Aug. 15,1925 
Soil Disinfection for Potato Wart 
343 
Table X. — Number of tubes giving positive tests for mercury at the various depths 
on each day after application to Leonardtown silt loam of 1 gallon per square foot 
of 3^ per cent mercuric chloride + #3^ P er cent sodium chloride solution, or its 
equivalent in chemical solutions plus water 
In soil containing 4 per cent or less of moisture 
6 to 7.. 
1 
3 
4 
7 to 8_ . 
6 
7 
3 
1 
1 
2 
1 
21 
8 to 9_ 
8 
16 
18 
10 
5 
11 
66 
9 to 10__ 
1 
5 
1 
1 
8 
lOto 11. 
1 
1 
In soil containing 15 to 21 per cent moisture 
7 to 8.. 
l 
1 
1 
1 
2 
5 
8 to 9_ 
15 
16 
4 
9 
2 
7 
65 
9 to 10__ 
.1 9 
6 
10 
8 
8 
41 
1 
In soil containing 43 per cent moisture 
9 to 10__ 
1 
10 to 11.. 
3 
3 
3 
2 
3 
4 
11 to 12_ 
7 
1 
3 
4 
12 to 13 . 
_I 
Total. 
As shown in Tables IX and X, exceptionally good penetration was 
obtained in these tubes. In general the depth of penetration increases 
as the percentage of moisture increases, tnough not regularly. Dif¬ 
ferences in penetration are not always shown by the penetration 
figures as taken. A set of tubes in which actual penetration was 
7 J4 inches is fisted as 7 to 8 inches and in these summaries is counted 
as 7 inches, just as another set in which actual penetration may be 
7J4 inches. The actual depth of penetration in two sets of tubes 
may be the same, and at the same time strong tests may be obtained 
for one set of tubes and very weak tests for the other set. Difference 
in the strength of tests was noted, particularly in studying the pene¬ 
tration where chemicals were applied in part of the water and the 
remainder of the water added later. 
Penetration Where All Chemicals Were Applied in Part of the Water 
Tables VII and IX indicate that penetration into the soil was 
about equally good whether all of the water was used in making up 
the chemical solution or whether only part was used and the rest 
applied later. 12 On the whole the figures indicate slightly better 
12 The effect of the amount of time elapsing between application of the chemical solution arid application 
of the water is discussed later. 
