106 PROCEEDINGS OP THE AMERICAN ACADEMY. 



II. 0.2007 gram of substance gave 0.3078 gram of carbonic dioxide 

 and 0.0789 gram of water. 

 III. 0.2040 gram of substance gave 20.5 c.c. of nitrogen at a tempera- 

 ture of 21° and a pressure of 759.6 mm. 



Calculated for Tound. 



CaH2(N02)3CH(COOC2H5),. I. II. HI. 



Carbon 42.05 ' 41.89 41.82 



Hydrogen 3.50 3.98 4.36 



Kitrogen 11.32 11.41 



The combustion of this substance must be carried on as slowly as pos- 

 sible, as it has a strong tendency to explode. 



The molecular weight of the substance was also determined by the 

 method of Raoult with the following results : — 



I. Weight of benzol used 19.2120 grams, substance 0.3291 gram. 

 Reduction of freezing point 0°.230. 

 II. Weight of benzol used 15.7244 grams, substance 0.3428 gram. 

 Reduction of freezing point 0°.306. 

 III. Weight of benzol used and weiglit of substance the same as in II. 

 Reduction of freezing point 0°.297. 



Calculated for Found. 



C6H2(N02)3CII(C00Cjn3)j. I. II. III. 



Molecular Weight 371 365.1 349.0 359.6 



From these results there can be no doubt that the preparation melting 

 at 64° was trinitropheuylmalonic ester. 



It is worth while to point out here that the form melting at 58° could 

 not have owed its peculiarities in melting point and crystalline form to 

 the presence of a small quantity of some impurity, since it was repeatedly 

 brought to a constant melting point both by Dr. Soch and by us ; and, if 

 this explanation were correct, this form should have been the first pro- 

 duct of the preparations in our later work, whereas, after we had once 

 obtained the form melting at 64°, we could not prepare the other. Dr. 

 Soch's analyses of the form melting at 58° also show that it was pure. 



Calculated. Found. 



Nitrogen 11.32 11.75 11.38 



We are therefore led to the conclusion that the trinitropheuylmalonic 



ester exists in two isomeric forms. 



The isomerism of these two forms is probably due to the same cause 



as that of the red and yellow anilidotrinitrophenyltartronic esters (melt- 



