346 
Journal of Agricultural Research 
. Vol. XXXI, No. 4 
The chemical solutions used in testing penetration in the sifted soil 
were HgCl 2 + NaCl (1 + 1) and 1 per cent formaldehyde (commercial 
solution). The penetration data secured in these sieved soils is 
tabulated in Table XII. As shown in this table penetration was 
better in the coarse than in the fine soil. However it does not seem 
likely, from the results secured, that variations in the proportions of 
the various sizes of particles would be sufficient to cause any im¬ 
portant variations in the depth of penetration in soils of the same 
general type. 
Table XII .—Effect of size of soil particles on penetration 
Soil 
Manor loam, air dry 
Leonardtown silt loam, 4.9 
per cent moisture 
Mercuric chloride + 
sodium chloride 1+1 a 
penetration in 3 days 
1 per cent formalde¬ 
hyde 1+0 ® penetration 
in 17 to 18)4 hours 
Mercuric chloride + sodium 
chloride 1+1 • penetration 
in 3 days 
Whole ... _ 
Inches 
6 to 7 * (2) 7 to 8 * (1).. 
Inches 
Inches 
7 to 8 (3). 
7 to 8 (3). 
7 to 8 (3). 
6 (1) to bottom of column. 
6 to 7 (1) to bottom of column. 
4 to 5 (3). 
20 to 40 c _ 
8 to 9 (9).. 
8 to 9 (6).. 
40 to 60_ 
60 to 80 d __ 
6 to 7 (6) 7 to 8 (3)_ 
7 to 8 (3) 8 to 9 (3)_ 
80 to 100_ 
6 to 7 d (2)_ 
6 to 7 (6)_ 
100 to 150_ 
6 to 7 (1)_ 
6 to 7 (6)___ 
100 to pan e _ _ _ 
150 to 200_ 
200 to pan_ 
Leonardtown silt loam 
whole. 
6 to 7 (4)__ 
5 to 6 (4)_ 
6 to 7 (1), 7 to 8 (2)- 
5 to 6 (2), 6 to 7 (3)- 
5 to 6 (1), 6 to 7 (5) 
* 1+1gallon 1 per cent HgCh+5 per cent NaCl+34 gallon water per square foot. 1+0=1 gallon 1 
per cent formaldehyde (commercial) per square foot. 
* Numbers inclosed in parentheses indicate the number of tubes showing the depth of penetration 
indicated. 
«The first figure gives the number of meshes p>er inch in the sieve the soil passed through and the second 
figure is the number of meshes per inch in the sieve holding the soil. 
<* The sifted soil was not equally divided among the various sizes. Very little was held in the 80-mesh 
sieve particularly, and not enough in some other sieves to run a full series of tests. 
* The 150 and 200 mesh sieves were not available when the Leonardtown silt loam was sifted. 
That the rate of penetration of a chemical solution in soil particles 
of different sizes may vary considerably is indicated by an experiment 
with formaldehyde in Manor loam. The six brass tubes were set 
up and 700 grams of sieved soil compacted in each tube. A 0.05 
per cent solution of commercial formaldehyde was supplied to these 
tubes until percolate dripped from the outlet of all tubes. The 
percolate gave a strong positive test for formaldehyde in every case. 
The mesh of the sieves is given as in Table XII, together with the 
height of the soil column through which the solution passed and the 
time elapsing after the solution was turned on until percolate ap¬ 
peared. The weight of solution held at the end of the test by each 
tube of soil is also given. The results of the experiment are shown 
in Table XIII. The figures in the table show that the volume of the 
soil did not vary greatly and bore no relation to the rate of penetra¬ 
tion. The penetration in the smallest particles was so slow that 
inspections were reduced to one per hour and a small amount of 
percolate had accumulated in the beaker under the drip when the 
inspection was made at the end of the tenth hour. The weight of 
the solution held by the 100 to 150 tube was exactly twice that held 
by the 20 to 40 tube. This ratio did not hold for the rate of pene¬ 
tration given above nor for the depth of penetration of one gallon of 
solution as given in Table XII. 
