Conjuring Credits

The Origins of Wonder

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Egg Writing

Instructions for making writing appear on the surface of a hard-boiled egg by painting on the shell with a solution of alum in vinegar have appeared for centuries in many collections of scientific amusements and conjuring. The stunt has been included in innumerable beginner's books on magic and is still ubiquitously published. Anyone following the instructions met with failure but assumed he did something wrong. Concerted efforts to discover the correct materials and procedure have fared no better. Given the porous nature of an eggshell, expecting any sort of clear image to be transferred to the surface of an egg is exceedingly optimistic. It turns out that this stunt is folklore, passed on from author to author without empirical testing. The earliest surviving record for this bogus stunt may be an encyclopedic work titled Kestoi, arguably written by Sextus Julius Africanus (c. 160–c. 240). The author of Kestoi recorded this: “Grind gall and alum with vinegar to consistency of ink; use this to write on egg; dry in sun; put egg into strong brine; dry, and remove shell. Cover egg with wax and write; then soak in vinegar overnight; remove wax.” The procedure and its result mutated and varied over the centuries, but none of the variants produced any more writing through the shell of an egg than the method given in Kestoi.