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QUANTITATIVE AGRICULTURAL ANALYSIS

NICOTINE INSECTICIDES
Nicotine in solution is an effective agent for destroying many
soft bodied insects, as aphides and pear psyllse. Solutions of
nicotine are valuable as insecticides because of the intensely
poisonous character of nicotine, whether eaten by the insect
or absorbed through its exterior covering. They may be
applied in various dilutions and in combinations with other
sprays to treat, all at once, certain sucking and biting insects
and fungus parasites. Nicotine is not injurious to foliage, in any
concentration. As a vegetable alkaloid it is a weak base and this
makes it possible to determine the amount of nicotine present in
a solution by titrating with a standard acid.

Y)

A	B	D
fig. 62.—Apparatus for distillation with steam.
Most dry tobacco waste contains from 2 to 3 per cent of
nicotine. An extract may be prepared for use as an insecticide
by stirring 25 to 30 Ib. of the tobacco waste with 50 gal. of water.
This will make a solution averaging about 0.06 per cent -of
nicotine.^1
The separation of nicotine from a solution is made by extract-
ing with ether. The extracted residue is dissolved in a base
^1 Va. Exp. Sta. Bull, 208 (1914).