OP ARTS AND SCIENCES. 71 



point 133°), a fact which confirms the formula assigned to it. We 

 may add, that we have failed in all our attempts to convert anilido- 

 trinitrophenylmalonic ester into its nitrite, or the corresponding tar- 

 tronic ester, by the action of nitric acid. 



We have also tried without success to convert the bromdinitrophe- 

 nylmalonic ester into diiiitrophenylenedimalonic ester by the further 

 action of sodium malonic ester. 



The remainder of the paper contains the experimental details of 

 the work. 



Preparation of Tribromtrinitrobenzol. 



The experience gained in making tribromtrinitrobenzol for the 

 work described in this paper has led us to introduce into the process 

 given in previous papers * from this Laboratory some improvements, 

 which are described in this section. 



To the preparation of tribromaniline we have nothing to add, but 

 in the conversion of it into tribrombenzol we have found it best to 

 proceed as follows: — 50 gr. of dry tribromaniline were dissolved 

 with the aid of heat in 300 c. c. of alcohol containinsr 75 c. c. of 

 benzol to increase its solvent power, and 20 c. c. of common strong 

 sulphuric acid added to the hot solution from a pipette. If this 

 formed a precipitate, it was dissolved by longer heating, more of the 

 solvents being added if necessary. 20 gr. of finely powdered sodic 

 nitrite were then sifted into the hot liquid, as rapidly as the violence 

 of the action would permit ; after which the whole was heated until 

 the effervescence had ceased, and, after standing over night, filtered, 

 washed, and dried, when the product could be treated directly with 

 nitric acid to make the tribromdinitrobenzol in the manner already 

 described.! The yield of tribrombenzol was good, 42-44 gr. from the 

 50 gr. of tribromaniline. The filtrate and washings contained so little 

 of the organic substance that it was not worth while to work them up. 



In the conversion of this body into tribromtrinitrol)enzol we have 

 found the cause of the much larger yield obtained by Dr. Moore X than by 

 Dr. Wing.§ This does not depend so much on the larger proportion of 

 fuming sulphuric acid used, as on the rapidity with which the boiling is 

 carried on. To get the best yield we found it necessary to raise the mix- 

 ture to the boiling point as quickly as possible, and to keep it boiling 

 violently during the whole of the three hours. Under these conditions 

 the yields varied from 8 to 10 gr. of tribromtrinitrobenzol from 20 gr. 



* These Proceedings, XXIII. 139, XXIV. 258, 273. 



t Ibid., XXIV. 274. X Ibid., XXIV. 268. § Ibid., XXIII. 140. 



