The Medici family are well known for their patronage of art, sculpture and architecture in Florence, but what is far less well-known is their involvement with alchemy. The first member of the family to show an interest in alchemy was Cosimo I, Grand Duke.

What was alchemy, and why was Cosimo the Grand Duke of Florence so interested in it? Superficially, it was the search for the philosopher’s stone, which would transmute lesser metals into gold and was also a panacea and provider of eternal life. In fact, alchemy was far more complex and intriguing. It was an interweaving of philosophical, psychological and chemical ideas, clothed in obscure symbolism that rendered it incomprehensible to all but the initiated. Its goals were both practical (better medicine and better methods of purifying metals) and esoteric (creating the philosopher’s stone). To a man like Cosimo, highly educated and interested in every aspect of life, alchemy held a deep fascination. He built a fonderia: a chemical-pharmaceutical, alchemical laboratory, in Palazzo Vecchio, when he was living there from 1540 to 1550, and provided funds for the most able alchemists to carry out their experiments.

Many different authors, including Michel Plaisance in 1974, mention his interest, which possibly began when he brought samples from his mines and began experimenting in metallurgical alchemy. This provided him with useful methods for purifying the metals from his mines. Or maybe it was his passion for herbal medicine which drove him to seek better distillation methods. But by the 1550s, he and his workers were involved in a great, messy, dirty melting pot of experimentation on plants and metals in his alchemical fonderia.

The best alchemists were not mystical dreamers, but skilled bench chemists. Several people, mentioned in the Magliabechiano XV, could have helped Cosimo, such as Cipriano Ferrini, a distiller, and Agostino Pini, who showed Cosimo how to extract silver from copper. Riguccio Galluzzi was scathing about Cosimo’s passion for alchemy, which he called “the most vain of all,” and depicts Cosimo in his laboratory, taking delight in transmuting metals and producing potent poisons. However, he admits grudgingly that, “since errors and vanities sometimes lead to the discovery of useful things, this laboratory became famous all over Europe for the remedies and medicines that were there produced.”

Bartolomeo Concini speaks of how Cosimo became sufficiently expert in alchemy to have perfected a method for tinting metals red. Vincenzo Fedeli reported in 1556 that: “Cosimo goes often (to his distillation laboratory) and there he works with his hands with great delight … to discover the miracles and the secrets of nature, which mostly regard the investigation of metals.”

Cosimo also read books on alchemy, such as Pompeo Florido’s transcription of Christophorus Parisiensis, L’Aspertorio Alfabeticale. As with all the other books he read, he made copious notes in the margins.

There was an explosion of interest in distillation in the sixteenth century. Everyone who could afford to was doing it secretly, from apothecaries to people in private homes to large scale laboratories. This may have been because glass was more available, better furnaces had been invented or because there were now several distillation manuals in circulation.

Alchemical distillation had been around for several centuries, first recorded by John of Roquetaillade, known as Rupescissa, 1310-1366, a Franciscan friar from Salerno monastery.

Many alchemists joined monastic orders, according to Chiara Crisciani in 1996. Monasteries were quiet, peaceful, and safe, and the monks had plenty of time to carry out long, complex alchemical experiments. They could translate ancient Greek and Arabic texts into Latin. Intertwining philosophy with experimentation, Rupescissa took Aristotle’s idea of an unattainable fixed essence and proposed producing it through a thousand-fold distillation of wine. This, he said, would provide a universal medicine, a quintessenzia, an aqua ardens, a panacea.

Ficino, who thought of himself as a doctor both of bodies and of souls, took Rupescissa’s idea of a healing quintessence and incorporated it into his philosophy as Spiritus Mundi, an active component of the world soul. This was not just a philosophical idea; like Rupescissa, Ficino, who was an alchemist, in addition to philosopher, doctor of medicine and priest, attempted to create his quintessence through distillation. His philosophy, a marriage of alchemical, Platonic and Christian ideas, had a huge influence on the thought patterns of his contemporaries as well as feeding back into the symbolism of alchemy.

The involvement of monks and nuns in alchemy may explain why many alchemical writings included all kinds of religious concepts, such as comparing metals to biblical people or events. Alchemists even gave their equipment names that reflected Christian ideas: for example, the word crucible, a vessel that can withstand high heat, derives from the Latin cruciare: to crucify, according to Theodore Ziolkowski in 2015.

Cosimo advertised the fact that he distilled plants for medicine, but kept quiet about the alchemical experiments he and his artisans were carrying out, for alchemy was necessarily cloaked in secret symbols, hidden in complex word and picture allegories. Alchemists used cover names to hide the ingredients of their recipes. All seven metals known at the time had astrological pseudonyms: the Sun represented gold, the Moon: silver, Mercury was mercury, Venus: copper, Mars: iron, Jupiter: tin and Saturn: lead. Sometimes alchemists compared metals to pagan deities or myths. Eggs, dragons and the Phoenix referred to marriage, death and resurrection.

Despite the necessary secrecy, Florence became one of the first great centres of alchemy in Europe under Cosimo’s sponsorship. Other European centres, such as Prague, under Rudolf II (1552-1612), followed his example, according to Ursula Klein.

When he and his family moved to the Pitti Palace in 1550, he had another fonderia built behind the palace, where the Boboli Gardens were being created, and one between the end of the Uffizi Gallery and the beginning of the corridor towards the river Arno, comprising eight rooms and a terrace. They contained alembics and glass vessels of every shape, furnaces, chimneys and numerous distillation tools and instruments. Cinelli describes two huge circulatori magni: furnaces with a quadruple ascending line of twelve tin flasks each penetrating the next and a similar one descending, in one of the rooms.

Artists typically painted or drew alchemists surrounded by strange vessels and dense smoke, chaos and madness, often in dilapidated buildings, with stuffed animals, such as lizards, crows or owls hanging from the rafters. The chaos and dense smoke may well have reflected aspects of Cosimo’s fonderie, but the buildings that housed them were certainly not dilapidated, and I doubt whether there were any stuffed animals or birds hanging from the ceilings.

Basic alchemical equipment included a fireplace or furnace, bellows to raise the temperature and distillation apparatus, such as an alembic. This consisted of a cucurbit: a gourd-shaped container which contained the liquid to be distilled and a cap which fitted over the mouth of the cucurbit to receive the steam, with a long sloping beak down which trickled the condensed steam into a receiving container. The alchemists’ retort was a distilling vessel in which the cap and the cucurbit had been combined to form a single vessel. The retorts I saw at the Leonardo exhibition in Florence were enormous, with multiple beaks projecting from their sides, veritable distillation factories.

Interestingly some of the equipment we were using to extract compounds from medicinal plants at the School of Pharmacy in London was similar to that of the alchemists. We did, however, use bunsen burners rather than fireplaces and bellows, and we did not have alchemical retorts, but the rest of our equipment differed little from that of the alchemists. They used glass beakers, flasks, crystallising dishes, funnels, filtering vessels and mortars, all of which we were also using. There was definitely less smoke in our laboratory than in that of the ancient alchemists, but almost as much chaos, at least on our benches, which were cluttered with every sort and kind of glass equipment. Of course, we had access to certain modern equipment, such as silica gel plates for separating compounds from raw plant material, a technique the alchemists would have envied, and we were able to subject the results of our work to spectroscopic analysis, something as incomprehensible to a lay person today as an alchemical formula.

Some alchemists focussed on the philosophical/psychological aspects of alchemy, seeking to perfect matter while perfecting their own inner natures. They may have followed a seven stage process:

1. Calcination: the stage in which the materia prima or starting material was heated so that it would produce white ashes, called a “salt” by alchemists. This was called the albedo (the white) stage. The root of the word calcination refers to the removal of carbon from limestone (calcium carbonate) to yield calcium oxide (quicklime). But the alchemists used the term to describe heating any starting material, such as mercury and sulphur, that could be separated by applying heat. Spiritually, this represented freeing oneself from worldly attachments.
2. Dissolution, dissolving the ashes in water. During this stage one descended into the unconscious. 
3. Separation, in which the pure essence was extracted from the rest of the mixture. During this stage, one left the ego behind.
4. Conjunction, in which the elements were re-combined so that, by the destructive power of Mercury, the matter was gradually broken down and brought into solution.
5. Putrefaction, or fermentation, which represented ‘The First Death’, the first cleansing of the base matter, during which it underwent ‘Mortification and Putrefaction’. This stage ended in a return to chaos, which was symbolised by a blackness that alchemists called the nigredo. During this stage, one came face to face with one’s fears.
6. Distillation, in which impurities were removed. During this stage, one overcame one’s fears.
7. Coagulation in which the distillate was left to solidify. Spiritually, this stage involved unification of spirit and matter, body and soul, masculine and feminine to form a single whole. It was called the rubedo, the final red stage, when the initiate became illuminated with the ultimate truth.

There were several other possible stages, such as exaltation, which referred to refining specific metals or refining the spirit of man. Multiplication was the process used to increase the potency of the philosopher’s stone or elixir, towards the end of the Great Work. Cosimo may well have followed some or all of these stages in the refinement of his metals.

The church did not approve of alchemy. Nor did Dante, who put alchemists in the tenth and final pouch of the Malebolge (Evil Pouches) in the Eighth Circle of Hell. Cosimo’s fonderie would indeed have resembled one of the layers of Dante’s Inferno, with workers enveloped in smoke, coughing from acrid fumes as they stooped to tend the furnaces. Unafraid of these terrible conditions, Cosimo stepped into his fonderie to use the equipment to extract the pure virtues (quintessences) from herbs, roots, seeds, gums and minerals. But considering the multiplicity of his other interests, I doubt that he spent a great deal of time there.

Perifano noted that while he was experimenting with metals, Cosimo was also creating herbal remedies for the good of his friends and family. He may well have learned from Luca Ghini, who was an expert at distilling medicinal plants and whose herbal formulas were recorded by Giovanni Battista Nardi. Baccio Baldini said:

“Cosimo began to employ his knowledge of plants for the welfare and benefit of society and thus he had many kinds of plants, leaves, and flowers distilled with various methods throughout the year in order to obtain precious essences and oils; he also produced many different medicines, both simple and compound, which he gave away to any of his subjects who needed them and to individuals throughout Europe who sent him their requests.”

Cosimo was succeeded by his son Francesco, who was so obsessed with alchemy that he neglected to govern his city and state. He was despised by the people of Florence, who said he spent all his time in his alchemical laboratory.

He accumulated a great library of books on alchemy and philosophy, absorbed the philosophical ideas of Rupescissa, Ficino and many other alchemical writers and wished to carry out the great work himself. He commissioned Giorgio Vasari to create a studiolo:a laboratoryin Palazzo Vecchio, for his alchemical experiments,with two paintings to adorn it. The first picture by Johannes Stradanus (1523-1605) was of an alchemical laboratory…

Georgiana Hedesan explains that Stradanus’s picture, supposedly based on Francesco’s laboratory in Palazzo Vecchio, shows him working among his artisans, under the watchful guidance of a physician. The painting shows the laboratory revolving around the production of the quintessence, with the still for its production at the front of the picture, the physician pointing to it and Francesco looking at it. The angelic central character in the painting, with his blond hair and feminine features, is the embodiment of the gold quintessence, which he holds in his hands. The painting makes clear that the alchemical production of the quintessence is the most important activity in the laboratory, and this is portrayed in idealistic terms.

Francesco wanted to produce a universal medicine or supreme panacea, working with Ficino’s idea that the Spiritus Mundi quintessence was the spirit of gold, distilled using the spirit of wine (pure alcohol). At the back of the picture is another, much larger, still, used to produce quasi-industrial quantities of plant distillates.

You can see Stradanus’s picture in the Palazzo Vecchio in Florence and imagine the alchemical experiments that were going on in secret corners, basements and hidden places during the Renaissance. Visit the monasteries where liqueurs are still created and imagine the monks with their distillation equipment in their alchemical laboratories. There is much more to Florence than beautiful paintings and wonderful buildings.

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Angela Paine grew up on a hop farm in Ken where her botanist father taught her about plants. She ended up in Florence in 1967, washing books in the National Library, after the great flood, later marrying, having two children and living in an old olive press in Tuscany. On her return to Britain she embarked on a first degree in Human Physiology, a post graduate diploma in Pharmacology, then a PhD in medicinal plant chemistry. She went on research trips to Africa and South America to collect plant material used as medicine, and collaborated with scientists around the world, publishing internationally in scientific journals. She spent time in the Golden Valley on the border with Wales, where she continued her research into the medicinal properties of the local, native plants which were used by the ancient Celts and wrote her first two books. She now lives in Stroud, where she wrote her next book: Healing plants of Greek myth. Always remaining in contact with Florence she was inspired to write her latest book: Healing plants of Renaissance Florence. She runs workshops and courses on medicinal plants and how to use them to make tinctures, oils, ointments and teas.