Definitions
from Right Use Of Lime In Soil Improvement
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
became mixed with the lime carbonate when the rock was being formed.
Calcium Hydroxide is a compound made by permitting calcium oxide to
combine with water, and is known as lime hydrate. It contains 56 parts
by weight CaO and 18 parts water, and has the formula Ca(OH)2.
Magnesium is an element, and is found in magnesium carbonate, a
compound that is effective in correcting soil acidity.
Magnesian Limestone. Magnesium carbonate is usually found in
combination with calcium carbonate, and when about 47 per cent of the
total carbonates is magnesium carbonate, the limestone is known as
dolomite.
Ground Limestone is the stone pulverized so that it can be
distributed. It is carbonate of lime (CaCO3), or a combination of
calcium and magnesium carbonate, and in a way has a right to be
designated as "lime," but such use leads to confusion.
Fresh Burned Lime. Calcium oxide (CaO) formerly was accurately
designated as "lime," but the words "fresh burned" are often prefixed to
prevent confusion with lime carbonate or the hydrate. It is known as
"lump lime," "caustic lime" and "stone lime."
Ground or Pulverized Lime. Fresh burned lime may be ground fine, so
that it can be spread on land without slaking. This product should not
be confused with ground limestone or hydrated lime. Fresh ground lime is
worth nearly twice as much per ton as ground limestone, but some of the
product on the market is far from pure. There is opportunity to grind up
unburned and waste material with the caustic lime, and this form of lime
usually contains some hydrated material.
Hydrated Lime is the compound formed by the action of water or steam
on fresh burned lime.
Air-Slaked Lime is a compound formed by the action of carbon dioxide
from the air on hydrated lime, and its formula is CaCO3, which is
that of pure limestone.
Next: Ground Limestone
Previous: Sources Of Lime
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