OF ARTS AND SCIENCES. 205 



solution after decolorization with bone-black. The acid may be 

 further purified by several repetitions of the same process. 



I. 0.2279 grm. substance gave 0.2935 grm. C0 2 and 0.0526 grm. 

 H 2 0. 

 II. 0.1147 grm. substance gave 0.1055 grm. AgBr. 



Brommethylpyromucic acid crj'stallizes in colorless branching 

 needles, which melt at 150-151°. It is readily soluble in alcohol, 

 ether, or chloroform, somewhat sparingly soluble in cold, more 

 readily in hot benzol. In carbonic disulphide or ligroin it dis- 

 solves but sparingly even on boiling. It is somewhat sparingly 

 soluble in hot water, and is deposited in clusters of branching 

 needles as the solution cools. The solubility of the acid in water 

 at ordinary temperatures we determined in the usual way. We 

 neutralized with baric carbonate the solution of the acid, and deter- 

 mined as sulphate the barium which had been dissolved. 



I. 17.598 grm. of a solution saturated at 21°. 4 gave 0.0271 grm. 

 BaS0 2 . 

 II. 16.031 grm. of a solution saturated at 21°. 4 gave 0.0264 grm. 

 BaS0 4 . 



The aqueous solution saturated at 21°. 4 therefore contained the 

 following percentages of the acid: — 



i. ii. 



0.27 0.29 



For the further characterization of the acid we also prepared cer- 

 tain of its salts. 



Baric Brommethylpyromucate, Ba(C 6 H 4 Br0 3 )2 • 4 H 2 0. — This 

 salt may readily be made from a solution of the ammonium salt by 

 precipitation. It is sparingly soluble in cold water, more readily 

 soluble in hot water, and crystallizes from the hot aqueous solution 

 on cooling in dendritic needles, which contain four molecules of 

 water. The salt is permanent in the air, but effloresces rapidly over 

 sulphuric acid. 



