A few days ago I mentioned the “smell of books” in the context of scents that various perfume and other scented-product manufacturers are trying to produce. The aroma is caused by various chemical compounds that are released as books age. Here’s a video that goes into more detail about exactly which compounds those are.
Now, if only they could find a way to attach these aromas to e-books. Scratch-and-sniff stickers on the e-readers? I doubt we’ll actually get a Kindle with a built-in potpourri burner.