CONDITIONS FAVORABLE OB NECESSARY. 
13 
On several occasions it was observed thai the tenl Felt somewhat 
damp when being handled, although the humidity recorded 1>\ a 
standard sling psychrometer had not reached complete saturation. 
On other occasions, as shown l>\ ilic above data, the Foliage was 
covered with a dew like a fine mist when the sling psychrometer 
indicated as much as 6 per cent below complete saturation. For 
practical purposes, however, the moisture on the leaves may be 
considered as indicating a condition of 100 per cent atmospheric 
moisture. Blank spaces in the table indicate that no note was 
made concerning tin's particular point, although the tent was evi- 
dently "wet" in experiments t0.2 and 50.2 and the leaves were 
evidently "dry" in experiments 45.21 and 45.22. In the experi- 
ments summarized in Table I the possibility of reducing the efficiency 
oi' the gas through absorption by the moisture on the leaves and 
tent had to be taken into consideration. To eliminate this feature 
and to determine the effect of the pis on larva 1 and pupa 1 of the 
white 1 fly when leaves art 1 wet artificially, tests were made by wetting 
the leaves both, by dipping and by means of an atomizer. The 
results are summarized in Table II. 
Table II. Effect of artificially wetting leaves on efficiency of fumigation. 
Experi- 
ment 
No. 
Air hu- 
midity. 
Amount 
Of cyanid 
used. 
Amount 
of cyanid 
recom- 
mended 
in table. 
Total 
number 
Of insects 
under 
observa- 
tion. 
Per cent 
Of insects 
killed. 
Number 
Of insects 
on leaves 
wet arti- 
ficially. 
Per cent 
Of insects 
killed on 
leaves 
wet arti- 
ficially. 
Method <>!' 
wetting. 
Per a rU. 
Ounces. 
Ounces. 
44 
20 
29 
242 
71 
21 
95. 2 
Dipped. 
4(1... 
47 
I7j 
21 
392 
88 
149 
90.6 
Sprayed. 
10.7 
.>.) 
8J 
13 
132 
80 
40 
87.5 
Dipped. 
in.s 
61 
1"! 
._.,,, 
223 
96 
93 
98.9 
Sprayed. 
40.9 
54 
12 
27 
342 
93 
20 
95 
Sprayed. 
40.13 
63 
24 
28 
736 
100 
567 
100 
Dipped. 
In the above experiments — omitting the last one, in which all 
insects were killed — 1,331 insects were under observation. Of these, 
323 were on leaves wetted artificially. The weighted average of tin 1 
insects killed on these leaves is 92.5 per cent. Of the 1,008 insects 
on the dry leaves 852, or 84 per cent, were killed. Tins seems to 
be of considerable significance in view of the fact that in every 
instance where less than 100 per cent of the insects were killed, the 
percentage of killed was greater on the artificially wetted leaves 
than on the dry leaves. 
Taken as a whole the results summarized in the two foregoing 
tables show conclusively that moisture on the leaves in the form of 
dew does not reduce the edicacy of the gas in destroying the insects, 
hut possibly increases it. In the experiments in which moisture was 
a factor no injury to the foliage followed, even when the dosage was 
increased fully one-half above the amount called for by the table 
in the appendix of this bulletin. The results give no justification to 
