530 
Journal of Agricultural Research 
Vol. XXIV, No. 6 
Six such experiments were carried out, of which the one shown in 
Table XVIII is representative. In this case the plants were sprayed with 
calcium arsenite^^ (i*95 gin*, iii 2 liters of water; no soap added). 
It will be seen that the humidity does not need to reach the saturation 
point (100 per cent relative humidity) to materially increase the injury 
over that in a drier atmosphere, although in the saturated atmosphere still 
greater injury was done. Presumably, other conditions being equal, the 
degree of injury will be in a certain relation to the relative humidity. 
Wetting the leaves at frequent intervals after spraying did not, how¬ 
ever, have the same effect as a humid atmosphere. 
Table XVIII .—Showing the increased injury caused by humidity produced by transpira¬ 
tion under bell jars 
Temperatures. 
CoMditions. 
Time. 
Wet 
bulb. 
Dry 
bulb. 
Relative 
humidity. 
Degree of injury. 
Under bell jar closed.... 
Under bell jar partly 
(“) 
8 a. m.. 
F. 
F. 
100 
Plant dead. 
S8^ 
62® 
79 
closed. 
•I p. m.. 
64 
66 
90 
5p.m.. 
64 
66 
90 
8 a. m.. 
I p. m.. 
60 
64 
62 
66 
89 
90 
Fartly defoliated. 
5 p. m.. 
8 a. m.. 
64 
66 
90 
56 
S8 
89 
I p. m.. 
58 
60 
89 , 
Not under bell jars. 
8 a. m.. 
57 
60 
64 
68 
63 
I p. m.. 
5p.n1.. 
61 
70 
61 
8 a. m.. 
I p. m.. 
58 
64 
68 
60 
54 
►Injury moderate. 
spin-- 
59 
67 
62 
8 a. m.. 
53 
69 
32 
I p. m.. 
55 
61 
68 . 
« Throughout. 
Both in the greenhouse and out of doors sprayed foliage was given 
a light application of water through a fine spray nozzle every few hours 
throughout the day. The surrounding air was hot and dry and the 
leaves dried off very soon after each application. Under these con¬ 
ditions, if no soap had been mixed with the arsenical, the injury was not 
in any case noticeably greater than on the control plants that were 
sprayed with the same arsenical but not sprayed with water afterwards. 
In case soap had been added there was a slight tendency to increase the 
injury by subsequent sprayings with water, but this injury was incom¬ 
parably less than produced by a humid atmosphere. 
EFFECTS OF SOIL MOISTURE 
As plants and trees can not always receive a sufficient amount of 
moisture through the roots it is but natural in spraying operations where 
foliage burning is liable to occur to raise the question as to whether or 
not a wilted condition of the leaves would affect the extent of injury. 
Baker's. 
