168 PROCEEDINGS OF THE AMERICAN ACADEMY 



his description is not very precise, it is sufficient to show that it was a 

 mixture tolerably complex in its nature. 



All my own attempts to isolate from the crude furfurol the sub- 

 stance essential to the formation of the jiyroxanthin have been unsuc- 

 cessful, its separation from the furfurol is a matter of some difficulty, 

 not only on account of the small quantities present, but also since it 

 appears to be closely allied to furfurol. In its boiling point or in its 

 behavior towards reagents, I have as yet found no differences suffi- 

 ciently well marked to form the basis for a method of separation. 



For the present, at least, a more careful study of the pyroxanthin 

 itself would seem to be the most speedy way to discover the mode of 

 its formation. 



MucoBROMic Acid. 



Mucobromic acid was first made by Schmelz and Beilstein, * in 

 1865, by the action of bromine and water upon pyromucic acid. They 

 found its salts so unstable that they made little attempt to isolate them, 

 but confined themselves chiefly to the study of the decomposition 

 which ensued when it was boiled with alkalies, and of the reaction 

 effected by argentic oxide. 



They found that the acid was rapidly decomposed when boiled with 

 baric hydrate, that bromacetylen was set free, and that baric carbonate 

 was precipitated. In solution, they found, beside baric bromide, a 

 sparingly soluble barium salt, to which they gave the name, baric 

 muconate, and the formula, BaC^Og . HoO. This formula was, how- 

 ever, based upon a single barium and two water determinations. 

 They also prepared the free muconic acid, but made no further study 

 of it than to establish the fact that it was a crystalline solid readily 

 soluble in water, and that its lead salt was insoluble. They expressed 

 the reaction which they supposed had taken place by the equation : — 



2 C^H.Bvfi, + IJ.,0 = C.H.Og + CoHBr -f 2 CO^ + 3 HBr. 



They also found that mucobromic acid was attacked when boiled 

 with argentic oxide and water, that argentic bromide was formed, and 

 at the same time a silver salt quite insoluble in water. This silver 

 salt, according to their calculations of the analytical results which they 

 obtained, had the formula C-HoBrgAgjO^, and they regarded this as an 

 intermediate product standing between mucobromic and muconic acids. 

 The acid was found to be a crystalline solid, which appeared to give 



* Ann. Chem. u. Pharu., Suppl., iii. 276. 



