50 PRACTICAL ORGANIC CHEMISTRY way until the two yellow bands have become distinct and separate during their passage to the lower portion of the column. Then continue the washing with fresh benzene until each band has been separately eluted in about 150 ml. of benzene, that of the o-nitroaniline emerging first from the tube.* Concentrate each of the two solutions (or eluates) to about 20 ml. by distilling off the greater part of the benzene, the dis-tilling-flask being immersed in the boiling water-bath. Then pour the concentrated solution into an evaporating-basin, and evaporate the remaining benzene (preferably in a fume-cup-board) in the absence of free flames, i.e., on an electrically heated water-bath, or on a steam-bath directly connected to a steam-pipe. Wash the dry residue from the first eluate with petrol and then dry it in a desiccator: pure o-nitroaniline, m.p. 72°, is obtained. Wash the second residue similarly with a small quan-tity of benzene and dry: pure p-nitroaniline, m.p. 148°, is
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