OF ARTS AND SCIENCES. 171 



The following analyses may serve to show the purity of the material 

 used in the course of the following investigations: — 



I. 0.7840 grm. substance gave 0.5390 grm. CO., and 0.0720 grm. 



11,0. 

 II. 0.9326 grm. substance gave 0.6340 grm. COj and 0.0712 grm. 



H,0. 

 m. 0.2347 grm, substance gave 0.3421 grm. AgBr. 

 IV. 0.2331 grm. substance gave 0.3410 grm. AgBr. 



IV. 



62.25 



Salts of Mucobromic Acid. 



Schmelz and Beilstein found that mucobromic acid decomposed 

 baric carbonate, and that the barium salt thus formed was readily 

 soluble in water, although it was decomposed during the spontaneous 

 evaporation of the solution. As it seemed a matter of some interest 

 to determine whether mucobromic acid was capable of forming salts, 

 Mr. 0. R. Jackson and I pursued the investigation one step further. 



Baric Mucohromate, Ba(C^HBr20g)2. We found that an aqueous 

 solution of mucobromic acid dissolved baric carbonate readily, that 

 the solution on standing soon turned brown, deposited a brownish 

 flocculent precipitate, and contained then a baric bromide in abun- 

 dance. On heating, the same change took place more rapidly, and when 

 the solution was boiled a substance was volatilized with the steam 

 which had a sharjj, acrolein-like odor, and reduced silver oxide on 

 heating. Although this change was rapid near 100°, we found that 

 it was sufficiently slow at 50-60° to allow the preparation of a solu- 

 tion saturated at this temperature which on cooling with vigorous 

 stirring deposited crystals of the barium salt. The mucobromic acid 

 was suspended in very little water, the whole warmed to 50-60°, 

 baric carbonate added in excess, and the solution filtered and cooled 

 as rapidly as possible. Even with these precautions we found it 

 difficult to saturate the acid completely without bringing about decided 

 decomposition. The salt, therefore, usually contained more or less 

 free acid, from which it could be completely freed by washing with 

 ether. The salt when dried in vacuo over sulphuric acid hardly lost 

 weight at 100°, but when heated a few degrees higher it turned 



