194 PROCEEDINGS OF THE AMERICAN ACADEMY 



Calculated for Found. 



C 6 H 2 S0 4 (NH 2 ) 2 . I. II. 



N 14.73 15.18 



S 16.84 17.00 



Action of Bromine. 



At ordinary temperatures dry bromine has little or no action upon 

 dry S-sulphopyromucic acid. At 100° in sealed tube a complicated 

 reaction ensues, which we have not yet fully investigated. Ordinary 

 dibromsuccinic acid is formed in considerable quantity, and at the 

 same time a small amount of mucobromylbromide, as was shown by 

 the blue color developed in alkaline solution, and by the formation of 

 mucobromic acid melting at 120-121° on heating with water. There 

 was also formed in small quantity a beautifully crystalline substance, 

 sparingly soluble even in boiling alcohol, which contained sulphur, but 

 no bromine. This substance we unfortunately have not yet succeeded 

 in obtaining in quantity sufficient for further study. 



In aqueous solution bromine rapidly oxidizes S-sulphopyromucic 

 acid, even in the cold. The final product of the reaction is fumaric 

 acid, and we have hitherto been unable to isolate any intermediate 

 products. It is probable, however, that maleic acid is in fact the first 

 product of the oxidation. If bromine be added to an aqueous solution 

 of the barium salt of the acid, baric sulphate is immediately thrown 

 down ; but since the amount of baric sulphate thus formed is slightly 

 less than the theoretical quantity, secondary products containing sul- 

 phur are doubtless formed. In the complete oxidation of the acid we 

 have used a slight excess of bromine, aud have finished the reaction 

 by gentle heat. The fumaric acid obtained was identified by qualita- 

 tive tests, and by the analysis of the silver salt. 



I. 0.2124 grm. of the salt dried at 120° gave 0.2406 grm. AgBr. 

 II. 0.2056 grm. of the salt dried at 120° gave 0.2332 grm. AgBr. 



Calculated for Found. 



Ag,C 4 H,0 4 . I. n. 



As 65.46 65.07 65.15 



-& 



The decomposition with bromine, therefore, takes place in great part 

 according to the equation, 



C 5 H 4 S0 6 + 3 Br 2 + 4 H 2 = C 4 H 4 4 + C0 2 + H 2 S0 4 + 6 HBr. 



Action of Nitric Acid. 



The oxidation of S-sulphopyromucic acid with dilute nitric acid takes 

 place but slowly, and even after long boiling with moderately concen- 



