When you walk into a library or a book store, the odor that works its way to your nostrils is a rather distinct one: the smell of old and new books. In fact, that unique smell is so loved that many avid readers still prefer physical books over the convenience of their digital versions.

Even science fiction author Ray Bradbury once said, "A computer does not smell ... if a book is new, it smells great. If a book is old, it smells even better... And it stays with you forever. But the computer doesn't do that for you. I'm sorry."

So it's sort of a surprise that it's only now that chemists have attempted breaking down the chemical composition of books that creates that smell. And it turns out it's a lot different for new books than old books.

Although new books are, well, new, they still give off a distinct odor. If you hold a new book up to your nose, you'll get a whiff of paper, ink and the book binding's adhesive. However, different books smell differently, because in today's modern age, different books use different chemical processes, paper treatments and adhesives in their making.

This makes it difficult to determine specific chemicals that contribute to that smell, but all new books have three things in common: paper, ink and adhesives for binding.

The process of creating paper from wood pulp itself involves a variety of chemicals, many which give off volatile organic compounds (VOCs), which release into the air and create odors. Then there's ink and adhesives, which also give off smells associated with books.

However, it's the chemical compositions of older books that is most interesting. Although some readers like new book smells, it is old book smells that many are the most fond of. And that chemistry is easier explained because the breakdown of compounds in the paper itself causes the smell.

Older books have paper that contains a lot more cellulose and lignin, which come from the paper's original source: trees. These chemicals degrade and release VOCs, releasing scents that remind us of almonds, vanilla and flowers.

The rate of these chemical breakdowns in paper is also used to date old books.

So, basically, it isn't any one thing that makes books smell the wonderful way that they do. But there is no denying that these smells are powerful and compelling.
