Medical Officers of the Army of India

23

The glass capsule registering loss by evaporation from a surface equal to
that presented by the cavity had lost 60 c.c. of water during the period. The
total loss from the cavity in the same time was 2,362 c.c. or 2,302 c.c. due
to the permeability of the soil. The diminution in daily loss from the cavity
coincident with the great increase in atmospheric humidity attendant on the
onset of the rainy season comes out very distinctly. During the entire course
of the previous experiment and in the early part of the present one the surfaces
of the block of soil appeared continuously dry, but when the atmospheric humid-
ity increased and the disappearance of water from the cavity conspicuously
diminished, the surfaces became evidently and constantly moist. Another phe-
nomenon, common to this and the previous experiments, but which came out
most conspicuously here, was the gradual diminution in the capacity of the
cavity due to the disintegrant action of the water on the soil. The floor of
the cavity was originally flat and flush with the lower edge of the glass cylinder
which formed its bounding wall. As time went on, however, it gradually swelled
up and in place of consisting of the dense material of the mass in its original
condition came to be composed of soft, loose mud derived from the disin-
tegration of the soil at the base of the cavity and from beneath the edge of the
cylinder, which ultimately, in place of resting on the firm soil, was suspended
over this soft, incoherent substance.

     Another experiment of a different nature was tried. In it a long glass tube
was rammed with some of the soil which had been previously dried over a gas
flame and thoroughly triturated. The rammed soil occupied 66c. of the length
of the interior of the tube. The tube was fixed in a horizontal position with
one end connected with the lower extremity of a glass receiver full of water, and
the other with an open U-tube containing fragments of chloride of calcium.
The experiment was initiated on the 20th May by opening the tap at the
bottom of the receiver and allowing the water to pass into the tube. The water
advanced along the portion of the tube occupied by the soil at a rate shown by
the following figures:—