When a package is filled, a piece of thin muslin, cut so as to just fit
into the top of the package and completely cover the butter, should be
wet in cold water and carefully placed over the top, having the edges
pressed down close to the sides of the tub. Then the cloth should be
completely covered with a thin layer of salt; and if the salt is
moistened, so as to form of it a thick paste that will become air-tight
when it dries, it will do much to keep the top of the butter clean and
sweet--for the more nearly air tight the package is when completed the
better it is for the preservation of the butter. Then put on the cover,
and seal the whole as tightly as possible.