FISH OIL AS ADHESIVE IN ARSENATE-OF-LEAD SPRAYS 
15 
to the spray mixtures in the same proportions as were used in the 
experiments in Somerville. The spraying was done on June 12 and 
13, except that for the miscible oil, which was done on June 24. The 
sprayed foliage was examined on June 26, July 22, August 5, and 
September 23, except that at Melrose Highlands, which was exam- 
ined on the last two dates only. On these four dates the total rain- 
fall after the dates of spraying was 1, 2J^, 3, and 163^ inches, respec- 
tively. In Table 2 are presented various data relating to these tests, 
more particularly the estimated percentages which remained of the 
adhering spray. Here, as in the preceding tests, the drying oils are 
shown to be superior to the other adhesives used. 
Table 2. — Data relative to tests of adhesives in arsenate-of-lead sprays at Saugus 
and Melrose Highlands, Mass., in 1924, on deciduous growth 
Date of 
spraying 
Date of examination, days after spraying, and estimated percent- 
age of spray remaining on foliage 
Adhesive 
June 26 
July 22 
Aug. 5 
Sept. 23 
Days 
Per 
cent 
Days 
Per 
cent 
Days 
Per 
cent 
Days 
Per 
cent 
June 12 
...do 
14 
14 
14 
13 
13 
13 
13 
55 
75 
95 
50 
95 
95 
45 
10 
10 
10 
9 
9 
9 
9 
30 
40 
90 
30 
90 
90 
30 
54 
54 
54 
53 
53 
53 
53 
42 
25 
30 
85 
25 
85 
90 
25 
65 
103 
103 
103 
102 
102 
102 
102 
91 
15 
20 
Corn oil .. .. ._ 
...do 
70 
Flour 
June 13 
...do 
...do 
...do 
June 24 2 
15 
Fish oil 
Linseed oil 
None 
Miscible oil 1 
75 
80 
15 
40 
Proprietary. 
2 Between June 12 and June 24 0.52 inch of rain fell 
SUPERIOR ADHESIVENESS OF DRYING OILS 
The value of any adhesive material is determined by the length of 
time that it will bind the spray to the foliage. Heavy rainfall or 
an excessive amount of fog or dew causes the poison gradually to 
disappear. Arsenate-of-lead sprays to which any of the three drying 
oils tested — i. e., fish oil, linseed oil, or corn oil — were added resisted 
throughout the season the washing action of the rain. The other 
materials tested were less satisfactory, as they failed to bind the 
poison firmly to the foliage. There was a tendency for the small 
particles of poison to become loosened and detached after having been 
exposed to considerable moisture, whereas the only observed effect 
of rainfall on the drying oils was a slight weathering of the poison 
on the sprayed surface. When growing foliage is treated a consider- 
able loss of poison per unit area results, owing to the rapid increase 
in the leaf area, with no increase in the quantity of poison on the leaf. 
This is true regardless of the adhesive used, but more spray remains 
if one of the drying oils named is added to the arsenate of lead. 
TESTS WITH A BARREL PUMP 
On August 15, 1924, two small plots in a mixed woodland at 
Saugus, Mass., were sprayed with the standard arsenate-of-lead 
mixture to which was added one-fourth of 1 per cent of linseed oil for 
one plot and one-fourth of 1 per cent of fish oil for the other plot. 
