pon the vital strength of the country, it is
necessary to take such measures as will arrest the outflow of this
valuable material. This can never be fully accomplished until laws shall
be made preventing the wastes of cities and towns. Such laws have
existed for a long time in China, and have doubtlessly been the secret
of the long subsistence and present prosperity of the millions of people
inhabiting that country.

We have, nevertheless, a means of restoring to fertility many of our
worn-out lands, and preserving our fertile fields from so rapid
impoverishment as they are now suffering. Many suppose that soils which
produce good crops, year after year, are inexhaustible, but time will
prove to the contrary. They may possess a sufficiently large stock of
phosphoric acid, and other constituents of plants, to last a long time,
but when that stock becomes so reduced, that there is not enough left
for the uses of full crops, the productive power of the soil will yearly
decrease, until it becomes worthless. It may last a long time, a
century, or even more, but as long as the system is--to _remove every
thing, and return nothing_,--the fate of the most fertile soil is
evident.

The source mentioned, from which to obtain phosphoric acid, is the bones
of animals. These contain large quantities of _phosphate of lime_. They
are the receptacles which collect nearly all of the phosphates in crops,
which are fed to animals, and are not returned in their excrements. For
the grain, etc., sent out of the country, there is no way to be repaid
except by the importation of this material; but, all that is fed to
animals, or to human beings, may, if a proper use be made of their
excrement, and of their bones after death, be returned to the soil. With
the treatment of animal excrements we are already familiar, and we will
now turn our attention to the subject of

BONES.

[Of what do dried bones consist?

What is the organic matter of bones?

The inorganic?

What can you say of the use of whole bones?]

_Bones_ consist, when dried, of about one third organic matter, and two
thirds inorganic matter.

The organic matter consists chiefly of _gelatine_--a compound containing
_nitrogen_.

The inorganic part is chiefly _phosphate of lime_.

Hence, we see that bones are excellent, as both organic and mineral
manure. The organic part, containing nitrogen, forms _ammonia_, and the
inorganic part supplies the much needed _phosphoric a