or tube of light wood, removed the screw cap, and drew out a
glass-stoppered bottle.

"This bottle contains hydrochloric acid," said Percy. "It is often
incorrectly called 'muriatic acid.' It consists of two elements,
hydrogen and chlorin, from which its name is derived. But you are
perhaps already familiar with the chemical elements."

"Well, I heard lectures at William and Mary for four years, and they
included some chemistry as it was then taught; but they certainly
did not include the application of chemistry to agriculture, and I
am greatly interested to know the meaning of these tests you are
making here on our own farm under my own eyes. You may take it for
granted that I know absolutely nothing of such use of chemistry as
you are evidently turning to some practical value."

"Any other farmer can make these tests as well as I can," said
Percy. "This bottle of acid cost me fifteen cents and it can be
duplicated for the same price at almost any drug store. The acid is
very concentrated, in fact about as strong as can easily be
produced, but it need not be especially pure. Some care should be
taken not to get it on the clothing or on the fingers, although it
is not at all dangerous to handle, but it tends to burn the fingers
unless soon removed, either by washing with water or by rubbing it
off with the moist soil."

"I use this acid to test the soil for the presence or absence of
limestone. Ordinary limestone consists of calcium carbonate. Here,
again the chemical name alone is sufficient to indicate the elements
that compose this compound. It is only necessary to keep in mind the