38 
FUMIGATION INVESTIGATIONS IN CALIFORNIA. 
From the following chart it is evident that with the acid andcyanid 
mentioned the largest amount of gas is available from two parts of 
water. As the proportion of water is increased above two parts the 
available gas is decreased until with eight parts of water we obtain 
only about 43 per cent of gas, or less than one-half as much as with 
two parts. In other words, 1 ounce of cyanid and 1 ounce of acid in 
combination with 2 ounces of water will produce much more avail- 
able gas than 2 ounces of cyanid and "2 ounces of acid with 1G ounces 
of water. 
The cause for the smaller amount of gas with one part of water 
than with two parts has already been explained (see p. 35). 
We can see from the chart that the proportion of water used is one 
of the most important factors in fumigation practice; and many of 
PRO 
CYAN/D 
PORT/L 
AC/D 
W50F 
WAT£fi 
PER CENT OF 6 A >S G/l/f/V OFF 
10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 
1 
1 
1 
1 
1 
1 
1 
1 
1 
1 
1 
1 
1 
1 
1 
1 
1 
87.84 
93.75 
89.95 
86.25 
81.68 
79.65 
73.47 
43.27 
1 
2 
3 
4 
5 
6 
7 
8 
Fig. 13.— Chart showing total amount of gas evolved when different proportions of water are used. 
(Original.) 
the poor results in field work can be directly attributed to the use of 
too much water. That the water should be measured as carefully as 
the acid is beyond question. 
Aside from variations in the amount of water used, due to lack of 
precision in measuring, the proportion of water recommended by dif- 
ferent authorities on fumigation has varied all the way from two to 
eight parts. It is no wonder we see widely differing results from the 
work of different men. It is a common practice with many funii- 
gators to increase the dosage when fumigating a tree that is severely 
infested with scale. It is also a common practice— in fact, so com- 
mon as to be almost universal — to increase the proportion of water 
when using heavy dosages. This is apparently done with a view to 
preventing injury to the fruit and foliage. In following out this prac- 
tice the fumigator has many times unconsciously prevented thevery 
resull lie wished t<> accomplish — that of obtaining a more concen- 
trated gas. 
THE CORRE( I PROPORTION <>i WATER. 
The chart (fig. 13 shows. that two part- o{ water to one part 
cadi of cyanid and acid will produce the maximum amount of avail- 
