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  • Writer's picture Armel Cornu

Putting the Senses to Chemical Use

Fig. 1: The Alchymist, 1850, Hellmer, Edmond. Courtesy of the Science History Institute.

Stepping inside a modern laboratory almost always conjures strong sensorial impressions. Few chemists don’t feel immediately transported to work when they catch the distinctive smell of technical grade acetone. But although sensorial impressions are constantly present in chemical work, it is easy to overlook their importance. The senses are often viewed as remnants of the past, as subjective, and unreliable ways to perceive the world. While sensible perceptions can sometimes be deceptive, or change from one person to the next, the senses have nevertheless played an important role in the history of chemistry and continue to be important to current chemical practice.

A common narrative of the early history of chemistry presents Lavoisier — the so-called father of the discipline — as the forerunner of modernisation, as he and his allies advocated for a renewal of chemistry in late eighteenth-century France. This scientific campaign, referred to as the “New Chemistry”, was characterised by a stated reliance on instrumentation and precise quantification. Because of the misguided dichotomy that opposes the rational and the sensorial, it is often thought that the sensory practices that had been part of alchemical and chemical practice for centuries had to be eliminated in order for chemistry to be modernised.

However, as shown by the publications of Lavoisier and his colleagues, the New Chemistry actually made no special efforts to abandon the senses. The most avid followers of Lavoisier — and the man himself — all frequently made use of their sensory capacities while conducting their science. This becomes clear from an important publication of the New Chemistry: the Annales de Chimie.

Fig. 2: Cover page of the Annales de Chimie, 1789. Courtesy of Google Books.

This periodical, published from 1789 onwards, compiled works from French chemists and their correspondents. Throughout the numerous memoirs, letters, and notes found throughout the Annales, very few contributions failed to feature the senses at least once. The most present sense, unsurprisingly, was sight. The majority of chemists described the changes they witnessed such as the colour of a precipitate or the sudden appearance of bubbles in a solution. But other senses featured often too. Many chemists described the taste of solutions, others identified specific airs by smell. The texture of various substances was also described using the vocabulary of touch. Sound, while less frequently featured, did find its way into various contributions too.

An important application of the senses was in the identification of substances. Chemists could instantly recognise the smell of sulfur, or burning arsenic, and they often used taste to differentiate between identical-looking salts. Sensory impressions were also used when tracking ongoing changes. Visual changes were a convenient way to note that a chemical change had occurred. Likewise, a sudden sound, the fizzle of a substance, or a fleeting scent, could all indicate that some noteworthy reaction had taken place, and were thus worthy of being reported.

In addition to their frequent use as tools of identification, the senses were often the point of the research itself. The contributors to the Annales de Chimie wrote about problems of common concern to the public. They studied new medicines and described their tastes so as to make them more appealing to apothecaries’ customers. Mineralogists often emphasised the visual quality of the stones they worked with, likely appealing to the interests of jewellers. Chemists also studied the composition of alternatives to certain food products, like chocolate, tea, or coffee, hoping that satisfactory substitutes would limit the reliance on foreign imports. In that way, chemists put their well-tuned senses to the service of the French industry.

A telling example of the applications of the senses to the support of societal issues can be seen with Chaptal’s memoir on saltpetre (a substance referred today as potassium nitrate, which was used in the manufacture of gunpowder). Jean-Antoine Chaptal (1756–1832) was trained as a physician in Montpellier before coming to Paris in 1776. There, he furthered his studies in chemistry and at this occasion met with some of the partisans of the New Chemistry. He later assumed a position as a professor of chemistry in Montpellier. During this time, he engaged in correspondence with Lavoisier, slowly becoming more acquainted with the work of him and his network of chemists. It is therefore no surprise that Chaptal, the author of a chemical treatise, went on to become a regular contributor and editor to the Annales de Chimie.

Fig. 3: First page of Chaptal’s memoir on Saltpetre. Photo by author.

Chaptal contributed a lengthy memoir to the 20th volume of the Annales, published in 1797.1 This memoir titled “General Views on the formation of Saltpetre and on the establishing of artificial Nitraries”, described different ways of synthesising saltpetre. Chaptal was aware of the importance of this product to the French state. Gunpowder could not be synthesised without saltpetre, making a steady supply of the product crucial to the war effort. He stated: “The liberated France which regards saltpetre as one of the most precious elements of its freedom [...] must seek ways of reanimating this portion of the national industry”.

Chaptal’s support of the French state and manufacture of gunpowder was conveyed using sensory means throughout the memoir. He described the variance in colour of the kinds of earths that were most suitable to saltpetre manufacture. Since those who worked in manufactures weren’t always trained as chemists, he used common and relatable language in his descriptions. He explained for example that: “poisonous plants, and those that have a strong and stinking smell, seem to be most favourable.” This kind of advice was practical, sufficient for the purposes of the industry, and easily understood by most people.

Chaptal was not alone in advising to use sensory means to improve chemical manufacturing. The contributors to the Annales de Chimie made frequent mentions of applications of chemistry to questions of public concern, which often had a sensory component. The diversity of these applications highlights a lesser-known facet of the New Chemistry, one which departs from the traditional focus on quantification and highlights a continuity with the longer history of chemical practice. The senses endured before, during, and after the “Chemical Revolution”, because they were useful. Chemists who wanted to improve the dairy industry, create appealing colours, or cheap gunpowder, needed to tune their own senses, communicate their sensorial impressions with one another, and effectively trained their bodies to become another chemical instrument.

References and further reading:

[1] Chaptal, “Vues Générales sur la formation du Salpêtre et sur l’établissement des Nitrières artificielles,” in Annales de Chimie, eds. Guyton et al. (1797) 20:318.

  • Nils Otto, Ahnfelt, Hjalmar Fors, and Karin Wendin. “Historical Continuity or Different Sensory Worlds? What We Can Learn About the Sensory Characteristics of Early Modern Pharmaceuticals by Taking Them to a Trained Sensory Panel.” Wissenschaftsgeschichte 43 (2020): 412–29.

  • Barwich, A. S., Smellosophy: What the Nose Tells the Mind. (Cambridge: Harvard University Press, 2020).

  • Hasok Chang, “What History Tells Us about the Distinct Nature of Chemistry”, Ambix, (2017): 360–374.

  • Lissa Roberts, Peter Dear, Simon Schaffer (eds), The Mindful Hand, Inquiry and Invention from the Late Renaissance to Early Industrialisation (Chicago: University of Chicago Press, 2007).

  • Pamela H. Smith, From Lived Experience to the Written Word, Reconstructing Practical Knowledge in the Early Modern World, (Chicago: University of Chicago Press, 2022).

  • Emma Spary, Feeding France, New Sciences of Food. (University of Cambridge, 2014).

  • Simon Werrett, “Fireworks and Color in the Sixteenth and Seventeenth Centuries,” Early Science and Medicine, Special Issue: Early Modern Color Worlds, 20, no. 4/6, (2015): 458–77.

* Armel Cornu graduated with a doctorate in History of Science from the University of Uppsala, Sweden. She is a postdoctoral fellow at the Science History Institute in Philadelphia, Pennsylvania. Her research takes a social, economic, and sensorial approach to the history of early modern science.

** This piece is based on the paper “Senses and Utility in the New Chemistry”, which was awarded the 2023 Partington prize. The full publication will be published in Ambix volume 70 and is available open access here.

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