The sea is a chemistry, too. Over 60 elements have been discovered in
measurable amounts in solution or in suspension in the ocean. Many of
these are in the form of salts, making seawater a highly efficient
electrolyte, and a most corrosive fluid. The study of corrosion and
techniques for combatting it is a continuous one in which nuclear energy
already has a principal role.
Because the sea is so much a chemistry, it is a potential source of
minerals for the world’s growing industrial appetite. All of our
magnesium and most of our bromine already are extracted directly from
seawater. Oil and sulfur are mined from the sea floor or beneath it, as
are coal (United Kingdom and Japan), iron ore (Japan), tin (Thailand and
United Kingdom), diamonds (Southwest Africa), and gold (Alaska). In the
layered sediments that cover the ocean-basin floors to depths of
thousands of feet, geologists believe there also may be found some
missing chapters of earth history.
[Illustration: _Nodules such as these containing manganese cover
millions of undersea acres on the ocean floor. Many nodules are rich
in nickel, cobalt, zirconium, and copper. Metallurgists are seeking
ways to recover the metals from these deposits._]
The ocean, by and large, is an opaque fluid through which light travels
only a few hundred feet and most other radiant energy not much more than
a few yards; yet through this same fluid, sound waves, by contrast, have
been transmitted and received over distances of many thousand miles.