Lawrence Principe was sorting through a collection of old chemistry books at the Chemical Heritage Foundation in Philadelphia when he stumbled upon a forgotten manuscript handwritten by Sir Isaac Newton. Any Newton manuscript is of interest, but this one was worth its weight in gold, literally—as Principe, a chemist and historian of science at Johns Hopkins University, recognized immediately. Holding the yellowed manuscript in his hands and studying the scribbled words, he understood that he was looking at one of the best-kept secrets in the history of science. Today revered as the father of modern physics and the inventor of calculus, Newton was describing a recipe for the Philosophers’ Stone, a legendary substance that reputedly could turn base metals like iron and lead into gold. Newton’s dabblings in alchemy are well known, but his belief that he had found the closely guarded blueprint for the Philosophers’ Stone was astonishing indeed.
Newton was not the only intellectual heavyweight from his era trying to make gold. The recipe for the Philosophers’ Stone had come from his older contemporary, the famed British chemist Robert Boyle. As it turns out, Boyle was a devotee of alchemy too.
If two of the greatest scientists who ever lived were dedicated alchemists, then alchemy needs a makeover, a big one, contend Principe and his colleague William Newman, a historian of science at Indiana University. Back in the day, the two argue, alchemy was not the misguided pseudoscience that most people think it was. Rather, it was a valuable and necessary phase in the development of modern chemistry. Among alchemy’s signature accomplishments: creating new alloys; manufacturing acids and pigments; inventing apparatus for distillation, the process used in making perfumes and whiskeys; conceiving of atoms centuries before modern atomic theory; and providing a template for the scientific method by running controlled experiments again and again.
Aiming to restore alchemy to its rightful status, Principe and Newman—who came to the field separately but joined forces after meeting at a conference in 1989—went through medieval alchemical texts, letters, and laboratory notebooks filled with odd symbols and coded language. Then they did something unheard-of in recent times: They made replicas of the laboratory glassware used by 15th-, 16th-, and 17th-century alchemists and re-created their experiments firsthand.
“There were reasons that alchemists thought they could make gold,” Newman says. “They had theories about the nature of metals that made them believe they could manipulate their structure. They also conducted experiments that they believed proved minerals could be made to grow.” In an age when there were no microscopes to penetrate living cells and no understanding of the nature of atoms and molecules, the alchemists were not misguided so much as misinformed, doing their best to make sense of a world they could not see. That they understood as much as they did is the real marvel: In pursuing what today seems like little more than witchcraft, the alchemists were in fact laying the foundation for modern experimental science.
Newman did not know much about alchemy as an undergraduate at the University of North Carolina at Greensboro in the mid-1970s. His passion at the time was literature. When he started to study the poets William Blake and William Butler Yeats, he did what young academics always do: He checked out their sources. To his surprise, he found that both poets had drawn inspiration from alchemy. Newman noted that Blake was born in 1757 and that Yeats died in 1939: “They reflected a creative interest in alchemy that spanned the late 18th to the early 20th century—exactly the ‘rational’ period of the Enlightenment and of modern science—at the same time that most historians were branding alchemy delusional.” What was going on? he wondered.
Newman decided to look more closely at the alchemists who had influenced Blake and Yeats. These included a shadowy 13th-century figure known as Geber, whose magnum opus was called The Sum of Perfection. “Not a modest title, right?” Newman says, laughing. Some historians had identified Geber as the translated name of an eighth-century Islamic alchemist, but Newman’s research turned up evidence supporting a different interpretation: Geber was actually the alias of Paul of Taranto, an obscure Franciscan monk from southern Italy. To alchemists toiling and tinkering in the laboratory, Geber was an infallible master; his book was regarded as the bible of alchemy. “That’s how much influence he had,” Newman says.
Whoever Geber was, Newman was struck by the range of ideas in his book, which contains everything from details about refining metals to a description of the essential behaviors of matter. It was clear that medieval alchemists were struggling with fundamental questions that would later become central to chemistry and physics. For instance, Geber believed that all matter was composed of invisible particles called corpuscles and that these corpuscles could be manipulated even though they could not be directly observed. He wrote about all sorts of material transformations (what we would now call chemical reactions) in terms of microparticles and pores, using concepts and terminology that foreshadowed the thinking that would emerge during the Scientific Revolution three centuries later.
The way to manipulate corpuscles, Geber instructed, was to “follow nature wherever possible.” In other words, alchemists had to discern and then mimic natural processes. Their idea of natural processes was much different from ours, however. “Most alchemists believed metals were not elements as we think of them today,” Newman says, “but rather compounds of sulfur and mercury or sometimes mercury, sulfur, and salt.” Sulfur was what made metal hard, they theorized; mercury made it more fluid. In that framework, iron was composed primarily of sulfur. Gold, which was malleable and softer, consisted mostly of mercury. Though the alchemists missed the mark, their conception was not too far from an understanding of pure metals as distinct from alloys and ores.
Misunderstanding which materials were elemental and which were composites led the alchemists to believe they could create gold from lead or other base metals if only they got the formula right. And the essential ingredient that would make it all happen? The elusive Philosophers’ Stone. Alchemists before Geber had used all sorts of ingredients derived from plants and animals in an attempt to make the Stone. Some had even experimented with human blood. According to Newman, one of the earliest promoters of science through experimentation, the 13th-century philosopher Roger Bacon, argued that creating the Philosophers’ Stone required blood because each person was thought to be a microcosm of the whole world. Therefore, human blood contained at least a little of everything in nature.
Geber, who tried to create gold by removing sulfur and adding mercury, pooh-poohed this idea in The Sum of Perfection. Using “organic materials as blood, fat, saliva, and so forth was irrational,” he wrote, “since Nature herself does not make the metals beneath the earth from human blood.” Geber’s way of thinking became the new standard for medieval alchemists as they started distilling mercury and combining it with different metals in an effort to make the Philosophers’ Stone.
As Newman read old alchemical texts, he discovered that by the late 15th and early 16th centuries (the time of da Vinci and the beginning of the Renaissance), alchemists had refined not just mercury but also their core ideas about matter. Newman links this shift in alchemical thinking to the wondrous new stories that miners of silver and copper ore in central Europe were then telling, of giant trunks of minerals branching out into limblike veins deep underground. The mineral finds were real—deposits of metallic silver truly can spread out in rock in shapes that resemble huge, intricate trees—but the interpretation was not: The apparent similarity between these deposits and trees inspired the notion that minerals might develop and change like living things. Renaissance alchemists now theorized that base metals (the ones earlier alchemists thought were made mostly of sulfur) were imperfectly developed, or immature, forms of gold. “In other words,” Newman says, “gold was the perfectly ripe ‘fruit’ into which subterranean base metals would eventually grow if left long enough within the earth.”
Following this line of thought, alchemists believed that gold became inert and stopped growing once it was removed from the earth, just as a flower dies after being plucked from a plant. There should be a way, then, to bring mined gold back to life. Reanimating gold, the reasoning went, would be easier than adjusting the formula of base metals by adding and removing sulfur and mercury. Thus began the Renaissance equivalent of the great California gold rush. Well-trained, intellectual alchemists sold the prospect of making gold to rich patrons, and less well-educated alchemists with day jobs tinkered the night away trying to make gold in makeshift kitchen laboratories. According to Newman, “the 17th century was the age of gold, both searching for it and making it.”
In his ongoing investigation into this remarkable era, Newman became intrigued by one of the most influential of the 17th-century alchemists—another mysterious figure, a man named Eirenaeus Philalethes, who was said to live in colonial America. His real identity was cloaked in secrecy, but his alchemical writings were read throughout Europe. Detective work by Newman proved that Philalethes did not really exist. Another respected American alchemist, George Starkey, had created him out of thin air to boost his career. In the European alchemy circles Starkey inhabited, he could boast that he was the only one who had met the great Philalethes. Better yet, Starkey confided to Robert Boyle, Philalethes had told him part of the top-secret process for making the Philosophers’ Stone. In 1651 Boyle took the bait and asked Starkey to teach him chemistry so he could make the Stone himself. (Boyle, considered the father of modern chemistry, knew almost nothing about it until he studied under Starkey, according to Newman.) A Boyle notebook uncovered by Principe in the mid-1990s describes how a wandering alchemist seemingly transformed lead into gold before his eyes. “The powder that was employ’d in the operations was not weigh’d,” Boyle wrote. “I cannot tell precisely how many parts of lead were transmuted by it, but I remember the Gold weigh’d much above half an ounce.” Whatever Boyle actually saw, it was enough to convince him that making gold was possible.
Like Newman’s, Principe’s immersion in the labyrinthine world of alchemy began in college, in his case in the early 1980s, after he read The Twelve Keys, an allegorical work written in the 15th century by an influential alchemist and supposed Benedictine monk, Basil Valentine. In his work, Valentine included an illustration that, Principe suspected, depicted a method for rendering gold—normally one of the most stable elements—volatile.
Looking around for other documents describing the volatility of gold, he found a treasure trove of writings on alchemy by Boyle. One of those manuscripts included a description of an absolutely real substance then called Philosophical Mercury—a liquid form of mercury that could dissolve gold slowly, a pivotal stage in gold making.
Today Principe suspects that Philosophical Mercury was the prized ingredient that Isaac Newton had sought from Boyle for years—a crucial component for making the Philosophers’ Stone. But like most alchemists, Boyle kept the details of his alchemical work hidden; he even withheld a part of the recipe for making red earth, which he believed was the direct precursor to the Philosophers’ Stone. “Red earth was thought to be about as close to the Philosophers’ Stone as you could get,” Principe explains. “It was said to change lead into gold, but a lot less efficiently than the Philosophers’ Stone itself. It was assumed that if you could create red earth, it would be relatively simple to get to the Philosophers’ Stone from there.” The age of scientific transparency was still a good century or two away.
Newton was even more secretive than Boyle, disguising his alchemical investigations (he wrote more than a million unpublished words on the subject) with codes, obscure symbols for chemicals, and colorful metaphors. His notes contain cryptic references to “Green Lion,” “Neptune’s Trident,” and the “Scepter of Jove.” Newman has not yet figured out what substances any of these terms refer to.
To really understand what Newton was seeing in his laboratory, Newman realized in 2002, he needed to repeat some of the old alchemical experiments himself. He started by building replicas of alchemical furnaces and glassware, including distilling apparatus, with the help of Indiana University’s chemistry department. One key alchemical experiment was called the Tree of Diana, a magical-looking demonstration that metals could grow like vegetation. Newman learned that the Tree of Diana really works. “If you immerse a solid amalgam of silver and mercury in nitric acid with dissolved silver and mercury, you produce tiny, twiglike branches of solid silver,” he says. Today this process is regarded as a simple matter of chemistry. But to Newton, the Tree of Diana was evidence that metals could be made to grow and, therefore, “possessed a sort of life.”
The image of the growing metallic tree can be found in another type of experiment, one that Starkey, Boyle, and very likely Newton all conducted: the attempt to synthesize the Philosophers’ Stone. Principe, who had studied the alchemical work of all three men, came to the same conclusion as Newman and decided that he, too, had to replicate the long-abandoned alchemical experiments firsthand. He culled recipes from alchemists like Starkey and, after “a lengthy process involving various materials and numerous distillations,” obtained Philosophical Mercury, just as Boyle had 350 years earlier. Principe mixed the Philosophical Mercury with gold, sealed it in a glass egg, and watched. Just as Starkey and other alchemists reported, strange things started to happen inside the egg. The mixture began to bubble, rising “like leavened dough,” Principe says. Then it turned pasty and liquid and, after several days of heating, transformed into what he likens to a “dendritic fractal”: another metallic tree, like the trees the miners saw underground, only this one was made of gold and mercury.
Principe’s tree, like all the trees any alchemist managed to create, did not actually grow any gold, of course; the gold that came out was no greater than the amount that he put in. But the experiments proved something that Principe had long suspected. Alchemists were not just tinkering blindly. In fact, they produced what he calls “a solid body of repeated and repeatable observations of laboratory results.” In their tightly controlled experiments they made metals bubble, change colors, and grow sparkling filaments, and they did it over and over again, establishing, in a crude way, the foundations of scientific experimentation. In the process they were learning fundamental principles of chemistry: breaking down ores, dissolving metals with acids, and precipitating metals out of solution.
Ever since he found that singular Newton manuscript, Principe has wondered what was going on in the mind of one of history’s most brilliant scientists. How close did Newton and Boyle think they had come to making gold? Did they believe that with just a few more tweaks, their experiments would eventually work? Principe says yes, they probably did. Why, otherwise, would the highly apolitical Boyle have lobbied the Houses of Parliament to overturn a law forbidding gold making? “He was a very scrupulous man, and before he went about doing transmutation, he wanted to make sure it wasn’t against the law,” Principe says.
Further evidence of their seriousness emerged after Boyle’s death in 1691. In life, Boyle had guarded his recipe for red earth as if it were the most precious thing in the world. But upon his death, his executor, the philosopher John Locke, also an alchemist, was more generous, sending Newton the recipe along with a sample that Boyle had made before his death.
No one knows what Newton did with the red earth. Principe notes that Newton suffered a mental breakdown a year after Boyle’s death and wonders if that episode might have been brought on by mercury poisoning. After all, the first steps in making red earth require repeatedly heating and cooling mercury. “Shortly after he would have gotten copies of this recipe, he was distilling mercury,” Principe says. But Newman thinks that Newton’s breakdown is just as likely to be related to Locke’s trying to set him up with a well-to-do widow. “Newton had a sort of pathological fear of females, and around that time Locke was pressuring him to date. That may be what pushed him over the edge,” he notes. (Newton is believed to have died a virgin, according to historian Gale Christianson.)
No matter how skillfully the two giants of 17th-century science manipulated the red earth and set their sights on the Philosophers’ Stone, they would have failed to make gold. We know now that such a transformation requires not a chemical reaction but a nuclear one, far beyond the reach of the technology of the time. By the early 18th century, alchemists had given up on their quest for gold. “They’d figured out that in a practical way their attempts to make the Philosophers’ Stone never worked,” Newman says. That does not mean that their other work was abandoned, however. As Newman says, “The goals of 18th-century chemistry—namely, to understand the material composition of things through analysis and synthesis and to make useful products such as pharmaceuticals, pigments, porcelain, and various refined chemicals—were largely inherited from the 16th- and 17th-century alchemists.”
Without the pioneering alchemists, none of that would have been possible. “They were the masters of premodern chemical technology,” Newman says. As the true power and limitations of chemistry came into focus, interest in the Philosophers’ Stone simply faded away, much as the belief in the classical Four Elements had faded away centuries before. Almost overnight, the perception of alchemy became conflated with an unforgiving view of the protoscientific world as one populated by mystics and superstitious fools.
As for Isaac Newton’s prized sample of red earth from John Locke, it was very likely thrown out after Newton died in 1727. Unless someone kept it. Imagine a little packet of Philosophers’ Stone stuck between the pages of a book from Newton’s library. If it is out there, for the sake of alchemy and science, let’s hope Newman and Principe are the ones who find it.