presence of fusel oil a red color is produced within a short time, which
can be detected when not more than 0.1 per cent. is present. But
Foerster[6] objects to this method because he finds the color to be due
to the presence of furfurol, and that pure amyl alcohol gives no color
with aniline and hydrochloric acid.

[Footnote 3: Pharm. J. Trans. [3] vi., 867.]

[Footnote 4: Berichte d. Deutschen Chem. Gesellsch., viii., 72.]

[Footnote 5: Pharm. Centralhalle, xxii., 3.]

[Footnote 6: Berichte d. Deutsch. Chem. Gesellsch., xv., 230.]

Hager[7] detects fusel oil as follows: If the spirit contains more than
60 per cent. of alcohol, it is diluted with an equal volume of water and
some glycerine added, pieces of filter paper are then saturated with the
liquid and exposed to the After the evaporation of the alcohol, the odor
of the fusel oil can be readily detected. For the quantitative
determination he distills 100 c.c. of the alcohol in a flask of 150 to
200 c.c. capacity connected with a condenser, and so arranged that the
apparatus does not extend more than 20 cm. above the water bath. This
arrangement prevents the fusel oil from passing over. If the alcohol is
stronger than 70 per cent., and the height of the distillation apparatus
is not more than 17 cm., the residue in the flask may be weighed as
fusel oil. With a weaker alcohol, or an apparatus which projects further
out of the water bath, the residual fusel oil is mixed with water. It
can, however, be separated by adding strong alcohol and redistilling, or
by treating with ether, which dissolves the amyl alcohol, and
distilling, the temperature being raised finally to 60°.