Turning the edges of cards:

A turned-down corner indicated that the card had been delivered in person, rather than by a servant. Some elaborate cards had the words Visite, Felicitation, Affaires, and Adieu imprinted on the reverse side, on the corners. So whichever corner was turned up, one of those corners appeared and explained the reason for the visit.

Could someone have mistaken "turning" for "burning"?