The boys and I did a little experiment with a couple of raw eggs.
One soaked in water, while the other soaked in vinegar. We covered them to minimize evaporation and keep the vinegar stink out of the room.
After a couple of days, this is what the egg in vinegar looked like.
After about one week of soaking in the vinegar, this is what happened to the shell. It was still on the egg, but it came off on my fingers like chalk when I touched it.
We were supposed to be able to bounce the egg in a bowl, but ours just broke. Oh well! The shell felt like a deflated balloon. It was pretty cool.