May 12,1923 lujuTy to FoUage by Arsenical Spray Mixtures 
529 
XVII .—Showing the increased injury caused by a high humidity, procured by 
keeping sprayed tomato plants under bell jars 
Chemical. 
Chemical 
in 2.000 
cc. 
Soap in 
2,000 cc. 
Injury. 
Under bell jars. 
Not imder bell jars. 
Arsenic trioxid, Baker. 
Do. 
Calcium arsenite, Baker. 
Calcium arsenite, Adler. 
Do. 
Lead arsenate, Baker, acid.... 
Do. 
Lead arsenate, Baker, ortho. .. 
Do. 
Lead arsenate (Corona). 
Do. 
Copper aceto-arsenite, Baker. . 
Do. 
Gm. 
1-3 
2 . 6 
1.9 
.6 
.6 
9-3 
9*3 
12. o 
12. o 
9-3 
9-3 
2.4 
2.4 
Gm. 
None. 
None. 
None. 
None. 
14.4 
None. 
28.8 
None. 
28.8 
None. 
14.4 
None. 
14.4 
Slight. 
.do. 
Dead.. 
Very bad. 
....do . 
None. 
Moderate. 
None. 
Moderate. 
None. 
Very bad. 
Nearly dead... 
Very bad. 
None. 
Do. 
Moderate. 
None. 
Do, 
Do. 
Do. 
Do, 
Do. 
Do. 
Do. 
Do. 
Very slight. 
To determine if it makes a difference whether the plants were placed in 
the saturated atmosphere immediately after spraying or after drying a 
short time, some were put under bell jars for the first three days and then 
removed while others were not covered at once but inclosed the fourth, 
fifth, and sixth days; and likewise some were kept under bell jars the first 
day only, others the second day only, and still others the third day only. 
Reducing the time, in another experiment some were covered the first 
hour after spraying, others the third hour, others the first hour of the 
second day and still others the first hour of the fifth day. The results 
showed that a saturated atmosphere for even so short a period as one 
hour considerably increased the injury, though a longer time caused still 
more damage.; Considering the results in all these experiments it 
appeared to make little difference at what time after spraying the plants 
were covered, if not more than a few days, provided the time spent in 
this saturated atmosphere was the same. 
It was noted that under the bell jars the plants were dripping with 
moisture; not only was the air saturated, but the surfaces of the plants 
were covered with films and drops of water. To learn if an increased 
amount of humidity is of significance when kept below the point of 
saturation, sets of tomato plants (three in a pot), were sprayed and dried, 
then one set was put under a tightly closed bell jar, one was put under a 
bell jar with the stopper removed and with a tiny crack underneath, and 
a third was left outside. All were kept in strong diffused light. 
Under the jar with the stopper removed were placed wet and dry bulb 
thermometers and a tiny fan run by a toy motor. This was used to fan 
the wet bulb for one minute before reading the temperature. 
The procedure was to spray 9 tomato plants, three sets of 3 in a pot, 
with the same mixture, let them dry for a few minutes, then inclose one 
set tightly under a bell jar 8 by 16 inches on a ground glass plate, inclose 
another set under a bell jar slightly open at the top and bottom as des¬ 
cribed above, and keep the third set on the table beside them without 
covering. After standing under these conditions for three days the 
plants were all carried to the adjoining greenhouse, where they were left 
uncovered for about 10 days, after which notes were taken. 
