Atlas Obscura, the website of all weird and wonderful places and things, recently published an article on Soap Sally, a wicked washerwoman, child murderer and entrepreneur from Appalachia with roots to the Old World. It’s a pretty fascinating read!
The tales of her evil-doings are rooted in the threat to misbehaving children that Soap Sally might lure them into her home, let them gorge themselves on candy and when they fell asleep, Soap Sally would stuff the kids into her stewpot where they would be melted into wax. (Yikes!!!)
According to the article, a linguist from the University of South Carolina traced the emergence of Soap Sally back to the 19th century when ash for lye was collected by families to make soap for the laundry. The theory was made that gruesome tales of Soap Sally were intended to keep children focused on their chores rather than getting to the ashes (or resultant lye solution) which could have been extremely harmful or even fatal.
You can read the full article (with some very nice old pictures) here.