Old Books, Chemistry, and the Science of Smellology

A Book Patrol exclusive: Scratch n’ Sniff this image for
“A combination of grassy notes with a tang of acids and
a hint of vanilla over an underlying mustiness.”

I don’t know about you, but when I have difficulty falling asleep at night, I reach for the latest issue of Analytical Chemistry. Take it from me, counting volatile and semi-volatile organic compounds (VOCs) is far more effective than counting sheep.

A recent issue, however, jumped out of my hands, conked me on the noggin, and made my nostrils itch.

“A combination of grassy notes with a tang of acids and a hint of vanilla over an underlying mustiness.”

Tasting notes from Robert Parker on a vintage ‘59 Romani-Conti? No, a description of the bouquet of old books by chemists who have introduced – finally! – a new method for linking a book’s physical state to its corresponding VOC emissions pattern.

Hallelujah!

Uh, what?

In AC’s review of a recent Analytical Chemistry paper, Material Degradomics: On the Smell of Old Books, Charles Schmidt writes:

“Leaf through an old book and one of the first things you’ll notice is a distinctive musty odor—the product of volatile and semi-volatile organic compounds (VOCs) from paper seeping into the air. This familiar scent speaks volumes about a book’s condition. As a book ages, the composition of its VOC emissions changes characteristically. Volatile compounds that account for an old book’s smell also supply clues to its condition.”

Matija Strli and colleagues from University College London, the Tate art museum (U.K.), the University of Ljubljana, and Morana RTD (both in Slovenia) studied this phenomenon, their goal being to “diagnose” decomposing historical documents non-invasively as a step toward protecting them. Ordinarily, “traditional analytical methods are used to test paper samples that have been ripped out,” Strli says. “The advantage of our method is that it’s nondestructive.”

Readers who’ve yet to have the sandman slug them into slumberville need to know that material degradomics correlates phenotype—i.e., a book’s condition—to metabolic byproducts: in this case, VOC emissions from degrading paper.

Asleep yet?

As I barely know what the hell I’m writing about, please allow the paper’s abstract to speak on my behalf:

“We successfully transferred and applied -omics concepts to the study of material degradation, in particular historic paper. 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. On the basis of volatile degradic footprinting, we identified degradation markers for rosin and lignin in paper and investigated their effect on degradation. Apart from the known volatile paper degradation products acetic acid and furfural, we also put forward a number of other compounds of potential interest, most notably lipid peroxidation products. The nondestructive approach can be used for rapid identification of degraded historic objects on the basis of the volatile degradation products emitted by degrading paper.”

That cleared things up, yes?

Here’s the point: Based upon their research and methodology, a hand-held analytical device can now “sniff” valuable holdings on a book-by-book basis, essentially smelling the book to determine its age, rather than removing a paper sample from the volume for chemical analysis and destroying it in the process.

This is science in the service of the humanities at its best. Yet, unschooled as I am, I believe I have a much more effective method for determining a book’s age without having to smell it or destroy a leaf. I hesitate to mention it before I’ve had a chance to contact the Patent Office but, dear reader, I trust you, so here it is:

Check the date in the book. If that doesn’t work, ask a knowledgeable rare book dealer or rare book librarian. Stump them?

Grab the bibliosmellometer.