SALT PRODUCTION [and "secret salt' ]
Continuous and reliable supplies
of Salt, were a matter of such importance that the establishment of early settlements, the
rise and decay of civilisations, demographic shifts of populations and the development of
agriculture, were intimately related to the immediate availability of salt.
The power to
control a population's salt supply, was power over life and death. Erratic sea level
changes, particularly in the Mediterranean where the minimal tide was
relied upon to fill coastal evaporation pans, prevented some of these civilisations from
obtaining consistent salt supplies, causing them to migrate or decay, conquor
or succumb.
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Boiling
[peat] - Solar pan evaporation - Rock mining - Saltpeter -
Tinder - Gunpowder - The East India Company
-Glass - Leather - table salt -
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Salt is physiologically
absolutely necessary for human life, but in the past [prior to the Industrial Revolution]
the known mineral salt sources were so limited that its supply was a
critical demographic power factor for most communities.
It was only available as visible
and exposed rock outcrops in arid regions, or as dried out salt cake on the shores of some
seas and salt lakes. In areas with wet climates, the protruding salt dissolved making it
almost impossible to discover. It is probably this, more than for any
other reason, that many of the great civilisations first developed near deserts and desert
climates, for example the Mediterranean region, at the edges of the "arid"
zones.
Solar evaporation on vast flat coastal areas was
considerably easier, than manually quarrying and hacking at rock salt. Though the
technology was not easy and was handed down from generation to generation. A large share
of the world's consumption of salt - is still made by the ancient methods of trapping
seawater or salt spring brines, and evaporating the brine and concentrating the salt,
either artificially, or under the sun's heat.
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| U.S. salt production has become
more efficient. At the time of the U.S. Civil War, 3,000 workers
produced over 225,000 tons of salt in the United States. Today, there is
a third more workers, but they produce 100 times more salt.
China has more than doubled its production in the last
10 years
Worldwide, salt production
tracks consumption which, in turn, reflects population growth (food
salt) and industrial development (chemical salt, salt for animal
nutrition, roadway safety, water conditioning, etc. Salt production
globally was about 250 million tons in 2006
see Salt Institute statistics
Table Historic Salt production per man employed [known figures]
Period Locality (tons) Men employed Method ofProduction One man makes per year (tons)
1900 Taodeni(Sahara) 4000 250 primitive mining 16
1900 Coserra(Italy) 6000 250 primitive mining 24
1890 Sicily 17,000 400 primitive mining 43
1660 Tirol(Austria) 12,000 250 (+300 for gathering wood) brining 48 (22)
1700 Rhe’(France) 4000 250 solar 16
1960 Reichenhall(Germany) 100,000 400 brining 250
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BRINE PRODUCTION
Ancient
coastal salt manufacture depended on the availability of wide flat coastal areas and in
making clever use of natural, shallow depressions, lagoons or manmade salterns about 15-20
cms deep. These had to be positioned at mid-tide level to facilitate filling [without
industrial pumps], the evaporation pans in order to concentrate the brine, and later
for harvesting and drying the precipitated crystallised salt.
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China
- Drilling for salt circa 400 AD - to depths of 3000 feet" |
"Chinese salt pan
production - still used today.
Yellow River - the great bend." |
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Chinese
Town Drilling rigs and wells |
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It takes approximately, 50000
cubic/m of sea water spread over 100000 sq/m, of flat solar evaporation area, to produce
1000 tons of salt a year. There are two other important conditions:
- # an equable climate with a warm breeze and a hot sun
- # a reasonably steady sealevel. [The Mediterranean tide
fluctuates only a few centimetres, whereas the oceans may have tides of more than than
some metres]
Such areas
were abundant when the sea was one or two metres below its present level; they became
comparatively rare with a sea level of one or two metres higher, Even in Delta areas of
the some rivers, like the Nile, Rhone, and the Euphrates, the establishment of new pond
levels was very difficult, and the cycling of the brines from one level of concentration
to the next could take months and years .
.A
change of climate conditions, or a minor ocean fluctuation could have had a serious effect
for ancient coastal saltmaking. Manual rock mining or inland salt springs or lakes
like the Dead Sea suddenly became the only alternative.
Table
Fuel needed for production of 1 ton salt |
Tons
of fuel |
Fuel |
Source of fueland salt |
Method used |
Location |
Year |
| 4 |
wood |
brining and wood gathering on 100,000 sq/m
woodland per year |
'camp' fire |
Tyrol |
1600 |
| 14 |
peat |
Ocean water |
Ash extraction |
Jutland |
1650 |
| 6 |
coal |
Ocean water |
Open pan |
England East coast |
1700 |
| 1 |
coal |
Brining |
Open pan |
Cheshire |
1700 |
| 0.2 |
coal |
20 kw/hr |
Vacuum pan |
Germany |
1950 |
| 0.02 |
coal |
200 kw/hr |
Vacuum pan - compression still |
Switzerland |
1950 |
| 0 |
solar energy |
100 sq/km of flat impermiable pan area at ocean
tide level |
Solar pan |
Mediterranean |
1950 |
Techniques
Among other important
concepts to move the huge quantities of brine, and technical innovations developed in
producing salt, were the measurement of density and pumping by screw, both ascribed to
Archimedes. The first use of impellers and sail type
windmills was to operate an Archimedean screw and chain pumps for controlling water and
brine flows. To move the huge quantities brine from the sea into the evaporation pans,
controlled flooding by tides was the only answer.
Boiling
In regions where solar
energy could not be used the salt maker was forced to use solid fuel to 'boil' brines. In
northern Europe, [PEAT PRODUCTION OF SALT] - and
also wood. Whole forests were devoured leaving only the stumps.
In Japan it was seaweed.
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HALLE Germany - boiling pan model |
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Luneburg Salt well before 1500 - In 1569
the well was converted to a pumping system Up to the year 1569 the brine was won out of
the "Sod" (well pit) with a barrel-like jar called "Öseammer". The
workers of the salt works called "Sodeskumpane" had to lift up the jars with
their own muscle power. A kind of seesaw called "Sodrute" served as a lever.
When visitors come upstairs from the basement they stand in front of a faithful copy of
such a "Sodrute" with a "Öseammer" hanging from it |
Solar pan Evaporation
Crystallisation of salt
in solar pans in hot climates, occurs naturally. The crystals first form on the surface of
the brine. As they become soaked - the evaporating surface brine reaches saturation
point before the cooler lower layers.
Salt mushrooms growing
in the Dead Sea - nucleation occurs
quickly upon anything protruding from the brine
Additional crystals grow beside these crystals which become
partially submerged, rather than below them, or above them, and a typical
"funnel" or wedge shaped form of crystals takes shape. The familiar salt
"mushrooms" can be seen growing in salt lagoons and pans.
Manual harvesting in Morocco
The specific gravity of a Sodium Chloride crystal is 2.16.
and the saturated brine at 25 C contains 26.7% salt. and has a specific gravity of 1.2004.
At 15 C a saturated solution contains 26.5% salt, and has a specific gravity 1.203. Hence
a solution saturated at a higher temperature is specifically lighter, even though it
contains a greater quantity of salt. It is this explanation that allowed salt makers to
crystallise "blocks" or briquettes of salt on
 the surfaces of ponds, using floating elements such as sticks and straws to
form the crusts of salt.
. It should be noted that with most other substances,
crystallisation can not occur at the the solution surface because their solubility
increases more rapidly than their specific gravity decreases. [see Jewish Salt Technology - Religion]
Dikes
enclosing solar evaporation ponds and pyramids of raked-up salt
At the end of the last Ice Age, around 17-15000 BC, the
ice sheets covering the earth's surface began to retreat, flooding the continental shelf
where many early populations seem to have lived. The average mean sea level rise was about
1 metre a century, the most rapid period being betwen 8,000 and 5,000 BC By about 2000 BC
the oceans had recovered from the Ice Age lowlevel, risen again and had probably reached a
metre or so above today's level.
Sea level variations, either seasonal, short lived or
long term may have been caused by different events or a combination of them. Among the
most obvious, may have been changes in atmospheric pressure, changes in ocean currents,
wind driven waves, storm surges, heavy rainfall increasing the run-off from rivers.
However, as the last ice age has demonstrated, [and of
present concern regarding global warming,] the colouring of Antarctica with Volcanic ash,
or other pollutants and the subsequent warming fusion [fractioning] and melting, of the
polar ice sheets and glaciers was, and is, of catastrophic proportion in comparison
Control of the colour of the Antarctic ice cap, and the
ALBEDO of the white snow cap, may be our immediate concern in the near future.
ROCK MINING and PRIMITIVE
SOURCES
Many regions of the Earth, for
instance equatorial Africa, consist of igneous rock where rain and ocean spray dust are
the only sources of salt . Plants exist which are capable of concentrating such
dilute solutions by evapotranspiration, and there are insects which can collect salt from
water containing less than 0.006% of chlorides and concentrate them in their bodies to
about 0.3% . Until recently some humans survived solely by drinking the blood and urine of
herded and wild animals. Roaming over wide areas these animals collected and concentrated
the salt in their blood by feeding on large quantities of
plants . (Man tribes like the Masai kept their animals alive for systematic bleeding.)
Springer's map of precolonial Africa shows immense areas where this happened and the low
population density of the African
Typical Calcolithic hammer
hinterland can be ascribed to
this diet of near salt-starvation . Furthermore, there is no doubt that early settlements
grew up around salty springs which hunting tribes had discovered by following animals to
their salt licks.
Another remarkable source of
salt is registered in Springer's [110] map, namely where people burned plants to use the
resulting ash as a supply of very poor grade salt; in effect they replaced the stomach of
the ruminant animal by combustion.
Cardona's Salt Mountain
One might almost call it the
first primitive agriculture. Shcultz a describes how "... in the Brazilian rain
forest, deep in the Amazon river watershed, live the Suya people. Their women collect
water hyacinth, dry them and burn their leaves. The ash is then passed through a kind of
grass filter after it has been dispersed in hot water. The filtrate is evaporated in an
earthenware pot over a wood fire until it becomes a thick brown sauce which jellies to a
dirty coloured mass when cooled down . This, divided into minute portions, serves as
spice..."
Although this ash is too rich
in potassium carbonate to serve as a good source of salt, it is almost the only way to
avoid salt starvation. The other alternative is cannibalism [19b]. As Springer points out,
"It is known that salt-starved animals eat part of their litter in order to stay
alive, and consequently several authors have ventured the opinion that extreme salt hunger
is one of the causes of cannibalism. This seems to have become habitual in parts of Africa
and New Guinea where people have been subject to serious salt deficiency for a long
time..." Primitive man living in rain forests far from the sea suffer the same
deprivation , as generally it is not practicable to transport ocean water, with its 97%
water-content, deep inland. The aborigines in New Guinea, however "... make secret
expeditions to the sea coast.... to put seawater into hollow bamboos which are carried
back to their tribe.
There were many early attempts
to quarry and mine salt. Salt tunnels containing stone hammers and axes have been found at
sites in Asia Minor, Armenia, South America and near the salt river civilization in
Arizona. The Hallstadt salt mines in the Austrian Alps and the Italian mines in Lungro,
Cosenza and Etruscan Volterra supported prehistoric communities forming important centers
of inland civilization. , Surprisingly, very similar specialized tools were used in all
four continents. , , The production of salt from concentrated brine is much easier than
quarrying or mining. The method consists essentially of bringing the natural brine into
shallow ponds enclosed by low earth walls and allowing the Sun to evaporate the water. The
deposited salt layers are then harvested. On the shores of the Dead Sea one may find
disused solar pans that were dyked by ancient saltmakers. In China very old solar pans described in 1882 by the German geologist von
Richthofen are still in operation at the saltwater swamps that lie in the great bend of
the Yellow River. Operations similar to those described by von Richthofen provided salt
for Iran's important Isfahan district. In Africa , Timbuctu and Kano were supplied for
thousands of years from Taodeni and Bilma.
Salt brine boiling
A striking feature of salt
swamps is the red colour caused by algae and bacteria multiplying in their stagnant water.
The salt produced there is red, whereas quarried salt is grey and usually contains gypsum
which gives it less flavour because of reduced solubility. The Madaba Map , dating from
about 550 A.D. shows two ships sailing on the Dead Sea , one loaded with reddish salt from
the old solar ponds and the other with grey salt from the quarry at Mt. Sodom.
The red brine not only looks like blood but also
tastes like it and makes a deep and disturbing impression. The Bible indicates this in
Kings II.3.22 "And they rose up early in the morning and the Sun shone upon the
water, and the Moabites saw the water on the other side as red as blood. And they said,
"This is blood".
Airphoto of 'red' brines in static ponds coloured by 'Dunaliella'
algae
This passage probably
refers to the red salt pans at Sodom. The old name ";Sodom" for the southern end
of the Dead Sea may be a contraction of the Hebrew words "sade" (meaning field)
and "adom" (meaning red). That reddish salt was made there at the time of the
Jewish uprising against Rome about 130 A.D. is proved by pieces of salt found by Yadin in
a burial cave of the period . This salt corresponds in colour and size of crystal, to what
would be expected from careful crystallization from red brine on sticks.
It was the Chinese who
about 400 A.D. conceived the modern idea of drilling
deep into salt deposits and bringing up the brine for evaporation. They used bamboo
pipes and some borings were as deep as 1000 meters. As fuel for evaporation they used
coal, wood or natural gas which came from the same wells .
Maya Treasure: Empire's First Wooden Artifacts
The remnants of a large
salt
factory are found submerged in a peat bog
off the coast of Belize.
By Thomas H. Maugh II, Times Staff Writer
A Louisiana archeologist has discovered the remains of a massive Maya
salt-production
complex submerged in a lagoon off the southern coast of
Belize.
Examination of the underwater site also revealed the first wooden
structural artifacts from the empire, including poles and beams used in
building the salt
factories. A wooden paddle from the canoes used to
transport the salt
via inland waterways also was discovered - the
first time such a Maya object has been found, researchers said.
Archeologist Heather McKillop of Louisiana State University reported
today in the Proceedings of the National Academy of Sciences that she
and her colleagues had so far discovered 45 facilities for
salt
production in the mangrove peat bogs of Punta Ycacos Lagoon.
"There are many more sites there," she said in an interview.
The discoveries are "tremendously exciting," said archeologist Tom
Guderjan of Texas Christian University, who was not involved in the
research. "We have never, in that region of the world, found
preservation of architectural materials [wood] like she has found
underwater."
The discovery of the paddle is particularly intriguing, he said,
because even though Maya art shows canoes, researchers have been unable
to find any traces of them.
"We've all been looking for the canoe," Guderjan said. "It could be six
inches under the muck."
Salt played a
crucial role in ancient economies because humans needed
it to survive and also desired its taste. It also has a variety of
secondary uses, such as preserving food.
The cities of the Maya civilization are largely in areas that have
little salt.
Researchers previously discovered ancient production
centers in the salt
flats of the Yucatan as well as along the Caribbean
coast, but none is large enough to have accommodated the needs of Maya
society, which dominated much of Central America from approximately the
4th century to the 16th century.
McKillop's findings suggest that many, if not most, of the Maya
salt
facilities were along the coast and became submerged during the last
millennium as ocean levels rose. The immersion actually led to their
preservation. Being buried in peat protects wood from decay, McKillop
said, and being underwater prevents artifacts from being trampled,
making identification and analysis much easier.
McKillop initially identified four
salt production
facilities in the
lagoon and decided to expand the search. A team of students equipped
with snorkeling gear divided the surface into grids and looked for
submerged pottery, buildings and other items.
In three weeks of study, they found 41 sites characterized by pottery,
wooden posts and beams, obsidian objects and other artifacts.
The largest structure was at Chak Sak Ha Nal, where 112 posts define
the exterior walls of a rectangular building measuring about 36 by 65
feet. Inside the perimeter are 31 posts marking off rooms. The
arrangement of the structure's other pieces of wood, such as beams,
remains to be mapped.
The interior areas contain remnants of large, apparently mass-produced
urns that sat over fires on clay cylinders about a foot high. Seawater
would have been placed in the urns, scientists say. The water would
boil away, leaving behind the
salt.
Although it has just begun examining the sites, McKillop's team has
found extensive evidence of artifacts produced in inland cities,
indicating well-developed trade over the Central American waterways.
The salt would have
been loaded into canoes and paddled upstream, where
it would be exchanged for a variety of goods.
The partially degraded paddle that was discovered - virtually
identical to those seen in Maya art - ties the
salt facilities to
inland trade, McKillop said.
The facilities "represent a new kind of economy that we haven't looked
at before," she said. Researchers have long studied the royal court
workshops in large Maya cities that manufactured goods for the elite.
At the opposite end of the scale, they have studied household economies
where family members made things for their own use.
The salt factories
represent an intermediate stage in which small
groups of people were producing things for the entire society, McKillop
said.
http://www.latimes.com/news/nationworld/world/la-sci-maya5apr05,0,723...
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