718 LIME. 
ed fod-kilns, in order to diftinguifh them from the other 
forts. When the whole of the contents of fuch kilns are 
grown cold, they are drawn or taken out from the hot- 
tom ; and the kiln again filled, if neceffary. Thefe kilns 
are obvioufiy intended for burning only one kiln-full at a 
time. But, as the burning of lime in this way is tedious 
and uneconomical, other methods and forms of kilns 
have been had recourfe to. Where lirneis much wanted, 
either for agriculture or other purpofes, they therefore ufe 
perpetual kilns, or what are more generally known bv the 
name of drazo-kilns. Thefe, as all lime-kilns ought to he, 
are, the author of Modern Agriculture fays, fituated by 
the fide of a rifing bank, or fiieltered by an artificial mound 
of earth. They are generally built either of ltone or brick ; 
but the latter, as being better adapted to Hand excefiive 
degrees of beat, is confidered as preferable. The outline 
form of fuch kilns is fometimes cylindrical, but more ge¬ 
nerally fquare. The infide ftiould be formed in the fhape 
of a hogfhead, or an egg, opened a little at both ends, and 
fet on the l'malleft ; being finall in circumference at the 
bottom, gradually wider towards the middle, and then 
contrafling again towards the top. In kilns confhufted 
in this way, it is obferved, fewer coals are neceffary, in 
confequence of the great degree of reverberation which is 
created, above that which takes place in kilns formed in 
the fliape of a fugar-loaf reverfed. Near the bottom, in 
large kilns, two or more apertures are made; thefe are 
fmall at the infide of the kiln, but are doped wider, both 
at the fides and the top, as they extend towards the out- 
fide of the building. The ufes of thefe apertures are for 
admitting the air neceffary for fupplying the fire, and alfo 
for permitting the labourers to approach with a drag and 
Ihovel, to draw out the calcined lime. From the bottom 
of the kiln within, in fome cafes, a fmall building, called 
a horfe, is railed in the form of a wedge, and fo con- 
ftrufted as to accelerate the operation of drawing out the 
burned lime-ftone, by forcing it to fall into the apertures 
which have been mentioned above. In other kilns of 
this kind, in place of this building, there is an iron grate 
near the bottom, which comes clofe to the infide wall, ex¬ 
cept at the apertures where the lime is drawn out. When 
the kiln is to be filled, a parcel of furze or faggots is laid 
at the bottom ; over this a layer of coals ; then a layer of 
lime-ftone, which is previoufly broken into pieces about 
the fize of a man’s fifl; and fo on alternately, ending with 
a layer of coals, which is fometimes, though feldom, co¬ 
vered with fods or turf, in order to keep the heat as in- 
tenl'e as poffible. The fire is then lighted in the aper¬ 
tures; and when the lime-ftone towards the bottom is 
completely calcined, the fuel being confiderably exhaufted, 
the lime-ftone at the top fubfides. The labourers then 
put in an addition of lime-fione and coal at top, and draw 
out at bottom as much as they find thoroughly burned; 
.and thus go on, till any quantity required be calcined. 
When lime-ftone is burned with coals, about three bulhels 
of calcined lime-ftone are produced for every bufliel of 
coals ufed in the procefs. 
A lime-kiln of this fort is deferibed in count Rum- 
ford’s Effays, which is in poffeftion of the Dublin Society, 
as well as the principal objects that ought to be had in 
view in conftrufting of the kiln pointed out; the firft of 
which is, “to caufe the fuel to burn in fuch a manner as 
to coniume the fmoke, which has here been done by 
obliging the fmoke to defeend and pafs through the fire, 
in order that as much heat as poflible might be generated. 
Secondly, to caufe the flame and hot vapour, which rife 
from the fire, to come in contact with the lime-ftone by a 
very large furface, in order to economize the heat, and 
prevent its going off into the atmofphere; which was 
done by making the body of the kiln in the form of a 
hollow truncated cone; and very high in proportion to its 
diameter ; and by filling it quite up to tbe top with lime- 
ftone, the fire being made to enter near the bottom of the 
cone. Thirdly, to make the procefs.of burning lime per¬ 
petual, in order to preyent the wafte of heat which un* 
K I L N. 
avoidably attends the cooling of the kiln, in emptying 
and nlling it, when, to perform that operation, it is ne¬ 
ceffary to pur out the fire. And, fourthly, to contrive 
matters fo, that the lime in which the procefs of burning 
is juft finished, and w hich of courfe is (till intenfely hot, 
may, in cooling, be made to give off its heat in fuch a 
manner, as to afiift in heating the freflt quantity of cold 
lime-ftone with which the kiln is replenifiied, as often as 
a portion of lime is taken out of it. To effeftuate thefe 
purpofes, the fuel is not mixed with the lime-ftone, but is 
burned in a clofe fire-place, which opens into one lide of 
the kiln, fome diftance above the bottom of it. For large 
litne-kjlns on thefe principles, there may be feveral fire¬ 
places all opening into the fame cone, and fituated on 
different fides of it ; which fire-places may be conftrucled 
and regulated like the fire-places of the furnaces ufed for 
burning porcelain.” 
It is a common practice to burn lime-ftone with furze 
in fome places. The kilns which are made ufe of in thefe 
cafes are commonly known by the denomination of flame- 
kilns, and are built of brick ; the walls from four to five 
feet thick, when they are not fupported by a bank or 
mound of earth. The infide is nearly fquare, being twelve 
feet by thirteen, and eleven or twelve feet high. In the 
front wall there are three arches, each about one foot ten 
inches wide by three feet nine inches in height. When 
the kiln is to be filled, three arches are formed of the 
largeft pieces of lime-ftone, the whole breadth of the kiln, 
and oppofite to the arches in the front wall. When thefe 
arches are formed, the lime-ftone is thrown promifeuoufiy 
into the kiln to the height of feven or eight feet, over 
which are. frequently laid fifteen or twenty thou fail'd 
bricks, which are burned at the fame time with the lime- 
ftone. When the filling of the kiln is completed, the 
three arches in the front wall are filled up with bricks al- 
moft to the top, room being left in each fufficient only 
for putting in the furze, which is done in fmall quanti¬ 
ties, the object being to keep up a conftant and regular 
flame. In the fpace of thirty-fix or forty hours, the 
whole lime-ftone, about one hundred and twenty or one 
hundred and thirty quarters, together with the fifteen or 
twenty thoufana bricks, are thoroughly calcined. Kilns 
conftrmfted in this way may be feen near Wellingborough 
in Northnmptonfhire, and other places in the northern 
parts of the kingdom. And in many of the northern 
counties of Scotland, which are fituated at a great dif¬ 
tance from coal, it is alfo a common practice to bum 
lime-ftone with peat; and, confidering.the rude ill-ccn- 
ftrufted kilns which are ufed for the purpofe, it is afto- 
nifiling with what fuccefs the operations are performed. 
In fome of thefe diftriets, it is ftated that lime-ftone is 
fufficiently calcined with peats, laid Jlratum fuper Jlratum, 
in kilns formed of turf; but, owing to the quantity of 
afhes which fall from the peat, the quality of the lime is 
confiderably injured ; and, from the open and expofed 
fituation of many of thefe kilns, the wafte of fuel is im- 
menfe. Mr. Dodfon, however, has had much fuccefs in 
burning lime by the ufe of peats; as he ftafes, in the Far¬ 
mer’s Magazine, that he is “convinced, from experience, 
that lime-ftone can be burnt to better purpofe, and at lefs 
expenfe, with peat than with coal. When coal is ufed, 
the lime-ftones are apt, from excefiive heat, to run into a 
folid lump, which never happens with peat, as it keeps 
them in an open ftate, and admits t(ie air freely. The 
procefs of burning, alfo, goes on mote flowly with coal. 
No lime can be drawn for two or three days; whereas, 
with peat, it may be drawn within twelve hours after fire 
is put to the kiln ; and in every fucceeding day nearly dou¬ 
ble the quantity of what could be produced by the ufe of 
coal. The expenfe is comparatively final]. A man and 
a boy wdll dig as many peats in one day as will burn 180 
bulhels of lime ; and the expenfe, including drying, will 
not exceed five Ihillings; while the coal neceffary for burn¬ 
ing the fame quantity of lime would have colt twelve (kil¬ 
lings at the pit. The wetnefs of feafons is no argument 
againft 
