OF ARTS AND SCIENCES. 147 



The barium salt is decomposed by warming, its solution giving 

 products similar to those obtaiued in the same way from tetrabroin- 

 propionic acid. This decomposition, however, we have not as yet 

 studied further. 



|3 Dichlordibrompropionic Acid. 



Although dibromacrylic acid assumes a molecule of bromine so 

 readily, we found at first great difficulty in preparing the corresponding 

 addition product with chlorine. If chlorine gas is passed into melted 

 dibromacrylic acid it is gradually taken up and the melting-point of 

 the acid is slowly changed. After long-continued action a considerable 

 quantity of the dichlordibrompropionic acid is formed, but so contam- 

 inated with oily by-products that its purification is a matter of some 

 dilRcidty. This addition of chlorine is, however, rapidly and neatly 

 accomjilished if the reaction is allowed to proceed in direct sunlight 

 at 100°. When at this temperature the melted acid becomes nearly 

 solid with separating crystals of the addition product, the chlorination 

 is interrupted. The product which we obtained in this way from 

 pure dibromacrylic acid melting at 85-86° was purified by crystalliza- 

 tion first from carbonic disulphide and finally from chloroform. On 

 analysis it gave the following results : — 



I. 0.5183 grm. substance gave 0.2335 grm. CO2 and 0.0431 grm. 

 H.O. 

 II. 0.1547 grm. substance gave 0.3400 grm. AgCl -}- AgBr. From 

 this by reduction was obtained 0.2214 grm. Ag. 



Calculated for (CglLClaBr.p.J. Found. 



I. II. 



12.13 

 0.92 



23.37 

 53.21 



Tills ^ dichlordibrompropionic acid crystallizes in oblique prisms 

 which melt at 118-120°, and in its behavior with solvents closely 

 resembles the a acid. In water, alcohol, or ether it dissolves very 

 easily, but with somewhat more difTiculty in carbonic disulphide, chlo- 

 roform, or benzol. The solution in carbonic disulpliide gave by slow 

 evaporation well-developed crystals whose elements Dr. W. II. Mel- 

 ville kiudlv determined. 



