120
The Last Resource
Arab invaders to centres of its production in Western Europe; and
it was an essential ingredient of a sh industry which contributed to
the wealth of British and other European traders. According to the
Domesday Book, the county of Essex was operating hundreds of
salt pans, and the excavation of peat for salt production in eastern
England left shallow pits which became ooded and today, as ‘the
Broads’, are centres for sailing and other water sports. In early
times the loss of salt—making capacity could bring repercussions in
commerce throughout the continent, but today, with the working
of rock salt and other deposits as well as extraction from sea—water,
such shortages are unknown. Nevertheless, some disparity of supply
still exists. For example in the United States the per capita con—
sumption of salt is 280 grammes per day or about four times the
world average, whereas the average consumption per person in
Bengal is a mere ve grammes. ln other words, some people can
still be vunerable to shortages of salt, particularly if they do not
receive enough ofit from other sources such as fresh meat.
In the previous chapter it was seen how the japanese, lacking
salt deposits of their own, turned to desalting sea—water. Normally,
feats of chemical process engineering are not associated with the
provision of salt, but they are denitely needed to extract both
bromine and magnesium from the sea. Apart from anything else,
these two chemicals are far less abundant than salt in the marine
chemical ‘soup’; sea—water contains 3- 5 per
cent salt, but only 0-13
per cent magnesium and even less, 00067 per cent, bromine.
Because they are such ‘lean ores’ vast volumes of sea—water must
pass through extraction plant in order to separate meaningful
quantities of either chemical—and, weight for weight, bromine
requires the processing of some twenty times as much water as
magnesium. Figures like a million gallons of sea—water an hour for
magnesium and more than twice this for bromine are typical
quantities handled by extraction plants.
Prominent in the commercial exploitation of the oceans’ bromine
and magnesium is the Dow Chemical Company of the United
States. Dr Herbert H. Dow, founder of the company, made possible
the economic extraction of bromine from sea—water and today the
Ethyl—Dow Chemical Company at Freeport, Texas, has the largest
bromine—extraction plant in the world. Other companies in the
United Kingdom and France use the Dow process under licence.
The process is essentially simple and consists of freeing the bromine
The Last Resource
Arab invaders to centres of its production in Western Europe; and
it was an essential ingredient of a sh industry which contributed to
the wealth of British and other European traders. According to the
Domesday Book, the county of Essex was operating hundreds of
salt pans, and the excavation of peat for salt production in eastern
England left shallow pits which became ooded and today, as ‘the
Broads’, are centres for sailing and other water sports. In early
times the loss of salt—making capacity could bring repercussions in
commerce throughout the continent, but today, with the working
of rock salt and other deposits as well as extraction from sea—water,
such shortages are unknown. Nevertheless, some disparity of supply
still exists. For example in the United States the per capita con—
sumption of salt is 280 grammes per day or about four times the
world average, whereas the average consumption per person in
Bengal is a mere ve grammes. ln other words, some people can
still be vunerable to shortages of salt, particularly if they do not
receive enough ofit from other sources such as fresh meat.
In the previous chapter it was seen how the japanese, lacking
salt deposits of their own, turned to desalting sea—water. Normally,
feats of chemical process engineering are not associated with the
provision of salt, but they are denitely needed to extract both
bromine and magnesium from the sea. Apart from anything else,
these two chemicals are far less abundant than salt in the marine
chemical ‘soup’; sea—water contains 3- 5 per
cent salt, but only 0-13
per cent magnesium and even less, 00067 per cent, bromine.
Because they are such ‘lean ores’ vast volumes of sea—water must
pass through extraction plant in order to separate meaningful
quantities of either chemical—and, weight for weight, bromine
requires the processing of some twenty times as much water as
magnesium. Figures like a million gallons of sea—water an hour for
magnesium and more than twice this for bromine are typical
quantities handled by extraction plants.
Prominent in the commercial exploitation of the oceans’ bromine
and magnesium is the Dow Chemical Company of the United
States. Dr Herbert H. Dow, founder of the company, made possible
the economic extraction of bromine from sea—water and today the
Ethyl—Dow Chemical Company at Freeport, Texas, has the largest
bromine—extraction plant in the world. Other companies in the
United Kingdom and France use the Dow process under licence.
The process is essentially simple and consists of freeing the bromine