288 PROCEEDINGS OF THE AMERICAN ACADEMY 



Calculated for CaCCjClBr^Ojjj. 



Ca 7.05 6.75 



Potassic P-Chlordibromacrylate, KC„CIBr202? — When a solution 

 of the acid was neutralized with potassic carbonate, concentrated on 

 the water bath, and evaporated to dryness over sulphuric acid, the po- 

 tassium salt was left in the form of a very deliquescent amorphous 

 mass. For analysis the salt was finally dried at 80°. 



1.0509 grm. of the salt gave 0.4397 grm. K^SO^. 



Calculated for KC,ClBr.Oo. Found. 



K 12.92 " " 12.42 



All attempts to prepare a silver salt of this acid were unsuccessful. 

 On the addition of argentic nitrate to a solution of the acid or any of 

 its salts, the solution immediately became turbid from the separation 

 of argentic bromide. This decomposition was not prevented to any 

 appreciable extent by the exclusion of light. 



Constitution of a- and ^-CnLORDiBROJiACRYLic Acids. 



The essential points of difference in the physical properties of these 

 acids, which appear in their general behavior and solubility in water, 

 as well as in their melting points, would seem to point to a difference 

 in structure. In the degree of hydration, solubility in water and com- 

 parative stability, their salts exhibit peculiarities as marked as those 

 of the acids themselves. Although the silver salt of the a-acid can be 

 prepared without difficulty, the corresponding salt of the ;8-acid cannot 

 be formed even with the greatest care. 



While the product obtained by the action of chlorine raonobromide 

 upon brompropiolic acid may have one of two forms, — 



Brompropiolic Acid. a-Chlordibromacrylic Acid. 



(1) (2) 



CBr CBrCl CBr,, 



III 11 II 



C CBr CCl 



I I I 



cooH coon cooii 



the acid resulting from the abstraction of the elements of hydrobromic 

 acid from chlortribrorapropionic acid can evidently have but one : — 



