the salt, then evaporating the brine down in
vacuum chambers to form solid crystals.
While some sea salt is still produced by
gradual solar evaporation from open-air salt
pans in sufficiently warm, dry regions, much
is now produced by more rapid vacuum
evaporation.
Removing Bitter Minerals Salt comes from
seawater, and seawater contains significant
quantities of several bitter minerals, the
chloride and sulfate salts of magnesium and
calcium. Producers have a couple of ways of
dealing with these minerals. They can remove
them from rock salt by dissolving the salt,
then adding sodium hydroxide and carbon
dioxide to the brine to precipitate magnesium
and calcium. They can remove them from
seawater by the same means, or else by slow
and gradual concentration in open-air pans,
during which the calcium salts become
insoluble, crystallize, and settle before the