Salt, Salt Making, and the Rise of Cheshire

Man obtains salt (sodium chloride — NaCl) from sea water, from naturally occurring rock salt, and from brine formed when water dissolves rock salt. Salt is necessary for the maintenance of life. It enhances the flavour of food. It preserves food by being toxic to micro-organisms and restricting their growth. Salt has long been used in agriculture, glazing pottery, curing leather and dyeing textiles. Its use in the manufacture of heavy chemicals dates from 1773 when Scheele isolated chlorine from salt. Chlorine bleaching became a feasible industrial process after 1799 when Tennant patented bleaching powder. In 1791 the introduction of the Leblanc Process for making soda from salt gave rise to the synthetic alkali industry.