OF ARTS AND SCIENCES. 179 



off, when the needles were heated in a test tube, dissolved the crystals 

 cliuging to the side of the tube, and that the substance dried at 100"^, 

 when recrystallized from absolute alcohol, gave white prisms like those 

 whose analysis is given above. The analysis which follows was made 

 with the white needles after they had been dried at 100°, and there- 

 fore freed from their alcohol of crystallization. 



0.2688 gr. of the substance gave on combustion 0.4092 gr. of car- 

 bonic dioxide and 0.1027 gr. of water. 



Found. 



41.52 

 4.25 



The substance contains no bromine. 



From these results it is evident that the substance is the dinitro- 

 resorcine dimethylether, but its melting point, 167°, shows that it is 

 isomeric with the substance * of this composition already known, 

 which melts at 67°. 



Properties. — The dinitroresorcine dimethylether was obtained crys- 

 tallized with one molecule of alcohol, and also in crystals free from 

 alcohol. When containing a molecule of alcohol it forms sheaves or 

 bunches of white needles, or slender prisms often a centimeter long 

 terminated by two planes at a very obtuse angle to each other, or less 

 often a single plane at an acute angle to the sides ; frequently also a 

 single plane at right angles to the sides was observed, but we were 

 inclined to consider this due to cleavage rather than a real termina- 

 tion of the crystal. These two prevailing forms, the two planes at an 

 obtuse angle, and the single plane at a right angle, give a general 

 square-ended effect to the crystals which is characteristic. On expos- 

 ure to the air these crystals turn purplish brown. "When containing 

 no alcohol of crystallization, it forms short thick and broad crystals, 

 apparently prisms of the monoclinic system somewhat like certain 

 felspars or rhombic crystals made up by the twinning of such prisms 

 along one diagonal of the rhomb, and having a lemon-yellow color, 

 which is not altered by exposure to the air. The melting point is 

 167°, but the white needles melt a degree and a half below this point,, 

 probably on account of the presence of the vapor of alcohol. The 

 substance is nearly insoluble in cold water, somewhat more soluble in 

 hot ; slightly soluble in cold ethyl or methyl alcohol, more soluble in 



* Honig, Ber. d. ch. G., xi. 1041. 



