JACKSON AND COHOE. — METADIBROMDINITROBENZOL DERIVATIVES. 79 



Properties of Bromanilidodinitrobenzol, 

 C G H 2 BrC 6 H 5 NH(N0 2 ) 2 (Br 1. C 6 H 5 NH 3. (N0 2 ) 2 4. 6.). 



This substance crystallizes from a mixture of benzol and alcohol, 

 sometimes in much modified short and thick flat prisms apparently of the 

 monocliuic system, resembling certain crystals of felspar ; at other times 

 in rhombic plates occasionally with some of the angles slightly bevelled, 

 which pass into forms like rhombohedra ; all of these crystals have a full 

 golden yellow color. Other crystals were distinguished from these by 

 their brilliant red color and by appearing in square prisms modified on 

 one of their angles or on two opposite angles. From these two colors, 

 red and yellow, and the difference at least in crystalline habit, if not 

 really in crystalline form, we infer that the substance appears in two 

 closely related modifications. The yellow form, in which the substance 

 is obtained from its preparation, becomes gradually converted into the 

 red by crystallization from a mixture of alcohol and benzol, but several 

 crystallizations are necessary to make this conversion complete. If, 

 however, the yellow form is dissolved in benzol alone, the solution 

 deposits, as it evaporates, a red oil, which on stirring solidifies to the red 

 crystals. All the other common organic solvents except the alcohols 

 also convert the yellow into the red form by a single crystallization. On 

 the other hand, if the red crystals are heated in an air bath, they begin 

 to assume a yellow color at 110°, and are completely converted into the 

 yellow form at 185° ; this conversion is attended with no change in 

 weight. The substance melts at 157°, forming a red liquid, which, when 

 cooled and stirred, solidifies to the yellow modification. It is obvious 

 that the melting point given above is that of the yellow form, since the 

 red is converted into the yellow at 135°. The bromanilidodinitrobenzol 

 is freely soluble in benzol; soluble in toluol or chloroform ; slightly sol- 

 uble in ether, acetone, amyl alcohol, or hot ethyl alcohol. The best 

 solvent for it is a mixture of benzul and alcohol. 



Determination of the Constitution of Metadibromdinitro- 

 benzol by treatment with sodic ethylate. 



One gram of the dibromdiuitrobenzol melting at 117° was mixed with 

 an excess of sodic ethylate prepared by the action of sodium on a consid- 

 erable excess of absolute alcohol, and after the mixture had stood for 

 some time at ordinary temperatures, the excess of alcohol was allowed 

 to evaporate spontaneously. The residue, after repeated washings with 



