Apr. 26, 1924 
Nonarsenic al Stomach-Poison Insecticides 
397 
Zinc cyanid has hitherto been considered a stable cyanid, but under spraying 
conditions it also loses HCN as the spray dries. This was proved by placing a 
freshly sprayed plant under a large bell jar closed at the top by a two-holed 
rubber stopper. Air was aspirated from the jar through two Drechsel wash 
bottles containing a solution of sodium carbonate to absorb HCN. After air 
had been drawn through the train for several hours, the contents of the wash 
bottles were analyzed, and HCN was found in the first bottle, but not in the second. 
This loss of HCN with large surface exposure of the cyanid to air and moisture 
was further shown by spraying a mixture of the cyanid and water on a glass plate. 
After the spray deposit had dried, it was scraped from the glass, weighed, analyzed, 
and compared with the fresh material. In every ease there was a considerable 
loss of HCN. Finally it was proved that under certain conditions a spray deposit 
of zinc cyanid would lose all its CN. A plate was sprayed with a mixture of 
the cyanid and water and the spray deposit was allowed to dry. It was then 
tested qualitatively for CN. The next day it was sprayed with water to 
simulate dew, and tested again after it dried. The spraying, drying, and testing 
were repeated daily till no test was obtained for CN; sufficient evidence for 
the complete hydrolysis of the compound. Examination of Table III shows 
that, while zinc cyanid was fairty effective against half-grown caterpillars, it 
did not kill full-grown caterpillars. It was toxic to the potato beetle (Table 
IV), but hardly even retarded the feeding of the Japanese beetle (Table V). 
Table III.— Results , against the tent caterpillar, of spraying or dusting wild- 
cherry foliage with cyanids 
j Application 
! 
Caterpillars 
Number dead 
Per cent killed 
Feeding 
Foliage 
injury 
i 
i 
; 
Compound 
Method 
flMO 
oo g 
£ 
"S §J2 
P3 
<D 
a 
& 
Stage 
of 
growth 
>> 
a 
'V 
W 
V. 
£ 
C3 
-d 
g 
o 
a> 
co 
& 
V 
2 
& 
r d 
A 
Sm 
pi 
o 
Ph 
!>» 
c3 
Xi 
£ 
£ 
C3 
Xi 
.a 
co 
>> 
03 
xi 
pi 
o 
t> 
a> 
CO 
Nickel cyanid.. 
Dust... 
40 
Half-grown 
o 
3 
3 
6 
30 
Slight.... 
i 
Cuprous cyanid 
...do.... 
40 
_do_ 
3 
13 
13 
11 
100 
do 
ujjp • 
Do. 
Zinc cyanid_ 
...do_ 
40 
.do_ 
0 
0 
0 
16 
40 
...do_ 
Do 
Copper nitro- 
Spray.. 
~”io" 
20 
_do_ 
0 
. 2 
1 
1 
2 
0 
5 
55 
...do_ 
Do! 
prussid. 
Zinc nitroprus- 
...do_ 
10 
20 
_do_ 
0 
0 
0 
0 
0 
0 
0 
0 
...do_ 
Do. 
sid. 
Cuprous cyanid j 
Dust... 
20 
Full grown. 
0 
0 
2 
1 
1 
7 
55 
...do_ 
Do. 
Zinc cyanid_; 
...do._. 
20 
_do_ 
0 
0 
0 
1 
1 
0 
10 
Medium. 
Do! 
Nickel cyanid..i 
...do_ 
_ 
20 
_do.. 
0 
0 
0 
0 
0 
0 
0 
Heavy... 
Do. 
Cuprous thio- [ 
...do_ 
_ 
20 
_do_ 
0 
0 
3 
1 
1 
6 
_ 
55 
Slight.... 
Do. 
cyanate. j 
Cuprous cyanid; 
Spray.. 
5 
20 
.do- 
0 
0 
4 
3 
1 
0 
1 
45 
—do_ 
Do. 
Zinc cyanid_1 
...do_ 
5 
20 
_do_ 
0 
0 
0 
0 
0 
0 
0 
0 
Heavy... 
Do. 
Nickel cyanid.. 1 
...do_ 
5 
20 
.do_ 
0 
0 
0 
0 
0 
0 
1 
5 
...do_ 
Do. 
Cuprous thio- 1 
...do_ 
5 
20 
.do_ 
0 
0 
10 
6 
3 
95 
Medium. 
Do. 
cyanate. I 
Lead arsenate. _!. 
...do... 
5 
20 
_do_ 
0 
0 
2 
7 
3 
4 
80 
Slight_ 
Do. 
Control. __j. 
1 
20 
.do_ 
0 
0 
0 
0 
0 
0 
— - 
0 
Heavy... 
94527—24t-8 
