Reasons for Designation
Limestone or chalk has been the basic ingredient for lime mortar from at
least Roman times. Since the medieval period, lime has also been used as
agricultural fertiliser and, since the early 19th century, widely used in
a variety of other industries: as a flux in blast furnaces, in the
production of gas and oil, and in the chemical, pharmaceutical and food
industries.
The lime industry is defined as the processes of preparing and producing
lime by burning and slaking. The basic raw material for producing lime is
limestone or chalk: when burnt at high temperature (roasted or calcined),
these rocks release carbon dioxide, leaving `quicklime' which, by chemical
reaction when mixed with water (`slaking'), can be turned into a stable
powder - lime. Lime burning sites varied in scale from individual small
lime kilns adjacent to a quarry, to large-scale works designed to operate
commercially for an extended market and often associated with long
distance water or rail transport. Lime burning as an industry displays
well-developed regional characteristics, borne out by the regional styles
of East Anglia, West Gloucestershire or Derbyshire.
The form of kilns used for lime burning evolved throughout the history of
the industry, from small intermittent clamp and flare kilns, to large
continuously fired draw kilns that could satisfy increased demand from
urban development, industrial growth and agricultural improvement.
Small-scale rural lime production continued in the later 19th and 20th
centuries, but this period of the industry is mainly characterised by
large-scale production and the transfer of technologies from the cement
and other industries. The demand for mortars grew steadily during the 19th
and 20th centuries. The successful production of mortars made with
artificial cement represented an economic challenge to lime production and
gradually replaced the use of lime mortars in major construction and
engineering projects.
From a highly selective sample made at national level, around 200 lime
industry sites have been defined as being of national importance. These
have been defined to represent the industry's chronological depth,
technological breadth and regional diversity.
Downham lime kiln survives well and is a good example of a small-scale local
commercial lime kiln. It is a rare example in north west England of a lime
kiln complete with an associated lime yard.
Details
The monument includes Downham lime kiln and an associated lime yard
located on the north side of Twiston Lane 50m north of Smithfield Farm. It
is a single pot flare or draw type kiln which was used to burn limestone.
Flare and draw kilns are structurally very similar and without documentary
evidence considerable difficulty can be encountered when trying to
distinguish these in the field. In the published literature the term flare
kiln is broadly applied to a permanent stone structure that was operated
as an intermittent kiln with fuel and stone kept separate, whereas the
draw kiln is generally taken to be a continuous, mixed-feed kiln (although
a kiln built and charged as a draw kiln could also be operated on an
intermittent basis).
Typically the limestone was tipped into the kiln from the top via the
charge hole then burned using wood, coal or coke as a fuel. The resultant
quicklime, also known as birdlime or slaked lime, was then shovelled out
from the draw hole at the bottom of the kiln. Lime has many uses including
spreading on lime deficient soils to encourage plant growth, the
whitewashing of walls and ceilings of buildings, and concrete and cement
production.
The lime kiln is located at the rear of a stone-walled lime yard which was
used for storage. It is constructed of blocks of coursed limestone rubble
and built into the hillside. There is an arched opening giving access to
the draw hole, also known as the fire hole. Above is a rounded stack
containing the charge hole which is now largely infilled.
All fences, fence posts and gates are excluded from the scheduling,
although the ground beneath these features is included.
MAP EXTRACT
The site of the monument is shown on the attached map extract.
