It may not seem like something as hard as marble would have anything in common with something as fragile as an egg (after all, a chunk of marble doesn't make a splattery mess if you drop it on the floor... a big dent, maybe...) but they are actually mostly made up of the same thing — calcium carbonate (CaCO3). Our teeth and bones also contain calcium carbonate.
Calcium carbonate can be damaged and eaten away by acids. Not just the kind of acids your science teachers tell you to stay away from either. Food and drinks can also contain acids that will have the same effect. You know how the parents are always after you about not drinking a lot of soda? Partly it's because of the sugar, but it's also because soda is acidic and acids eat up calcium carbonate. (Soda isn't the only acidic food, of course — for this experiment we'll use vinegar.)
Now, we didn't think you'd want to give up a tooth or a bone (or a perfectly good soda) and marble can be expensive to come by, so we turn to the good ol' egg.
Materials you will need:
1 egg (uncooked) vinegar
1 drinking glass
Place the uncooked egg in its shell in a glass of vinegar overnight. The next morning, pour the vinegar down the drain and replace it with fresh vinegar (be careful not to break the egg!)
Let the glass with the egg in it sit undisturbed for seven days.
What you will be left with is what people call a naked egg. Its clothes, or in this case, its shell, disappears!
So, if Aunt Mabel or Uncle Pete tell your folks that vinegar is a great natural cleaner for the entire house, you can be the hero that stops them before they ruin that beautiful marble floor!