146 PROCEEDINGS OF THE AMERICAN ACADEMY 



purification of this substance was attended with such great difficulties 

 that we have abandoned for the present the further study of this re- 

 action, in which the nitro groups undoubtedly play a part. 



Properties. — The trianilidotrinitrobenzol forms an orange powder, 

 crystallizing from alcohol or chloroform in fine red needles, which 

 melt at 238°. It is essentially insoluble in water, soluble with diffi- 

 culty in alcohol, but easily in chloroform, soluble in ether, benzol, 

 glacial acetic acid, or acetone. The best solvent for it is a mixture of 

 alcohol and chloroform. Hydrochloric acid has no action on it, and 

 in general it shows no more tendency to form salts than the corre- 

 sponding amido compound. Strong nitric acid produces no change of 

 color when added to it. 



Tetrabromdinitrobenzol, C 6 Br 4 (NOo) 2 - 



As has been already stated, during the preparation of the tribrom- 

 trinitrobenzol from tribromdinitrobenzol by the action of nitric acid 

 and fuming sulphuric acid there was formed invariably another sub- 

 stance which melted in the crude state at about 230°, and was left 

 behind with the tribromtrinitrobenzol after the tribromdinitrobenzol 

 was removed with alcohol, and was separated partially from it by 

 crystallizing the residue from chloroform, in which the trinitro com- 

 pound is less soluble than the other substance. In this way it is 

 easy to get the trinitro compound in a state of purity ; but to purify 

 completely the other substance it is necessary to submit the residue 

 from the evaporation of the chloroform mother-liquors to systematic 

 fractional crystallization from a mixture of alcohol and benzol, which 

 removes a small quantity of tribromtrinitrobenzol. These crystalliza- 

 tions lowered the melting point instead of raising it, as is usual, and 

 after it had been brought down from about 230° to 224° it remained 

 constant, and then the substance, dried at 100°, was analyzed with the 

 following results. 



I. 0.3526 grm. of the substance gave 18.7 c.c. of nitrogen at 24° 

 temperature and 764 mm. pressure. 

 II. 0.1690 grm. of the substance gave, by the method of Carius, 

 0.2606 grm. of argentic bromide. 



