40 BULLETIN 1147, U. S. DEPARTMENT OF AGRICULTURE. 
RELATIVE TOXICITY OF PURE ARSENIC OXIDS AND OF BASES. 
In order to judge as accurately as possible the relative toxicity of 
various bases when combined with the oxids of arsenic, the mate- 
rials used are grouped in Table 19. In each mixture of the bases, 
0.48 gram of the base was used in 100 cubic centimeters of water. At 
this rate from three to five times as much base was used as is present 
in the arsenical mixtures. 
The following data are not given in Table 19: Silkworms, 1 set 
(variation 47-54, average 50); webworms (H. cunea), 1 set (161-761. 
average 280) ; tent caterpillars, 4 sets (565-1030, average 805) ; ana 
potato-beetle larvae, 2 sets (105-279, average 152). 
Table 19. — Relative toxicity of pure arsenic oiids and of bases on 4 species of insects after 
deducting mortality of control with food, 1919. 
Material and controls. 
Percentage of insects dead within- 
3 days. 
6 days. 
Arsenious oxid 
Arsenic oxid 
Calcium oxid , 
Calcium arsenate 
Lead oxid 
Aeddlead arsenate 
Zinc oxid 
Zinc arsenite 
Magnesium oxid 
Magnesium arsenate 
Copper oxid 
Paris green 
Copper barium arsenate 
Barium oxid 
Barium arsenate , 
Control without food 
Control with food 
Control with food, omitting tent 
caterpillars 
40.0 
100.0 
.0 
96.0 
12.8 
96.0 
.0 
85.7 
.0 
96.0 
.0 
100.0 
12.2 
.0 
21.6 
23.1 
.0 
12.5 
.0 
39.1 
.0 
4.8 
.0 
7.2 
.0 
18.7 
10.0 
.0 
4.3 
.0 
.0 
4.6 
68.1 
.0 
54.3 
.0 
53.1 
.0 
73.8 
19.2 
65.1 
.1 
64.8 
30.5 
50.4 
4.3 
59.8 
5.1 
73.8 
.0 
65.7 
63.1 
.0 
57.9 
21.4 
64.1 
.0 
56.9 
10.8 
59.6 
1.1 
56.0 
5S.0 
.4 
1.9 
14.i 
4.1 
.0 
100.0 
31.9 
100.0 
.0 
9S.0 
.0 
100.0 
.0 
61.2 
.0 
67.3 
77.6 
.0 
69.2 
.0 
91.8 
.0 
32.7 
.0 
51.6 
.0 
67.0 
66.9 
.0 
43.7 
28.7 
50.5 
85.2 
.0 
89.6 
1.5 
S6.5 
.0 
90.0 
15.3 
5.5 
23.1 
65.0 
.7 
63.4 
46.3 
51.2 
12.0 
58. 9 
5.5 
70.3 
.0 
64.9 
68.9 
4.1 
63.4 
20.7 
49.7 
82.0 
.2 
80.8 
19.9 
82.4 
3.0 
69.9 
6.7 
