AESENICALS. 
41 
Table 19. — Relative toxicity of pure arsenic oxide and of bases on 4 species of insects 
after deducting mortality of control with food, 1919 — Continued. 
Material and controls. 
Percentage of insects dead within- 
10 days. 
20 days. 
S2^ 
S s- 
3 c £ 
70.0 
Arsenious oxid 
Arsenic oxid 
Calcium oxid 
Calcium arsenate 
Lead oxid 
Acid lead arsenate — 
Zinc oxid 
Zinc arsenite 
Magnesium oxid 
Magnesium arsenate. . 
Copper oxid 
Paris green 
Copper barium arsenate 
Barium oxid 
Barium arsenate 
Control without food. . I 71.5 
Control with food | .0 
Control with food, 
omitting tent cater- 
pillars 
2.0 
100.0 
.0 
' '2.0* 
95.6 
94.2 
.0 
92.7 
.0 
93.7 
.0 
66.7 
1.3 
84.7 
.0 
93.7 
91.1 
6.4 
4.1 
78.9 
87.6 
1.1 
87.7 
4.8 
87.3 
.0 
23.9 
51.7 
.0 
51.8 
45.7 
45. 5 
13.3 
45.6 
1.7 
55.5 
.0 
47.9 
54.1 
5.1 
52.1 
67.1 
83.4 
.3 
83.0 
24.3 
81.6 
3.8 
74.8 
10 
100.0 
79.3 
12.3 
42.5 
14.7 
.0 
2." 6' 
100.0 
.0 
All. 
All. 
.0 
All. 
4.1 
All. 
.0 
70.2 
2.2 
74.8 
2.5 
All. 
All. 
7.7 
66.3 
All. 
21.0 
All. 
All. 
0.0 
All. 
0.0 
All. 
0.0 
All. 
35. 1 94. 6 
All. 100.0 
All. 
50.5 
1.7 
All. 
All. 
All. 
24.1 
All 
26.9 
100.0 
65.3 
100.0 
35.0 
97.8 
8.6 ! 29.6 
All. 97.9 
46.1 
76.5 
0.2 
73.5 
18.3 
74.5 
2.6 
66.9 
27.0 
100.0 
100.0 
47.2 
93.7 
100.0 
57.1 I 32.2 
0.0 
All. 
All. 
8.7 
All. 
8.5 
9.6 
3.5 
143.4 
I 7.4 
148.6 
I 2.8 
119.8 
22.0 
105.5 
14.2 
106.9 
3.9 
10.8 
70.3 
28.0 
ioo.'o 
26.0 
1 First 8 and next to the last figures to be compared; next 8 and last figures to be compared. 
J Based on webworms (H. cunei) and tent caterpillars. 
Comparing the mortality of the insects fed on the various bases 
with that of the control insects (Table 19), it appears that calcium 
oxid is beneficial to insects (sample 11, 26.9 per cent, and control, 
32.2 per cent), that zinc oxid (sample 22, 35 per cent, and control, 
32.2 per cent), magnesium oxid and copper oxid (samples 63 and 
65, 29.6 per cent and 27 per cent, and control, 26 per cent) are 
slightly injurious, that barium oxid (sample 72, 47.2 per cent, and 
control, 26 per cent) is moderately injurious, and that lead oxid 
(sample 12, 65.3 per cent, and control, 32.2 per cent) is the most 
effective of all the bases used. 
Since the arsenious oxid (sample 9) used in the 1919 experiments 
had a low toxicity, a commercial white arsenic (As 2 3 ) was used in 
the experiments conducted in 1920. Sample 9 contained only 17.77 
per cent of water-soluble arsenious oxid, while sample 27 contained 
38 per cent. To obtain its average toxicity on four species of insects 
in comparison with the toxicities of pure arsenic oxid (sample 10) 
and acid lead arsenate (sample 39), the following insects were used: 
Silkworms, 2 sets (each of 50); webworms (H. cunea), 1 set (varia- 
tion 100-136, average 120); tent caterpillars, 3 sets (221-446, aver- 
age 292); and honeybees, 2 sets (each of 50). The average per- 
centages of toxicity are as follows: Sample 27 (arsenious oxid), 
62.4; sample 10 (arsenic oxid), 74.3; and sample 39 (acid lead arse- 
nate), 71.2. 
