The Book of Household Management by Mrs. Beeton

808. To KEEP THE BACON SWEET AND GOOD, and free from hoppers, sift fine

some clean and dry wood ashes. Put some at the bottom of a box or chest long enough to hold a flitch of bacon; lay in one flitch, and then put in more ashes, then another flitch, and cover this with six or eight inches of the ashes. The place where the box or chest is kept ought to be dry, and should the ashes become damp, they should be put in the fireplace to dry, and when cold, put back again. With these precautions, the bacon will be as good at the end of the year as on the first day.