6 BULLETIN 1221, U. S. DEPARTMENT OF AGRICULTURE. 
A second set of tubes was filled by dropping the soil into them from 
a uniform height, the drop remaining the same for each 2-inch section 
filled. This was the method employed by the late Dr. R. H. Lough- | 
ridge. In this case also two tubes were filled with the same soil and 
one of them was inverted before being placed in water. | 
A third set was filled by packing a uniform weight of soil into each 
1-inch section of the tube. 
A fourth method employed was that of filling the tubes in 2-inch © 
layers and tamping each layer with a wooden rod slightly smaller in 
diameter than the tubing. 
The dropping of a weighted tamping rod a-definite distance upon 
each 1-inch layer also was tried. 
As it was not the purpose of these experiments to determine the 
best method of packing tubes, it is sufficient to say that an analysis 
of the data did not indicate that the methods of packing were in any 
way responsible for the distribution of moisture found. The data 
did indicate, however, that the method of packing influenced to some 
extent the total quantity of water held in the tube. 
VENTILATION OF TUBES. 
In the first experiments each joint between the 1-inch sections was 
made air-tight by wrapping with friction tape. This made each soil 
column practically air-tight from one end to the other. Then, if air- 
trapping did occur in the soil column used by other experimenters it 
would also occur in these tubes. In order to provide for a rather free 
air circulation within the soil column, some of the tubes were left with 
the joints between sections unwrapped. Thus the air could enter or 
escape from the soil at each inch in height. A third set of tubes 
having a slot one-fourth inch wide cut from one end to the other was 
made for two of the soils. This slot was covered with a very fine 
wire gauze. 
After a tube had been filled with soil it was placed on end in a ves- 
sel of water and the water maintained at a uniform elevation covering 
the bottom half inch of the soil column. The tubes were allowed to 
stand in position for various lengths of time before sampling was 
undertaken. 
SAMPLING. 
Various methods were employed in breaking a soil column into its 
l-inch sections at the termination of an experiment. In some cases 
the tube was removed from the water, the bottom section discarded, 
and the remainder of the tube separated into sections inch by inch. 
As fast as a 1-inch section was removed the soil from that section was 
placed in a tared glass bottle and the top screwed on. In other in- 
stances the tube was left standing in water and the column was dis- 
mantled inch by inch, commencing at the top. In other cases the 
tube was removed from the water, laid on its side, the tape joints 
were cut quickly, and the tube was broken up into 1-inch sections as 
rapidly as possible and before any of the samples were placed in the 
bottles. Some of the tubes were allowed to stand in a vertical posi- 
tion for 24 hours after having been removed from the water before 
sampling. 
In all cases, unless specially noted, each inch in height or each 1-inch 
section constituted a separate sample. 
