OP ARTS AND SCIENCES. 275 



and treating the residue with sodic hydrate and a little alcohol, which 

 convert the new substance into its sodium salt, and this can be re- 

 moved from the unaltered tribromdinitrobeuzol by washing with 

 water ; when the wash-waters were acidified, and the precipitate puri- 

 fied in the same way as the main portion, the substance was dried in 

 vacuo, and analyzed with the following results : — 



I. 0.2683 gr. of the substance gave on combustion 0.3788 gr. of 



carbonic dioxide, and 0.0748 gr. of water. 

 II. 0.2512 gr. of the substance gave 16.7 c.c. of nitrogen at a tem- 

 perature of 22° and a pressure of 759.7 mm. 



III. 0.2067 gr. of the substance gave, according to the method of 



Carius, 0.1041 gr. of argentic bromide. 



IV. 0.2141 gr. of the substance gave 0.1059 gr. of argentic bromide. 



Calculated for Found. 



C6H2Br(N02)XH3COUHC03aH5. I. II. III. IV. 



Carbon " '38.41 ' ' 38.50 



Hydrogen 2.93 3.09 



Nitrogen 7.47 . 7.33 



Bromine 21.33 21.43 21.05 



The yield of bromdinitrophenylacetacetic ester, prepared by the 

 method described above, is satisfactory on the whole, the best result 

 beincr as follows : — 



15 grs. of the tribromdinitrobenzol yielded 6.5 grs. of the ester, and 

 3.1 grs. of unaltered tribromdinitrobenzol were recovered, leaving 11.9 

 grs. which had entered into the reaction. 11.9 grs. of tribromdinitro- 

 benzol should yield 11.0 grs. of bromdinitrophenylacetacetic ester. 

 The actual yield, therefore, was 59 per cent of the theoretical. In 

 other preparations the yield varied from 54 to 34 per cent, the lowest 

 which was obtained from this process. The yield was not improved 

 by increasing or by diminishing the proportion of acetacetic ester to 

 the tribromdinitrobenzol. In our first preparations the reaction was 

 allowed to run in the cold, as an experiment, in which the mixture had 

 been heated less than one hour, seemed to give a very unmanageable 

 product ; in this case, however, the yield was very much less than that 

 obtained by the process described above, in which the mixture was 

 heated one hour. 



In order to throw light on the way in which the reaction runs, we 

 determined the amount of bromide of sodium formed in two prepara- 

 tions as follows : — 



I. 12 grs. of tribromdinitrobenzol yielded 4.43 grs. of bromine in 

 the form of sodic bromide. 



