Salt repels demons and evil things because it is pure in its whiteness, is a preservative, and is linked to life and health. Salt is contrary to the nature of demons, who are intent upon corrupting and destroying. It should be avoided in magical rituals for conjuring demons.
Salt repels witches and the evil eye. A test for bewitchment is the inability of a person or animal to eat anything salted. Inquisitors in the European witch hunts protected themselves by wearing a sacramental amulet that consisted of salt consecrated on Palm Sunday and blessed herbs, pressed into a disk of blessed wax. One means of torturing accused witches was to force-feed them heavily salted food and deny them water.
Salt is a magical remedy for evil spells. An old recipe for breaking an evil spell calls for stealing a tile from a witch’s roof, sprinkling it with salt and urine, and then heating it over fire while reciting a charm. In American Ozark lore, women who complain of food being to salty are suspected of being witches. One way to detect a witch is to sprinkle salt on her chair. If she is a witch, the salt will melt and cause her dress to stick to the chair.
In superstition it is considered bad luck to spill, borrow, or run out of salt, perhaps because in times past, salt was a valuable and scarce commodity. Spilling salt makes one vulnerable to the Devil; the bad lucky may be negated by tossing a punch of salt with the right hand over the left shoulder.
In Christianity, blessed salt is mixed with blessed water to make holy water.