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and the tribromfiirfuran obtained from the crude pyromucic tetrabro- 

 mide is undoubtedly identical with it. 



Of the four formulae for dibromfurfuran, which are possible if the 

 formulo3 of furfurau we have adopted be correct, 



the first undoubtedly represents the structure of a dibromfurfuran 

 which has already been described in a preliminary paper by Sir. George 

 T. Hartshorn and one of us.* The mode of its formation, and its re- 

 actions, leave no possible doubt as to its constitution. It seems to us 

 that there can be no reasonable doubt that the two dibromfurfurans 

 which we have just described must have the structure represented by 

 the second and third formulse, corresponding to the formulae of the 

 two dibrompyromucic acids formed at the same time. The latter 

 formula, then, probably represents the more stable substance of lower 

 boiling-point. 



* Ber. der deutsch. cheni. Gesell., xviii. 448 



