348 PROCEEDINGS OF THE AMERICAN ACADEMY 



Since the fiS dichlorpyromucic is but slowly attacked even by 

 concentrated nitric acid, it was not thought worth while to study the 

 reaction in detail. 



;^ Dichlorpyromucic Acid. 



The formation of the ethyl ether of this acid by the decomposition 

 of ethyl pyromucic tetrachloride has already been described. The 

 ether was recrystallized from hot alcohol, and saponified by alcoholic 

 sodic hydrate. On tlie addition of hydrochloric acid to the aqueous 

 solution of the sodium salt, a sparingly soluble acid separates, which 

 may easily be purified by recrystallization from hot water. 



The acid dried over sulphuric acid gave on analysis the following 

 results : — 



I. 0.2196 grm. substance gave 0.2672 grm. COo and 0.0237 grm. H2O. 

 11. 0.2212 grm. substance gave 0.3492 grm. AgCl. 



Found. 



II. 



39.03 



^ dichlorpyromucic acid is readily soluble in ether or alcohol, and 

 but sparingly soluble in cold water. In hot water it is freely soluble, 

 and crystallizes as the solution cools in long needles which melt at 

 197-198°. The acid readily sublimes unchanged below its melting 

 point. Sodium amalgam slowly reduces it to pyromucic acid melting 

 at 129-130°. 



The solubility of the acid in water at 19°. 5 was determined in 

 the usual manner. A solution of the acid saturated at 19°. 5 was 

 boiled with baric carbonate, and the barium dissolved determined by 

 precipitation with sulphuric acid. 



I. 38.2670 grm. solution saturated at 19°.5 gave 0.0322 grm. BaSO^. 

 II. 37.5125 grm. solution saturated at 19°. 5 gave 0.0301 grm. BaSO^. 



The solution saturated at 19°. 5 therefore contained the following 

 percentages of acid : — 



I. n. 



0.13 0.12 



Baric X Dichlorpyromucate, ^ai{C^YLC\.f)^^ . 4 H,,0. — The barium 

 salt may most readily be prepared by boiling the acid with baric car- 

 bonate. The salt is quite readily soluble in cold water, more soluble 

 in hot water, and crystallizes in columnar aggregations of prisms which 



