This summer the Smithsonian blog noted an article from the International League of Antiquarian Booksellers on the chemistry of that smell:
Scientists say that “old book smell” is more than just mustiness; it contains hints of grass and vanilla. That’s because all the compounds used to make the book release distinctive odors as they break down. For example, lignin, which is present in all wood-based paper, is closely related to vanillin. As it breaks down, the lignin grants old books that faint vanilla scent.The abstract of the underlying scientific paper, published in 2009, goes into more detail:
It’s even possible to approximate the age of a book based on its smell. Chemists have identified 15 substances often present in books (known as VOC’s) that degrade (and therefore emit a gas) at a predictable rate.
The main volatile degradation products of paper, constituting the particular “smell of old books”, were determined using headspace analysis after a 24 h predegradation procedure. Using supervised and unsupervised methods of multivariate data analysis, we were able to quantitatively correlate volatile degradation products with properties important for the preservation of historic paper: rosin, lignin and carbonyl group content, degree of polymerization of cellulose, and paper acidity.Those scientists, some working with the Centre for Sustainable Heritage in Britain, appear to have been most interested in the preservation and dating of books. But I can also imagine interest in their findings from people who wish to create books as luxury items. What could be more luxurious than a book that smells wonderfully old but is actually in great shape?