12 PROCEEDINGS OF THE AMERICAN ACADEMY 



filtered out and the filtrate thrown away, as it gave almost no residue 

 on evaporation, and no extract when shaken with ether. 



The crystals were purified by crystallization from dilute alcohol (three 

 parts of water to one part of alcohol). If the temperature was kept 

 below 150°, the product was nearly pure, as it came from the tube ; but 

 if it had risen above this point, a small quantity of a lower melting 

 substance was formed, which it was almost impossible to remove with 

 dilute alcohol. In this case the best plan was to dissolve the substance 

 in chloroform, when the impurity separated at first as a pasty mass, 

 leaving the principal product in solution, which after one crystalliza- 

 tion from dilute alcohol showed the constant melting point 170°. It 

 was dried at 100°, and analyzed with the following results. 



I. 0.1307 grm. of substance gave on combustion 0.1634 grm. of 

 carbonic dioxide and 0.0278 grm. of water. 

 II. 0.2162 grm. of substance gave 0.2688 grm. of carbonic dioxide 

 and 0.0495 grm. of water. 



III. 0.2136 grm. of substance gave 18.3 c.c. of nitrogen at a temper- 



ature of 22° and a pressure of 760 mm. 



IV. 0.1197 grm. gave 10.2 c.c. of nitrogen at a temperature of 28° 



and a pressure of 762.9 mm. 

 V. 0.2212 grm. of substance gave by the method of Carius 0.1365 

 grm. of argentic bromide. 

 VI. 0.2120 grm. gave 0.1275 grm. of argentic bromide. 



VI. 



26.29 25.59 



These numbers agree tolerably well with those required for the 

 formula C c H 2 Br(N0 2 ) 2 C 3 H 5 2 . 



Calculated. 



Carbon 33.86 



Hydrogen 2.19 



Nitrogen 8.77 



Bromine 25 08 



But the formula cannot be considered definitely established, until we 

 have supported our analytical results by a careful study of the deriva- 

 tives of the substance. 



