The Leidenfrost effect is a phenomenon in which a liquid, in near contact with a mass significantly hotter than the liquid’s boiling point, produces an insulating vapor layer which keeps that liquid from boiling rapidly. This is most commonly seen when cooking; one sprinkles drops of water in a skillet to gauge its temperature—if the skillet’s temperature is at or above the Leidenfrost point, the water skitters across the metal and takes longer to evaporate than it would in a skillet that is above boiling temperature, but below the temperature of the Leidenfrost point.
Graham crackers were originally marketed as “Dr. Graham’s Honey Biskets” and were conceived of as a health food as part of the Graham Diet, a regimen to suppress what he considered unhealthy carnal urges, the source of many maladies according to Graham. Reverend Graham would often lecture about the adverse effects of masturbation, or “self-abuse” as he called it. One of his many theories was that one could curb one’s sexual appetite by eating bland foods.