, 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 deg..
[Footnote 7: Pharm. Centralhalle, xxii., 236.]
Marquardt,[8] like Betelli, extracts the fusel oil from alcohol by means
of chloroform, and by oxidation converts it into valeric acid. From the
quantity of barium valerate found he calculates the amount of amyl
alcohol present in the original solution; 150 c.c. of the spirit, which
has been diluted so as to contain 12 to 15 per cent. of alcohol, are
shaken up thoroughly with 50 c.c. of chloroform, the aqueous layer drawn
off, and shaken with a fresh portion of chloroform. This treatment is
repeated several times. The extracts are then united, and washed
repeatedly with water. The chloroform, which is now free from alcohol
and contains all the fusel oil, is treated with a solution of 5 grammes
of potassium bichromate in 30 grammes of water and 2 grammes of
sulphuric acid, and then heated in a closed flask for six hours on a
water bath at 85 deg.
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