DEFINITIONS

_Technical Terms._ The practical man uses a great number of technical
terms in his own field of labor, and often fails to recognize the fact
that they are technical, and may be puzzling to many other people. He
uses such terms for the sake of accuracy, desiring to express to his
fellow-workmen exactly what he means. The farmer, stockman, carpenter,
banker--all have command of such terms, and need them, but the chemist
who, in a way, must come even nearer to accuracy in expression, finds
that many people who want his assistance do not care to master and use
any of his terms. Failure to do so compels misunderstanding. Anyone who
is interested in the right use of lime should be willing to add a few of
the chemists' technical terms to the scores in his own line of work that
he uses constantly, and thus let the whole matter of liming land come to
appear more simple to him. Acquaintance with a few terms is necessary
to any understanding of statements of analyses upon which purchase
should be made.

_An Element_ is a substance that cannot be divided into simpler
substances. The number of elements necessary to the growth of plants is
small, and of this number calcium is one and magnesium is another.

_Compounds._ We do not find these elements merely mixed with other
elements to form a soil. They unite in definite proportions by weight to
form chemical compounds. As conditions change, many of these compounds
undergo change, giving up one element, or group of elements, and uniting
with another element or group from a different compound. Heat, moisture
and the action of bacteria are factors in promoting the changes. There
is no more restless activity than may be found among the elements
composing a productive soil.

_Calcium_ is an element which will unite with oxygen and carbon dioxide
to form a compound known as calcium carbonate. The chemist's symbol for
calcium is Ca.

_Calcium Oxide_ is a compound left after the burning of limestone, and
is known as fresh burned lime, or quick lime. Its formula is CaO. It
contains, when pure, 40 parts of calcium and 16 parts oxygen by weight.

_Carbon Dioxide_ is a compound whose formula is CO2.

_Calcium Carbonate_, known also as carbonate of lime, has a definite
composition, containing, when pure, 56 parts CaO and 44 parts CO2. It
is known to the chemist as CaCO3, and forms practically all of very
pure limestones. Impure limestones contain some earthy materials that