332 
Journal of Agricultural Research 
Vol. XXXI, No. 4 
of a number of different treatments at the same time for comparative 
purposes. To avoid confusion the tubes used in each experiment 
were numbered consecutively after the experiment was set up. 
How Solutions were Applied 
Preliminary tests showed such uniform penetration following ap¬ 
plications by simply pouring the proper amounts of solution from a 
graduate onto the soil in the tubes that no other method of applica¬ 
tion was tried. In many cases the chemicals to be applied were 
dissolved in part of the water and then used, the remainder of the 
water being applied later. For convenience notations were used to 
indicate this, as follows: 
1+0=1 gallon of solution per square foot. 
1 + 1 = 34 gallon of solution per square foot + 34 gallon of water. 
1 + 3 = 34 gallon of solution per square foot + J4 gallon of water. 
1 + 7=34 gallon of solution per square foot + % gallon of water. 
(1 + 1) +0=34 gallon of solution per square foot +34 gallon of solution. 
In other words, these figures are based on applications totaling 
1 gallon per square foot, the first figure showing the number of parts 
of the water used in making up the chemical solution applied and 
the second figure showing the number of parts of water applied later. 
These figures are used particularly for applications ol mercuric 
chloride, and, unless otherwise specified, indicate the application of 
1 gallon of one-half of 1 per cent mercuric chloride plus 234 per cent 
sodium chloride per square foot, or its equivalent. 
Determination of Soil Moisture 
Although only approximate soil-moisture determinations were re¬ 
quired, they were made with considerable care. The crucibles used 
for soil-moisture determinations were of known weight. Weights to 
balance the crucible to be used were first placed on one side of the 
analytical balances and a 50-gram weight added. The crucible whs 
then removed from the desiccator and put on the other scale pan with 
soil added to balance. After 48 hours in the electric oven at 95° C. 
the crucible was placed in a desiccator to cool and was then reweighed. 
The weight in milligrams was recorded. The per cent of moisture 
equals weight lost divided by the dry weight of soil. While the 
time the samples were kept in the oven often varied somewhat, the 
percentages oi moisture obtained are accurate enough for our purposes. 
Method of Handling Soil Samples Tested for the Presence of Chemicals 
After tubes of soil treated with chemical solutions had remained 
in position for the desired length of time the soil was removed an 
inch at a time and each inch tested for the presence of the chemical 
applied. Before removing any soil from a tube a wax pencil was 
used to mark the tube off into 1-inch sections, starting from the top. 
The bottom inch or fraction of an inch of soil was then carefully re¬ 
moved with a spatula and stirred up with 50 c. c. of water in a 250 
c. c. beaker. The number of the tube from which this soil section 
was taken and the number of inches from the top of the soil column 
to this particular section was marked on the beaker. The same pro¬ 
cedure was followed until each inch of soil in the tube had been simi¬ 
larly treated. When the soil in the beaker had settled, the clearer 
liquid on the surface was decanted and filtered into test tubes. This 
