3?g 
Lime Kilns. 
SELECTIONS, 
Lime Kilns. 
Limestone used to be calcined in a very rude kiln, 
formed by enclosing a circular space of 10 or 15 feet 
diameter, by rude stone walls 4 or 5 feet high, and fill¬ 
ing the cylindrical cavity with alternate layers of turf 
or coal and limestone broken into moderate pieces. 
A bed of brushwood was usually placed at the bottom, 
to facilitate the kindling of the kiln. Whenever the 
combustion was fairly commenced, the top, piled into 
a conicle form, was covered in with sods, to render the 
calcination slow and regular. This method being 
found relatively inconvenient and ineffectual, was suc¬ 
ceeded by a permanent kiln built of stones or brick¬ 
work, in the shape of a truncated cone with the 
narrow end undermost, and closed at bottom by an 
iron grate. Into this kiln, the fuel and limestone were 
introduced at the top in alternate layers, beginning, of 
course, with the former; and the charge was either 
allowed to burn out, when the lime was altogether re¬ 
moved at a door near the bottom, or the kiln was suc¬ 
cessively fed with fresh materials, in alternate beds, 
as the former supply sunk down by the calcination, 
while the thoroughly burnt lime at the bottom was suc¬ 
cessively raked out by a side door immediately above 
Fig. 19. 
the grate. The interior of the lime kiln has-been 
changed of late years from the conical to the elliptical 
form; and probably the best is that of an egg placed 
with its narrow end undermost, and truncated both 
above and below; the ground plot or bottom of the 
kiln being compressed so as to give an elliptical sec¬ 
tion, with an eye or draft-hole towards each end of that 
ellipse. A kiln thus arched in above gives a reverbe¬ 
ratory heat to the upper materials, and also favors their 
falling freely down in proportion as the finished lime is 
raked out below; advantages which the conical form 
does not afford. The size of the draft-notes for ex¬ 
tracting the quick-lime, should be proportionate to the 
size of the kiln, in order to admit a sufficient current 
of air to ascend with the smoke and flame, which is 
found to facilitate the extrication of the carbonic acid. 
The kilns are called perpetual , because the operation 
is carried on continuously as long as the building lasts; 
and draw-kilns , from the mode of discharging them by 
raking out the lime into carts placed against the draft- 
holes. Three bushels of calcined limestone, or lime- 
shells, are produced on an average for every bushel of 
coals consumed. Such kilns should be built up against 
the face of a cliff, so that easy access may be gained to 
the mouth for charging, by making a sloping cart road 
to the top of the bank. 
Fig. 20. 
Figs. 19, 20, 21, 22, represent the Ihne kiln of Rii- 
dersdorf, near Berlin, upon the continuous plan, excel¬ 
lently constructed for economizing fuel. It is triple, 
and yields a threefold product. Fig. 20, is a view of 
it as seen above ; Jig . 22, the elevation and general ap¬ 
pearance of one side ; Jig. 19, a vertical section, and 
Jig. 21, the ground plan in the line a b c d of Jig. 19. 
The inner shaft Jig. 19, has the form of two truncated 
cones, with their larger circular ends applied to each 
other; it has the greatest width at the level of the fire- 
door b, where it is 8 feet in diameter; it is narrower 
below at the discharge door, and at the top orifice, 
where it is about 6 feet in diameter. The interior 
wall d, of the upper shaft, is built with hewn stones, 
to the height of 38 feet, and below that for 25 feet, 
with fire-bricks d d, laid stepwise. This inner wall is 
surrounded with a mantle e, of limestones, but between 
the two there is a small vacant space of a few inches 
filled with ashes, in order to allow of the expansion of 
the interior with heat taking place, without shattering 
the mass of the building. 
The fire-grate b, consists of fire-tiles, which at the 
middle, where the single pieces press together, lie upon 
an arched support /. The fire-door is also arched, and 
is secured by fire-tiles, g, is the iron door in front of 
that orifice. The tiles which form the grate have three 
