196 PROCEEDINGS OP THE AMERICAN ACADEMY 



nounced tliat they were engaged in making from bromalid a dibrom- 

 acrylic acid, which we thought probable, although upon very insuffi- 

 cient grounds, would prove to be identical with ours, we felt compelled 

 for the moment to suspend our investigations. The other portions of 

 the re^earch afterward claimed so much attention that no study of the 

 acid has yet been made sufficiently extended to establish the condi- 

 tions essential to its preparation in a pure state. It has been found, 

 however, that an acid melting at 84-85° contains but a slight excess 

 of bromine (I.), and that the pure acid (II.) melts at 85-86°. 



I. 0.2204 grm. substance gave 0.3621 grm. AgBr. 

 XL 0.2650 grm. substance gave 0.4336 grm. AgBr. 



Calculated for CaHjBrjOj. Found.- 



I. n. 



Br 69.56 69.90 69.65 



For purposes of comparison, certain determinations of the solubility 

 of the acid and its barium salt may find a place here, although they 

 were not made with absolutely pure material, and are therefore sub- 

 ject to revision. In determining the solubility of the acid, the satu- 

 rated solution, made according to the method of V. Meyer, was 

 neutralized with baric carbonate, and the dissolved barium determined 

 by precipitation with sulphuric acid. 



I. 14.7798 grm. of a solution, saturated at 20°, gave 0.4488 grm. 

 BaSO,. 

 II. 8.6788 grm. of a solution, saturated at 20°, gave 0.2630 grm. 

 BaSO,. 



According to these determinations, an aqueous solution of the acid, 

 saturated at 20°, contains the percentages : — 



I. n. 



5.98 5.98 



8.4992 grm. of a solution of the barium salt, saturated at 20°, gave, 

 on evaporation with HgSO^ and ignition, 0.1912 grm. BaSO^. 



The aqueous solution of baric dibromacrylate, saturated at 20°, 

 therefore contains 5.74 per cent of the dry salt. 



In studying the behavior of this dibromacrylic acid towards reagents, 

 we have been able to use only the product melting at 83-84°, which 

 may easily be obtained in any quantity desired. When boiled with 

 an excess of baric hydrate, the acid is completely decomposed, baric 

 carbonate is precipitated, bromacetylen set free, and at the same time 

 baric malonate is formed in abundance. For complete identification, 



