236 PROCEEDINGS OF THE AMERICAN ACADEMY 



The yield of pure product by this method has been about sixty per 

 cent of the amount theoretically required. The mother liquors of the 

 first crystallizations gave by evaporation an oily product, which solidi- 

 fied on standing, but which could be purified only with considerable 

 difficulty. This substance crystallizes in flat, white, six-sided plates, 

 very sparingly soluble in cold water, readily in hot, and very soluble 

 in ether, alcohol, carbonic disulphide, and ligroin. It melts at 160°, 

 and sublimes slowly at higher temperatures, apparently unchanged. 

 A yellow coating is formed on the surface when it is exposed to the 

 action of light, yet the decomposition by nitric acid in the estimation 

 of the halogens is not complete below 300°. 



The following results were obtained by analysis : — 



0.5188 grm. substance gave 0.1682 grm. COj and 0.0180 grm. HgO. 

 0.2004 grm. substance gave by Carius' method 0.3276 grm. Agl -(- 

 AgBr. 



Calculated for CaTjBrOjH. Found. 



C 8.93 8.84 



H .25 .39 



I^ + Br 82.87 82.96 



The solubility in cold water was determined by the method of V. 

 Meyer. The filtered solution was neutralized with baric carbonate, 

 evaporated to dryness, and the barium estimated by ignition with 

 sulphuric acid. 



I. 11.7286 grm. solution gave 0.0707 grm. BaSO^. 

 II. 13.3239 grm. solution gave 0.0793 grm. BaSO^. 



The solution, saturated at 20°, contains, therefore, the percent- 

 ages : — 



I. n. 



2.08 2.05 



Hence diiodbromacrylic acid requires for solution 48.37 parts water 

 at 20°. 



Salts of Diiodbromacrylic Acid. 



Baric Diiodbromacrylate, Ba(C8T2Br02)2-4H20. A solution of the 

 acid was heated with an excess of baric carbonate, filtered, and con- 

 centrated by evaporation. The salt crystallized, on cooling, in flat 

 prisms arranged in stellate groups. It is very soluble in hot, less 

 soluble in cold, water. 



