Sodium Chloride: The Salt of the Earth

Sodium chloride pairs a metal that reacts violently with water and a gas once used as a weapon, yielding a crystal everyone eats. Its cubic lattice was the subject of the first X-ray diffraction studies of atomic structure. Salt once paid Roman soldiers and shaped trade routes. Today it de-ices highways, preserves food, and feeds the chlor-alkali industry that makes chlorine and caustic soda..

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