Dear Readers,

As you may have seen elsewhere, in mid February my wife and I suffered the loss of our home in a fire, in the hills of central Massachusetts. The good news is that we got out safely and had no animals in our care at the time. The fire crews were able to contain the fire from spreading, in what turned into a 3-alarm, 5-hour-long ordeal in subzero temperatures; they did amazing work, and no one was injured. The bad news is that all of my physical historical materials and research of 30 years have gone up in smoke. As a result I have decided to suspend this blog for the time being. It will remain online as a resource for those interested in the history of glass and glassmaking in the seventeenth century and beyond. I do intend to resume writing when I can, but for now my time and energy are required in getting us back on our feet.

Friends are providing temporary shelter for us nearby and our intention is to rebuild as soon as possible. To those who have reached out with a steady hand, to those who have opened their wallets, and offered advice in our time of need, we thank you from the bottom of our hearts. In what are already difficult times for all of us, you have made a huge difference in our lives.

Paul Engle
6 March, 2021

Friday, November 29, 2013

A Matter of Plagiarism

Francesco Lana Terzi (1631-1687)
The seventeenth century Jesuit scientist Francesco Lana Terzi (1631-1687) is famous for his design of a "flying boat"; he has been immortalized as the father of aeronautical engineering. What is not generally known is that he plagiarized the entire text of Antonio Neri's manuscript Discorso.

The original was never published by Neri, perhaps due to his premature death, but even as a manuscript, it must have circulated widely. It would be interesting to know the history of its diffusion, in order to understand how it became the subject of plagiarism. Lana Terzi, well known in the Italian Academia of the late seventeenth century, published his Prodromo in 1670. The entire chapter 20 is an exact reproduction of Neri's Discorso. Lana Terzi was fascinated by experimentation and manual arts. The Jesuit order refused their members permission to write about magic and alchemy; Jesuits with such esoteric interests could never write books directly devoted to these subjects, however, they could write works on the different aspects of natural philosophy. In this broader context chemical philosophy could be admitted. 
Title page of Lana Terzi's Prodromo

Neri was popular in his own time for his glassmaking knowledge. L'Arte Vetraria was widely read and its reprints and translations appeared over the centuries. Nevertheless, Neri enjoyed a considerable reputation among his contemporaries also for his 'chemical philosophy'. Discorso is a complete treatise on the subjects of chemistry and philosophy, to all appearance not different from many others written during the sixteenth century. It holds a similar structure, with an introduction defining the subject and the description of procedures. The final part lists possible objections raised against the validity of chemistry and gives Neri's timely responses. In this sense Discorso belongs to the alchemical traditions and Neri shows his deep knowledge of the Paracelsian doctrine and literature. Even so, the main features of the new 'scientific' mindset are present in Neri's treatise: the study of "the great book of nature" and the value of experimental practice. The traditional reliance on the authority of ancient wisdom loses its legitimacy. "We should not so easily give credence to all the histories," Neri claims, but we should "prove the possibility of this art of transmutation with certain […] experiences". Knowledge is acquired "with the practice of many experiences." It does not come from a divine revelation or from the study of many books.

There is no contradiction between the alchemist Neri and the glass-conciatore Neri; the will of gaining a deep knowledge of nature, based on the observation and experimentation, is common to both. Neri is always 'the technician' and never 'the philosopher'. Alchemy, the "Great Art," is the result of a deep study of nature and its aim is not to give an imitation of nature, but to make it perfect.

The 'modernity' of Neri can also be understood in his way of talking about chemical philosophy. He does not pretend to teach eternal truths, but only to indicate the way to achieve greater knowledge, by "understanding the modus operandi of nature." Consequently, the writer does not use the form of a dogmatic essay, but that of a conversational chat, or 'discourse'.

It would be interesting to discover how Lana Terzi came into possession of Neri's manuscript. Perhaps he was attracted by the mixture of old and new which was also a predominant theme of his time, when different models of knowledge coexisted and intertwined. Discorso offered him the chance of introducing the topic of alchemy without being accused of magism.

-M. G. Grazzini
Conciatore is pleased to welcome our first guest writer, independent researcher Maria Grazzini. Maria holds a Ph.D. in Philosophy from the University of Florence, where she studied Antonio Neri under the late Prof. Paolo Rossi, philosopher and historian of science. Recently, she published an annotated English translation of Neri's manuscript Discorso in the journal Nuncius. By day, she runs the hotel Albergo Natucci, in Montecatini Terme, with her husband Vincenzo. Please join me in welcoming Maria to Conciatore:

Wednesday, November 27, 2013

Cardinal del Monte

Portrait of Francesco Maria del Monte.Ottavio Leoni (1578–1630)
In the early seventeenth century, Cardinal Francesco Maria del Monte was the unofficial Florentine cultural ambassador in Rome. He regularly entertained visiting dignitaries and represented the Medici family's interests within the Vatican. He was an avid art collector, glass enthusiast and amateur alchemist.  He was a patron to the artist Caravaggio, to the astronomer Galileo and a dear friend to Neri's employer Don Antonio de' Medici.

There is a chance that he met Glassmaker Antonio Neri in person; in 1602 he visited the Casino di San Marco, where the glass foundry was located and returned in 1608, although by then Neri was in Antwerp. The strong bond of affection between Don Antonio and Cardinal Del Monte is clear from their extensive correspondence and gifts to each other.  In addition to their passion for alchemy, the two shared a strong interest in glassmaking technology.

Del Monte collaborated with Niccolò Sisti, the grand duke's glass foundry master at Pisa, where Neri also worked for a time. Sisti often provided Del Monte with glassware for Medici customers within the College of Cardinals in Rome. Thanks to the cardinal's patronage, many glassmakers in Rome were brought to the appreciation of the papal court.  

There are indications in Neri's 1600 manuscript that he visited Rome. If so, it is hard to imagine him not seeking an audience with the cardinal, either at his villa on the Pincio,  overlooking the city or at the Palazzo Madama, now offices of the Italian Senate. The palazzo was Del Monte's main residence near the center of Rome, appointed in fabulous luxury and arranged to accommodate a constant flow of dignitaries from around the world. The villa, on the other hand, was where his alchemy laboratory was located. This was a more secluded retreat where the cardinal could entertain guests with more discretion.


The Portland Vase
Del Monte's will shows that at the palazzo he maintained an entire room, "gabinetto dei vetri" [cabinet of glasswork] that housed five hundred pieces of glassware. It cannot go without mention that he was also the proud owner of what has become one of most celebrated pieces of ancient glass, now referred to as the Portland Vase.

Monday, November 25, 2013

Tin into Silver

The Alchymist, (Joseph Wright of Derby, 1771)
In Discorso sopra la chimica, a manuscript written by Antonio Neri in 1613, he discusses his philosophy of chemistry and gives several examples of recipes for the transmutation of metals. An instructive example is his conversion of tin into silver. He starts with a ball of pure English tin. He encases it in lute—clay that can withstand high temperatures—and then forces it below the surface of a bath of molten silver. After a time, the ball is removed and cooled. The clay is then cracked away to reveal that the tin inside is now silver. Neri explains that the "spirit" of the silver has penetrated the clay ball and its noble properties have converted the tin. 

In the light of current knowledge it is not hard to assign a more accurate understanding of what was taking place. Tin is a much less dense metal than silver and melts at a lower temperature. By forcing the luted ball down into the liquid silver, the tin inside quickly melts and its buoyancy forces it out of any small holes or cracks in the clay, even if microscopic in size. Much the same way as a sealed rubber balloon filled with helium deflates over time. As tin escapes the rigid ball it is replaced by silver from the surrounding melt, pushing inward. Once the tin escapes the clay, it will rise to the surface, but it also mixes, diffusing into the silver. Depending on the quantities and the temperature of the melt, a thin layer of alloyed silver-tin might form on the surface and some would evaporate into the air. Neri describes this as "malignant fumes" of the tin and goes on to say anyone discovering something "that would repress these vapors would have a very great secret."

Even though the clay encasement might appear to be a solid barrier, buoyancy forces cause much of the tin to escape the ball and to be replaced by silver. If the process of mixing were allowed to complete, the comparatively small amount of tin in the ball would disperse throughout the much larger silver melt. An assay would reveal a high silver content in the luted metal. Given the historical lore of alchemy and the level of scientific knowledge at the time, this was a very persuasive argument in favor of transmutation, even for seasoned experts. A valid criticism of Neri's explanation is that he was simply not skeptical enough; the presence of silver inside the sealed ball does not, in itself, prove transmutation. Indeed, a careful accounting of all the materials involved would have revealed to him that the total amount of silver had not changed in the experiment. 

For the viewers of such a demonstration there are other considerations. There was an unmistakable theatrical flair to these events. Audiences often included princes and other royals. Even before the demonstration begins, there is an air of anticipation, the expectation to witness something extraordinary. It is not hard to imagine the same sort of performance atmosphere for Neri's demonstration that was and is still a critical part of legerdemain and conjuring acts. Even if not intentional, this charged setting leads to a suspension of disbelief. It can have a powerful effect on our perceptions. The same state of mind that allows us to be amazed by a "magic act" can blind us to seeing nature as it is in truth. Despite his interpretation, Neri’s experiment does involve repeatable chemistry, conducted without trickery that has a legitimate explanation, even if not the same one advanced in the early seventeenth century.

For further reading, see M. G. Grazzini 2012, p. 351.

Friday, November 22, 2013

Transmutation

Hermes Trismegistus,
 floor mosaic in the Cathedral of Siena
In the introduction to his book, L’Arte Vetraria, Antonio Neri is quite direct about his interest in matters other than glassmaking. Speaking about the potential of chemistry in medicines, he writes, "These are matters of nature to which I believe there is no higher calling in the service of humanity." As the son of a renowned physician, and the grandson of a surgeon, it is not surprising that Neri would be occupied with thoughts of healing injuries and curing disease. 

In a 1608  letter to a friend in Florence, Neri wrote that he spent time working in Mechelen in Flanders, at the Hospital of Malines, and describes his great success with medicinal cures of Paracelsus, "To the great wonderment of Antwerp."

Within the realm of alchemy, it was commonly thought that a substance known as the "philosopher's stone" could be used to cure all disease and perhaps even arrest the process of aging. The philosopher's stone was an ancient concept, said to be discovered by an Egyptian priest, Hermes Trismegistus, and then subsequently lost. It was believed to be a substance which manifests such a harmonious balance of the four elements, air, water, earth and fire, that it would spontaneously form a fifth element or "quintessence." Besides curing disease, it was thought to have the power to turn base metals into gold in what Neri thought was the acceleration of a natural maturation process of the metal.

In his manuscripts on alchemy, it is clear that Neri studied the work of many famous alchemists. He expresses disdain for those who pursued the stone seeking personal profit, and was convinced that he himself had found the secret. With special material from a mine, the importance of which he did not realize until later, he says he successfully transmuted gold, but that ultimately, the ability for the method to work is determined by divine providence, which he called "the gift of God." 

Neri held his gold transmutation methods close, but for lesser metals, he did leave us with lucid descriptions. We can see from these, how the subtleties of physics and chemistry conspired to convince honest thoughtful men that transmutation was not only possible, but could be easily verified in the laboratory. In his manuscript Discorso sopra la Chimica, Neri describes his method for turning tin into silver. In the next post, we will take a closer look.

Wednesday, November 20, 2013

Cinquantesimo

At the Neri Chapel in Florence.
Today marks the fiftieth post to this blog. It may not be a momentous event, but certainly worthy of a short pause to reflect. I would like to express gratitude to all my readers, regular and occasional, who have taken the initiative to stop by and read about the life and times of Antonio Neri. What started as a promotional platform for my forthcoming book, Conciatore (Feb. 2014), has begun to breathe on its own, with a slightly different rhythm from the book. It is my hope that through either, the book or the blog, a bit of my enthusiasm for the subject will rub off and you will seek to learn more about the fascinating history of glassmaking, alchemy and early modern science.

One thing that I find wonderful about Neri's era, the late sixteenth and early seventeenth century, is that we can easily recognize aspects of daily life, it was not so long ago, yet it was a period when alchemy and Aristotle's four elements (earth, air, fire and water) still loomed large. At the same time, men like Galileo were busy laying the foundations for what we now call modern science. It was a time fraught with apparent contradictions, and in taking a closer look at them, we can discover some surprising things about our current attitudes towards art, science, religion and a host of other topics. 

American man of letters Guy Davenport once wrote "Religion, science, and art are all alike rooted in the faith that the world is of a piece, that something is common to all its diversity, and that if we knew enough we could see and give a name to its harmony." By extending our knowledge of history to include Neri's era, we can make some progress toward naming that harmony. In his time, it was commonly thought that one metal could be purified (transmuted) into another, and that the "essence" of a substance could be transferred through physical manipulation. It is astonishing that sophisticated chemistry was performed successfully and regularly, albeit based on a model that would soon crumble into dust. 

Armed with this, our own history, we cannot help but look at our current concept of the universe, and wonder about which pieces are destined to crumble, despite our technological successes. Knowledge of the past gives us the perspective of time, the space to broaden our view of the world and our place within it. Taking a moment out of our hectic lives to learn a bit of our past can provide a little oasis for the contemplation of larger ideas. I urge you to continue to join me here, and to think big.

Monday, November 18, 2013

Galileo and Glass


Portrait of Galileo Galilei, 1636 (detail),
by Justus Sustermans (1597-1681)
No known direct contact occurred between Antonio Neri and the astronomer Galileo Galilei, but the two men lived simultaneously in Florence and then in Pisa. Their paths crossed many times, orbiting around each other like planets. 

As a youth, Galileo was taught at the Cestello monastery by court mathematician Ostilio Ricci. This was around 1580 when Galileo was sixteen, and Neri was a four year old toddler, living only a block away and attending the Cestello church with his family. Neri's father and grandfather had just been granted citizen status, already well known for their medical prowess. Galileo would go on to become good personal friends with Prince Don Antonio de' Medici, Neri's sponsor. Later, the astronomer would have telescope tubes made by Jacopo Ligozzi, a regular at the Casino di San Marco, where Neri worked as an alchemist and took his first steps into the craft of glassmaking. As Galileo started to experiment with lenses, Neri was leaving for Antwerp and would be absent for seven years. Meanwhile Galileo landed a job at the Florentine court as mathematics tutor to Grand Duke Ferdinando's son, Cosimo II. 

Both Galileo and Neri worked hard for their achievements. In the hindsight of history, innovations are often romanticized into shining moments of inspiration, forgetting the painstaking effort and dogged persistence required to bring those ideas to fruition. For his telescopes, Galileo encountered tremendous difficulty both in the production of suitable glass and in grinding that glass into usable lenses. His celestial observations included sunspots, lunar craters and the planet Jupiter with its moons, which he named "Medicea Sideria" after his Medici benefactors. As these revelations became known, there was a clamor of orders for telescopes from princes throughout Europe and Galileo struggled to keep up. He maintained a circle of trusted craftsmen on Murano in Venice, and elsewhere, but still, the majority of output was unusable.

Initially, he had reasonable success grinding and polishing broken pieces of mirrors. In early 1610, Galileo held a demonstration in Pisa for his former pupil, Grand Duke Cosimo II. A short time later, the grand duke ordered that a special batch of glass be made for Galileo by Niccolò Sisti, for whom Antonio Neri had worked just a few years earlier. At the time, Neri himself was still in Antwerp and would not return until the following year.

Neri returned to Tuscany and wrote his book on glassmaking, but then turned his attention to other pursuits. This, just as Galileo's quest for high quality glass to make his lenses took off in earnest. Neri’s final manuscript places him in Pisa working on alchemical recipes. There was no more optimal moment for the two men to meet; both were working in Pisa, both knew Niccolò Sisti, Neri had just published his book, and the astronomer was becoming desperate for clear flawless glass. If such a meeting ever occurred, it has not been recorded, and shortly thereafter, in 1614, Neri died of an unspecified illness.

On 20 December of that same year, four days before Christmas, Tommaso Caccini, Neri's childhood next-door neighbor, delivered a scathing denouncement of Galileo from the pulpit of Santa Maria Novella church. While the sermon earned Caccini a reprimand, and was an embarrassment to his family, it did also serve as a start to Galileo's troubles with the inquisition.

While Antonio Neri may have never encountered the astronomer, shortly after the time of the priest’s death, the astronomer acquired Neri's book on glassmaking. One copy was sent to Rome, to Federico Cesi, founder of the Accademia dei Lincei, a scientific society to which Galileo belonged, and another copy was saved for the astronomer's personal library. Galileo continued his quest for flawless glass, and in his correspondence he takes on the same obsession with purity of ingredients that Neri exhibits throughout his book.  

Friday, November 15, 2013

The Dance of Lead Crystal

Roemer type drinking glass c. 1677,
George Ravenscroft.
The entire fourth part of Antonio Neri's book L'Arte Vetraria is devoted to the preparation of lead glass, a forerunner of what is now commonly known as lead crystal. This section is unique in the book in that it contains the only instance of the author giving direct advice to glass artists themselves:
"To work lead glass into various drinking glasses or other vessels, or even to draw cane for beadmaking, it is necessary to raise the punty [out of the melt], and to make a gather of glass by turning. Take it out, let it cool somewhat and then work it on a well-cleaned marble [marver]. The marble should be somewhat cool, and well bathed with water before use."
He goes on to describe what might be termed a kind of dance with the glass. As with a human partner, gentle patience is required in learning the boundaries of what can and cannot be done. Ultimately, an artist must come to understand the material's behavior and personality in order to result in a great partnership. For the artist who makes unrealistic demands, glass can be a heartbreaker.  
"This sort of glass, lead glass, is so runny that were it not cooled, and taken up by turning [the punty] to wind a gather, it would be impossible to work. It is so runny that it would not even hold onto the punty, because it is as loose as soup. This arises out of [the fact that] the lead calx causes it to become very fluid."
"Namely, gather the glass little by little, allow it to cool, and work it over marble frequently bathed in water. Furthermore, make sure to keep the pot of glass rather calm, and in a place in the furnace where it will not see too much heat, otherwise it will not be possible to work this glass at all."
It is true that the formulation of modern lead crystal is a relatively recent development. This is a composition of crushed silica (sand or quartz), potash (potassium carbonates) and lead oxide substituting for calcium to stabilize the composition. It is also true that lead has been added to glass since its invention a few thousand years ago. It is not clear that this addition was always intentional, but a Babylonian tablet of 1700 BCE gives a recipe for pottery glaze that explicitly contains lead. At some point, a discovery showed that small amounts of lead and pigment smeared on glass and fired made stained glass paintings possible. The earliest examples of colored stained [1] glass windows date to first century Pompeii and Herculaneum.  In medieval Europe, leading up to Antonio Neri's time, lead glass was used in mosaic tesserae and in artificial gems.

Finally, it is worth noting that Neri's childhood church in Florence, Cestello (now called Santa Maria Maddalena dei Pazzi), was then run by Cistercian monks. It was the Cistercian luminary St. Bernard of Clairvaux who, in the twelfth century, built the first church with large windows, urging, "The soul shall seek the light by following the light."

[1] See post dated 11 Nov 2014.

Wednesday, November 13, 2013

The Inquisition

Insignia of the Inquisition, 1574.
The mandate of the Catholic Church's inquisition was to stamp out heresy. Empowered to impose sanctions that included torture and execution, they were not an organization with which to trifle. In 1600, just over a decade before Neri's book was printed, former Dominican friar Giordano Bruno was tortured, convicted of heresy and burned at the stake in Rome's Campo de' Fiori market. Shortly before that, the inquisition ordered Neapolitan polymath Giambattista della Porta to disband his group of scientific investigators and to cease all publication without special written permission from the Church. Famous French essayist Michel de Montaigne complained of having books confiscated upon entering Rome, although in Florence he was welcomed with open arms by Francesco de' Medici at the Casino di San Marco, where Antonio Neri would later work.

There was special attention paid to books, because they carried the potential to 'corrupt' large numbers of people over a wide geographic area. Heresy was considered a disease of the mind, the devil's work, and books were seen to be a potential source to spread the infection, especially books from the Protestant quarters of Europe, but also from the 'misguided' notions of early scientific investigators.

The last page of Neri’s L'Arte Vetraria is devoted to the official permissions that were necessary to print and sell the book. Here we read that Pie[t]ro Niccolini, Vicar of Florence (a man destined to become the archbishop) ordered Canon Filippo del Migliore of the Florentine archdiocese to review the manuscript. Upon doing so, he found nothing that "contrasts with Christian conscience." Next, it was passed to the Holy Office of the Inquisition, where the head inquisitor of Florence, Fra Cornelio Priatoni from Manza, assigned that the manuscript be reviewed by Agostino Vigiani, Regent of Servants. Final approval came from Florentine Senator Niccolò dell’ Antella.


Within a few years, Cornelio Priatoni would  be embroiled in the investigation of Galileo. In fact, the reviewers of Neri's glass book reads like a cast of characters from the initial investigation of the famous astronomer. The Galileo case would also include Ferdinando Ximenes, the brother of Antonio Neri's good friend Emmanuel. Ferdinando was prior of Santa Maria Novella where the inquisition was based. In fact, Emmanuel's uncle, after whom he was named, also worked in the Holy Office of the Inquisition in Florence and would give testimony in the Galileo affair.

Writing that could be perceived to defy the Church's teaching was a serious concern for authors in Italy, even those under the protection of the liberal Medici family. Although not overtly heretical, Neri's other manuscripts could have easily fallen into this category. Thankfully for our alchemist and glassmaker, upon reading Neri's book, Vigiani stated "I have not found anything repugnant to the Christian conscience and good customs, but [a book] full of things and natural secrets, no less useful than curious."  

Monday, November 11, 2013

San Giovanni

"Florence - Church of San Giovanni, the Baptistry",
Photo: Giacomo Brogi (1822-1881).
The San Giovanni Baptistery stands in the heart of Florence, directly in front of the city's most famous structure, Santa Maria del Fiore Cathedral, also known as The Duomo. The church and its dome are so large that they dwarf the baptistery by comparison. Nevertheless, a simple look inside its cavernous, octagonal space easily shatters this illusion. In Antonio Neri's time, this place was a civic hub; a space where masons and tailors rubbed shoulders with nobles and princes. One of the oldest structures in the region, it was also one of most cherished, clad in polychrome marble, with imposing bronze doors intricately sculpted by masters. Michelangelo dubbed them "the gates of heaven." It was here, in this ancient basilica that the future of Tuscany could be seen plainly, in the eyes of its youth. New generations of Florentines were welcomed into the world by their neighbors, anointed and christened, as they had been for centuries. The current structure dates to the eleventh century, but it replaces octagonal baptisteries built on the same spot as early as the fourth century, originally surrounded by a cemetery.

Antonio Neri was baptized here, as were all his brothers and sisters, his parents, some grandparents and quite possibly some much earlier relatives. His sponsor, Prince Don Antonio and his Medici ancestors were also given rights at San Giovanni, in the same octagonal marble bath at its center. The unusual font was a sister to the one still standing in the identically named baptistery in Pisa. Along each side, there was a drywell. By standing in it, a priest could perform the ceremony and avoid jostling by the crowd. Legend tells that one of the stations showed the repair made after poet Dante Alighieri took an axe to a well in order to free a child who had become entangled and was at risk to drown. The font was replaced later in the same year of Antonio Neri’s birth, 1576, on orders of the Grand Duke, in preparation for a royal baptism.

The ancient mosaic tile floor, although repaired many times, still shows its original signs of the zodiac and other early Christian iconography. As a newborn infant, tightly wrapped in swaddling, Antonio Neri would have been carried across that floor, busy with families and children, and then gently handed to the priest, perhaps by his father, already a famous physician. Joining them would be his grandfather the barber surgeon, his other grandfather the lawyer to Michelangelo, his godparents, other family, friends and perhaps a wet nurse. His mother stayed at home with her close friends to recuperate from the ordeal of birth, and to prepare for a neighborhood celebration. Even in the dead of winter, if his eyes were open, the sparkling glass mosaics covering the entire domed ceiling of San Giovanni could not have failed to catch the wandering eyes of this future glassmaker.

Friday, November 8, 2013

Black is Beautiful

Black glass cameo vase, c. 1900
Thomas Webb.
Antonio Neri was a technical adept, a student of alchemical history and a glassmaker extraordinaire. He was also a gear in the Medici innovation machine. The glass recipes he developed were likely put to work in the glass shops sponsored by the ruling family in Florence, Pisa and elsewhere. Making advances in technology gave the region a competitive advantage, encouraging the arts cemented a reputation for creativity that endures to this day throughout Tuscany.


Black is one color that has given glassmakers difficulty ever since the material's invention over four thousand years ago. It is easily approximated for large, heavy objects, but to achieve a true solid black in blown vessels, or thin layers is a challenge even for current technology.

Obsidian is a naturally occurring volcanic glass that was prized in antiquity, most often occurring in black or very dark brown. In prehistoric times, it was coveted for cutting tools and arrowheads. As technology advanced, it was ground and polished for mirrors. Later, obsidian became popular in ornamental objects ranging from dinner plates to jewelry. The production of obsidian, gemstones and other natural materials through artistry was a quest that kept glassmakers busy.

In many ways, making black glass shows the other side of challenges in making colorless crystal; instead of a formulation that will transmit virtually all the light falling on it, the aim is to produce a glass that will absorb virtually all the light. In his book, L' Arte Vetraria, Neri presents three recipes for "velvet black" glass (# 51-53), and three recipes for black enamel (#100-102).

His first black glass is made with the discarded broken pieces of "glass of many colors." To this, he adds 'zaffer,' a cobalt ore used to produce deep dark blue, and manganese, which produces a magenta color. He advises that it will be good for bead making cane and other work. For his second black glass, he starts with high quality frit to which he adds lead and tin oxides. This forms an opaque, white lead crystal, which he tints with calcined "steel" (probably bronze) and pulverized iron flake. He claims that after twelve hours "the glass will be a most beautiful velvety black." Neri's ultimate black glass is his simplest. He starts with his 'rocchetta' frit, and adds the dried, pulverized dregs left in red wine casks, advising us to go slowly since it froths up. He allows it to cook on the fire for four full days, and finally "washes" the glass by flinging a ladle-full at a time into clean cold water. He then re-melts it; "You will have a black fit for any job and more marvelous than all the other blacks of which I have written."

Wednesday, November 6, 2013

The Purse of Envy

Antonio Neri, "The Mineral Gold"
Ferguson 67, f. 5r.
As a young man, Antonio Neri faced a decision that had confronted virtually all accomplished artisans since the dawn of time and continues to do so today; whether or not to freely share hard-won technical knowledge with others. The indications are that Neri's thinking on the subject evolved over his lifetime. Testimony given by Florentine metals refiner Guido Melani indicate that as a twenty-year-old, Neri was willing to share his most precious secrets, albeit reluctantly.

Melani reported that in July 1596, Neri performed a transmutation of base metal into "twenty-four carat" gold. Upon being pressed, Neri confided that he had learned the secret from a German, who performed the gold transmutation with a "tablet of medicine." The German told him the medicine was nothing but the simple quintessence of green vitriol and the method to produce it was described by Paracelsus.

The motivations for keeping techniques secret are obvious; potential monetary reward and personal prestige. Aside from the immediate gratitude of confidants, the motivation for sharing technical secrets can be more subtle; the satisfaction of serving a greater good by advancing the art. It is indeed an ancient and very human dilemma. Five centuries before Neri, in the early 1100s a glassmaking Benedictine monk wrote on the subject. In Hesse, Germany, Theophilus Presbyter penned these lines in his De Diversis Artibus [On Various Arts]. "Do not hide His [God's] gifts in the purse of envy, nor conceal them in the storeroom of a selfish heart" and "Do not hide away the talent given to you by God, but, working and teaching openly and with humility, … faithfully reveal it to those who desire to learn." Although it is doubtful that this particular writing was ever seen by Neri, his access to the most extensive libraries in Italy, along with his knowledge of Latin and the writings of other alchemists ensured a comprehensive understanding of his subject and the politics surrounding it.

Two centuries after Neri's death, historian Francesco Inghirami published details of an incident, which if true, might have contributed to a change of heart with our priest:
He [Neri] claimed he had found the secret of making the famous philosopher's stone and it was said he had discovered it among some of his confidants.  Some thugs learnt of this and attacked him at night, in order to obtain the secret by force. He shrewdly gave them a certain recipe he had in his pocket and explained the figures written on it, claiming it to be the secret oil required. But that night, Neri left Florence and traveled to various parts of Europe.

Nevertheless, in his travels to Antwerp it is clear that Priest Neri continued to share his knowledge of glassmaking, in the shop of Filippo Gridolfi, and of course, upon his return to Florence seven years later in the publication of his famous book, L' Arte Vetraria. In contrast, on the subject of transmuting gold and silver, Neri had decided to take his secrets with him to the grave, a decision that he justifies in a manuscript, Discorso, which he completed shortly before his death:
We must also consider the danger to its possessor if it became known to others and particularly to the princes. For that reason even if someone knows and practices this art, he is obliged to keep it hidden and to conceal it; and I know of what I speak.

Neri outlines his fears that such a momentous discovery, if generally known could lead to abuse of power, a collapse of the monetary system, and general chaos in society. In spite of his deep reservations, we see a final glimmer of his innate desire to share. He did, in fact, leave behind his recipe for the philosopher's stone, but in coded, obscure language that has never to this day been deciphered. As he put it: "I wrote the words so strangers will not understand." 

Monday, November 4, 2013

The Duke's Mouthwash

Ferdinando de’ Medici (1549-1609),
 Scipione Pulzone (1544 - 1598), Private collection.
Antonio Neri's father, Neri Neri, was royal physician to the family of Grand Duke Ferdinando de' Medici. As such, he regularly interacted with other members of court, ranging from the archbishop of Florence, to his colleagues in medicine, including the royal apothecary (speziale), Stefano Rosselli. Rosselli shared more than a professional relationship with Neri Neri. They both admired the work of an ancient Greek physician named Discorides; Rosselli was something of an authority on his methods. In addition, he ran the 'Speziale al Giglio' shop, once owned by Tommaso del Giglio, who's chapel Neri Neri took over at Cestello church. Rosselli's son, Francesco, and Neri Neri were among the four chosen to revise and update the famed Ricettario Fiorentino, the official reference for medicinal cures in Tuscany. 

On 21 September 1589, Rosselli started to compile his own book of recipes to pass down to his two sons, Francesco and Vincenzo, who would go on to continue the pharmacy. The book begins with a poison remedy credited to none other than Cosimo de' Medici. Recipe no. 9 is the grand duke’s antispasmodic oil, presented by Niccolò Sisti, with whom Antonio Neri would later work at the glass house in Pisa. No. 20 is the duke's oil for deafness, also presented by Sisti. No. 41 is a poison antidote revealed to Francesco de' Medici by the Archduke of Austria. It was tested on a prisoner at the Bargello prison, a man who was poisoned, then revived with the antidote in the presence of Stefano Rosselli and Baccio Baldini, the long time physician to Cosimo I.


Recipe No. 30 carries perhaps a bit less risk; it is titled "Acqua da gengie di messer Nerj Nerj" (Mouth wash of Neri Neri):

Take a quarter of a bushel of mastic buds,a quarter of a bushel of myrtle buds, a quarter of a bushel of red roses, three ounces of alum, a half ounce of salt and a quarter ounce of hard rose honey. Mash the herbs with a mortar and pestle and put them in nine pounds of Greek wine for twenty-four hours, then boil in a bain-marie and reduce to two-thirds. In this, we bathe the gums: it makes them dry and firm.
The date that Stefano Rosselli started his book of secrets is interesting because it is the same day that Neri Neri, with the grand duke's two other physicians, Cini and Da Barga, were busy making medicinal wine based on Dioscorides' ancient recipes. Perhaps they all met that day at Rosselli's shop, for his advice. 

Friday, November 1, 2013

Women in Early Modern Science


Antonio Neri, 1598-1600,
MS Ferguson 67, f. 25r.
Within a year of his ordination in the Catholic Church, Antonio Neri began an ambitious treatise, illustrated in his own hand, devoted to "all of alchemy." Six of the illustrations in this manuscript, completed in 1600, show women tending equipment. What is remarkable is that, in the historical record, female participation in alchemy is otherwise extremely rare

Two pictures show female alchemists at work. In both cases, the
Antonio Neri, 1598-1600, 
MS Ferguson 67, f. 35r.
technician stands behind a dedicated piece of apparatus, facing forward, giving the impression of propriety in an arranged portrait. The first drawing depicts a furnace and vessels used to make liquid mercury from its ore. The other shows a different type of furnace with a 'tower,' used as an efficient way to cook ceruse (white lead oxide). These images are part of a larger set of two dozen similar drawings that each illustrate the equipment used to prepare a specific product, many include a furnace and glassware. Nine of these show a single individual, (or in one case two men) tending the equipment. 


Three other illustrations in the manuscript are notable for their

Antonio Neri, 1598-1600, 
MS Ferguson 67, f. 37r.
engagement of women. These pictures show details of kitchen and nursing work; what might be termed more traditional female roles in the sixteenth century. Two of these illustrations are devoted to the respective arts of preparing plants and animals. They show women working alongside men performing various tasks. A third illustration shows medicinal fogging tents tended by a woman. Inside one tent, a male patient sits on a bench, exposed and breathing fumes pumped in by a large vessel perched over a fire.

These images also present clues to the circumstances of Antonio Neri's work environment. We may well be looking at operations inside the Casino di San Marco soon after prince Don Antonio de' Medici's occupation of the facility. The presence of women among Neri’s colleagues indicates a social setting with a camaraderie not displayed in other alchemical works of the period.