262 PROCEEDINGS OF THE AMERICAN ACADEMY 



trophenylmalonic ester is formed, had settled beyond a doubt the com- 

 position of the ester, which before this and the similar investigation 

 made by one of us and W. S. Robinson had rested principally on 

 the analyses of its salts (see these Proceedings, xxiv. 4). We have 

 confined ourselves therefore to a single analysis of the sodium salt, 

 and a preliminary study of the copper salt, the results of which are 

 given below. 



Sodium Salt, C 6 HBr(N0 2 ) 3 CNa(COOC 2 H 5 ) 2 . — This substance was 

 made in two ways. First, by digesting solid pure sodic carbonate 

 with a solution of bromtrinitrophenylmalonic ester in absolute alcohol. 

 The red solution was filtered from the excess of sodic carbonate, 

 evaporated to dryness on the water bath, and dried at 100°, when it 

 gave the following result on analysis : — 



0.2373 gr. of the salt gave after being heated with sulphuric acid 

 0.0418 gr. of sodic sulphate. 



Calculated for 

 C 6 HBr(N0 2 ) 3 CNa(C0 2 C 2 H 5 ) a . Found. 



Sodium 4.87 5.71 



The bad result is probably due to a slight excess of sodic carbonate, 

 which dissolved in the alcohol. The salt looked black and somewhat 

 decomposed. 



The second and better method was that used for making the salt of 

 the corresponding dinitro compound, that is, by the action of an alco- 

 holic solution of sodic hydrate or ethylate on an alcoholic solution of 

 the ester, taking care that the ester is in excess. For the necessary 

 precautions see these Proceedings, xxiv. 7. No analysis was made 

 of this preparation, as from our experience with the acetacetic com- 

 pound we were sure that no accurate analytical results would be 

 obtained. 



Properties. — The sodium salt forms an amorphous blackish red 

 mass, soluble in ethyl or methyl alcohol, water, or acetone ; tolerably 

 soluble in ether; slightly in chloroform ; insoluble in benzol or ligroine. 

 All the solutions have a deep blood-red color. When the salt is treated 

 with an excess of strong nitric acid (of specific gravity 1.36), it is at 

 first decolorized, but almost immediately turns vivid red owing to the 

 formation of the substance produced by warming the free ester with 

 nitric acid. This behavior is characteristic, as it appears with none 

 of the similar substances which we have studied. 



Copper Salt. — We took up the study of this salt in the hope of 

 throwing light on the composition of the ester, but after analyzing 



