Chemistry

The following sections are included:

• PREFACE

• ACKNOWLEDGEMENTS

• CONTENTS

Look around you! How many of the objects in your immediate environment are products of synthetic chemistry? Of course, the answer to this question will depend on where you are. For those of our readers fortunate enough to be trekking through a rainforest in Costa Rica, perhaps some of the clothes you are wearing and the ink on the pages of this book are the only such products. For the majority of you reading this book in your home, your office or your classroom, much of what surrounds you is made up in part or in totality of synthetic polymers, usually coloured using synthetic dyes made in factories that transform petroleum into the rainbow of colours so characteristic of contemporary interior design. In many modern environments — the interior of an aeroplane, a train or a car — it is probably easier to try to pick out the few materials that are not synthetic chemicals (metal, wood, leather, cotton, wool, brick, plaster, etc.) and assume that the rest is fabricated from petroleum-based rubbers, plastics or other synthetic polymers. Even natural materials are now usually covered by some synthetic coating, and few paints or lacquers are still made entirely of naturally occurring materials…

For many people, the opposite of something "chemical" is something "natural" and this dichotomy is conceived as being both exhaustive (everything is either chemical or natural) and exclusive (something cannot be both chemical and natural). But you do not need to find a particularly pedantic scientist to remind you that all natural objects and materials are composed of chemicals, as is all matter, and that many products, such as aviation fuel, for example, that we talk of as being "chemical" are simply purified "natural" substances. Nevertheless, to dismiss this opposition between "chemical" and "natural" as groundless, an approach sometimes adopted by chemical companies in their communication strategies, is to miss the deep sociological or psychological message that lies behind this widely accepted distinction.

In the previous chapter we used the history of chemistry to explore and explain the recent (or perhaps not so recent) crisis of confidence in chemistry. This problem is accentuated by the fact that the crisis resonates with much older traditions and perceptions of chemistry. Thus, our modern-day fear of chemistry reflects a much longer collective memory that stretches back at least to the medieval period. Although largely unconscious, this memory is regularly reactivated and accentuated by the media as well as by popular scientific literature and fiction.

Why is it that chemists are so reluctant to entertain any universal philosophical perspective — to view nature from an Archimedean point located somewhere outside the world? This philosophical distinction reflects a geographic specificity of chemistry — the laboratory. While situated in the wider physical world, the laboratory is a space set aside for productive sweat and toil, for putting the material world to the test by means of a human being's manual engagement with substance. The laboratory, as its name suggests, is above all a place of labour, and this distinctive site of knowledge, invented by the alchemists, remained the exclusive domain of chemists until it was in turn adopted by the other experimental sciences as they started to emerge in the seventeenth century. The fact that the laboratory remained the exclusive property of chemistry for such a long period of time obliges us to examine this object in more detail, with more than just a suspicion that it might hold the key to our initial question. Thus, it is important to try to understand what kind of knowledge is produced in this characteristic site, and ask what special powers, if any, the laboratory might possess…

Earlier, we argued that the picture that Diderot and Venel presented of the chemist as a skilled artisan helped to construct a positive image of a laborious science in which all knowledge was earned at the price of the scientist's sweat and toil. Despite the various changes in chemical laboratories brought about by the introduction of physical instrumentation over the course of the twentieth century, being able to see at a glance — le coup d'oeil — remains central to being a good experimentalist. This ability has oriented the science towards a particular method of investigation — the indexical method. Carlo Ginzburg has elaborated this kind of approach in his historical work, suggesting a parallel with Sherlock Holmes's method whereby one searches for any available clues and then follows the avenues that they open up.¹ This approach is as much about intuition as it is about any formalized or formalizable reasoning. However, neither the painstaking work of Diderot's heroic artisan nor the intuition of Ginzburg's detective-scientist are capable of establishing the chemical truth or of winning over other chemists to a proposed interpretation of nature. This is why the "sentimental empiricism" promoted by Venel and Diderot was replaced by Lavoisier's new experimental style of chemistry. In order to illustrate this transformation, and to try and understand what is involved in the "work of proof" — to use an expression of Bachelard's — we will examine one of Lavoisier's best-known experiments involving the analysis and synthesis of water.

"Chemistry creates its object. This creative faculty, akin to that of art, forms an essential distinction between chemistry and the other natural or historical sciences."¹ This famous claim made in 1876 by the French chemist Marcellin Berthelot has been regularly cited by chemists throughout the twentieth century, notably by two Nobel laureates: Robert Burns Woodward in 1956, and Jean-Marie Lehn in 1987.² This phrase has continued to ring true for chemists for more than a century, despite the profound transformations undergone by the science. The aim of this chapter is, therefore, to try to understand what essential truth about modern chemistry is conveyed by the claim that chemistry creates its object, at least in the eyes of the chemists themselves…

The following sections are included:

• The Ancient Concept of Phusis

• Atoms versus Elements: Two Rival Systems

• Is Chemistry Aristotelian?

• The Aporia of the Mixt

• Mixts or Compounds, Stahl or Lavoisier

• A Vexing Question

• Notes

While it is evident that attempts to explain chemistry in terms of quantum theory could only appear following the development of quantum mechanics in the twentieth century, this type of reductionism has a much longer history. In general, reductionism is the idea that a science, such as chemistry, can be reduced to a more "fundamental" science, in this case physics. As we shall see in what follows, the very conception of reductionism assumes a hierarchy in the sciences between the more fundamental sciences, usually physics and mathematics, and those that are seen as derivative or epiphenomenal, starting with chemistry, and passing via biology to the human sciences such as sociology or psychology. Thanks to the popular press and other media, we are familiar with the attempts to reduce human psychology to neuroscience, for example, although this kind of endeavour is recent when compared with the effort to reduce chemical interaction to the laws of physics. In 1669, Bernard Le Bovier de Fontenelle, the first and most famous lifetime secretary of the Royal Academy of Sciences in Paris, proposed the following comparison:

Through its visible operations, chemistry resolves bodies into a certain number of crude tangible principles; salts, sulphurs, etc. while through its delicate speculations, physics acts on the principles as chemistry acts on bodies, resolving them into other even simpler principles, small bodies fashioned and moved in an infinite number of ways: this is the principal difference between physics and chemistry. […] The spirit of chemistry is more confused, more dense; this spirit is more like mixts, where the principles are mixed together one with another, while the spirit of physics is clearer, simpler, less obstructed, and, finally, goes right to the origins of things, while the spirit of chemistry does not go to the end.¹…

Today, we are surrounded by artificial chemical substances, ranging in sophistication from household bleach to the modern polymers that encase our MP3 players or form the resistant kitchen surfaces that wipe clean with a brush of an equally artificial "sponge". Nevertheless, despite the omnipresence of these chemical products, no particular substance symbolizes chemistry as effectively as a simple chart displaying all the elements known to modern science presented in a specific pattern. Indeed, just the outline of the periodic table with its characteristic block layout is enough to evoke an association with the discipline of chemistry in the minds of scientists and laymen alike. It was the discovery of the periodic repetition of similar properties exhibited by a series of elements of increasing atomic weight that first allowed the organization of all the known elements in an ordered structure in the nineteenth century. While today's chemistry student learns the explanation of the periodic table in terms of the electrons filling the orbitals around a nucleus, this theoretical justification was completely absent when Mendeleev first proposed the periodic relationship. Indeed, for this Russian chemist working in the 1860s the existence of these series of elementary octets was an entirely empirical proposition. Mendeleev was, however, happy to go beyond simple empirical observation and even left empty spaces in his table; spaces that were to be occupied by elements yet to be discovered. Thanks to his table, Mendeleev was even able to estimate the atomic weight of these currently unknown elements…

One of the great philosophical questions that has challenged humankind at least since the first written traces of philosophical inquiry is: What can one know? There are two parts to this question; one ontological, the other epistemological. The ontological question is what exactly is there to know? What makes up the world? The epistemological question is what out of the range of things that make up the world can we know? Of course, these two questions are intimately associated because philosophers are constrained in their ontological thinking about what makes up the world by their mode of knowing, be it divine revelation or scientific empiricism…

The opposition of nineteenth-century French chemists to atomism is difficult for many philosophers and historians to understand except when it is presented as a stubborn refusal to look objectively at the scientific evidence for ideological or philosophical reasons. Nevertheless, this difficulty in understanding this opposition to atomism arises from another amalgam, this time concerning not positivism but atomism. The atomism proposed by certain organic chemists of the time as the basis of a controversial structural theory was not the atomism of the early-twentieth-century physicists like Rutherford and Bohr. The physicists' atom was the answer to the physicists' question concerning the structure of matter, and, as such, has focused philosophers' attention to the exclusion of all other answers. This exclusive focus on the physicists' atom has the advantage of providing the last step in the classic version of the positivism-atomism fable outlined above. In this view, the experimental demonstrations of Jean Perrin, followed by the elucidation of sub-atomic structure by Rutherford and Bohr, were finally able to force the recalcitrant positivist chemists to accept the reality of atoms…

In this chapter, as we approach the end of the book, we will move on from the more epistemological issues to focus on the chemist's ontology. Having offered a critical evaluation of the chemist's power to know things and the means at their disposal, we now want to try to understand what type of ontology they can adopt, or, more precisely, raise the question of what ontology might be appropriate in light of their scientific practice…

To Eric K. Drexler, the champion of molecular manufacturing, the traditional art of chemical synthesis is a messy and primitive way of making things. The chemist chooses certain reactants and mixes them up together in a vessel in the hope that a sufficient number of molecules will come together to make the desired product. Drexler advocates a radically new technology that involves manipulating individual atoms and molecules, piecing them together like Lego® bricks, thereby delivering complex molecular products cleanly and efficiently. In contrast to this dream of synthesis without waste, Drexler characterizes current organic synthesis as a haphazard and somewhat unreliable approach to making complex molecular chains:

Chemists have no direct control over the tumbling motions of molecules in a liquid, and so the molecules are free to react in any way they can, depending on how they bump together. Yet chemists nonetheless coax reacting molecules to form regular structures such as cubic and dodecahedral molecules, and to form unlikely-seeming structures such as molecular rings with highly strained bonds. Molecular machines will have greater versatility in bondmaking, because they can use molecular motions to make bonds, but can guide these motions in ways that chemists cannot.¹…

While new technologies may be reviving old alchemical ambitions to play God by creating life, we do not want to suggest that all chemists are or have been tainted by this Faustian spirit. There are doubtless as many visions of the ambitions of chemistry as there are chemists. Likewise, there is no eternal essence to chemistry to be traced back across the centuries. Nevertheless, there is a relatively consensual public perception of chemistry that has emerged over the course of the twentieth century but this does not represent any essential reality about the discipline. Thus, chemistry's Janus-face image of both modest servant (supplying the materials demanded by modern society) and arrogant creator (imposing its polluting products while claiming to improve on nature) is a cultural artefact shaped over time in specific historical contexts that has in turn deeply influenced our understanding of modernity. To see this we need only think about the values and attitudes traditionally promoted by chemists, or at least by many chemical companies. These values include progress through material consumption, the multiplication of choice by the introduction of new substances, and constant industrial expansion, often assuming a model with unlimited raw materials and an indefinite capacity for the environment to absorb by-products and waste.¹ These values are associated with the dominant ideology of industrial and post-industrial culture, making it quite logical that political movements criticizing modern consumer society should target chemistry in their attacks.

The following sections are included:

• BIBLIOGRAPHY

• INDEX