Aug. 15, 1925 
Soil Disinfection for Potato Wart 
345 
Table XI. — Effect of delaying second part of applications made in two 
parts , 1 + 1, 1+8, 1 + 7 , (l + D + O 
Depth of penetration in inches 
Method of 
application 
1 + 1 «_ 
1+1 _ 
1+0 . 
1+1 _ 
1+1 _ 
1+1 - 
(l+D+o 
(l+D+o 
1+3- 
1+3_ 
1+7. 
1+7- 
Time elapsing be¬ 
tween two parts 
of application 
10 to 15 minutes_ 
17 hours. 
Only one application. 
17 hours_ 
10 to 15 minutes_ 
18 hours... 
10 to 15 minutes_ 
18 hours_ 
10 to 15 minutes_ 
20 hours_ 
10 to 15 minutes_ 
20 hours_ 
Time after application of first part until test was made 
21 hours 
Inches 
7 to 8 
6 to 7 
2 days 3 days 4 days 
Inches 
8 to 9 
7 to 8 
7 to 8 
7+ 
8 - 
8 + 
8 - 
7 to 8 
Inches 
* 8 + 
8 - 
7+ 
7+ 
Inches 
8 to 9 
8 to 9 
7 to 8 
8 to 9 
9- 
8 - 
8 to 9 
8 to 9 
5 days 6 days 7 days 
Inches 
8 to 9 
8 to 9 
8 + 
8 to 9 
8 to 9 
8 to 9 
Inches 
9- 
9- 
8 + 
8 + 
Inches 
8 to 9 
8 to 9 
8 + 
8 to 9 
8 + 
8 to 9 
Soil 
mois¬ 
ture 
Per cent 
14 to 16 
14 to 16 
10 
10 
10 
10 
10 
10 
18.6 
18.6 
18.6 
18.6 
® For explanation of symbols, see “How solutions were applied,” p. 332, and footnote of Table VII. 
& Three tubes of each lot were tested each day. Where all three tubes gave positive tests (H 2 S precipita¬ 
tion method) to the same depth, that depth is indicated by 7 to 8,8 to 9, etc.; when the depth varied, plus 
or minus signs are used, e. g., 8+=2 tubes gave positive tests at 8 to 9 inches and the third at 9 to 10 inches; 
8—=2 tubes gave positive tests at 8 to 9 inches, and the third at 7 to 8 inches. Soil, Manor loam. 
RESULTS OBTAINED FROM EXPERIMENTS COVERING SPECIAL PHASES OF SOIL PENE¬ 
TRATION BY CHEMICALS, PARTICULARLY BY MERCURY IN HgCl 2 +Na Cl SOLUTIONS 
In addition to the foregoing experiments, the data from which are 
included in Tables VI to XI, a number of experiments were con¬ 
ducted to secure data on other phases of the problem of chemical 
penetration in soil. These include experiments to determine: (1) 
The effect of the size of soil particles on the depth of penetration; 
(2) the effect of a high water table on the depth of penetration; (3) 
the amount of lateral penetration of mercury in the soil; (4) the up¬ 
ward penetration of mercury in soil; (5) the depth of penetration m 
tubes which had been allowed to stand for three montns after being 
set up and before being treated; (6) the effect of passage through sou 
on the toxicity of a solution of HgCl 2 + NaCl; and (7) the relation 
of depth of penetration to the amount of liquid applied. 
Effect of Size of Soil Particles on the Penetration and Percolation 
in Them of Chemical Solutions 
It is well known that different soils are composed of different 
proportions of various sizes of soil particles. In gravelly soils, com¬ 
posed of very coarse particles, water penetrates with great ease and 
rapidity. In clay soils, composed of very fine particles, water 
penetrates with difficulty and very slowly. Samples of Manor loam 
and of Leonard town silt loam were sieved and tests made to determine 
penetration in the various sizes of soil particles obtained. The soil 
samples were air dried, rolled fine and sieved with an electric sieve 
shaker. The sieves used had 20, 40, 60, 80, 100, 150, and 200 meshes 
per inch. It was found that a considerable proportion of the soil 
went through all of these sieves, that practically all soil passing 
through the 60-mesh sieve passed also through the 80-mesh sieve so 
that very little soil of this texture was available for the experiments, 
and that the proportion of soil held by the other sieves varied 
considerably. 
