286 PROCEEDINGS OP THE AMERICAN ACADEMY 



Several attempts were made by Mr. Huntington to determine the 

 crystalline form of this acid in order to compare it with that of a-chlor- 

 dibromacrylic acid. But unfortunately all the crystals we were able to 

 obtain for that purpose gave very imperfect reflections, and Mr. Hun- 

 tington was able to say only that in their general habit they resembled 

 closely those he had already measured of the a-acid. A few planes 

 gave fairly good reflections, and the angles thus measured were nearly 

 tlie same as those of the a-acid. 



The composition of the purified acid was established by analysis. 



I. 0.2472 grm. of the substance gave 0.48G9 grm. AgCl + AgBr. 

 II. 0.20G0 grm. of the substance gave 0.401 G grm. AgCl + AgBr. 



III. 0.7")GG grm. of the substance gave 0.3690 grm. CO2 and 0.0325 



grm. H.^0. 



IV. 0.4714 grm. of the substance gave 0.2319 grm. CO^ and 0.0227 



grm. Hp. 



The solubility of the acid was determined by the method of V. 

 Meyer. After neutralization with baric carbonate the barium was 

 precipitated from the filtered solution with sul])huric acid. 



I. 7.1822 grm. of a solution saturated at 20° gave 0.0789 grm. 

 BaSO,. 

 II. 5.3623 grm. of a solution saturated at 20° gave 0.0548 grm. 

 BaSO,. 



From these results the following percentages were calculated : — 



I II. 



2.69 2.50 



A study of the salts of this acid developed important differences be- 

 tween them and the corresponding salts of a-chlordibromacrylic acid. 



