21st century technology cracks alchemists' secret recipe PhysOrg - November 22, 2006
Now, writing in Nature, the researchers reveal using petrographic, chemical and X-ray diffraction analysis that Hessian crucible makers made use of an advanced material only properly identified and named in the 20th century. Dr Marcos Martinón-Torres, of the UCL Institute of Archaeology, who led the study, explains: "Our analysis of 50 Hessian and non-Hessian crucibles revealed that the secret component in their manufacture is an aluminium silicate known as mullite (Al6Si2O13). "Today mullite is used in a wide range of modern conventional and advanced ceramics, such as building materials, electronic packaging devices, optical materials and catalytic converters, as well as in ceramic matrix composites such as thermal protection systems and liners for aircraft and stationary gas turbine engines. "This material was only first described in the 20th century, though Hessian crucible makers were already taking advantage of this peculiar aluminium silicate 400 years earlier: they synthesised mullite by manufacturing their crucibles with kaolinitic clay and then firing them at temperatures above 1100 degrees.
"Mullite is extremely resistant to thermal, chemical and mechanical stresses, and that's what made the crucibles so fit for their functions. It is thanks to the availability of Hessian crucibles that the discovery of some elements and their thermochemical behaviour could take place. Crucible makers were not aware of mullite, but they mastered a very successful recipe, and that's why they kept it constant, and secret, for centuries. Professor Ian Freestone, Cardiff School of History and Archaeology, said: "Manufacture of the crucibles used in early metallurgy and alchemy challenged the potters as they were required to withstand conditions more extreme than those required of other ceramics. In this case we find that the properties of a material which we regard as modern and high-tech, in this case mullite, were being exploited centuries ago by craftsmen who had a limited scientific understanding of their products but a great deal of skill and ingenuity."
Alchemy: Then and Now - Washington Post - March 22, 1999Alchemy: Then and Now
After one experiment, Newton wrote in an unpublished manuscript that he thought he had the "great secret of Alchemy," a sort of "living" mercury that "makes gold begin to swell . . . . and also to spring forth in sprouts and branches." The process didn't pan out, but the secret, he felt, was nearly within his grasp. It wasn't. But mercury can, indeed, be turned into gold. The secret lies in understanding the structure of the atom's nucleus and the technology of accelerating atomic particles. That knowledge wouldn't arrive, however, until 250 years after Newton and 20 centuries after alchemists first sought the recipe for gold.
Gold is soft enough to cut with a knife, so it has never been useful as a material for tools. Although its malleability makes it easy to shape into jewelry, it also dents and scratches easily, which is why even a high-quality, 18-karat "gold" ring is 25 percent other metals. Gold is extremely heavy. A gold bar is twice as heavy as the same-sized bar made of lead. After plundering Persia of its gold in 334 B.C., Alexander the Great decided to bury portions of the treasure along the trail to lighten the burden on his soldiers. Nonetheless, many early civilizations treasured gold and silver for its value as ornamentation. But about 3500 B.C., when people in the new towns of ancient Mesopotamia began to use the metals as money to facilitate trade, gold and silver took on new value. Until then, families were largely self-sufficient in food and bartered for foodstuffs or objects that they didn't grow or make.
But as more people lived in towns and became less self-sufficient, the need to trade increased. Instead of accepting a herd of goats in exchange for his cloth and then trading the goats for the sheep he really wanted, a craftsman could accept silver and, knowing that his neighbors valued the silver as he did, buy sheep directly. At first, the gold and silver were traded in chunks that merchants had to weigh, but by about 2800 B.C., Mesopotamians had formed it into rings of standard weights. Gold didn't tarnish like copper or silver or rust like iron and wasn't damaged by heat. In fact, until medieval alchemists concocted the acid known as aqua regia, gold was considered indestructible. Moreover, gold is rare, about six times rarer than silver. On average, to extract an ounce of gold from Earth's crust, one must smash and process about three tons of rock. People who held their wealth in gold did not often find their riches suddenly diluted by appearance of a large new supply.The desirability of gold has always been enhanced by associations that people make with it. Because it seemed imperishable, the ancient Chinese thought that gold might convey its immortality to its owners. Gold coins reminded people of the golden sun with its warming, life-giving qualities. Bernard Trevisan, a medieval Italian alchemist, wondered, "Is not gold merely [the sun's] beams condensed to a solid yellow?" Anthropologist Kaj Arhem notes that the Makuna people of Brazil believe that "gold contains the light of the sun and stars."
AN ANCIENT PEDIGREE
Newton and many of his contemporaries, including chemist Robert Boyle and philosopher John Locke, were among the last of a long line of intellectuals who believed in alchemical transmutation of base metals. The Adam of the lineage was Aristotle. He believed that all materials in the physical world were made of four elements -- water, earth, air and fire -- and that the proportion of the elements in any substance determined what the substance was. Although he never tried to prove it, Aristotle predicted that one material could be transformed into another by altering the mix of its elements. He also believed, as did most people of the time, that metals grew in the ground, like plants, although much more slowly. Just as seeds grew into more "perfect" plants and children grew into more "perfect" adults, so all metals eventually would attain the ideal form of metals, gold, he believed. When Alexander the Great marched into Egypt, he took the ideas of his tutor, Aristotle, with him. The Egyptians drew on sophisticated goldsmiths' techniques and other chemical knowledge gained in glassmaking and dyeing to try putting Aristotle's ideas to practical use. Through elaborate mixing and heating procedures, they attempted to make gold by changing the proportion of elements in base metals or hurrying "natural growth" of these metals into gold.
One of the earliest alchemists whose identity has survived was a Jewish woman who is known as Marie, who lived in Egypt about 100 A.D. and conducted experiments with mercury, which was tantalizing silver-colored, and sulfur, whose yellow hue seemed related to gold. In her work, she invented several devices for heating her ingredients. One is used today -- the double-boiler, known in French as a bain-Marie, or "Marie's bath." By 300 A.D., perhaps from lack of success, Egyptian alchemists turned increasingly to mystical approaches.
Zosimos of Panopolis, whose recipes sometimes came to him in dreams, wrote that "the soul of copper must be purified until it receives the sheen of gold and turns into the royal sun-metal." The mystics' recipes, filled with symbols based on magic and astrology, would intrigue alchemists until Newton's time.
Dreams - One of Zosimos' texts is about a sequence of dreams related to Alchemy, and presents the pseudo-science as a much more religious experience. In his dream he first comes to an alter and meets Ion [the Sabeans consider him the founder of their religion], who calls himself "the priest of inner sanctuaries, and I submit myself to an unendourable torment." Ion then fights and impales Zosimos with a sword, dismembered him "in accorance with the rule of harmony" [refering to the division into four bodies, natures, or elements], and then pulls the skin off Zosimos' head [a reference to the Apocalypse of Elijah which mentions those who are cast "into eternal punishment": "their eyes are mixed with blood"; and of the saints who were persecuted by the ANti-Messiah: "he will draw off their skins from their heads"]. He takes the pieces of Zosimos to the alter and "burned [them] upon the fire of the art, till I preceived by the transformation of the body that I had become spirit." From there, Ion cries blood, and horribly melts into "the opposite of himself, into a mutilated anthroparion" [which, Carl Jung precieved as the first concept of the homunculus in alchemical literature.]
Zosimos wakes up, asks himself "Is not this the composition of the waters?" and returns to sleep, beginning the visions again [he constantly wakes up, ponders to himself and retuns to sleep during these visions]. Returning to the same alter, Zosimos finds a man being boiled alive, yet still alive, who says to him "The sight that you see is the entrance, and the exit, and the transformation... Those who seek to obtain the art [or moral perfection] enter here, and become spirits by escaping from the body" [which can be regarded as human distillation, just as how distilled water purifies it, distilling the body purifies it as well]. He then sees a Brazen Man [another homunculus, as Jung believed any man described as being metal is precieved as being a homunculus], a Leaden Man [named Agathodaimon and also a homunculus]. Zosimos also dreams of a "place of punishments" where all who enter immediately burst into flames and "submit theirself to an unendourable torment."
Jung believed these visions to be a sort of Alchemical allegory, with the tormented homunculi personifying transmutations [burning/boiling themselves to become something else]. The central image of the visions are the Sacrificial Act, which each Homonculus endures. In alchemy the dyophysit nature is constantly emphasized, two principles balancing one another, active and passive, masculine and feminine, which constitute the eternal cycle of birth and death. In ancient alhemy this cycle was represented by the symbol of the uroboros, the dragon that bites its own tail. Self-devouring is the same as self-destruction, but the unison of the dragon's tail and mouth was also thought of as self-fertilization. Hence the text of "Tractatus Avicennae" mentions "the dragon slays itself, weds itself, impregnates itself." In the visions, circular thinking appears in the sacrificial priest's identity with his victim and in the idea that the homunculus into whom Ion is changed devours himself [he spews fourth his own flesh and rends himself with his own teeth]. The homunculus therefore stands for the uroboros, which devours itself and gives birth to self. Sice the homonculus represents the transformation of Ion, it follows that Ion, the uroboros, and the sacrificer are essentially the same.
After Egypt came under Roman control with the defeat of Cleopatra in the 1st century B.C., alchemy did not fare well. Diocletian, emperor of Rome from 284 to 305 A.D., ordered destruction of all Egyptian alchemical writings, concerned that alchemists' gold would fund a rebellion. When Constantine made Christianity the official religion of the Roman Empire in the middle of the 4th century, alchemy and other Hellenistic thought was suppressed for its pagan associations. However, many of the forbidden manuscripts were saved by a sect of dissident Christians, called Nestorians, who took them to Persia about 400. Between 640 and 720, followers of the prophet Mohammed conquered an empire that stretched from India to Spain and included Egypt. Arab alchemists, too, adopted Aristotle's ideas, from Nestorians and Egyptians. During crusades to Jerusalem in the 12th century, Europeans rediscovered the store of alchemical and other classical works by Arabs. To the mix of Aristotelian philosophy, Egyptian mysticism and the Arabs' practical chemical knowledge, Europeans added concepts of religious transformation from Christianity. If bread and wine could change into the body and blood of Christ, some alchemists thought that, with God's help, a man of pure spirit might turn lead to gold. Because the Roman Catholic Church came to support Aristotle's basic ideas, with an added role for God, alchemy no longer was anathema. In fact, many European alchemists of the medieval era were clerics.
It may seem odd that alchemy survived for so many centuries without producing gold. One reason is that the early alchemists believed they had done so. One ancient Egyptian recipe for "diplosis" (doubling) of gold called for a heated mixture of two parts gold with one part each of silver and copper. Indeed, twice as much of a golden material results. Egyptian alchemists believed that the gold acted as a seed in the copper and silver. The seed grew, eating the copper and silver as food, until the whole mixture was full-grown gold. Today, we know that, because the silver gives the gold a greenish tint and the copper gives it a reddish tint, mixing both hardly changes the color of the gold. Early alchemists also believed that they were making gold because, at the time, it wasn't clear what gold was. Gold found in nature often is combined, or alloyed, with other minerals or metals, so the standard for gold was imprecise. If a metal looked like gold and felt like gold, it might as well be gold. Even when people knew that what looked like gold actually could be a mix of gold and another metal, it was difficult to determine whether a sample was pure gold.
A hard, black stone known as a touchstone was an ancient device for determining the quality of gold. Scraping a piece of gold across it left a streak of gold. Depending on the brightness of the streak, an expert could estimate how much gold was in the sample. Unfortunately, a touchstone wasn't precise and couldn't determine whether the gold was only a coating on a metal of lesser value.
As early as 1500 BC, Mesopotamians discovered a method for purifying gold called cupellation, which involved heating impure gold in a porcelain cup called a cuppel. Impurities were absorbed by the porcelain, leaving a pure gold button. Later alchemists used cuppellation to prove that their transmutations were successful. They would put lead on which they had experimented into the cuppel and heat it. When a small bit of gold appeared in the bottom, they wrote in all good faith that their alchemy worked, citing the bit of gold as evidence that the lead was on its way to becoming all gold. They didn't know that most lead ore has a little gold or silver in it. That was what they had found. Alchemists also were encouraged by amazing substances they did make, including nitric, hydrochloric and sulfuric acids. With a hiss and some smoke, these ate through all kinds of metals.
In about 1100, alchemists made aqua regia, a combination of nitric and hydrochloric acids that could destroy gold. Alchemists assumed that the ability to destroy gold would be followed quickly by their ability to create it.
THE NEW ALCHEMY
Alchemists, of course, never could make gold. Gold is an "element," a substance composed entirely of one kind of atom and not further divisible by chemical processes into other kinds of atoms. Not until the late 18th century, when chemists Joseph Priestly, Henry Cavendish and Antoine Lavoisier experimented with air and fire, did it became clear that some substances are elements and others are compounds. Compounds are made of two or more elements. Water, for example, is a combination of hydrogen and oxygen.
Throughout the 19th century, through experimentation, scientists compiled a growing list of elements.
Just before World War I, British physicist Ernest Rutherford and others developed a model of the atom as composed of a nucleus containing a tightly bound cluster of positively charged protons and electrically neutral neutrons and surrounded at a distance by orbiting, negatively charged electrons.
In an electrically neutral atom, the number of electrons is equal to that of protons.
Why couldn't alchemists transform one element into another? An atom of any element is determined by the number of protons in its nucleus. The simplest atom, hydrogen, has one positive proton in its nucleus and one negative electron circling it. The element with two protons is helium, and the element with three protons is lithium. In the nucleus of an atom of gold are 79 protons and 79 electrons. Changing one element into another requires changing the number of protons in the nucleus, a very difficult procedure. Any proton aimed at a nucleus is repulsed by the positive charge of the nucleus. The only way to insert a proton is to sling it with enough energy to overcome that electrical repulsion. In 1919, Rutherford bombarded nitrogen atoms, with their seven protons and seven neutrons, with alpha particles. These are helium nuclei containing two protons and two neutrons. The helium protons penetrated the nucleus of the nitrogen atoms and produced an isotope of oxygen (eight protons and nine neutrons) and hydrogen (one proton). Rutherford was first to transmute an element successfully. Still, the transmutation was not entirely man-made. Rutherford worked his magic by taking advantage of naturally occurring radioactivity to achieve the energy to break into a nucleus.
In 1932, British physicists J. D. Cockcroft and E.T.S. Walton developed a device for accelerating protons and aimed a beam of protons at a sample of lithium. One more proton joined lithium's nucleus of three protons and four neutrons, which transmuted into two atoms of helium, each with two protons and two neutrons. This was the first time anyone had transmuted one element into another artificially. To be sure, new information and high technology were required to achieve what alchemists had attempted for 2,000 years. But a different approach to knowledge also was needed. We now call it the scientific method, whereby experiment must confirm all ideas. Failure of their experiments did not make alchemists question the ideas. They assumed that they had not fully understood the ideas or had failed to follow the recipe accurately. John Maynard Keynes, the English economist who collected Newton's alchemical notes and manuscripts, called Newton "the last of the magicians" who saw the world as a sort of philosopher's treasure hunt with clues scattered about in the evidence of the heavens and in obscure writings and traditions passed through the ages.
Today, scientists use much more powerful accelerators and can accelerate nuclear particles with 1 million times the energy of the device used by Cockcroft and Walton. In the late 1960s, Judith Temperley, a physicist at Edgewood Arsenal in Maryland, studied properties of various metals by bombarding them with high-energy neutrons. In one experiment, the target metal was mercury, an element with 80 protons. Under these conditions, a neutron enters the nucleus, which ultimately causes destruction of a proton by a process called "electron capture." The result is an atom with only 79 protons, making it an atom of gold.
So the alchemists were correct: A base metal can be turned into gold, but only with extreme patience.