Apr. 26, 1924 
Nonarsenical Stomach-Poison Insecticides 
399 
failed completely, as did the other cuprous compounds and another thiocyanate. 
All efforts to attribute the toxicity of cuprous cyanid to one ion or the other 
proved fruitless. It is but another of the many instances which show how far 
we are from understanding the relation between toxicity and the chemical 
constitution of insecticides. 
Table VI.— Results, against the Japanese beetle, of spraying smartweed with 
cuprous cyanid and lead arsenate 
Compound 
Rate of application 
(pounds per 50 
gallons water) 
Number of insects 
Number dead 
Per cent killed 
Feeding 
Foliage 
injury 
First day 
Second day 
Third day 
Fourth day 
Fifth day 
Sixth day 
Seventh day 
Cuprous cyanid___ 
2 
20 
0 
0 
1 
3 
3 
7 
70 
Medium.. 
None. 
Do____ 
3 
20 
1 
2 
1 
0 
0 
9 
65 
Slight_ 
Do. 
Do.... 
4 
20 
0 
0 
1 
1 
1 
6 
45 
...do.. 
Do. 
Do___ 
5 
20 
0 
2 
0 
1 
2 
6 
55 
...do_ 
Do. 
Lead arsenate___ 
2 
20 
0 
2 
0 
1 
4 
3 
50 
Medium.. 
Do. 
Do... . _ 
3 
20 
0 
2 
3 
0 
4 
6 
75 
...do _ 
Do. 
Do .. . 
4 
20 
0 
0 
3 
2 
5 
4 
70 
Slight_ 
Do. 
Do___ 
5 
20 
1 
2 
2 
4 
2 
2 
65 
...do_ 
Do. 
Control..... 
20 
0 
0 
0 
0 
0 
0 
— 
0 
Heavy_ 
The nitroprussids of copper and zinc were prepared and tested. Their 
toxicity was so low that no effort was made to work out the disposal of CN. 
Hofmann and Hochtlen 3 describe additive compounds formed by the addition 
of benzene, phenol, or aniline to an ammoniacal solution of nickel cyanid. The 
compounds break down into their component parts on the addition of dilute 
acid or alkali. With a “shot-gun” remedy of such properties it seemed almost 
impossible to miss the beetle, but the compounds showed only low toxicity. 
ABSORBED ORGANIC COMPOUNDS 
It was thought that gaseous, liquid, or soluble solid organic compounds which 
might be destructive to plant tissues could be applied if they were absorbed on 
inert materials like clay; it being assumed, of course, that the insect would 
liberate the adsorbed toxic compound. Unfortunately there was not time to 
test the assumption by using an adsorbed compound of known toxic properties 
and of known concentration on the inert material. A series of clays and char¬ 
coals was prepared on which such substances as carbazol, anthracene, quini- 
line, amyl alcohol, and dimethylaniline had presumably been adsorbed. They 
were entirely without effect; but since the idea was not given a fair trial, it is 
still worth considering. 
A silica gel and a charcoal, on which three war gases and arsenious oxid had 
been adsorbed, were obtained from the United States War Department. The 
percentage of each poison in the preparations was given. The gases were not 
held very tightly at the temperature at which the dusting was done, because 
their odor was apparent at a distance from the unstoppered bottles. Neverthe¬ 
less, none of the war gases had the slightest effect on insects as susceptible as 
the potato beetle and the tent caterpillar (Table VII). Moreover, phosgene, or 
perhaps its decomposition product HC1, burned the foliage severely. Arsenious 
oxid burned the foliage as severely as if it had been in water solution. 
* Hofmann, K. A., and Hochtlen, F. abnorme verbindunqen des nickels. Ber, Deut. Chem. 
Gesell. 36: 1149-1151. 1903. 
