MM. Schmelz and Beilstein on Pyromucic Acid. 361 



off from the mercury and treated with sulphuric acid, by which 

 the alcohol in question was deposited as a reddish-brown oil. 

 To purify this oil it was dissolved in alcohol, the alcoholic solu- 

 tion mixed with ether, water gradually added, and the whole 

 well shaken, by which two layers were obtained, one containing 

 a solution of the alcohol of pyromucic acid in ether, and the 

 lower one an aqueous solution of pyromucate of soda. On eva- 

 porating the ethereal solution, a reddish liquid was obtained 

 which decomposed on evaporation. By the action of alkalies this 

 alcohol appears readily to pass into pyromucic acid. 



When bromine is added to pyromucic acid a violent reaction 

 is set up, accompanied by disengagement of carbonic acid. This 

 reaction is at first moderated by cooling, but its completion 

 requires the aid of heat. It is also necessary that an excess of 

 bromine be added, and that the solution be of the proper degree 

 of concentration. When these conditions are complied with, 

 and the solution is concentrated in the water-bath, it yields crys- 

 talline lamiuse of a new body, mucobromic acid. This is a deci- 

 dedly acid substance, and forms salts, which, however, are ex- 

 tremely unstable, and have hence not been further examined. 

 Its formation is expressed as follows : — 



G 5 H 4 3 -r8Br + 2H 2 0=G 4 H 2 Br 2 3 + G0 2 + 6HBr. 



Pyromucic Mucobromic 



acid. acid. 



This reaction only expresses the final decomposition of pyro- 

 mucic acid ; and an oily body is first formed which is perhaps 

 G 4 H 2 3 . The action of excess of bromine on the soda-salt of 

 pyromucic acid is the same as on the free acid. 



The decomposition of pyromucic acid by chlorine is quite 

 analogous to that of bromine ; it gives rise to mucochloric acid 3 

 G 4 H 2 CI 2 O 3 . Iodine is without action upon pyromucic acid. 



By comparing the formula of mucobromic acid, G 4 H 2 Br 2 3 , 

 with that of mellithic acid, G 4 H 2 O 4 , it is seen that the latter 

 acid might be formed by the simple replacement of the bromine 

 of the former by oxygen. 



By treating mucobromic acid with baryta the bromine was 

 removed, but the decomposition in other respects was different. 

 When the acid is boiled with excess of baryta, air being excluded, 

 carbonate of baryta is deposited, and a gas is liberated which 

 spontaneously inflames in the air, and is brominated acetylene, 

 G 2 HBr ; and the solution contains the baryta-salt of a new acid 

 which the authors call muconic acid. The formula of this salt is 

 G 4 Ba 2 O 3 -f- ^ H 2 0, and the free acid is obtained in crystals from 

 its lead-salt by treatment with sulphuretted hydrogen. 



In the formation of this acid the elements of water are con- 



