STUDIES ON CONTACT INSECTICIDES. 
TOXIC CONCENTRATIONS OF SELECTED COMPOUNDS. 
Table 2. — Relative toxicity of selected compounds to Aphis rumicis. 
Toxic concentration. 
Compound. 
Gram 
molecules 
per liter. 
Grams 
per 100 
cubic centi- 
meters. 
Boiling 
point. 
0.0004 
.0002 
.032 
.035 
.036 
.052 
.074 
.14 
.15 
.15 
.15 
.21 
. 22 
!28 
.33 
.33 
.38 
.39 
.41 
.44 
.46 
.47 
.50 
.58 
.59 
.SO 
.94 
1.2 
1.5 
1.6 
kl 
2.1 
2.S 
3.2 
3.2 
4.7 
8.3 
( l ) 
(?) 
( l ) 
( l ) 
0.007 
.009 
.35 
.94 
.60 
.50 
5 
1.5 
2.0 
2.0 
3.0 
3.5 
3 
3 
5 
6 
5 
5 
3.5 
3 
5 
5 
5.5 
5.5 
5 
9 
10 
15 
12.5 
15 
16 
31 
28 
34 
25 
25 
35 
50 
( l ) 
( l ) 
0) 
( l ) 
247 
246 
CresoKU.S.P.) 
Quinoline 
195-205 
238 
246-250 
Benzylamine 
185 
Methvl salicylate 
222 
208-218 
174-185 
179 
145 
Methvlamine hydrochloride 
Benzvl alcohol 
206 
Benzaldehy de 
180 
280 
Phenol 
183 
106 
Chlorobenzene 
132 
136-141 
Pvrogallol 
293 
81 
Aniline 
184 
Toluene 
111 
77 
124 
Chloroform 
61 
80 
Pyridine 
115 
n-Butyl alcohol 
117 
n-Propyl alcohol 
97 
66 
Ethyl alcohol 
78 
57 
Methyl-ethyl ketone c 
80 
1 Pure liquid kills less than 95 per cent. 
DISCUSSION OF TABLE 2. 
The compounds which have received the most attention are 
grouped in Table 2. These are arranged in the order of their tox- 
icities on the basis of concentration expressed in gram molecules per 
liter. Their toxicities in grams per 100 cubjc centimeters, togetner 
with their respective boiling points, are also included. The nitrogen- 
containing compounds, in general, are found to be grouped at the 
head of the series. In the middle portion of the series (molar con- 
centrations between 0.33 and 1.7) the cyclic derivatives predominate 
and of these three contain nitrogen. Two aliphatic compounds 
appear, one of which contains nitrogen. The remaining compounds 
of lowest toxicity are aliphatic with the exceptions of benzene and 
pyridine. Pure liquid methyl and ethyl alcohol, acetone, and 
methyl-ethyl ketone killed less than 95 per cent of the aphids. 
