Alum
Our family involvement in the
important alum trade.
The Textile
Fixing Agent
Alum has
been used since ancient times for many purposes including medicinal. It has
variously been used as cure for haemorrhages, nits and dandruff, and other
ailments. From the Middle Ages it began to be used to increase the suppleness
and durability of leather and in the textile industry as a mordant to make
vegetable dyes fast.
Until the
middle of the fifteenth century the supply of alum primarily came from Turkey.
There was a flourishing trade between Asia Minor and Italy. The Italians used
alum for their dyeing establishments. After the capture of Constantinople by
the Turks in 1453, they looked for alternatives to Muslim sources. John di
Castro, who had been a dyer of cloth in Constantinople and had watched the
manufacture of alum, discovered an alum rock at Tolfa, a commune of Rome and
part of the papal states, and an industry began there which still exists. There
was soon a papal monopoly in alum.
The economy
of England, prior to the Industrial Revolution, centred around wool and linen.
This was very much a legacy of the monasteries. They had established the
rearing of sheep, in very large numbers, from which to produce the wool, and
the cultivation of flax, from which to produce the linen. The elite classes of
Tudor England liked to wear bright, rich colours. The only dyes available at
that time were derived from plants and minerals. These were not colour fast
during washing. To fix these natural dyes to the natural fibres of the wool and
linen cloth, it was necessary to soak the cloth in a mordant before putting it
through the dye bath. Alum could be used as a mordant.
Until the
reign of Henry VIII, alum had been sourced from the Italian sources which
remained under the tight control of the Pope. When Henry VIII seized domestic
control of religion from the Pope, it became imperative to find a domestic source
of alum. After some fifty years of prospecting and experimenting, a viable
process evolved for manufacturing alum from a rock stratum that was
particularly abundant in north east Yorkshire.
The earliest
prospecting for alum, towards the end of Henry VIII’s reign, took place in
Ireland, around Wexford. During the reign of Elizabeth I, further prospecting continued on Lambay Island, off
the Irish east coast. In England, the earliest attempts to make alum were on
the Isle of Wight and in Hampshire.
Elizabeth I
encouraged the domestic mining of minerals in order to escape customs payments
to the Pope, and she invited to Britain certain foreign chymistes
and mineral masters. Among them was Cornelius Devoz,
to whom was granted the privilege of mining and digging in our realm of
England for allom and copperas.
The
Process
Alum a
colourless crystal, is a double sulphate of aluminium and one other element, usually
either potassium or ammonium. The manufacturing process was very slow. From
first quarrying the alum shale, to shipping the first cargo of alum crystal,
could take twelve months or more.
Alum was
extracted from quarried shales through a large scale and complicated process
which took months to complete. The process involved extracting then burning
huge piles of shale for nine months, before transferring it to leaching pits to
extract an aluminium sulphate liquor. This was sent along channels to the alum
works where human urine was added.
The first
part of the production process took place outdoors in a quarry. The quarry was
known as the Alum Works, which included all its associated fittings such as
bared rock, a burning place, steeping pits and storage cisterns.
Here men
would use pickaxes to excavate the rock from the quarry face, and then use
mauls to break the pieces down to a more usable size. Shovels would be used to
load the broken rock into wooden wheelbarrows, in which it was transported
along wooden planks, later iron plates, to the burning place. Here the rock
would be calcined in heaps known as clamps.
The clamps
were created by laying down a base of brushwood, about five metres across and a
metre high. Around and on top of this, the rock was added until the pile was two
metres high. At this point the brushwood was lit and the burning started. More
rock was added to the heap and around its sides, until the clamp was perhaps fifty
metres in diameter and twenty metres high. The clamp was then left to burn, in
a controlled manner. The skilled eye of the heap controller would gauge when
the burn had progressed to a suitable state.
At that
point, the burnt rock, now called mine by the alum workers, was removed
and placed in an empty steeping pit. Spring water and collected rainwater was
used to leach the soluble salts out of the mine, resulting a solution
called the liquor. The steeping process was a complicated affair, involving
pumping of the liquor from one pit to another in a carefully regulated
sequence. Eventually, the liquor arrived at the strength desired. It was then
pumped into a holding cistern, to await being sent to the alum house. When it
was required at the alum house, it would be transported there along wooden
troughs or stone conduits.
The Alum
house was the collection of buildings in which the liquor from the steeping
pits was processed through to the finished product, the alum crystals.
On arrival
at the alum house, the liquor was run into cisterns and left to stand
overnight. This allowed debris and detritus to fall to the bottom or float on
the surface. Either way, the clarified liquor could then be used in the alum
house. It would first be run into large evaporating pans set over open coal fired
furnaces. The pans were made of lead and were around three metres long, two
metres wide and one metre deep. They were set on iron plates which, in turn,
were set on iron bars, with the coal fires below them. The liquor was brought
to the boil and kept there until the desired strength was arrived at.
When it
arrived at the appropriate strength, the liquor was run off into settlers where
an alkali was added. The effect of the alkali was twofold. First, it brought
about reactions whereby unwanted chemicals were precipitated out. Second, it
reduced the acidity to the point at which the alum crystals could form. Once
the waste products had precipitated, the liquor was run off into coolers which
were large wooden casks with numerous wooden frames suspended in them. Here the
alum crystals had large numbers of surfaces on which they could form and grow.
Next the
mixture was transferred to small coolers to crystallize. The resulting crystals
of alum were then further boiled and condensed to get rid of impurities.
It was recorded
that the workers suffered terrible conditions. The heaps of shale gave off
poisonous sulphurous fumes. Their wages of 6d a day were often withheld or they were given in half rotten meat and corn.
The alum workers were described as poor snakes, tattered and naked, ready to
starve for want of food and clothes.
During the
final part of the process the crystals were scraped off the frames and the
sides of the coolers and washed with fresh spring water, to remove any remaining
surface impurities. The crystals were transferred to a roaching pan, smaller
than the evaporating pans but made of lead. Just enough hot water was then
added to dissolve the crystals. The liquor, after a final check on its
strength, was transferred to the roaching casks. Here it would cool for about
10 days. The outer cask would then be dismantled, revealing a column of solid
alum crystal. This would be left for another ten to fifteen days to allow the
liquor within the column to have a chance to crystalize further. At the end of
that period, the column would be broken into. The saleable alum was finally
bagged, ready for transport.
Alum in
Cleveland
Alum Shale
is found in beds immediately beneath the sandstone of the North York Moors.
The first
alum works in Cleveland started at Belman Bank in Guisborough Woods at the turn of the seventeenth
century by Sir Thomas Chaloner the Younger, who suspected the presence of alum
because the trees in the district were of a weak colour. He had visited alum
works in the Papal States where he observed that the rock being processed was similar to that under his Guisborough estate. He seems to
have induced Italians to leave the papal works at Tolfa and come to Yorkshire,
for which he was personally excommunicated. Thomas Chaloner of Guisborough is
reputed to have sold his own urine for one penny a firkin, which was about nine
gallons. There were many
odd names for imperial measures including pecks and gills and a firkin a fortnight
for urine.
Alum was
produced near Sandsend Ness five kilometres from Whitby in the reign of James
I.
In the Skelton area alum production
began from about 1603. The first profitable site in Yorkshire was opened in
1603 at Spring Bank, Slapewath, which was then part
of Skelton. This was the project of John Atherton, joint owner by marriage of a
third part of the Skelton Estate. Robert Bell wrote There was a house at
Spring Bank, near Mygrave (Margrove
Park) erected, but not completed for the manufacture of Alum. On the 15th
November 1603 an agreement was made between John Atherton and Katherine his
wife of the one part and Mr Leycolt of the other,
under which the Athertons were, at their own cost, to
complete the house and furnish it with the necessary appliances, namely, four
Furnaces and four pans of lead and iron for boiling Alum, Coolers of lead for
congealing , and convenient Cisterns of lead for keeping and saving the
"mothers" or strong liquors of alum and Copperas (green vitriol
or Iron Sulphate). They were also to set up a lead-finer with furnace, a balnium for trial of the earth for alum and copperas, pits,
pipes, vessels for draining the earth and making liquors and all other
necessary implements.
Once the
industry was established, imports were banned. Britain gradually became
self-sufficient. Whitby grew significantly
as a port as a result of the alum trade and by
importing coal from the Durham coalfield to process it. In 1610 James I made alum
production a monopoly of the Crown.
In 1616 alum
production began at Coombe Bank, Boosbeck and Selby
Hagg between Skelton and Brotton, located to the east of Hagg Farm and
would seem to have had three distinct periods of operation.
It is said
that ships anchored off Saltburn
to transport the finished product. They brought with them casks of urine, which
was mixed with the liquid that had been obtained from the calcined shale. We
don’t know where this process was carried out initially, but it was later done
in an Alum House sited near Cat Nab in Saltburn. The shale liquid ran from
Selby Hagg by gravity down a trough that followed the course of Millholme Beck.
From the
early seventeenth century until the 1860s it was extensively mined at Guisborough and along the East Cleveland
coast. The actual extraction of alum from shale was a long and expensive
process and it took an average of fifty tons of shale to produce one ton of
alum.
The early
works consistently struggled to make alum. There was little chemical knowledge
to turn to. Everything was done by trial and error. Large sums of money were
spent in trying to perfect the process. Something like £150,000 pounds or more
had been spent between 1550 and 1630. At least half a dozen prospectors were
bankrupted.
Nevertheless
after 1630, alum works sprang up all around the northern escarpment of the
North York Moors and along the coastal cliffs from Loftus to Ravenscar.
Competitor works started to emerge at Pleasington in
Lancashire, at Hurlet and Campsie in Scotland, and at
Neath in South Wales.
In the mid
eighteenth century the price of alum was particularly high and reached a peak
of £24 per ton in 1765. It therefore became commercially viable to mine in more
difficult locations. Several new mines were therefore opened including one east
of Ayton at Ayton Bank, just north of
Hunter’s Scar. Cockshaw Alum Works at Gribdale
quarried and processed the shale to produce alum crystals in the eighteenth
century.
At the peak
of alum production the industry required two hundred
tonnes of urine every year, equivalent to the produce of 1,000 people. The
demand was such that it was imported from London and Newcastle. Buckets were
left on street corners for collection and public toilets were built in Hull in order to supply the alum works. This unsavoury liquid was
left until the alum crystals settled out, ready to be removed. An intriguing
method was used to judge when the optimum amount of alum had been extracted
from the liquor by testing whether an egg could be floated in the solution.
The Alum
workings at Hummersea, Loftus
were worked well into the 19th Century.
By the mid
nineteenth century, an industrial process for making alum was patented by Peter
Spence. His works at Pendleton, Lancashire and Goole, Yorkshire were each
capable of producing more alum in one month than the entire Yorkshire alum
shale works ever produced in a year.
By 1871 the
last two alum works in northeast Yorkshire had ceased operation. They were driven
out of business by more efficient production processes and the arrival on the
market of synthetic dyes that did not require a mordant to make the colour
fast.
5 –
Belman Bank; 8 – Selby Hagg; 9 – Saltburn (the alum house for Selby Hagg); 10 –
Loftus; 11 – Boulby; 12 – Kettleness; 13 – Sandsend; 20 –
Eskdaleside
The
Farndales and the alum industry
John Farndale
wrote that Johnny
Farndale, who was a Kiltonian,
employed many men at his alum house, and
many a merry tale have I heard him tell of smugglers and their
daring adventures and hair breadth escapes.
He also
recalled in his works of
about 1870 Lofthouse, and their long famed alum
works, which has been the support of Lofthouse for ages gone, but now
discontinued. How well I remember my school days when we faced all weather
through Kilton Woods, and how I respected my masters – the Rev Wm Barrick, Mr
Wm King, the great navigator, and Captain Napper, steward to the works. The
popular Midsummer Lofthouse fair was the only fair we children were allowed to
attend.
or
Go
Straight to Chapter 17 – John Farndale and the Industrial Revolution
The
Alum Industry of North-East Yorkshire, Chris Twigg, 17 January 2018
A Brief
History of the Alum Industry in North Yorkshire 1600-1875, Roger L Pickles, The Cleveland
Industrial Archaeologist Issue no.2, 1975
Boulby Alum: The Works Diary
of George Dodds 1772-1788, K Quinn, Cleveland Industrial
Archaeology Society Research Report No 9, 2010
The Alum Farm, Major Robert Bell Turton Whitby,
Horne & Sons, 1938