204 PROCEEDINGS OP THE AMERICAN ACA.DEMY 



The decomposition of mucobromic acid by baric hydrate, under the 

 conditions described, may be expressed by the following equations. 

 The first action would seem to be the assimilation of a molecule of 

 water and the formation of dibromacrylic and formic acids. 



C.H^BrA + H,0 = C3H,Brp, + CH,0, 



This action is immediately followed, even in the cold, by the subtrac- 

 tion of hydrobromic acid, — 



CsH^BrPj — HBr = CgHBrO^ 



The brompropiolic acid is then either decomposed by heat, — 



CgHBrOg = C^HBr + CO^, 



or is converted into malonic acid, — 



CgHBrO^ + 2H2O = CgH.O, + HBr 



Since a large percentage of dibromacrylic acid was converted into 

 brompropiolic acid in this reaction, and it had previously been proved 

 that a portion of the mucobromic acid entirely escaped decomposition 

 when the proportion of baric hydrate was materially lessened, I re- 

 cently attempted to increase the yield by reversing the mode of pro- 

 cedure. I therefore added baric hydrate, gradually, to mucobromic 

 acid suspended in a little water ; taking care, after the acid was neu- 

 tralized, to make the solution but slightly alkaline, and to wait until it 

 was again neutral before further addition. I found, however, that an 

 entirely different reaction had taken place under these conditions, and 

 that among the products of this reaction little or no dibromacrylic acid 

 could be found. This decomposition is at present under investigation 

 in this laboratory, and all discussion of the results we have already 

 obtained must therefore be reserved for a subsequent paper. 



Mdcochloric Acid. 



Mucochloric acid was discovered in 18 Go by Schmelz and Beil- 

 stein,* and since that time, as far as I know, it has never been further 

 studied. The discoverers found its preparation so very laborious, and 

 the yield which they obtained so small, that they made no extended 

 investigation of it, but contented themselves with giving a short de- 

 scription of the acid, together with the analyses necessary to establish 

 its composition. Although their account was certainly not encourag- 



* Ann. Chcni. u. Pharni., Suppl., iii. 280. 



