Prout's Hypothesis

Alchemy became a bad word. Alchemists were recast as frauds, charlatans, and tricksters, claiming to tell you the secret to unlimited wealth and health – for suitable payment. History is glossed over and framed from the point of view of the winners – the modern chemists. We do real chemistry! The dark magic of alchemy is merely an illusion that dissolves in the light of true science.

 

But reality is much more complicated. In his 2014 Dibner Library Lecture, Lawrence Principe tells a surprising story, not known to most chemists. The lecture is titled “Alchemy and Chemistry: Breaking Up and Making Up (Again and Again)”. Principe is both a chemist and a historian. He’s written the landmark book about the history of alchemy. And in my last blog post, I discussed his investigation into the phosphorescence of the Bologna Stone. Having read a number of his works, I thought I was well versed in the (hi)story of alchemy, but I gained some new insights from reading the text of his Dibner lecture.

 

I had thought that alchemy essentially died when modern chemistry was ushered in by Lavoisier and his contemporaries towards the end of the 18^th century. But I was wrong. Alchemy’s name had been sullied, but it was still alive and kicking, biding its time quietly. The new reigning paradigm was that once you distilled substances to their most fundamental, these “elements” were fundamental. You couldn’t transmute or change one element to another. But in the 19^th century there came three new developments that questioned whether indeed elements were immutable.

 

The first of these, thanks to Lavoisier’s insistence of very careful measurements of atomic weights, was the following observation (in Principe’s words): “the atomic weights of nearly every known element, about fifty at that time, turned out to be integral multiples of the weight of the lightest element, hydrogen. Carbon weighed exactly six hydrogens – oxygen eight, sulphur sixteen. There was no reason to expect this striking regularity… This strange outcome led William Prout (1785-1850) to propose in 1817 that all the known elements were actually condensations of hydrogen, such that hydrogen was the unique material building block of everything.”

 

Determining the fundamental building block of all matter was an old philosopher’s trade going back to the sixth century BCE. Thales thought it was water. Anaximenes thought it was air. Heraclitus thought it was fire. Xenophanes thought it was earth. Empedocles brought them together as the Four Elements theory, later championed by Aristotle, and it was a fundamental building block for the early alchemists. I tell this story on the first day of class before moving on to Lavoisier and Dalton (he of atomic theory fame). I’ve known about Prout’s hypothesis, but hadn’t figured out how to discuss it effectively in class; I used it once (but students just seemed puzzled) a number of years ago but have since left it out. I have written about pantogen.

 

Prout’s hypothesis had its detractors and supporters. Berzelius, who was integral to transforming the alchemical mess of elemental symbols into the standard ones we use today, was against the hypothesis. Berzelius argued that some elements, notably chlorine and copper, had masses that could not be a multiple of hydrogen. (A quick look at the periodic table will show you that most of the elements have atomic masses close to an integer value, but there are some exceptions, including chlorine and copper.) Dumas, on the other hand, was a supporter of the hypothesis because of the discovery of isomerism. As Principe says: “Isomerism implied that some unsuspected internal arrangement of their common components determined the properties of these substances, rather than merely the kind and number of atoms they contained. A similar dependence of properties on internal structure rather than on composition appeared in the phenomenon of polymorphism…”

 

The third observation came from the “radical theory” of organic chemistry. A notable example is ammonium (shown to contain one nitrogen and four hydrogens) which moved as a cluster (“radical”) or a unit. In particular, ammonium could substitute for the metal in a salt. Principe explains that this was “a type of substitution reaction that had long been recognized to occur among various metals, but only among metals. The implication was that ammonium was itself a metal composed of two nonmetals… that metals could be compounds after all, just so tightly bound that the means of decomposing them had simply not yet been found.”

 

Threading through Principe’s lecture is the story of an individual I had never heard of: Cyprien-Theodore Tiffereau (1819-1909), later known as “the alchemist of the 19^th century”. Alchemy wasn’t dead, but it had gone underground. Principe argues that, in France, shortly after its premier scientific academy was founded, political figures and administrators forbade members of the academy from studying the transmutation of metals, characterizing such activity as both futile and fraudulent. However, according to Principe: “The Academie’s chymists, however, acted the way all academics should towards administrators. They ignore them.” Principe provides several examples leading up to the late 18^th century when alchemy peters out with the theories of Lavoisier and Dalton.

 

Tiffereau is an interesting character. He goes to Mexico to learn more about making daguerreotypes (forerunners to photography), but what’s he’s really interested in is metals and their ores, and the possibility of transmutation. Principe writes that in 1846, “he achieved a result that would inspire (or haunt) him for the rest of his days. After exposing nitric acid to strong sunlight for several days, he poured it over filings of a silver-copper alloy and left the mixture in the sun. A portion of the filings dissolved. He then boiled the mixture to dryness and added more acid. Upon repetitions of the process, the initially greenish-black residue grew increasingly lighter in color, and finally turned a brilliant metallic yellow. His tests (and those done by others later) showed the yellow material to be gold.” He was successful three times. The ores he obtained came from mining operations where gold was also found. Tiffereau’s explanation builds off Prout’s hypothesis: He thinks that copper is converted to silver by incorporating oxygen, and then in turn, the silver is converted into gold. Nitric acid acts as an oxidizer.

 

The Mexican-American war forces Tiffereau to return to France. But he is not able to replicate his experiments, and he beseeches the Academie for funds (and help) to do so. And thanks to the work of Dumas, they seemed at least open to the possibility, although ultimately no help was forthcoming. Tiffereau thought the problem might be the weaker sunlight in France compared to Mexico. A similar argument was made by John William Draper (who became the first president of the American Chemical Society). Draper made a claim that he had succeeded in converting silver into something with similar properties to gold when he did his experiments in America, but they failed in the weaker sunlight of England. These arguments might sound spurious to us today, but I’m now more circumspect given that the difference in light can lead to very significant differences in the wide world of biology that I’ve been learning from The Optics of Life.

 

By the late 19^th century, alchemy and the transmutation of metals had fallen out of favor again. Principe argues that this was because “the occultist revival and its radical interpretation of alchemy… had now made the subject more distasteful, even embarrassing, to scientists. Many occultists set themselves in explicit opposition to the scientific establishment, decrying chemistry as mechanical and lifeless and chemists as blind… In the context of the occult revival, it was now alchemy’s turn to spurn chemistry.” Meanwhile, Tiffereau shoulders on, now thinking that the missing link could be the (recently discovered) nitrogen-fixing bacteria present in the soil and the ore. He called them “mineral microbes”.

 

But in the 20^th century, the twin discoveries of radioactivity and the internal structure of the atom would revive transmutation. With more modern apparatus that could alter the composition of the atomic nucleus (usually with neutron bombardment), scientists would successfully convert platinum or mercury into gold. (Platinum and mercury are the left and right neighbors of gold on the periodic table.) Chemistry classes all over the world now teach that elements are uniquely defined by the number of protons in the nucleus (known as the atomic number). Hydrogen’s atomic number is 1 and its most common isotope only has a single proton in its nucleus. In a way, one might say Prout’s hypothesis has been revived – different elements can be formed by adding protons or hydrogen nuclei. However, the energies required to effect this transformation are huge, and most of what we call chemistry – involving the movement and transfer of valence electrons far outside the nucleus – takes place at more accessible lower energies.

 

Principe says in his conclusion: “The successive making-up and breaking-up of alchemy and chemistry underscores the commonality of goals and practices expressed by the word chymistry when speaking of the early modern period. The desire to understand and control matter and its transformations lies at the heart of both alchemy and chemistry… The story also underscores how difficult it really has been (and remains) to understand the microstructure – indeed the very nature itself – of matter, a realm forever beyond the limits of human sense perception.”

 

This blog post is just a small excerpt from a wealth of interesting information provided by Principe in its lecture. Do an internet search and read it in full for yourself!

Bologna Stone

Today, if you encountered a glowing rock, you are likely not to touch it with your bare hand. Who knows what it might do to your flesh? It might be radioactive. It might be an egg of a dangerous alien species, ready to emerge and gruesomely kill you. Modern science and sci-fi have conditioned our response to be cautious about glowing rocks. But you’d still be curious about it. Very curious. You might contact NASA – maybe it fell from the sky? Or perhaps a scientist at the local university? All this assumes you’ve taken pictures and video with your smartphone, all at arm’s length, to document your find!

 

Back in 1602, a cobbler found that certain stones, after being roasted in a furnace, could glow in the dark. These stones only came from a specific location: along the slopes of Monte Paderno near the city of Bologna, Italy. These stones were phosphorescent; they absorb light, and then emit light for some period of time before the effect fades away. (Not to be confused with fluorescence which is closely related, but the light emission is much quicker and is not persistent. Also not to be confused with chemiluminescence where chemical energy is converted into light emission.) This became known as the Bologna stone. It only worked with the stones from this particular region.

 

I learned about the Bologna stone reading Peter Wothers’ book on the origin of element names in today’s Periodic Table. The cobbler, Vincenzio Cascariolo, who discovered the stones’ phosphorescence didn’t know anything about its chemistry. He called it spongia solis, meaning ‘sponge of the sun’, thinking that the stone soaked up the rays of the sun akin to a sponge. The famous scholar and polymath Athanasius Kircher thought that “the stone was a kind of magnet acting on light in the same way that an ordinary magnet acts on pieces of iron.” Turns out that moonlight can also be sponged up by the Bologna stone, and it became known by many names including lapis phosphorus, meaning ‘the stone that carries light’.

 

It turns out that the Bologna stone has no phosphorus. To learn more about the history and chemistry, I read Lawrence Principe’s article, “Chymical Exotica in the Seventeenth Century, or, How to Make the Bologna Stone” (Ambix 2016, 63, 118-144). Principe has also written a superb book on the history of alchemy that is now on my bookshelf, one of the rare instances where I buy the book after reading a copy from the library.  In the Ambix article, Principe details the investigations of Wilhelm Homberg on the Bologna Stone. But Principe isn’t just an armchair historian, and he goes through the process of trying to reproduce the lost art of making these stones phosphorescent. In the process, he discovers that it’s not just the particular type of ore (chemically-speaking) that you begin with, but impurities present in the preparation can enhance or inhibit the phosphorescence.

 

The story takes many twists and turns. To acquire his vast expertise in these ‘chymical exotica’, Homberg trades in chemical secrets. I’ll tell you a secret preparation that I know if you tell me one that you know. No one outside of Bologna could prepare these stones, so Homberg travels there and learns. Eventually the methods were published, but they were hard to reproduce. One might suspect that perhaps a crucial step or ingredient was purposefully left out in the published procedure to maintain the value of the secret, but this does not seem to be the case. Homberg himself was very confused when after being successful in Italy, he was unable to reproduce the effect in Paris where he now had a prestigious position in the Academie Royale des Sciences. After failing over and over again, and trying to avoid his imploring fans and colleagues to show them the process, he stumbled upon success in a fascinating tale that Principe elaborates. Here’s an excerpt with Homberg as narrator.

 

What chagrined me more was that I had promised to teach one of my friends the method of making the stones luminous, and he was pressing me strongly to keep my word to him. After many excuses, I ran into this friend one day on the street in his neighbourhood, and he led me to his house and showed me some raw Bologna stones and a furnace which he had had made expressly for this calcination according to the design I had given him… Being thus pressed, I began again the operation which had so often failed, and to speak the truth, I was trembling all the while, for I had not told him that I had always failed at it in Paris. When the operation was finished I found the stones the most brilliant and luminous that I had ever seen. My astonishment was enormous, for I had changed nothing in the operation. These were the same stones as mine, for I had given them to him. After having examined everything well, I found no difference except that in this last operation I used a bronze mortar… in place of the iron mortar which I had used in my laboratory in Paris.

 

The primary ore of the Bologna stone is barium sulfate (BaSO₄) which does not exhibit phosphorescence. Roasting in the furnace drives off the oxygen turning it into barium sulfide (BaS). For that, you need both a reducing agent and the right (high) temperature to facilitate the chemical reaction. But the key to phosphorescence is the impurity of the Bologna stone. It contains trace amounts of copper(I). Wothers explains: “During exposure to light, electrons in the copper ions become energetically excited and trapped in defects in the barium sulfide crystal. Over time, the electrons return to their lower-energy tate, emitting the stored energy as light once again.” The presence of iron significantly inhibits the phosphorescence, which is why Homberg failed in his Paris laboratory. Bronze, on the other hand, is an alloy containing almost 90% copper. Thus, the grinding in the bronze mortar introduces more copper impurities and the brighter glow!

 

Principe learns much more from his process. It begins with going to Bologna to look for the stones and finding that no one sells them, he has to make use of the seventeenth century accounts to find them in nature. It is a credit to the early writers in their specificity and a wonder that modern development had not destroyed the original site that Principe was able to find the right ores. Many crystalline ores in the vicinity looked similar, but Principe knew that the barite (common name of BaSO₄) would feel much heavier in the hand. Getting the furnace with the right conditions is also tricky. The standard chemical explanation that you just need to burn it with charcoal (elemental carbon) as the reducing agent will work. We can even write a balanced chemical equation for it (BaSO₄ + 2 C à BaS + 2 CO₂). I even used this equation in a stoichiometry G-Chem exam question some years ago.

 

When Principe designed the furnace according to Homberg’s description, he figures out that there won’t be complete combustion because the vents are too small. He also notices that the flames have a purplish hue just outside the vent (but not inside the furnace). Thus, the reducing agent acting on barite at the furnace temperature is actually carbon monoxide. If there was complete oxidation within the furnace, carbon dioxide can instead react with the ore to form barium carbonate (BaCO₃) instead of the desired BaS. In his conclusion, Principe notes that “chemical processes, even the ‘simple’ ones, frequently turn out to be far more complicated in practice than one would imagine, and this is often the case because of subtle or unnoticed differences in materials… [These materials] have their own histories, which include the problems of finding starting materials that are correct and consistent, and developing methods of preparation, many (perhaps most) of which will fail, more often with some practitioners than others… Considering the enormous variation in materials such as purity, particle size, and origin, as well as more obscure factors like scale, climate, and the reactivity of vessels and instruments, it is amazing that anything beyond the most tri vial chemical reaction actually works the same way twice.” There is also a visceral feeling that you can only get when you repeat the experiment, and not as an armchair theoretical chemist. The stones, when correctly prepared, stink. Principe finds that he “could accurately predict how brightly a stone would glow based on how strongly it smelled… when the calcined Bologna Stone ages and ceases to luminesce, the odour of Sulphur likewise vanishes.”

 

I learn from Wothers that while the Bologna Stone was unique when first discovered, eventually more glow-in-the-dark were discovered. Seventy years later, in a serendipitous discovery Balduin’s Phosphorus – a preparation of calcium nitrate that contained no phosphorus whatsoever – was discovered. It gave rise to the word ‘phosphoresence’. Around the same time, phosphorus was discovered and purified. The light emitted from phosphorus does not come from phosphorescence. Rather it is chemiluminesence. Phosphorus (the ‘white’ version that is molecular P₄) oxidizes quickly and flashily and is dangerous to handle. And in the eighteenth century, fluorite (calcium fluoride ore, CaF₂) was found to emit light, but it does so only when heated up, having absorbed radioactive rays over a long period of time that have trapped excited electrons in the crystal. Once the emission is over, the fluorite cannot easily and quickly be recharged (unless exposed to a strong radioactive source). Turns out this is a great way to carry out ‘thermoluminescent dating’ of ancient pottery and ceramics.

 

Today, modern chemists can easily make glow-in-the-dark novelties that employ a variety of physicochemical mechanisms. They’re so common now, perhaps they are no longer novelties. But back in the day when the Bologna Stones were ‘discovered’, it must have been an enigma to experience.

Chemist's Basilisk

The element bismuth (#83 on the periodic table) was also known as the chemist’s basilisk. I learned this reading Peter Wothers’ book on the naming of chemical elements, aptly titled Antimony, Gold, and Jupiter’s Wolf. What is a basilisk? If you’ve read Harry Potter and the Chamber of Secrets, you’d know that it was a serpent that turned you into stone if you looked into its eyes. Hermione cleverly figures out that this king of serpents was making use of pipes (or the plumbing system) to travel through Hogwarts.

 

Why would bismuth be connected to the basilisk? Turns out that artisans making pewter would mix bismuth with tin “that it may confer splendor and hardness to it… bismuth hardens and gives a shine to tin”. That’s why bismuth was also known as tin-glass. The German chemist Rudolf Glauber referred to bismuth as a Demogorgon, “named after the dreadful snake-haired sisters whose look turns the beholder to stone.” (This is not to be confused with the Demogorgon of Stranger Things, although it is likely related.) Apparently, bismuth also strengthens silver (with the side effect of turning it black) and apparently also hardens gold. Glauber, who lived in the 17^th century, apparently suggested that “Great Princes also might have Armour and Arms made of this hardened Sol, which would be much better than any of Iron or Steel, which easily take rust, to which Sol is not subject.”

 

You’ve likely guessed that Sol refers to the sun. Indeed, in the ancient world, the seven known metals were associated with the seven known heavenly bodies. In the Earth-centric astronomy of the day, from closest to furthest, these would be the Moon (silver), Mercury (mercury), Venus (copper), the Sun (gold), Mars (iron), Jupiter (tin), Saturn (lead). Way back then, shiny liquid mercury was called quicksilver. The alchemists, in their secret recipes for the philosopher’s stone, would allude to the ingredients in a cryptic manner. Thus, one would read allusions to the sun or the moon or the gods, when what they were really referring to was chemical substances.

 

I also learned from Wothers’ book that metallic bismuth and antimony share with water the rare property that the liquid form is denser than the solid form. Just like ice floats on water, solid bismuth floats on liquid bismuth. For the vast majority of substances, the solids are denser than the liquids, and thus the solids sink. Antimony (#51) is in the same column and just above bismuth on the periodic table. It was often confused with bismuth because of their similar chemical properties. Antimony has the symbol Sb referring to the Latin stibium – apparently related to an Egyptian word that refers to eyeliner. Scarily, it was in ancient times as an eye dilator, part of beauty preparations for women. That sounds like a bad idea to the chemist in me.

 

Antimony was used to purify gold. In another 17^th century text, antimony is known as the ‘Wolf of Metals’ because it ‘devours all Metals but God’. I take this to mean that it preferentially reacts with other metals in a mixture that contains gold, thus allowing the gold to separate from the mixture. Once again, the alchemists couch this in cryptic language: “Take the most ravenous grey Wolf, which by reason of his Name is subject to valorous Mars, but by the Genesis of his Nativity he is the Son of old Saturn, found in Mountains and in Vallies of the World: He is very hungry, cast unto him the Kings, body that he may be nourished from it; and when he hath devoured the King, make a great fire, into which cast the Wolf, that he be quite burned, then will the King be at liberty again.” Wothers provides the picture of a 17^th century engraving.

 

Lead (#82) is just to the left of bismuth in the periodic table. In ancient times, it was also used to purify gold. Wothers describes the process “known as cupellation, the impure gold would be roasted with lead in a porous vessel known as a cupel. Remarkably, this process, relatively unchanged over the centuries, is still carried out today during the assaying of gold. Perhaps through analogy with Saturn consuming his children, the lead is said to devour all the metallic impurities. In the high temperatures of the assay furnace the lead and impurities form molten oxides which are absorbed into the cupel itself, leaving the gold behind.” Saturn is the Roman name for the Greek Titan Kronos, father of Zeus. Jupiter is the Roman name for Zeus. I’m not sure exactly how antimony is Jupiter’s Wolf in particular. Zeus did not eat Kronos. Before dispatching Kronos, Zeus feeds him an emetic so that all those who were previously eaten are disgorged. Yuck. Turns out antimony is an emetic because it’s poisonous and therefore your body tries to get rid of it. You could add powdered antimony oxide to wine (it was known as vinum emeticum) or you could make an antimony glaze on your cup (known as the ‘emetic cup’) to help you vomit.

 

That’s probably more than you wanted to know about antimony. Turns out there are many other speculatory guesses about where it got its name. Besides the eyeliner theory, there is the monk-killer theory, the ‘enemy of solitude’ translation, and more. But for all this wonderful detail, I’d recommend you read Wothers book. It’s a little dry in parts, and not as engaging as Periodic Tales. But for someone like me who’s interested in the alchemical connections, I’m enjoying Antimony, Gold, and Jupiter’s Wolf.

Credit for Alchemy

In the seventeenth century, there was a shortage of circulating money. One solution was to debase one’s coin, an infamous incident in the prior century being Henry VIII’s replacing the amount of gold and silver with cheaper metals. (Henry had an extravagant lifestyle and also needed to funds his wars.) A decreased influx of precious metals from the Americas and other parts of the world exacerbated the situation. One solution to the problem was to make more gold those cheaper metals via transmutation – the promise of alchemy! Thus, European courts and kings retained the services of alchemists in the hope of improving the state’s financial situation and turn the economy around.

 

I’m learning about this history after stumbling on an article with an intriguing title: “Credit-Money as the Philosopher’s Stone: Alchemy and the Coinage Problem in Seventeenth-Century England.” The author is Carl Wennelind and the citation is History of Political Economy 2003, 35, 234-261. As a chemist who’s interested in history, I’ve read a fair bit about alchemy and the philosopher’s stone. I also discuss the role of the alchemists as forerunners to the chemists and how we define chemical elements, on the first day of my introductory chemistry classes. I had never previously considered the influence it might have had on political economy.

 

Wennelind briefly describes historical landmarks in the alchemical tradition, leading to Francis Bacon and subsequently the Hartlib Circle. I’d never heard of Samuel Hartlib, but apparently his group “served as a link between Gresham College – the first systematic effort in England to apply scientific lessons to the practical affairs of the state and the demands of commercial expansion – and the Royal Society.” Robert Boyle and Benjamin Worsley were members; and the group was known as the “invisible college”, a precursor to the Royal Society’s formation.

 

The alchemists did not succeed in turning cheap metals into gold, despite the efforts of Worsley. Thus, the Hartlib circle turned to the idea of “setting up a land bank that would issue credit-money on the security of the land.” The idea was that “land is the most concrete and stable of commodities” and while you’d think “the banking sector was the most appropriate institution for the development of this kind of credit-money scheme”, Hartlib argued that such “deposit banks” were essentially pawn shops and thus limited in increasing the circulation of money. One member of the Hartlib Circle “advocated for the creation of a merchant bank that would issue promissory notes for domestic circulation” (i.e., essentially paper money in function) by making an analogy to alchemy, even referring to such credit-money as the philosopher’s stone.

 

Another reason why the land bank may be preferable to alchemy was that the money would not be debased if the alchemy was successful and large quantities of gold flooded the market. Land, in this sense, was more concrete than gold at least as a measure of security. Hartlib’s specific idea did not ultimately come to fruition, but by the end of the seventeenth century, the Bank of England was founded to pay for (via credit-money) the building of the British naval fleet. (The close ties between monetary-debt systems and war has been amply argued by David Graeber in his masterful treatise.) Alchemy on the other hand fell further by the wayside, no longer needed by monarchs and business titans. And with the rise of science as a distinct methodological suite, the death knell of alchemy was assured. I give alchemy credit for staying alive as long as it did.

The Chemistry Laboratory

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.

The Alchemist's Daughter

Reading fiction is for the holidays. Why? Because Mortimer Adler convinced me (in a non-fiction book) that fiction is best enjoyed in a large block of undisturbed time. This allows the reader to immerse in the fictional world. During the school year, non-fiction is suitable for a twenty or forty-minute block in the evening before bedtime. Weekends are when chores and other errands get done.

I kicked off winter break with The Strange Case of the Alchemist’s Daughter by Theodora Goss. My sister had recommended the book, knowing of my interests in settings where the distinction between science and magic was blurred. The setting is 1890s England. The protagonist is one Mary Jekyll. Readers of Victorian era literature will recognize the connection to The Strange Case of Dr. Jekyll and Mr. Hyde by Robert Louis Stevenson.

The 2017 novel by Goss is a modern mash-up of fictional 19^th century literary characters whose own stories intertwine the strange and macabre of that era. A strange case requires a detective, and so Sherlock Holmes gets involved. The Whitechapel murders form one thread of the case. There is also a fourth-wall undercurrent running through the story that is slightly distracting and highly amusing at the same time. Sisterhood is explored in interesting ways, and the book has a breezy 21^st century feel – the plot keeps moving, and I won’t be surprised if this book gets adapted into a movie or miniseries.

I won’t give away the plot other than to say that a shadowy group of neo-alchemists are involved, although our protagonist needs to explore her way through the case to figure things out. The setting however is interesting. It presumes that the alchemists have moved on from the failed quest of transmuting the chemical elements. Thanks to Darwin’s theory of evolution, the new quest is the transmutation of biology. The mutants could be seen as 19^th century versions of today’s X-Men or X-Women. Science is the driving force in this case, similar to origin stories in many of today’s familiar comic book super-powered mutants.

Folks from the 19^th century would see today’s scientific tools for transmutation in modern biology as magical. CRISPR technology reminds us of the ethical issues debated over the last century as biochemistry and molecular biology have raced ahead in technology. Unfortunately The Strange Case of the Alchemist’s Daughter does not go into any scientific details, which I would have undoubtedly found interesting. But the book is still a delight to read. At 380 pages, it took me 4.5 hours at a leisurely pace since I read fiction slowly to immerse myself in that world. If any of the above sounds interesting, you might enjoy it too!

20 Years of Harry Potter

Technically, the first book in the series Harry Potter and the Philosopher’s Stone was published in late June of 1997, so this post might be a month late. So I’m posting my reflections to coincide with Harry Potter’s birthday!

To celebrate the 20^th anniversary of the books, the National Library of Medicine (NLM) featured an exhibition titled Harry Potter’s World: Renaissance, Science, Magic and Medicine. There were two lectures at NLM on June 27 and June 29 celebrating the occasion. The first one that focused on fandom I found less interesting even though I was less knowledgeable about this area. (I did learn about “wrock” music.) The second one by Stephen Greenberg titled Monsters in the Stacks was excellent, and I recommend it (archived here). Greenberg is an engaging and humorous speaker, and it was fun to see pictures of rare books related to the Harry Potter world.

While I was familiar with a number of the connections to alchemy mentioned by Greenberg including references to Paracelsus and others, I learned a number of new interesting factoids. In a sound-bite both funny and sad, Greenberg offhandedly said “What is alchemy anyway? It’s chemistry that doesn’t work.” Technically, that’s not true. The alchemists helped to invent and refine many experimental chemistry laboratory techniques. In the Q&A, someone who was amused by Greenberg’s wisecrack about non-working-chemistry commented that this made her an alchemist because “I practiced it when I took chemistry in college.” It just goes to show how much more work we need to do as teachers of chemistry.

Listening to Greenberg (who specializes in rare books) made me want to visit NLM. Incidentally I will be going to DC in late August for the American Chemical Society (ACS) national conference. I wasn’t originally planning to attend the Fall meeting since I took a bunch of students to the Spring meeting in San Francisco back in April, but I was invited to give a talk in a symposium of interest to me. I’ve only been to DC once for the Fall ACS conference back in 2009. The highlight of my time in DC was the Smithsonian mineral gallery, and hopefully I can find time for a return visit. Incidentally the ACS logo contains an alembic (a distillation apparatus) – Greenberg showed one of these from a page in one of the old books. His explanation of how these books were made and printed was fascinating.

But what have the Harry Potter books done for me the last twenty years? I think they helped spark my interest in the history of chemistry, and finding out more about the alchemists in particular. (This is an excellent book about the history of alchemy.) It also got me interested in the history of medieval monsters and beasts, now commercialized in an unprecedented way with Fantastic Beasts, a Harry Potter spin-off. By situating Harry Potter in contemporary England but connecting it to a medieval literary past, Rowling’s books helped spark a curiosity in historical areas I didn’t know much about. Interestingly Tolkien, my most-read author, didn’t spark similar interests possibly because Middle Earth and its predecessors were situated in a different realm. I also read Tolkien when I was much younger, before I knew I was interested in history, chemistry, science and philosophy. Reading Rowling’s books as an adult and academic has given me different touchstones.

Harry Potter helped start this blog when I was casting about for a theme. Ensconced in education, the prominent role of Hogwarts provided me with many things to think about related to education. While I don’t think Hogwarts provides an ideal education by any means, it does raise interesting questions about the role of theory and hands-on practice, different teaching styles, what’s important in an education, and how/why one gets admitted into a school in the first place. Education can be magical. But not all magical education turns out that way. Besides broader educational issues, I’ve also enjoyed thinking about the theory of magic and what a Potions class might resemble, through this blog. While Harry Potter related blog posts have decreased over time, I’ve kept up with writing about things of interest to me – and I see that as a good thing!

Happy Birthday, Harry Potter!

The Last Sorcerers

The Last Sorcerers. The title font on the cover page is similar to my edition of Harry Potter and the Sorcerer’s Stone. It sounds like the title of a fantasy novel, but it’s actually about the history of chemistry. The cover art might have given it away – it juxtaposes an eighteenth century Alchemists painting by Pietro Longhi and a page showing Dalton’s atoms. (I use the latter in my class.) It’s also the last book by author Richard Morris, who writes books at the intersection of science and society. (Graphic from Amazon.)

The book consists of ten short chapters covering “the path from alchemy to the periodic table”. The writing is clear, crisp, and light. It doesn’t bog down in too many details – as history of science books are wont to do. Morris explains the key alchemical and scientific questions in very clear prose. While the book is pitched to a very general audience, scientists will also find enough that is engaging. What distinguishes it from other books on this subject is its focus on the interesting (and quirky) lives of the alchemist-scientists. I’m halfway through the book, just finishing up the entry on Joseph Priestley. Antoine Lavoisier is next, and I’m looking forward to Dalton, Mendeleev, and more. (If you want a more detailed and comprehensive history of alchemy, I suggest The Secrets of Alchemy by Lawrence Principe.

While I am familiar with many of the major characters in the book, I was delighted to learn a number of things new to me. Chapter 2 focuses on Paracelsus. I knew his theories and his bombastic name, Philipus Aureolus Theophrastus Bombastus von Hohenheim. I did not know that he chose Aureolus as his own alchemical name, or that technically he had no legal right to the von Hohenheim title, his father being an illegitimate child. He also gave himself the name Paracelsus (meaning “greater than Celsus”), and in fact he thought he was greater than everyone else who came before him. Criticizing others was something he did often, although he was apparently a capable physician. He had to keep moving from town to town because he regularly angered prominent townfolk.

Chapter 3 focuses on Robert Boyle, famous for his book The Sceptical Chymist and Boyle’s Law – the latter is taught in introductory chemistry classes in the “Gases” chapter. I did not know that Boyle also wrote “religious romance” novels. Apparently his Seraphic Love was a hit during his time with nine editions and translations into other languages. Besides fiction he also wrote a number of theological treatises that led to him being “offered high positions in the Anglican Church more than once. Characteristically, he refused them…” Boyle was also an alchemist, and like other alchemists, these writings were in “a variety of ciphers and invented code words for different chemical substances or alchemical procedures. Like most other alchemists, he believed that if methods of preparing the Philosopher’s Stone became widely known, the results would be catastrophic.”

Last week, as I was reworking my General Chemistry course, I wrote up a section on atomic line spectra. Shown above is an example from an older website that I like because the accompanying information is both useful and interesting information. The hydrogen line spectrum, in particular, played a crucial role in discovering the quantum nature of electrons in atoms. Also, each element in the Periodic Table has its own unique “fingerprint” spectrum, and this led to the discovery of new elements. I had included the discovery of helium in my lecture notes, but I had forgotten Robert Bunsen’s discovery of cesium (“sky blue” from the Latin caesius) and rubidium (“dark red” from the Latin rubideus) from the spectral lines. Yes, he’s the eponym of the Bunsen burner, and his collaboration with Gustav Kirchoff led to a plethora of new discoveries. Interestingly, Bunsen finally isolated the very reactive cesium and rubidium by commissioning “a chemical factory near Heidelberg to spend several weeks evaporating and chemically treating some 12,000 gallons of Durkheim water”. This water came from the Durkheim mineral springs that Bunsen had first analyzed. The process yielded 10 grams of rubidium and 7 grams of cesium.

I should include cesium and rubidium when I talk about spectroscopy since I’ve used this old Brainiacs YouTube video in a number of my classes. Don’t try it at home! Reading about the many experiments on gases, and how integral they were to the rebirth of atomic theory, I’m wondering if I should cover the “Gases” chapter differently. It normally shows up at the end of the semester, partly because of the textbook we’re using, but I’m wondering whether I should split it up and sprinkle the topics across the semester. (I did this with Electrochemistry for the second semester in a similar situation.)

The book also made me think about how the first Harry Potter title was changed from the British Philosopher’s Stone to the American Sorcerer’s Stone. For many years, I thought that Philosopher’s Stone was the much better choice because of alchemical history. But now I think that Sorcerer’s Stone isn’t a bad choice. The cast of characters in Morris’ book both exhibited the traits of natural philosophers and alchemical sorcerers. In that time period, magic and science were not so different from each other. I wonder what they would have thought about our clear-cut distinctions. In any case, for more on the colorful lives of the early scientists, I recommend reading The Last Sorcerers in full. I’m looking forward to reading more vignettes in the second half of the book that I can use in my classes.

The Hemodote Potion

I am now in the home stretch of my semester with just three more weeks of classes before Finals week. Today, in my non-majors chemistry class we discussed the details of the final project: Designing a Magical Potion. To prepare the students for the project, I had written a Prologue to the project seven weeks ago, and I make occasional references to potions in class sessions. One class was dedicated to talking about drug design, after the students had learned about protein structure and intermolecular forces.

A couple of weeks ago I wrote a full example of what a Final Project would look like. Thus, I invented the Hemodote Potion. Along with this sample, I provided detailed parameters for the project, and in class today we discussed and agreed upon the final due date, and the mechanics of what, when and how to provide me information on their projects. I had included a question on the previous problem set asking the students to list two potions they might invent with a one-paragraph of justification for each.

In class we divided into small groups and batted around some initial ideas of the science and chemistry that needs to be considered, before having a whole-class discussion. Cure for cancer and levitation potions are inherently challenging, but we came up with some ideas for camouflaging, memory-enhancement, skin anti-aging, and more. The best suggestion from a student, which I would never have thought of myself, was a potion that magically and non-toxically dissolves the skin or peel of vegetables and fruits. Just pour the potion on the desired object and moments later you are ready to eat (or cook) the food item!

Here are the required components for the project (per my instructions to the students):

Think of your project as adding an entry to a Potions textbook. Your entry must contain:

1. Name of your potion and the names of the authors contributing to the entry.

2. Background information on why this is a useful potion. Key features of the active chemical substances and how they might interact should be described here.

3. Design Considerations: A detailed section that describes each of the important substances that will be included in the recipe. This is where you justify the proposed chemical interactions you hope to achieve, and how this might interact with the larger scale organism or object to which the potion is applied.

4. Amount Considerations: This is where you show calculations estimating how much of each active substance will be needed.

5. A Detailed Recipe as you might see in a cookbook.

6. A list of potential side-effects or cautions for your potion. This is not just a generic list but is tied to the effects of the specific potion you have proposed.

7. References

There are also certain requirements such as some number of chemical equations and structures, minimum number of active ingredients, and calculations involving masses, moles and molarity. No specialized reagents can be used directly. They must either be synthesized or extracted from a magical creature or plant. Two different font colors must be used to highlight the “creative” parts of the project and the “science-y” parts.

Hemodote is a powerful easy-to-use liquid antidote against hemoglobin poisons such as cyanide and carbon monoxide. I had sketched out my initial ideas in a previous blog post, but here is the more detailed version of the “Design Considerations” section in the full example provided to the students. I have made minor edits removing the figures, and I did not renumber the references since this text is about one page of a four-page document. I have a detailed recipe with calculations and amounts, but since I’m taking on the mantle of an alchemist, I will keep my recipe a secret for now. (My students have seen the full recipe.) Except I can’t resist telling you that I have good reason to believe that mincing and boiling the liver of the Blue Behemoth will provide one of the active ingredients. Enjoy!

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To counteract hemoglobin poisoning, there are two general approaches: (A) Introduce substances that bind cyanide or carbon monoxide more strongly compared to hemoglobin. (B) Provide an infusion of oxygen to reduce or prevent cell death due to the poison.

Two kits used to treat cyanide toxicity are Cyanokit and Nithiodote.⁶ The active agent in Cyanokit is hydroxocobalamin, a molecule closely related to hemoglobin and Vitamin B12.⁷ Hydroxocobalamin actively binds cyanide more strongly than hemoglobin, and thus can scavenge the cyanide away freeing the hemoglobin to bind to oxygen. The active center in hydroxocobalamin is a cobalt ion instead of an iron cation in hemoglobin. Cyanide displaces the hydroxide and binds strongly to the copper center. A natural source of hydroxocobalamin comes from eggs, dairy, and meat.

Nithiodote contains sodium thiosulfate (Na₂S₂O₃) as an active ingredient. This compound can be prepared from mixing sulfur with concentrated lye (or sodium hydroxide, NaOH).⁸ In the presence of Na₂S₂O₃, a natural enzyme in our bodies, rhodanese, converts cyanide into thiocyanate (SCN^-).⁹ While both kits require intravenous transmission in the Muggle world, acquiring the equivalent of hydroxocobalamin from the appropriate magical creature should suffice for an oral potion.

The treatment for carbon monoxide poisoning is to obtain an oxygen infusion.¹⁰ This will also help in cases of cyanide poisoning. Finding a hyperbaric oxygen chamber or an oxygen tank to breathe from can be challenging when the cells in your body are being rapidly depleted of oxygen. One way to quickly deliver oxygen is by using hydrogen peroxide (H₂O₂). It rapidly decomposes into H₂ and O₂ because of the weak O–O single bond in H₂O₂. However H₂O₂ cannot be consumed directly because it is a very strong oxidizing agent and will damage the cells in our body.

Recent scientific work on delivering oxygen to cells in our body is to enclose calcium peroxide (CaO₂) in a polycaprolactone polymer casing.¹¹ Calcium peroxide can be synthesized by heating slaked lime (calcium hydroxide) with hydrogen peroxide.¹²

Ca(OH)₂  +  H₂O₂  -->  CaO₂  +  2 H₂O

Caprolactones are cyclic esters and can be found naturally in flower aromas and insect pheromones.¹³ Using caprolactone as a monomer to form polycaprolactone requires catalysts that are specialty chemicals not found in nature but synthesized by chemists.¹⁴ However, extracting caprolactones from an appropriate magical insect or plant should also provide the catalysts needed to form an appropriate polycaprolactone that will encase the CaO₂ for delivery into the bloodstream.

[6] http://emedicine.medscape.com/article/814287-treatment (Cyanide Toxicity Treatment & Management)

[7] https://en.wikipedia.org/wiki/Hydroxocobalamin

[8] https://www.youtube.com/watch?v=J_IboipV5A8 (Preparation of Sodium Thiosulfate)

[9] https://chemm.nlm.nih.gov/countermeasure_sodium-thiosulfate.htm (Reference to “Effects of thiosulfate on cyanide pharmokinetics in dogs”)

[10] http://www.mayoclinic.org/diseases-conditions/carbon-monoxide/basics/treatment/con-20025444 (Carbon Monoxide Poisoning Treatment)

[11] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3708668/ (Oxygen Releasing Biomaterials for Tissue Engineering)

[12] https://en.wikipedia.org/wiki/Calcium_peroxide

[13] https://en.wikipedia.org/wiki/Caprolactone

[14] http://pubs.rsc.org/en/Content/ArticleLanding/2009/CS/b820162p (Synthesis of polycaprolactone: A review)