December, ’23] deong: volatility and toxicity of nicotine 487 
the nicotine from the combining acid. The addition of soap, ostensibly 
as a spreader, has a double value for besides its film-forming value, it 
increases the alkalinity of the solution. In our experimental work, 
however, it was found that tap water, slightly above the average of 
hardness and requiring 1.3 cc. of n /50 sulfuric acid to neutralize 100 
cc., did not give the fullest toxicity possible even with the addition of 
soap. An increase in efficiency of from twenty to forty percent occurred 
in solutions where sufficient alkali was added over those which were 
neutral. Such results were secured both in spraying and fumigating 
and in volatilizing experiments. 
Experimental 
Nicotine solutions, made with free nicotine and with nicotine sulfate 
with varying degrees of alkalinity and in tap water, were compared in 
three ways: (1) Rate of volatilization as a film on leaf surfaces and from 
solutions, (2) Efficiency as a spray on aphids, (3) Efficiency as a fumigant 
on aphids. 
Volatilization Experiments. The nicotine solutions used in this 
as well as in the spraying and fumigating experiments were, with the 
Table I. Foliage Tests of the Volatility of Nicotine in Various Alkaline 
Solutions and Under Contrasting Meteorological Conditions 
A. Laboratory Tests in clear weather. 
B. Laboratory Tests in cloudy, rainy weather. 
Series (1) Nicotine residue determined after three hours. 
Series (2) Nicotine residue determined after twenty-four hours. 
Series (3) Nicotine residue determined after forty-eight hours. 
A Clear weather 
Percent of Nicotine 
Recovered 
No. 
Type of Solution 
Ser. (1) 
Ser. (2) 
Ser. (3) 
1 
Nicotine sulfate, no alkali 
48.5 
29.9 
trace 
2 
Nicotine sulfate + .25 cc. n/1 NaOH 
50.0 
25.1 
4.8 
3 
Nicotine sulfate+ .5 cc. n/1 NaOH 
42.7 
13.7 
trace 
4 
Nicotine sulfate in tap water 
51.5 
15.7 
trace 
5 
Nicotine sulfate in tap water plus 
soap equal to 4fbs per 100 gallons 
36.6 
8.9 
3.0 
6 
Nicotine sulfate + .75 cc. n/1 NaOH 
27.9 
trace 
trace 
7 
Nicotine sulfate + 1.0 cc. n/1 NaOH 
10.4 
trace 
0 
8 
Free nicotine+ .013 gm. Na2S0 4 
14.1 
0 
0 
B 
Cloudy and rainy weather 
1 
82.6 
46.1 
13.4 
2 
Descriptive 
52.7 
18.5 
7.0 
3 
matter 
26.9 
7.7 
6.0 
4 
as 
35.8 
12.5 
19.0 
5 
above 
33.2 
7.4 
0 
6 
15.5 
trace 
trace 
7 
17.9 
0 
trace 
8 
41.9 
trace 
2.7 
