During the American Revolutionary War, America's first secret agents risked their lives to help win their independence. Early American spies used all sorts of techniques to hide and transfer important, top secret information. You might've already known about invisible ink, but did you know that they even used hard-boiled eggs?

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