The first edition of this standard was approved July 1949. The standard was revised January 1978 and ANSI approved it in April 1978. This standard covers the purchase of sodium chloride in the form of rock (rock salt), vacuum- evaporated granular, compressed evaporated, or solar evaporated salt for use in the recharging of cation-exchange materials for softening municipal and industrial water supplies. The following sections are included: material specifications, general conditions including compliance and rejection, definitions, impurities, physical and chemical requirements, marking, inspection, sampling, packing, shipping, and testing methods. In this edition evaporated salt and compressed evaporated salt have been combined and a specification has been included for solar salt. The history of the standard is also included.