800 pounds of organic matter
added, including 230 pounds of nitrogen, seem to have entirely
disappeared.

It becomes interesting and important to know what has become of this
added matter. That it was absorbed into the particles of the earth, is a
matter of course; and the result proves that after such absorption it
was subjected to such a chemical action of the concentrated oxygen
always existing in porous dry material as led to its entire destruction.
Porous substances condense gases--air, oxygen, etc.--in proportion to
the extent of their interior surface. The well-known disinfecting action
of charcoal--the surface of the interior particles of which equal from
fifty to one hundred square feet to each cubic inch of material, and all
of which surface is active in condensing oxygen--is due not simply to
an absorption of foul-smelling odors, but to an actual destruction of
them by slow combustion, so that the same mass of charcoal, if kept dry
and porous, will continue almost indefinitely its undiminished
disinfecting action.

The earth used in the closet is a porous material, sufficiently dry for
the free admission of air or of oxygen. The foulest materials when
covered with dry earth at once lose their odor, and are in time as
effectively destroyed by combustion (oxidized) as though they had been
burned in a furnace. The process is more slow, but none the less sure;
and it is clear that in the case of my dirt-heap the foul matters added
have thus been destroyed. The practical bearings of this fact are of the
utmost importance. Earth is not to be regarded as a vehicle for the
inoffensive removal beyond the limits of the town of what has hitherto
been its most troublesome product, but as a medium for bringing together
the offensive ingredients of this product, and the world's great
scavenger, oxygen. My experiment seems to demonstrate the fact that
there is no occasion to carry away the product from the place where it
has been produced, as after a reasonable time it has ceased to exist,
and there remains only a mass of earth which is in all respects as
effective as any fresh supply that could be substituted.

The quantity necessary to be provided can be determined only by extended
trial. My experiment proves that the amount needed does not exceed one
thousand pounds for each member of the household, and that this amount
once provided will remain permanently effective to accomplish its
purpose.

With a suitable publ