By Aeiffert, 9/5/2018


Secret Agent's Egg

Secret Agent

About this Experiment

During the American Revolutionary War, the first US spy ring was created, the Culper Spy Ring. Early American secret agents used all sorts of techniques to hide and transfer secret information. You might've already known about invisible ink, but did you know that early spies also used hard-boiled eggs?

In this demonstration, we're going to see how, with a simple ingredient sometimes used in pickling, we can use a chemical reaction to conceal information below the shells of hard-boiled eggs. Hope you brought your appetite for breakfast!



  1. In the bowl, dissolve the alum into the vinegar.

  2. Dip the cotton swab into the alum-vinegar solution and write a secret message on the eggshell.

  3. Wash the egg with water so that there's no evidence of the secret message inside.

  4. Carefully peel back the shell to reveal the hidden message written into the egg itself.

Analysis and Conclusion

Hmm... it seems nobody's added a conclusion for this experiment yet. You can suggest one here.



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