OF ARTS AND SCIENCES. 



221 



the conversion of tins sulphonic acid by the action of nitric acid into 

 /3y-dibroni-8-nitropyroruucic acid and aa-dinitro-/3/3-dibromfurfuran. 



NO, 



O 



NO.,, 



There can be no doubt that the neutral substance formed by the 

 action of fuming nitric acid upon S-sulphopyromucic acid at the same 

 time with the S-nitropyromucic acid is aa-dinitrofurfuran. 



HC 



HC 



The structure of the /3-brom-S-sulphopyromucic acid is determined 

 by its reduction to S-sulphopyromucic acid, and by its formation from 

 /S-brompyromucic acid, the constitution of which has been established 

 by Hill and Sanger.* The sulphonic acid and the nitro-acid formed 

 from it must be 



BrC 



H-C 



Concerning the structure of the sulphonic acid formed from S-brom- 

 pyromucic acid, it is impossible to draw conclusions equally definite. 

 When we bear in mind, however, the fact that bromine, like sulphuric 

 acid, first replaces the S-hydrogen atom of the pyromucic acid, and in 

 acting upon the 8-brompyromucic acid thus formed the /3-hydrogen 

 alone can further be replaced by bromine, there seems no reasonable 

 doubt that the sulphuric acid in acting upon fi-brompyromucic acid also 

 replaces by the sulpho-group the /3-hydrogen atom. This view is still 

 further confirmed by the fact that the •y-hydrogen atom of the /38-dibrom- 

 pyromucic acid seems incapable of such replacement. If this view be 

 correct, the sulphonic acid in question has the form 



* These Proceedings, xxi. 181. 



