OF ARTS AND SCIENCES. 109 



The silver salt of this acid proved to be so unstable that vfe did not 

 succeed in preparing it in a form sulRcicntly pure for analysis. On 

 the addition of argentic nitrate to an aqueous solution of the acid, 

 even in the cold it immediately became turbid from the separation of 

 argentic chloride. 



Although the barium salt is comparatively stable, we found that it 

 was slowly decomposed when heated iu aqueous solution. In order to 

 identify the products of this decomposition, the acid was distilled with 

 an excess of baric hydrate. The distillate was caught in bromine 

 water, the excess of bromine allowed to evaporate, and the solution 

 extracted with ether. The oily residue left by evaporation of the 

 ether solidified at 0", and possessed an odor characteristic of the sub- 

 stituted ethans. It would seem probable, therefore, that the volatile 

 product of this decomposition was tribromethylen ; but it was formed 

 in such small quantity that further study was rendered extremely 

 difficult. The residue in the retort contained baric chloride in abun- 

 dance, but it gave no reaction for baric bromide. The formation of 

 tribromacrylic acid is thus rendered extremely probable ; but the resi- 

 due unfortunately was lost before it could be subjected to a more 

 critical examination. Since the summer term soon after closed, we 

 were unable to repeat our work, and it must therefore be reserved for 

 future study. 



Chlorbromacrylic acid forms also an addition-product with hydro- 

 bromic acid. When it is heated to 100° in a closed tube with concen- 

 trated hydrobromic acid, an acid is formed which melts at 80°. Further 

 study of this substance, which is probably chlordibrompropionic acid, 

 will be postponed for the present. 



