46 
FUMIGATION FOR THE CITRUS WHITE FLY. 
for 170 cubic feet of space, all of the rates are more or less greater 
than those used in the experiments in which from 95 per cent to 
99.9 per cent of the insects were killed. It is evident that the increase 
in number of cubic feet per ounce of potassium cyanid from 110 to 
170 must be calculated at a rate which is in direct proportion to the 
percentage of increase in cubic contents. The method employed in 
these calculations is shown in Table VIII, which gives the figures 
with the ratios ranging from 1:1.0 up to 1:3.6. 
Table VIII. — Rates of dosagi as affected by ratio of number of squart feet in surfact to 
th number of cubic /'<< t m volunu . 
Per cent 
Number 
Differ- 
ence be- 
Increase 
Number 
Differ- 
ence be- 
of in- 
of cubic 
tween 
in num- 
ber cubic 
feet per 
of i n- 
of cubic 
tween 
in num- 
ber cubic 
Ratio. 
crease in 
feet per 
number 
Ratio. 
crease in 
number 
cubic con- 
ounce 
cubic feet 
cubic con- 
ounce 
cubic feel 
tents. 
cyanid. 
per ounce 
and 170. 
ounce 
cyanid. 
1:2.4 
tents. 
cyanid. 
per ounce 
and 170. 
ounce 
cyanid. 
1:1 
------ 
76.8 
93.2 
....„„.. 
4.34 
133.5 
36.5 
1.7 
1:1.1 
86.1 
83.9 
1:2.5 
4.16 
135 
35 
1.5 
1:1.2 
9.09 
93.7 
76.3 
7.6 
1:2.6 
4 
136.4 
33. 6 
1.4 
1:1.3 
8.33 
100.1 
69.9 
6.4 
1:2.7 
3.85 
137.7 
32.3 
1.3 
1:1.4 
7.69 
105.4 
64.6 
5.3 
1:2.8 
3.7 
138.9 
31.1 
1.2 
1:1.5 
7.14 
110 
60 
4.6 
1:2.9 
3.6 
140 
30 
1. 1 
1:1.6 
6.66 
114 
56 
4 
1:3.0 
3.44 
141 
29 
1.03 
1:1.7 
6.25 
117.5 
52.5 
3.5 
1:3.1 
3.33 
142 
-N 
.97 
1:1.8 
5.88 
120.6 
49.4 
3.1 
1:3.2 
3.26 
142.9 
27.1 
.91 
1:1.9 
5.55 
123. 3 
46.7 
2.7 
1:3.3 
3.12 
143.8 
26 
1:2.0 
5.26 
125.8 
44.2 
2.5 
1:3.4 
3.03 
144.5 
25.4 
.79 
1:2.1 
5 
128 
42 
2.2 
1:3.5 
2.94 
145.3 
24.7 
.75 
1:2.2 
4.76 
130 
40 
2 
1:3.6 
2.86 
146 
24 
.71 
1:2.3 
4.54 
131.8 
38.2 
1.8 
In Table VIII the number of cubic feet of space per ounce of potas- 
sium cyanid increases toward 170, representing the rate when the 
ratio is 1 to infinity, and the dosage increases in rate (= decrease in 
the number of cubic feet per ounce of potassium cyanid ) as the units 
of cubic contents become infinitely small in number as compared 
with the units of square measure of leakage surface. Using the 
above rates as a basis, the doses for trees measuring from 10 to 76 
feet over the top have been calculated. The dimensions of the tented 
trees and volumes of the inclosed spaces have been calculated in 
accordance with the formula? given in the preceding pages. Table IX 
gives the original calculations, while in the appendix the recommended 
doses alone are given, in a form more convenient for practical use in 
the field. 
