In his sixteenth book entitled "If Invisible Writing." ("Wherein are handled secret and undiscovered Notes."), he details a myriad of techniques used
to accomplish what could be considered today as Steganography the art of hiding or disguising secret information. An excerpt from chapter four is
reproduced below:
"How you may write in an Egg.
Because when prisons are shut, Eggs are not stopped by the Papal Inquisition, and no fraud is suspected to be in them, I will show you how letters may
be writ on the upper shell and white of an Egg also. For example,
That letters may be seen upon the white.
Yellow, and better when the Egg is boiled. Boil an Egg hard and roll it in Wax, and engrave the letters on the Wax with an Iron point, that the marks
may lie open. Put this Egg into Liquor with Alom and Galls powdered. Then put it into sharp Vinegar, and they will penetrate, and taking off the
shells, you shall see them in the white of the Egg. Africanus teaches it thus. Grind Galls and Alom with Vinegar, till they be as thick as ink. With
this write what you will on an Egg, and when the writing is dried in the Sun, put it into sharp Pickle. Dry it, boil it, and take off the shell, and
you shall read the writing. I put it into Vinegar, and could do nothing of it. Perhaps, he means by Pickle, Capital Lees. The cause is this. The
Eggshell' is porous, and has large holes, which is plain. For being set to the fire, it will sweat, and water will come forth. And looking at it
against the light, it will show clear. So then, Vinegar being subtle, penetrates by the pores, and makes the shell tender. And when it is mingled with
the Alom and Galls, it carries their substance with it, and makes them appear on the white. And when it is put into cold water, it is condensed, and
comes to be hard as it was. But observe, it must not stay long in Vinegar. For that will eat off all the shell, and will leave the Egg bare, having
nothing but a thin skin to cover it. And if you put that into cold water, the shell will not come again. If you will know," |
