﻿40 



BULLETIN 1147, IT. S. DEPARTMENT OF AGRICULTURE. 



RELATIVE TOXICITY OF PURE ARSENIC OXIDS AND OF BA8E8. 



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) ; and 

 potato-beetle larvaa, 2 sets (105-279, average 152). 



Table 19. — Relative toxicity of pure arsenic oxids and of bases on 4 species of insects after 

 deducting mortality of control with food, 1919. 



Material and controls. 



Arsenious oxid 



Arsenic oxid 



Calcium oxid 



Calcium arsenate 



Lead oxid 



Acidlead arsenate 



Zinc oxid 



Zinc arsenite 



Magnesium oxid 



Magnesium arsenate 



Copper oxid 



Pans 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 



Percentage of insects dead within- 



3 days. 



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 



14.6 



21.4 

 64.1 

 .0 

 56.9 

 10.8 

 59.6 

 1.1 

 56.0 



6 days. 



58.0 



.0 



100.0 



31.9 



100.0 



.0 



98.0 



.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 



86.5 



.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 



80.6 

 19.9 

 82.4 

 3.0 

 69.9 



6.7 



