216 PROCEEDINGS OP THE AMERICAN ACADEMY 



I. 0.4509 grm. of substance gave 0.1597 grm. AgCl and 0.0063 



grm. metallic silver. 



II. 0.7458 grm. substance gave, on precipitation with HBr, 0.3635 



■grm. AgBr. 



Calculated for AgCgHBrlOs. Found. 



I. n. 



Ag 28.13 28.05 27.99 



With hydrochloric acid, the addition takes place much more slowly ; 

 still, after long standing, the chlorbromacrylic acid is formed. 



Of the products formed by the addition of halogens to brompropiolic 

 acid, we have thus far examined in detail only the tribromacrylic, 

 although we have also made the diiodbromacrylic by the addition of 

 iodine. 



Tribromacrylic Acid. 

 Tribromacrylic acid may easily be made by adding slowly a slight 

 excess of bromine to an aqueous solution of brompropiolic acid. The 

 color of the bromine gradually disappears, and the product of the 

 reaction separates partially in the form of an oil. This oil gradually 

 solidifies, and more of the same product can be extracted with ether 

 from the aqueous solution. The resulting solid must be well pressed 

 out, and may then be recrystallized from chloroform, or, better, from 

 benzol. Thus prepared, it forms colorless, oblique j^risms, which are 

 very soluble in ether or alcohol, less soluble in cold chloroform or 

 benzol, readily in hot, and soluble in carbonic disulphide or ligroin. 

 It is but sparingly soluble even in boiling water. Melting point, 118°. 



I. 0.3449 grm. of the acid gave 0.1428 grm. CO., and 0.0183 grm. 

 H,0. 



II. 0.1782 grm. substance gave 0.3229 grm. AgBr. 



III. 0.1433 grm, substance gave 0.2625 grm. AgBr. 



Calculated for CgHBraOs. Found. 



I. II. m. 



C 11.65 11.29 



H 0.32 0.59 



Br 77.67 77.13 77.94 



The acid when boiled with an excess of baric hydrate is hardly 

 affected, although it is slowly decomposed by a boiling alcoholic solu- 

 tion of potassic hydrate. We have as yet isolated no products of this 

 decomposition. 



The solubility of the acid in water at ordinary temperatures we 

 have also determined by the method of V. Meyer. 



