Salt scattered at a threshold, dissolved in a bath, or left in a bowl in a corner, usually at the new moon and usually described as clearing.

Salt as a purifier turns up in Shinto, in Jewish practice, in European folk custom and in modern witchcraft, which is a lot of independent arrivals at the same substance. The likely reason is that it visibly preserves food — a thing that stops rot is an obvious candidate for stopping other kinds of rot.