136 PROCEEDINGS OP THE AMERICAN ACADEMY 



agents, and describes a derivative resulting from the action of bromine 

 water, to which he gives tlie formula C^IIgBr^Oj. By heating the 

 pyromucic tetrabromide he also obtained an acid melting at 180°, to 

 which he assigned no formula, but which from his analyses was evi- 

 dently a monobrompyromucic acid. 



About the time of Toennies's first publication, Schiff and Tassinari * 

 described two acids which they had obtained by allowing one molecule 

 of bromine to act upon ethyl pyromucate, and decomposing the product 

 thus obtained by alcoholic potash. These acids contained but one 

 atom of bromine, one melted at 180° the other at 157°, and they were 

 named by SchifF and Tassinari the a and j3 monobrompyromucic acids. 

 The only statement which they make, beyond a mere description of 

 the physical properties of the two acids, is that one acid may be con- 

 verted into the other by continued boiling with concentrated hydro- 

 chloric acid. This change they consider analogous to the conversion of 

 /3-bromcinnamic acid into a-bromcinnamic acid under similar circum- 

 stances, and following this analogy they assign to the two acids the 

 formulte 



HC-C-COOH HC-C-COOIi 



II 1^0 II To 



BrC-CH IIC-CBr 



In a paper published rather more than a year after the appearance of 

 a preliminary note upon this subject by one of us,t Canzoneri and 

 01iveri,t without in any way alluding to this previous publication, 

 described certain salts of the dibrompyromucic acid of Toennies and 

 of one of the monobrompyromucic acids of SchifF and Tassinari, while 

 they showed that the isomeric acid melting at 157° had no real 

 existence. Our own experiments had already led us to the same 

 conclusion. 



Since of the various acids which could be formed by the replacement 

 of the hydrogen atoms of pyromucic acid by halogens at most but 

 three had been prepared, and none of these had been studied in any 

 detail, we undertook the preparation and study of the brompyromucic 

 acids. In the preparation of pyromucic tetrabromide, which first at- 

 tracted our attention, we found it impossible to prevent completely the 

 evolution of hydrobromic acid. Since Toennies's analysis of a product 



* Berichte d. deutsch. chem. Gesellsch., xi. 842 ; Gazzetta Chimica, viii. 297. 

 t Berichte d. deutsch. chem. Gesellsch., xvi. 1130. 

 X Gazzetta Chimica, xiv. 173. 



