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The
Alum Industry.
Alum
was Britain’s first chemical industry beginning
in the early 1600s. Alum shales were quarried
and processed at Guisbourgh, Loftus and Boulby
in East Cleveland for over 200 years.
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The
processing of alum from shale is often considered
the earliest chemical industry in the British
Isles. Alum shales were quarried and processed
at Guisbourgh, Loftus and Boulby in East Cleveland
from the early 1600s onwards.
Alum
was principally used in the textile industry as
a fixing agent for dyes. It was also used by tanners
to produce a more supple leather.
The
process involved in extracting alum from alum
shale was long and complicated. The shale was
first quarried from inland hillsides, such as
Belman Bank, Guisborough or coastal cliffs, such
as Boulby, leaving massive quarries scarring the
landscape.
The
shale was then heaped into large mounds (often
up to 30 metres high), fired and left to smoulder
for up to 9 months. The roasted shale was then
tipped into leaching tanks where it was left to
soak in water.
The
solution, containing aluminium sulphate (the active
ingredient of alum), was then drained off and
ran along stone or wooden conduits to the ‘Alum
House’. Here the water was boiled away from the
solution in evaporating pans.
An
alkali, derived from human urine or burnt kelp,
was added to cause precipitation of the alum crystals.
The crystals were then bagged and transported
for sale. The burnt shale left in the leaching
pits was either disposed of nearby to form enormous
shale tips (inland sites) or simply thrown in
to the sea (coastal sites).
The
Alum industry in North Yorkshire began in the
first decade of the 17 th century. Despite the
scale of the industry it was rarely profitable
and mines had frequent gaps in operation. Only
three mines in Redcar and Cleveland continued
in use into the 19 th century. These were at Guisborough,
Hummersea and Boulby. These mines became uncompetitive
in the 1860s when faced with competition from
works in Lancashire, Humberside and Scotland and
the last Cleveland Alum mine closed in 1871.
The
remains of the alum works have left a dramatic
impact on our countryside. The coastal quarries
at Boulby and Hummersea have an almost unworldly
feel; standing on the red shale heaps you almost
feel you could be on another planet. Boulby is
the best preserved site and surviving remains
include the steeping pits and part of the alum
house. The site has been designated by the Secretary
of State as a Scheduled Ancient Monument.
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