OF ARTS AND SCIENCES. 253 



form to the other with great ease, so that it is doubtful whether 

 they should be considered true isorneres. Nevertheless, it has 

 seemed to us that, in the present state of our knowledge of isorneres, 

 a description of such closely related modifications as these might 

 be of advantage to the science, and we therefore publish our results, 

 which we think the more interesting because the triparatoluidodi- 

 nitrobenzol shows an exactly similar behavior. On the other hand, 

 we have not succeeded as yet in obtaining such forms from the 

 triorthotoluidodinitrobenzol, although it is possible that they may 

 exist, but that the second modification is less stable than those of 

 the anilido and paratoluido compounds. 



In searching for isomeric forms of the trianilidodinitrobenzol, 

 which we have done by a great number of varied experiments, we 

 discovered a compound of this substance with chloroform having 

 the formula C 6 H(C 6 H 5 NH) 3 (N0 2 ) 2 CHC1 3 , which crystallized in 

 blackish red well formed prisms, but lost its chloroform partially 

 even at ordinary temperatures. A similar addition product was 

 obtained with the corresponding para- but not with the ortho- 

 toluido compound; an attempt will be made in this Laboratory to 

 trace the limits of this reaction. 



Numerous attempts to prepare a second modification of trianili- 

 dotrinitrobenzol or of anilidotrinitrophenylmalonic ester have led 

 to negative results without exception, as no change in the full 

 yellow color or the crystalline form of either of these substances 

 could be observed, but this result seems so strange in view of the 

 occurrence of two modifications of the trianilidodinitrobenzol on 

 the one hand, and of the anilidotrinitrophenyltartonic ester on the 

 other, that a more careful study of these substances will be made 

 hereafter, and the work extended to other substances, in the hope 

 of collecting in time enough observations to determine the cause 

 of the isomerism of the substituted tartronic ester. 



Experiments with Trianilidodinitrobenzol. 



In searching for isomeric forms of the trianilidodinitrobenzol we 

 studied more carefully than before the crystallization of it from 

 various solvents, and found that, when a mixture of benzol and 

 alcohol was used as the solvent, it appeared in crystals of two sorts, 

 one the nearly square prisms of an orange color like that of potassic 

 dichromate already described, the other as yellow as potassic chro- 

 mate in bladed crystals, or plates looking like flattened monoclinic 

 prisms terminated by two planes, or less commonly with square 



