Dissolving eggshell

Another egg experiment took us a week to complete. That's how long we had to wait to see the results.

How can we make an eggshell on an unboiled egg disappear and the egg bouncy?
Simply place the whole egg with uncracked shell in vinegar and let it sit in it for a few days.

This is how the egg looked like after one week:

And here is a one minute long clip from our experiment:

In the clip I say that this brown stuff is the leftover eggshell, but it's actually the membrane that's between the egg and the shell. Thanks to that membrane which did not dissolve, the egg still holds it shape (until Jaś bounces it too many times).

What has happened?
The vinegar contains acetic acid (kwas octowy) which reacts with the calcium carbonate (węglan wapnia) that the eggshell is made of. The acid simply breaks the calcium carbonate into calcium and carbonate. The calcium ions float freely in the vinegar and the carbonate goes to make carbon dioxide which shows as bubbles on the egg.