252 PROCEEDINGS OP THE AMERICAN ACADEMY 



toliiidine were dissolved in about 12 c.c. of acetone, 8 c.c. of common 

 alcohol added, and the mixture acidified with strong sulphuric acid, 

 after which 1.5 grs. of sodic nitrite, about twice the calculated amount, 

 was added in small portions at a time, and the liquid warmed gently 

 until the evolution of nitrogen ceased, when the larger part of the 

 acetone and alcohol was distilled off at first on the water bath, finally 

 on the sand bath, and the residue distilled with steam ; the dinitrotoluol 

 passed over into the receiver in small white crystals, which were 

 removed by filtration, and crystallized from hot alcohol until they 

 showed the constant melting point 71°. It was not worth while to 

 dilute the distillate of acetone and alcohol, as no precipitate was ob- 

 tained in that way. For greater certainty the product was analyzed, 

 with the following results : — 



0.2456 gr. of the substance gave 33.1 c.c. of nitrogen at a tempera- 

 ture of 22° and a pressure of 764.2 mm. 



Calculated for 

 C6H3CH3(N02)2. Found. 



Nitrogen 21.31 21.71 



There is no question therefore that the substance is the orthopara- 

 dinitrotoluol, CHg, NO.,, NOg, 1, 2, 4, and the bromdinitrotoluol accord- 

 ingly has the following constitution: CH,, Br, NO.^, NO^, 1, 3, 4, 6. It 

 follows also that our dinitrotoluidiue is identical with that described 

 by Kolb, and, if Staedel had given its melting point, it would not have 

 been necessary for us to determine its constitution. As has been 

 already stated, this dinitrotoluidiue melts at the same point as that 

 made by Hepp from alcoholic ammonia and his y trinitrotoluol. To 

 establish the relation between these substances more firmlj^ we made 

 the dinitrophenyltoluidine by treating our dinitrobromtoluol with ani- 

 line, and found that the product showed the same melting point, 142°, 

 as that of the compound made by Hepp from y trinitrotoluol and 

 aniline. The y trinitrotoluol of Hepp therefore has the following 

 constitution : CH.,, NOo, NOg, NO,, 1, 3, 4, 6 ; which is in harmony with 

 Laulienheimer's rule,* that a nitro group is removed by the action of 

 alcoholic ammonia only when it is in the ortho position to another 

 nitro group. 



Metahromtrinitrotoluol, CgHCH3Br(N02)3. 



In preparing the metabromdinitrotoluol, we found, if a mixture of 

 fuming nitric acid and sulphuric acid was u.sed, that a new substance 



* Ber. d. ch. G., ix. 766, 1828. 



