From The Food Encyclopedia by Jacques Rolland and Carol Sherman
Also canning salt, canning and pickling salt. Pure, fine-crystal salt with no impurities or additives, such as iodine and/or anti-caking agents, which darken pickles and make brines cloudy. Pickling salt can be used in the same manner as table salt, but other sources of iodine should be included in the diet to prevent thyroid diseases caused by iodine deficiency.
