Aug. 15, 1925 
Soil Disinfection for Potato Wart 
347 
Table XIII. — Percolation of 0.05 per cent formaldehyde solution in soil particles 
of different sizes 
Soil 
Height 
of soil 
column 
Time to percolate 
Water 
held by 
soil ° 
20 to 40 b _ 
Inches 
13 
uy 2 
15% 
15% 
14 % 
16 minutes.. . 
Grams 
264 
436 
506 
528 
407 
453 
40 to 60... 
rin 
80 to 100..... 
32 minutes_ ____ _ 
100 to 150_ 
2 hours, 1 minute_ _ __ 
150 to 200.. 
2 hours, 55 minutes.. _ ____ 
200 to pan_ 
9 to 10 hours__ __ 
a The last column shows the gain in weight during treatment. 
* Sieves as in Table XU. Soil= Manor loam, air dry, 700 grams per tube. A strong positive test for 
formaldehyde was obtained in the percolate from each tube. 
Effect of a High-Water Table on the Penetration of Mercury in the 
Soil 
The influence of a high-water table on the penetration of mercury 
in HgCl 2 + NaCl solutions was tested by setting tubes of soil in 
beakers and adding water to the beakers. The results of these tests 
as shown in Table XIV were very erratic. The first set of tubes was 
set up and the application made to the tops of the tubes about 20 
minutes after the water had been added to the beakers, and the 
visible water line showed that the water had risen 5 inches in the 
tubes. The penetration was about the same as in the tubes treated 
in the usual manner. The second set of tubes was set up and the 
chemical solution and water applied to the soil tubes almost imme¬ 
diately after the water had been added to the beakers. In this case 
the penetration was not nearly so great as in tubes treated in the 
usual way. The beakers were removed from half of the high-water 
table tubes at the end of one day to permit drainage. Penetration 
in these tubes then improved so that a week after the treatments 
were given they nearly equaled the tubes treated in the ordinary 
manner. It was thought that the poor penetration of the high- 
water table tubes in this set was due to the fact that the chemical 
solution only penetrated far enough to meet the upcoming flow of 
water. If tne water is added to the beakers beforehand the upward 
flow will become nearly stationary in a few minutes in damp soil, 
the flow being slower in dry soil. With the glass tubes used the rise 
of the water line was easily observed. 
A third set of tubes was prepared and water added to the beakers 
and allowed to stand overnight. The soil, being dry, had taken 
up practically all of the water so that more was added. In this case 
the tubes treated regularly did not show as good penetration as 
those with the high-water table. Removal of the beakers did not 
seem to improve penetration in this set. 
The results of the fourth experiment confirmed those already 
obtained. The tubes receiving applications some time after water 
was added to the beakers showed good penetration, and tubes receiv¬ 
ing applications at the same time water was added to the beakers 
showed poor penetration. An additional lot of tubes receiving 
applications before water was added to the beakers showed poor 
penetration. The results of these experiments indicate that a nigh 
water table, if stable or receding, would not prevent adequate penetra¬ 
tion. A rising water table would be expected to interfere seriously 
with penetration. 
