In a digital age, the smell of old books seems to be getting rarer. Scientists therefore propose to label dying smells as cultural heritage and have already investigated how you can 'catch' such a smell. They developed a scent wheel as a framework.
A recognizable scent immediately evokes memories and the accompanying emotions. Take the smell of a pipe. It immediately reminds you of those pleasant afternoons at your grandfather's. Nowadays, fewer and fewer people smoke a pipe and the smell is disappearing more and more from everyday life.
Until now, fragrances are not officially part of our heritage, which mainly includes old buildings, art and traditions. But why not? Since 2001, there has been a list in Japan with a hundred typical Japanese scents, such as the scent of sea breeze, antique wood and sake distilleries, which must be preserved for future generations. Wouldn't we want to put the smell of fresh apple pie, speculaas or Brussels sprouts on a Dutch heritage list to save them from extinction? Smells that have already disappeared and therefore unknown can also give us a better picture of life in the past.
Making smell concrete
In any case, scientists at University College London (UCL) thought that smell as a cultural heritage was a good idea. That is why, for the first time, they have systematically tackled the role of smell in our perception of heritage. But smell is abstract and is often experienced in different ways. In order to properly record a odor, a framework is therefore needed with the description of that odor and the chemical components that make up the odor.
As a case study, the researchers used the recognizable smell of old books. They asked people to describe it and also examined the chemical properties of the scent. Based on the results, they then made a scent wheel of the old-book air. This scent wheel makes the scent more concrete.
Snooping for science
Naming the smell of old books was already a difficult task. In our western languages we do not have specific terms for smells. We describe them or name a raw material that the smell reminds us of, such as wet dog, earth or acid. This is partly culturally determined:the Jahai-speaking hunters and gatherers in Malaysia do have words for special scents, Dutch scientists showed earlier. It is much easier for them to name the smell of something.
So the researchers collected the descriptions people gave of the smell. They watched as visitors to the library at St. Paul's Cathedral described the smell of the space in the guest book. In addition, they had 79 visitors to the Birmingham Museum and Art Gallery smell a sample of the scent of a book from 1928. Of the library visitors, 100% used the word 'woody', 86% 'smoky' and 71% 'ground'. The sample from the old book mainly reminded the test subjects of coffee, cocoa and also wood.
Chemical tests
It is therefore often difficult to describe odors and not to store them by placing them in a display case. When they become part of our cultural heritage, it is necessary to identify them correctly and then conserve and protect them. This is where the chemical part of the research came into play. The researchers performed several chemical analyzes of the volatile organic compounds responsible for the odor we perceive. These substances evaporate very quickly and can already be smelled in low concentrations. A scent is always a mixture of many different substances and because of the low concentrations it is difficult to determine exactly which substances you smell. But certainly with strong odors, a number of substances are dominant and these determine our first association with a smell.
The scientists put a 1928 book in a plastic bag for two weeks. They then also put a neutral piece of fiber in that bag, in order to be able to take a sample of the air in the bag – and therefore the odor. They then used extremely sensitive measuring techniques to determine which substances were on the piece of fiber. This resulted in a list of substances that we associate with various scents.
For example, the researchers found furfural ('biscuits'), benzaldehyde ('almond'), limonene ('citrus') and nonanal ('burning wood'). But also substances such as propanoic acid ('trash'), heptanal ('dirty socks') and undecane ('diesel'). All smells that you don't immediately think of when you think of an old book. That gives an idea of the chemical composition of the smell that old books spread. The fibers have also been used to take odor samples from the air in the library, analyze them and compare them with odor samples from the old book.
In addition, a piece of paper from the old book was soaked in methanol to extract various components, from which the scientists made an 'extract' of the old paper. This extract was then sniffed and described by visitors to the Birmingham Museum. By the way, they didn't know that they smelled an old book. The visitors got to smell various 'anonymous' things and had to describe the smell. This is to get as neutral a description of the smell as possible.
Recreating scents is not easy, but the descriptions given by visitors to Birmingham partly matched the descriptions of the scent in St Paul's library. The scientists processed all the results of the test subjects into a spider web diagram. This shows with which words the smell of old books was most often described and in which gradations the different smell descriptions recur.
Scent Wheel
With all the data, the scientists then created the scent wheel. These types of wheels are also used in perfume making and wine making. The research is modest in scope and intended as a starting point for a debate about the preservation of scents as cultural heritage. The old-book scent wheel can serve as an example of how scents with cultural significance can be identified, analyzed and documented.
The scientists' idea is that heritage scents can not only be preserved, but that museums can use them as an extra 'experience' for visitors. It would also help conservators to know how their objects should smell, to recognize decay. Another usefulness of the scent wheel would be that they can recreate (almost) extinct scents. However, this last point is debatable. Scents are very complex to imitate, especially because we do not yet know what exactly is in many scents. And because general descriptions usually don't cover the load well. The smell of, for example, 'coffee' is not always the same. In addition, everyone experiences scents in a different way. It just depends on whether you have good or bad memories of a scent…
Dutch research
Asifa Majid, Linguist at Radboud University, studies how sensory perceptions are expressed. The English scientists also cite her work. Majid:“In Dutch science too, there is a growing interest in scent as a cultural heritage. As the UCL scientists have already shown, chemical research alone is not enough. It is important that we understand a smell and language, and the way we articulate smells, is crucial. It is difficult without fixed words for scents. This developed scent wheel with standardized vocabulary makes it a lot easier. With regard to the experience of cultural heritage, it is very useful to investigate how we can preserve scents. We already have images and audio for posterity, but we are still missing the scent history!”
Which fragrance would you like to have on the Dutch heritage list?