64 FUMIGATION INVESTIGATIONS IN CALIFORNIA. 
Second. — An economy of cyanid results from the accurate measure- 
ment of the water. Three parts of water are always used, resulting 
in the maximum amountof available gas for practical work, as already 
explained (pp. 38-39). Under the old system the water is usually 
measured with an ungraduated dipper at the tree, and as the cyanid 
and acid have been previously measured out into small cans, which 
are in turn placed on a tray to he carried from tree to tree, the sched- 
ule is not carried along for consultation in estimating the water, but 
the required amount of water is guessed at from the amount of chem- 
icals in the cans intended for that particular tree. Owing to the vari- 
ation in the proportion of water which results in this way, the maxi- 
mum amount of available gas is seldom produced by the reaction. 
Third. — By the old method the cans on a tray sometimes become 
confused, in consequence of which some trees get the dosage measured 
out for others. This error is eliminated under the improved system. 
as the dosage for each tree is measured out just before that particu- 
lar tree is fumigate* 1. 
Fourth. — The tent pullers seldom get more than one or two trees 
ahead of the cart. As a result, all trees receive the same length of 
exposure. Under the old system, when the tent pullers got far ahead 
of the cart at the end of a row, these trees received a much shorter 
exposure than the first trees. 
DOSAGE SCHEDULE. 
Having obtained the dimensions of the tented tree, the next step 
is to determine the dosage. It has been previously stated that the 
cubic contents can be calculated from these two dimensions. This 
might be done in the field and the trees then dosed in proportion to 
the contents. The time required for the calculation of the dosage, 
however, even after determining the cubic contents of the tree, would 
not only prevent rapid field work and allow an opportunity for error, 
but would cause a lack of uniformity in dosage, from the consideration 
of the cubic contents alone, as will be explained later. This diffi- 
culty has been obviated by preparing a dosage schedule from which 
the required dosage may be learned without any figuring as soon as 
the measurements of the tree are known. 
The orchardists in the citrus section about Whit tier, Cal., desired 
to commence fumigating for the purple scale during the latter part 
of July. The question immediately arose as to what dosage could be 
used at that time of the year without injuring the young fruit. As 
stated under experiment Xo. 4 (p. 52), while the fruit is small a dosage 
of 1 ounce to 100 cubic feet could be used on trees from about 10 to 1 5 
feel in height without injury to the fruit, whereas smaller trees 
would stand a heavier dosage. A- tin- was the limit of dosage which 
