Apr. 9,1917 
Water-Retaining Capacity of Soil 
5i 
DISTRIBUTION OF MOISTURE WHEN EQUILIBRIUM HAS BEEN 
ATTAINED AFTER ADDING WATER TO THE BASE OF A COLUMN 
WHOSE MOISTURE CONTENT IS APPROXIMATELY EQUAL TO ITS 
HYGROSCOPIC COEFFICIENT 
This experiment was similar to the preceding, except that the water 
was applied to the base of the column instead of to the surface. Similar 
cylinders were filled with the same soils, in the same manner, and at the 
same time, and were then placed upright in the small metal trays and 
the same amounts of water added as in the preceding experiment. The 
water was quickly absorbed through the small holes. The covers had 
been left off to permit the ready escape of the air expelled from the soil 
by the ascending water, the intention being to have these replaced as 
soon as the water had been absorbed, for which only a very short time 
was necessary, and then have both the opening between the cover and 
the cylinder wall and the holes in the bottom at once sealed with paraffin. 
Through a misunderstanding the covers were not placed on the cylinders, 
but all the latter being placed close together, each still resting in its tray, 
were covered with a large sheet of oilcloth and left in the basement room. 
Three days later, when the error was discovered, it was found that the 
oilcloth had been moved so that some of the cylinders were uncovered; 
but no one employed about the laboratory knew when the oilcloth had 
been disturbed or, accordingly, how long some of the cylinders had been 
exposed to evaporation. None had been weighed after being filled; 
but the weights of the empty cylinders, those of the different soils used, 
the initial moisture content, and the amount of the added water per¬ 
mitted a close calculation of what the weight of each should have been, 
provided no loss through evaporation had occurred. All the cylinders 
were at once covered and weighed. Those filled with soils A, D, and H 
had suffered the greatest loss, it having been, as closely as could be esti¬ 
mated, sufficient to lower the moisture content of a section of the soil 
column 6 to 8 inches deep by 2 or 3 per cent. As we decided to allow 
the cylinders to stand and determine the final moisture conditions, all 
were sealed and stored in the box of soil in the basement room and other¬ 
wise handled like those in the parallel experiment. 
The duplicate cylinders of each of the loams showed a similar dis¬ 
tribution of moisture; and, hence, only the averages are reported in 
Table XVII. In every cylinder the final moisture content of the upper¬ 
most section was found to be below the initial water content, the up¬ 
ward movement of water during the period of 74 to 1x5 days not having 
been sufficient to compensate for the loss into the still atmosphere in 
the darkened room during two and one-half days. This striking evi¬ 
dence of the extreme slowness of the upward movement of water under 
moisture conditions of the subsoil that resemble those met in dry-land 
fields with the water table far below that surface may possibly give 
the experiment an even greater value than it would have possessed had 
the misunderstanding not occurred. 
