Alpena weekly argus. [volume] (Alpena, Mich.) 1871-1893, 1889-09-11
Lime.

LlIu6 IL the OAlut VI CdlCiuni, WuiCn
! in combination with carbonic acid,
forms carbonate of lime, the chief
constituent of limestone as we see it in
nature in the form of lime rock, mar
BILE, shells of marine animals, etc.
White marble, such as the famous
stone of which the masterpieces of
sculpture were made, is the purest
limestone in existence but even this
is not perfectly pure, for the theoret-
ical limestone, containing 56 per cent
of lime and A Of carbonic acid, is
never found in state of nature.
Lime is made by freeing the stone
from its acid. and this is accomplish
ed by heat, by which the acid is vola-
tilted and caused to pass away into
the atmosphere, leaving the white,
brittle and flaky substance known as
lime or quick lime. When water is
applied to lime it causes it to boil, and
when perfect chemical combination
has been effected the slaked lime alb
serbs carbonic acid from the atmos-
phere with great avidity and becomes
hard, or set. This is the principle in
volved in the use of lime in making
mortar for the purpose of cementing
brick and stone work, the sand being
added TO the slaked lime to furnish
centers of attraction around which the
particles of lime shall gather in hard
ening, thus adding to its strength
The mortar, when used in laying ma
sonary, gradually loses its surplus
water and absorbs carbonic acid until
it becomes hard, thus firmly cement
ing the stones or bricks together.
Lime is calcined in kiln, SO con-
structed that the heat shall enter into
the kiln near the bottom and pass up
ward through the stone, previously
broken into small chunks, the top of
the kiln being left open for the escape
of the smoke and gas and to create a
draft. The degree of heat required is
not specific, but the more intense the
heat the quicker the process of driv-
ing out the acid is completed, and it is
chiefly in the matter of better appli-
cation of the heat generated in the
furnaces that improvements have been
made in the process. The primitive
form of kiln, that most generally in
use by those operating on small
scale, is known as spot kiln" This
consists of well of masonry built up
a few feet from the ground, with an
opening on one side along the ground
for fire box. The limestone is piled
up inside the kiln, a small space being
left in the center, at the bottom, con-
Meeting with the fire opening. A fire
is maintained in the opening at the
bottom, the heat passing up through
the stone and gradually heating the
whole mass. When the acid has all
been expelled the fire is extinguished
and the lime is taken out with long
handled shovel through the ground
opening. This process is very slow
and burns but small quantity at a
time. A decided improvement upon
this is the stone kiln in general use
until late years where lime was burn
ed on larger scale than by using pot
kilns. In this there is a radical
change in principle, as the kiln is so
arranged that the fire is never drawn.
except to repair the kilns and the lime
is drawn of gradually from the bot
tom as fast as calcined, an equal guam
THY of rock being fed into it from the
top at the same time. There are four
furnaces, two each on opposite sides of
the kiln, entering it about four feet
above bottom. In drawing lime, all
that occupying the space between the
fire and the bottom is taken out
through an opening in the bottom
The kiln consists of wall of mason
ry about twenty feet high and eight
teen square, supported outside by
heavy cross timbers and having a CYL
indrical space in the center five feet
in diameter. Above this is a wooden
crib the full size of the kiln, into
which the stone is dumped, making
the kiln self feeding as the lime is
drawn away. Improvements in this
latter method have been made which
give total product nearly fifty per
cent greater.-The West Shore.
M