This week I’m enjoying reading Chemistry: The Impure Science by Bernadette Bensaude-Vincent and John Simon. It’s about the philosophy of chemistry and the unique place that chemistry occupies within the natural sciences. Naturally, it takes a historical slant, and traces the evolution of chemical theory and practices. Today’s blog post focuses on Chapters 4 and 5 (“The Space of the Laboratory” and “Proof in the Laboratory”).
What is the laboratory? You can guess that it involves hard work, evinced by the word ‘labor’. The practice of the alchemists in their labors foreshadowed what chemists today do in labs. In fact, the lab ‘practice’ of the alchemists has been adopted by all the experimental sciences. Old paintings of alchemists show dark rooms mirroring the obscure secretive practice of the alchemists. I’m glad that today we work in bright well-ventilated labs, although the chemistry lab has few windows because fume hoods take up much of wall real-estate.
The chemistry lab however differs from the physics or biology lab in many respects. Quoting the authors: “Material is brought into the laboratory to be manipulated and changed into something else.” The essence of chemistry is transformation, be it through synthesis or analysis, the two main operational modes in lab. (Modern instrumentation now allows for ‘non-destructive’ analysis.) The authors also make a nice connection between chemical transformation and knowledge transformation (learning!) as a result of the experiments performed.
The lab occupies an interesting isolated artificial space that I had not quite considered until prompted by the authors: “In order to achieve this kind of control over material transformation, the laboratory has to be a closed, well-delimited space protected from the haphazard, complex circulation of materials and processes that characterize the natural world. Indeed, this is the very meaning of a laboratory, a characteristic paradox that has led to so much productive work in science studies over recent decades. The laboratory is a place deliberately isolated from the rest of the world, and so has little in common with it. Yet, it is a place intended to generate truths about the natural world… Chemists deliberately isolate themselves from natural phenomena to better understand nature.”
I’m a computational chemist, so my ‘lab’ exists in an even more artificial environment than the ‘wet’ labs of my experimentalist colleagues. This reductionist approach to studying nature employed by the sciences has yielded many insights, although it consistently fails when attempting to dissect complex systems. Biology, in its own right, is quite distinct from physics in its methodological approaches. Chemistry occupies an interesting interdisciplinary yet distinct space between the two, and in my biased opinion, is the most interesting of the three!
For chemistry, laboratory work was also the way you proved something. Lavoisier’s famous experiments in 1785 to ‘decompose’ water (an Aristotelian element) into hydrogen and oxygen (known as ‘inflammable air’ and ‘dephlogisticated air’ respectively), and then recompose them back into water, were actually quite complicated given the equipment back then and the deep-seated conviction of the audience to Aristotelian principles. How do you prove things you can’t see with the naked eye? You have to use measuring instruments and your audience has to believe that you aren’t trying to hoodwink them with other means. There’s a reason why glassware is made of transparent glass, although that’s not the only reason.
Lavoisier’s experiment also illustrates three important characteristics of ‘chemical proof’. Quoting the authors: “First, chemists materialize the abstract processes of analysis and synthesis in terms of chemical operations and observable phenomena, an approach that distinguishes chemistry from geometry… practical manipulations as the ultimate proof of veracity. [Second, ]… every step of Lavoisier’s demonstrated is loaded with theory… the fundamental principles such as the conservation of matter… there are no such thing as theory-independent facts… Third, the demonstration by analysis and synthesis mobilized not only theory, but also abstraction… to have the demonstration function, Lavoisier needed to insist on the purity of the raw materials he used, as well as the abstract universal nature of the products. The natural history of these elements and compounds was deemed irrelevant… [paradoxically] this very materialization of Lavoisier’s chemistry… involved a complementary idealization of the material bodies that he put in play.”
These ideas of abstraction and theory-laden facts are very interesting to me as an instructor. What distinguishes the novice from the expert is that the latter has a seemingly invisible scaffolding of concepts, theories, models, and other abstractions. As a chess-master easily recognizes significant positions on the chessboard, so the chemist in me quickly recognizes chemical structures and chemical equations beyond lines, letters, and symbols. How do I help my students build this scaffolding one step at a time, taking into account the invisible basis of atoms and molecules, while connecting it to macroscopic phenomena, and abstract principles represented by symbols? That’s both the challenge and joy of teaching chemistry!
The utility of expert ability has taken interesting turns in the history of science. Gabriel-Francois Venel, who wrote an article on “chymistry” (or perhaps it should be ‘chemystery’!) in 1753 for the Encyclopedie, “defends the chemists’ right to cultivate their own epistemological style… While the chemist’s language might well be difficult, dense and obscure, this is precisely because it reflects their unique empirical experience of the world, an experience that is drawn both from the science and the chemical arts.” Yes, chemistry is as much art as it is science, and in my opinion, sits comfortably with the liberal arts. There’s an equally strong emphasis on what you actually sense (sights and smells) to abstractions in your mind of what’s going on. I think it’s neat that our sense of smell allows us the direct detection of tiny invisible molecules! Too often we rely on sight as our primary sense.
I close with the authors’ discussion on “Seeing at a Glance”. This is the expert’s ability, to combine “several senses at once in the process of developing an intrinsic and non-verbal form of knowledge characteristic of the skilled artisan… this ability of seeing at a glance is not innate. Instead, it is learned through a lifetime of practical experience that breeds practical instincts or intuitions… [for example] a technician specialized in ultrasound techniques has no problem picking out the heart and legs of a foetus where the uninitiated just sees a play of light and shadows.”
Venel uses ‘artist’ in two senses: “as artisan… who by continued application, has trained… [in] a series of techniques that serve as tools in his trade” but also as a “creative genius”, one who cannot easily describe his or her own process of eliciting the tacit knowledge within. I can’t remember how I learned the chemistry that I understand today. I know that in my first two years of high-school chemistry, I didn’t understand anything. Somewhere along the way, something clicked, but I can’t break down that process analytically for myself. It’s likely different for different individuals. However, here’s the rub. This “seeing at a glance” expertise is increasingly supplanted by modern instrumentation in the lab. We can’t just trust our senses, we have to measure something carefully and accurately using the appropriate device to be sure. And increasingly, we are asking machines imbued with artificial intelligence to do this analysis.
And yet, none of the appropriate experiments can be conceived and designed without the tacit knowledge of the expert. Otherwise, Garbage In, Garbage Out. The chemical laboratory might look different today than in previous eras, but the abstract principles behind its operations are perhaps not so different.
No comments:
Post a Comment