Scientists Create a Wheel of Old Book Smells

In a first step toward understanding what they call the “heritage of smells,” researchers at University College London have diagrammed the various aromas associated with old books. They published their findings in the journal Heritage Science.

“We don’t know much about the smells of the past,” the authors write. “Yet, odors play an important role in our daily lives: they affect us emotionally, psychologically and physically, and influence the way we engage with history. Can this lead us to consider certain smells as cultural heritage?”

Scientist Cecelia Bembibre sampling the volatile organic compounds of a historic book using solid phase microextraction. Image Credit: © H Mahgoub

 
To explore this question, the researchers conducted a series of experiments on the intersections between aroma, culture, history, and place. First, they collected samples of the air inside an 18th-century library and analyzed it to identify all its scent-producing chemicals.

Next, they asked visitors to the library to describe the library’s scent as specifically as they could. Every single visitor said “woody,” and many called it “smoky” or “earthy,” and 70 percent agreed that the smell was pleasant. Some called it “pungent.”

For their last experiment, the researchers presented visitors with eight common smells, including a coal fire, a fish market, coffee, and old books. Again, they were asked to describe each scent, although it was old-book smell that the researchers really cared about.

Perhaps surprisingly, the most common descriptor was some variation of “chocolate.” Coffee, burning wood, “old,” “dirty socks,” and fish all made appearances as well.

The researchers collected each descriptive term and organized them into a diagram much like a color wheel. At the center are major scent profiles like grassy/woody, sweet/spicy, and fishy/rancid. Each major group is then split into individual object smells like vinegar, biscuits, and old clothing—each of which has its own chemical type.

"Our study opens a discussion about developing a vocabulary to identify aromas that have cultural meaning and significance," corresponding author Cecilia Bembibre said in a statement. She said the wheel of smells also “… has the potential to be used as a diagnostic tool by conservators, informing on the condition of an object, for example its state of decay, through its olfactory profile."

Wheel image: Bembibre & Strlič 2017. Heritage Science.