148 PROCEEDINGS OF THE AMERICAN ACADEMY 



salt which first separates from a dilute solution. The acid obtained 

 by acidifying the concentrated solution we have then recrystallized 

 from hot water. The acid dried over sulphuric acid gave on analysis 

 the following results. The material used' in Analysis IV. was made 

 from the dibrompyromucic acid melting at 191-192°. 



I. 0.533G grm. substance gave 0.6117 grm. CO^ and 0.0828 grm. HgO. 

 II. 0.1996 grm. substance gave 0.1967 grm. AgBr. 



III. 0.2064 grm. substance gave 0.2031 grra. AgBr. 



IV. 0.2115 grm. substance gave 0.2089 grm. AgBr. 



Found. 



II. in. IV. 



41.97 41.88 42.05 



/3-Monobrompyromucic acid is readily soluble in alcohol or ether, 

 quite soluble in chloroform or benzol, more sparingly soluble in ligroia 

 or carbonic disulphide. It is very readily soluble in hot water, and as 

 the solution cools it separates at high temperatures as an oil ; at lower 

 temperatures, in fine silky needles, which melt at 128-129°. On 

 heating, it sublimes readily without decomposition. The solubility of 

 the acid in water at ordinary temperatures we determined by neu- 

 tralizing the solution with baric carbonate and precipitating with 

 sulphuric acid the barium dissolved. 



I. 21.1125 grm. of asolution saturated at 20° gave 0.1598 grm. BaSO^. 

 II. 15.7586 grm. of a solution saturated at 20° gave 0.1198grm.BaSO4. 



The aqueous solution saturated at 20° therefore contained the fol- 

 lowing percentages of the acid : — 



I. II. 



1.24 1.25 



Baric j3-Mbnobrompyromucate, Ba(C5H2Br03)2H20. — By neutral- 

 izing an aqueous solution of the acid with baric carbonate, and concen- 

 trating the solution on the water bath, we obtained the barium salt in 

 the form of irregular leafy scales, which were sparingly soluble in cold 

 water, readily in hot. The air-dried salt lost nothing over sulphuric 

 acid, and proved to contain one molecule of water. 



I. 0.9389 grm. of air-dried salt lost at 120° 0.0334 grm, H^. 

 II. 1.9210 i;rm. air-dried salt lost at 130° 0.0676 grm. H,0. 



