fact that the ending _-ate_ on the common chemical names signifies
the presence of oxygen Thus calcium carbon_ate_ is composed of the
three primary elements, calcium, carbon and oxygen.

"Of course the chemical element is the simplest form of matter. An
element is a primary substance which cannot be divided into two or
more substances All known matter consists of about eighty of these
primary elements; and, as a matter of fact, most of these are of
rare occurence--many of them much more rare than the element gold.

"About ninety-eight per cent. of the soil consists of eight elements
united in various compounds or combinations; and only ten elements
are essential for the growth and full development of corn or other
plants. If any one of these ten elements is lacking, it is
impossible to produce a kernel of corn, a grain of wheat, or a leaf
of clover; and in the main the supply is under the farmer's own
control. But we can discuss this matter more fully later. Let us see
what we have here."

Percy poured a few drops of the hydrochloric acid into the hollow of
the cake of soil.

"What should it do?" asked Mr. West.

"If the soil contains any limestone, the acid should produce
foaming, or effervescence," replied Percy; "but it is very evident
that this soil contains no limestone. You see the hydrochloric acid
has power to decompose calcium carbonate with the formation of
carbonic acid and calcium chlorid, a kind of salt that is used to
make a brine that won't freeze in the artificial ice plants. The