From this book:
In the Chemistry section, I did Experiment 196 – Rubbery Egg.
I put an egg in vinegar in a glass, and I waited several days.
Today we went to see the egg. We took it out and it felt rubbery.
Here’s the explanation:
The vinegar reacts with the calcium in the eggshell, dissolving it. This makes the shell rubbery. This shows the importance of calcium to make the shell strong, just like the calcium in are bones.Keep drinking that milk!
I don’t know how but the vinegar must have done something to the calcium in the shell!