212 PROCEEDINGS OP THE AMERICAN ACADEMY 



The anhydrous acid melts at 153-154°, and on cooling forms a 

 viscous gummy mass. Sodium amalgam reduces the acid without 

 difficulty, and yields the w-oxymethylpyromucic acid already 

 described. The barium salt of the acid is readily soluble in water, 

 and crystallizes in clustered short needles, but we have made no 

 further study of its salts. 



Methylpyromucic Tetrabromide. 



We have already spoken of the instability of the addition pro- 

 duct which methylpyromucic acid forms with bromine. We suc- 

 ceeded in isolating it by adding two molecules of bromine diluted 

 with a little chloroform to a solution of methylpyromucic acid in 

 five times its weight of chloroform well cooled with ice and salt. 

 The bromine was slowly added with constant shaking, and at this 

 low temperature but little hydrobromic acid was noticed. The ad- 

 dition product soon began to separate in flat colorless needles, which 

 were frequently twinned at right angles. After the bromine had 

 all been added, the whole was allowed to stand for a short time, and 

 the product then quickly filtered upon the pump and washed with 

 cold chloroform. It was then pressed with filter paper and dried 

 in desiccator. As we fouud it impossible to recrystallize the sub- 

 stance without serious decomposition, we analyzed it without fur- 

 ther purification. On exposure to moist air it rapidly liquefied, 

 and even over sulphuric acid it soon evolved hydrobromic acid in 

 abundance. Analyses IV. and V., made with material which had 

 stood for two and four days respectively in desiccator, show how 

 rapidly the decomposition progresses. 



I. 0.2695 grm. substance gave 0.1668 grm. C0 2 and 0.0383 

 grm. H 2 0. 

 II. 0.3509 grm. substance gave 0.2182 grm. C0 2 and 0.0467 

 grm. H 2 0. 



III. 0.2011 grm. substance freshly made gave 0.3393 grm. AgBr. 



IV. 0.1564 grm. of same substance after two days gave 0.2601 



grm. AgBr. 

 V. 0.1520 grm. of same substance after four days gave 0.2513 

 grm. AgBr. 



