was tlien completed in a shorter time. The tubes 

 opened without marked pressure, and the crystalline product separated 

 from the acid mother-liquors by filtration upon a perforated platinum 

 cone was dried upon porous tiles. When treated in this way the 

 dibroraacrylic acid gave about its own weight of crude tribrompro- 

 pionic acid. The acid can readily be purified by recrystallizing it 

 successively from ligroin and carbonic disulphide. The use of car- 

 bonic disulphide causes considerable loss, but with ligroin alone we 

 failed to obtain as high a melting-point. After several recrystalliza- 

 tions the acid showed a constant melting-point, and gave on analysis 

 the required percentages. 



I. 1,0329 grm. substance dried over IIjSO^ gave on combustion 

 0.444G grm. CO., and 0.0994 grm. H,0. 

 II. 0.2184 grm. substance gave 0.3963 grm. AgBr. 

 III. 0.1938 grm. substance gave 0.3525 grm. AgBr. 



Calculated for CsHaBrgO. . Found. 



I. II. III. 



C 11.57 11.74 



H 0.96 1.07 



Br 77.17 77.29 77.39 



This tribrompropionic acid is very soluble in alcohol or ether, some- 

 what less soluble in chloroform, carbonic disulphide, benzol or ligroin. 

 It dissolves freely in hot water, but is quite rapidly decomposed on 

 boiling with the formation of hydrobromic acid. From the hot aque- 

 ous solution the acid crystallizes on cooling in pearly scales. Repeat- 

 edly recrystallized from carbonic disulphide, the acid melts at 118°. 



Argentic Tribrompropionate, AgC3lI.,Br302. Argentic nitrate added 

 to a cold aqueous solution of the acid precipitates the silver salt in 

 small clustered rhombic plates. On warming it with water argentic 

 bromide is rapidly formed, but it may be dried over sulphuric acid 

 without essential decomposition. 



0.2901 grm. of the salt dried over H2S0^ gave by precipitation with 

 HBr 0.1316 grm. AgBr. 



Calculated for AgCaHoBrgO^. Found. 



Ag 25.83 26.05 



The barium and calcium salts were readily soluble in water, and 

 their solutions could not be warmed without the instantaneous forma- 



