64 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Yol. 11 
the plates but it was found that two plates could be treated at one 
time with the same precision as one. During the washing the outfit 
was swung slightly so as to distribute the water equally to all parts 
of the plates. The temperature of the water was recorded before 
each washing. In fact every effort was made to have all tests uniform 
that the various brands or combinations tested in the several series 
could be compared. Each brand or combination was tested by treat¬ 
ing from two to five plates identically. 
We first attempted to spray the mixtures on the plates but found 
it difficult to apply comparable amounts of material. The question 
of drying the plates was most perplexing. We first tried drying them 
in a water jacketed oven, regulated by a thermostat but found this 
method unsatisfactory. All the plates did not receive the same 
amount of heat so the upper and lower ones dried first and also there 
was not the proper air currents to carry off the moisture. This ob¬ 
stacle can be overcome only by means of a change of apparatus, 
entailing considerable expense so has not been attempted. We 
might add that drying at room temperature yields fairly accurate 
results. 
Ground glass plates have been substituted for the ordinary ones, 
thereby simulating, it is believed, the more or less corrugated surface 
of the leaf but these have shown little advantage over the smooth 
plates. Glass has been used in all these experiments because of the 
necessity of using chemicals to thoroughly cleanse the plates before 
and after each test. It is true that these results are not identical with 
tests on foliage but they give us a method of comparing the adhesive¬ 
ness of various substances under identical conditions. 
Experimental Results 
During the winter of 1912-1913, about 500 tests were made with 
different brands of arsenate of lead and other insecticides to determine 
their sticking properties either alone or with other materials. As 
many of the experiments were conducted with the aim of finding 
mixtures that would be both attractive and also possess adhesion 
and since this work is still in progress we will confine our remarks to 
characteristic tests with arsenate of lead used alone and with molasses. 
These data are set forth in the following table. 
Before discussing this table, we would state that the several plates 
treated identically in each series gave amounts of material retained 
that were fairly uniform, so no serious error is introduced by using 
averages. 
From this table we note (1) that the percentage of material remain¬ 
ing on the plates after sprinkling differs considerably with the different 
