OF ARTS AND SCIENCES. 351 



0.1441 grm. substance dried over H 2 S0 4 gave 0.1377 grm. AgCl. 



Calculated for 



C 4 H 3 C10 4 . Found. 



CI 23.59 23.62 



The x dichlorpyromucic acid, like the (38 dichlorpyromucic acid, 

 therefore gives with aqueous bromine as tbe chief product chlorfumaric 

 acid according to the equation 



C 5 H 2 C1 2 3 + 2 Br 2 + 3 H 2 = C 4 H 3 C10 4 + C0 2 + HC1 + 4 HBr. 



Since the oxidation with bromine had shown with sufficient precision 

 that one of the chlorine atoms of the x dichlorpyromucic acid occupied 

 the 8 position, we thought it unnecessary for our purposes to study 

 also the action of nitric acid. 



Action of Fuming Sulphuric Acid. 



The two isomeric dibrompyromucic acids had shown marked differ- 

 ences in their behavior toward fuming sulphuric acid.* While the 

 /Sy acid had rapidly been converted into the corresponding sulphonic 

 acid, brommaleic acid in nearly theoretical quantity had been formed 

 from the (38 dibrompyromucic acid, and no trace of a sulphonic acid 

 could be detected. Preliminary experiments proved that the /?y and 

 /8S dichlorpyromucic acids showed a similar difference in their behavior 

 toward fuming sulphuric acid. While the formation of chlormaleic 

 acid in the latter case could not definitely be pi'oved, certainly no 

 sulphonic had been formed, and it seemed to us of interest to study 

 also the behavior of the third isomeric dichlorpyromucic acid under 

 the same conditions, x dichlorpyromucic acid dissolves readily in 

 fuming sulphuric acid, and if care be taken to prevent any marked 

 elevation of temperature no very essential decomposition ensues, 

 although a slight effervescence is noticeable. After the solution of 

 the acid in four times its weight of fuming sulphuric acid had stood for 

 thirty-six hours, it was poured into a large amount of cold water, the 

 solution cooled, and thoroughly extracted with ether. The ethereal 

 extract left on evaporation a small quantity of a colorless oil which 

 reduced silver oxide, and whose vapor vigorously attacked the eyes 

 and nose. The amount of oil thus obtained was wholly insufficient 

 for further study. On standing, it deposited a few clustered needles, 

 which probably were unaltered acid, although they may possibly hive 

 been the decomposition product subsequently described. From the 

 aqueous solution the barium salt was prepared in the usual way, and, 



* These Proceedings, xxiii. 218. 



