114 PROCEEDINGS OF THE AMERICAN ACADEMY. 



results with bromdinitrophenylacetic acid ; * but, whereas with that sub- 

 stance a few drops of sulphuric acid were sufficient to prevent the for- 

 mation of the substituted toluol, we found that even one per cent of acid 

 did not produce this effect with the triuitrophenylacetic acid, and that 

 the amount must be raised to five per cent to insure perfect safety. For- 

 tunately it was not necessary to use this rather strongly acidified water, 

 as benzol proved to be an excellent solvent for the substance. Accord- 

 ingly the crystals, which formed the product of the saponification (see 

 the preceding section), were filtered from the sulphuric acid through 

 glass wool, washed with water, dried, and recrystallized from benzol 

 until they showed the constant melting point 161°, when they were dried 

 at 100°, and analyzed with the following i-esults : — 

 I. 0.2020 gram of the substance gave 28.2 c.c. of nitrogen at a tem- 

 perature of 22° and a pressure of 750.8 mm. 

 II. 0.2093 gram of the substance gave 28.4 c.c. of nitrogen at a tem- 

 perature of 20° and a pressure of 758.3 mm. 



Calculated for Found. 



CoU,(NO„)3CU.,COOH. I. II. 



Nitrogen 15.50 15.59 15.46 



Properties of Trinitrophenylacetic Acid. — It crystallizes from benzol 

 in short needles arranged in sheaf-shaped bunches, and melts at 161°. 

 As at first prepared it is white, but it turns pink on standing, even when 

 in a corked tube, and this change is due to decomposition, as it is accom- 

 panied by an alteration in the melting point. It dissolves in ethyl or 

 methyl-alcohol with a pink color, but this solution produces a decompo- 

 sition, the trinitrophenylacetic acid losing carbonic dioxide and forming 

 trinitrotoluol, which is left in a nearly pure state on the evaporation of the 

 solvent. It was recognized by its melting point, 81°. Willbrand f gives 

 82°, Mills I 78°.84 and B0°.52. (It is possible that further cr\stalliza- 

 tion miglit have raised the melting point of our specimen to 82°.) Ihe 

 trinitrophenylacetic acid, therefore, is less stable than the bromdinitro- 

 phenylacetic acid, as two evaporations with alcohol were necessary to 

 convert this entirely into the corresponding bromdinitrotoluol. One crys- 

 tallization of the trinitrophenylacetic acid from boiling water was suf- 

 ficient also to form the trinitrotoluol, and, as has been already said, the 

 addition of five per cent of sulphuric acid was necessary to prevent this 

 action. The aqueous solution had a pink color like that of the alcoholic 

 solution, but we have not succeeded in discovering the cause of this color- 



* These Proceedings. XXIV. 241. t Ann. Chem., CXXVIII. 178. 



X Phil. Mag., [5], XIV. 27. 



