146 PROCEEDINGS OF THE AMERICAN ACADEMY 



tals of fumaric acid, and still more may be obtained by evaporation. 

 The weight of fumaric acid thus obtained amounted to a little more 

 than sixty per cent of that calculated from the equation, 



C.H^BiOg + 2 + H,0 = C,H,0, + CO, + HBr. 



The acid recrystallized from water and dried at 100° gave on analy- 

 sis the following results : — 



0.1728 grm. substance gave 0.2613 grm. CO^ and 0.0575 grm. H.^O. 



Beside the fumaric acid could be isolated a small quantity of an 

 acid readily soluble in cold water, whose melting-point suggested the 

 possibility of its being maleic acid. Since at the high temperature 

 which we had employed in oxidation it was to be expected that the 

 maleic acid formed would be almost entirely converted into fumaric 

 acid, we repeated the oxidation with stronger nitric acid (sp. gr. 1.42) 

 and kept the temperature carefully between 30° and 35°. At this 

 temperature the oxidation went on vigorously, and constant cooling 

 was necessary. For complete oxidation three parts of strong nitric 

 acid were found to be advantageous. After the oxidation was com- 

 plete, the gaseous products of the reaction were removed by a current 

 of air, the solution was then diluted, filtered from a slight flocculent 

 precipitate thus formed, and neutralized with baric hydrate. In this 

 way was precipitated a sparingly soluble crystalline barium salt, which, 

 when recrystallized from hot water and dried by exposure to the air, 

 proved to hav'e the percentage composition of baric maleate. 



I. 1.0940 grm. of the air-dried salt lost at 158° 0.0794 grm. H,,0. 

 ir. 0.7644 grm. of the air-dried salt lost at 160° 0.0551 grm. H^O. 



Calculated for Found. 



BaC^HoOi . HoO. I. II. . 



11,0 6.69 ' 7.26 7.21 



I. 0.5036 grm. of the anhydrous salt gave on ignition with H2S0^ 

 0.4675 grm. BaSO,. 

 II. 0.2776 grm. of the anhydrous salt gave on ignition with HjSO^ 

 0.2579 grm. BaSO,.^ 



Ba 



