Wednesday, May 31, 2017

Travels to the East

Jean de Thévenot, from
"Relation d'un voyage fait au Levant" (1664)
In 1652, at the age of eighteen, a wealthy Frenchman named Jean de Thévenot finished his studies at the University of Paris. He celebrated his achievement with a grand tour that would take him, not just through Europe, but unexpectedly half-way around the world, where among other things he would find glass being made. 

In Rome, he befriended fellow Parisian, Barthélemy d'Herbelot, where they conspired to travel together to the Levant. 

Circumstances detained d'Herbelot and after waiting five months in Malta, Thévenot gave-up on his companion and set out on his own to Constantinople. Four years later, in 1659. He returned home only to prepare for an even more epic adventure, one that would last until his 1667 death in Azerbaijan from an accidental pistol shot. 

Thévenot kept a travel diary, he picked up languages easily and endeavored to blend-in to local culture as much as possible. Throughout his travels he made keen observations of people, customs and of the natural world around him. He published a volume of his adventures to great acclaim, two more would follow after his death. In 1687 his work was translated into English, when it found a whole new audience. 

Of special interest to us are his numerous observations about the glass trade. This was a subject to which he had no special interest or connection, but his natural curiosity and communication skills open a window into an otherwise poorly documented piece of the glass history puzzle.

On Malta, even before embarking for the Far East, he notes that “sore eyes” are a problem because of the bright sun on the white (limestone) earth of the island “which makes many commanders and knights wear green spectacles”; certainly an early incarnation of sunglasses. [1] In Constantinople (today Istanbul) he visited the great mosque Hagia Sophia and remarked “it is full of lamps and curiosities in glass balls, of which one for instance, contains  a little galley, well rigged, another a model of the mosque in wood and the rest a great many pretty knacks of that nature.” [2] Having booked passage out of Alexandria, Egypt on an English gun boat, he explains that the sailors kept track of their speed with a “little slat and very thin piece of wood tied to a line and when they throw it into the sea, they turn a half-minute sand glass […] every seven fathoms of the line making a mile in an hour.” [3] This is the origin of the nautical unit of speed known as the 'knot', the method of paying out line spaced with knots tied in the line at intervals of  8 fathoms - 47 feet 3 inches (14.4 m). This method of reckoning progress with a line was used well into the nineteenth century, the units are still used today, both for boats and aircraft.  A vessel travelling at 1 knot along a meridian travels approximately one minute of geographic latitude in one hour. [4]

In Damascus, Syria, he visited the great mosque there (Umayyda). Some natives kindly offered to take him in, disguised with a turban on his head, but he declines, fearing that if discovered, he will be forced to choose between his life and his Christian faith. Nevertheless he walks around the tremendous structure and observes that “The pavement is all of lovely stones that shine like lookinglass” and he continues “I went up to the terrace-walks, to the windows of that mosque, which are made like the windows of our churches and have panes of glass set in plaster, which are wrought into figures.” [5]

West of Aleppo, Syria, on the banks of the Euphrates River, Thévenot explains that, “barks loaded with glass (of which I will presently speak,) go to Bassora [Basra].” A ‘bark’ or ‘barque’ was a small three masted sailing ship. “While I was at Aleppo, the Sheik Bandar hired a bark to carry five or six hundred cases of glass, which he sent to the Indies.” And “I wondered to see that they who baled up these chests for the Sheik Bandar, tumbled them so rudely that they broke all the glass; but they told me, that it mattered not, though it were all broken into pieces, because the Indian men and women buy it only to have little pieces set in rings, which serve them for lookinglasses to see themselves in. That glass is all over laid with quicksilver on one side and is a very salable commodity in the Indies and profitable to the merchants.” [6]

One implication from this passage is that the named Sheik Bandar ran a glassmaking operation in Aleppo. It is interesting to note that Florentine glassmaker Antonio Neri had an uncle, his father’s brother Francesco, who was a merchant living in the Tuscan enclave inside Aleppo about sixty years earlier.

In the next installment we will continue to follow the thread of glassmaking references in the chronicles of Thévenot’s travels which take him to Persia, where he finds a glassmaking center.

[1] Jean de Thévenot, “The Travels of Monsieur Thevenot Into The Levant” (London: H. Clark, 1687) v.1, p. 6.
[2] Ibid, p. 22.
[3] Ibid, p. 268.
[4] See Wikipedia http://en.wikipedia.org/wiki/Knot_(unit).
[5] Ibid, v.2, p 17.


[6] Ibid, p.40.

Monday, May 29, 2017

We Were Trojans

Giovanni Domenico Tipeolo, 
Procession of the Trojan Horse in Troy. 1773
In January of 1600, Antonio Neri finished an ambitious manuscript called Treasure of the World, which was devoted to "all of alchemy." On the first page of text after the contents, above the first recipe, on the first line, written in Neri's own hand, are two solitary words, "fuimus troes"; a celebrated quote in Latin from Virgil’s epic poem, The Aeneid. The words translate to "We were Trojans" or more specifically "We Trojans are no more." They lament the fall of a city, sparked by the deception of the great wooden horse concealing enemy soldiers. These were words spoken in grief, in a charged, emotional scene, accepting defeat. We were once proud Trojans, but no more. While the intended significance in Neri’s manuscript may be lost, it is further affirmation of his academic grounding. What rings through the fog of history in these words, is the unmistakable passion behind them.

        Tis come, the inevitable hour,
        The supreme day of Darden power;
        Our history’s ended: Troy’s no more,
        And all her mighty glory o’er. 
            - Aneid 2,324.
            (William King, trans.)

The scene in the Aeneid takes place at night, under the stars. The hero Aeneas  sound asleep, wakes from his bed to the burning pillage of his city. After years under siege, the gates of Troy were breached – not by brute force, but by cunning deception. The streets are in flames, piled with the bodies of slaughtered innocents. Panthus, the priest from the temple of Apollo, with his grandson in tow, runs to Aeneus and exclaims that Troy and the Trojans are no more: "Fuimus Troes, fuit Ilium." He entrusts Aeneus with the sacred vessels and icons from the temple. Aeneus fights his way out to safety, carrying his own father on his back. He goes on to wander the Mediterranean. Later he enlists the help of the Etruscans (the ancient Florentines). Together, on the banks of the Tiber River, he fulfills his destiny by founding the city of Rome, or so the story tells.

In its broadest interpretation, those two words written by Virgil in the first century BCE, fuimus troes, have since been used to evoke the human drive to continue after a devastating blow. The loss of their widowed father in 1598 put the Neri children into a similar situation. The following year, Antonio's younger brother Emilio died at the age of sixteen on Christmas day. Two simple words scribbled at the top of a manuscript, yet they evoke the imagery of a man fighting his way out of a burning city, carrying the temple's sacred treasure. Behind all the recipes for glass and medicine and alchemy, there is a man of flesh and blood, one who felt life’s cruelties yet did persevere.

This post first appeared on 30 August 2013.

Friday, May 26, 2017

A Matter of Plagiarism

Francesco Lana Terzi (1631-1687)
Conciatore is pleased to reprise the guest-post of independent researcher Maria Grazzini. Maria studied Antonio Neri under the late Professor Paolo Rossi, philosopher and historian of science at the University of Florence. In 2012, Dr. Grazzini published an annotated English translation of Neri's manuscript in the journal Nuncias. [1] In the course of her research, she discovered a plagiarized version of the manuscript, published by 
a famous Jesuit professor in Brescia. His version matches Neri's handwritten manuscript of 1614 word for word. Here is what Maria had to say on the subject:

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  in 1670. [2] The entire chapter 20 of his Prodromo is an exact reproduction of Neri's. 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. His L'Arte Vetraria  was widely read and its reprints and translations appeared over the centuries. [3] 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

[1] Grazzini 2012.
[2] Lana Terzi 1670.
[3] Neri 1612, 1613.
* this post first appeared here on 20 November 2013.

Wednesday, May 24, 2017

Neri In Pisa

Majolica vase by Niccolò Sisti,
decorated in the grotesque style.
Antonio Neri's career in glassmaking took him from the city of his birth, Florence, to Pisa, Antwerp and possibly other places yet to be confirmed, such as Rome and Venice. Under the reign of Grand Duke Ferdinando de' Medici, a glass furnace at Pisa became an important source of diplomatic gifts in both glass and ceramics. Antonio Neri worked at this facility in the first years of the seventeenth century. Later, the same foundry would receive an order for exceptionally clear glass to be used by Galileo in his telescopes. It is unknown how that particular project worked out, but the furnace master, Niccolò Sisti, made a name for himself supplying glassware to the Vatican, the king of Spain and many nobles throughout Italy and Europe. Undoubtedly, Neri's glass career was strongly influenced by his tenure in Pisa with Sisti. 

In the early seventeenth century, there were several glass furnaces in Pisa. One was run at the pleasure of Grand Duke Ferdinando by Niccolò Sisti. Raised in Norcia in Perugia, he likely learned his trade at an early age;  Sisti's father, Sisto de' Bonsisti, was said to be an expert in making paste gems. This would account for the son's apparent skill in the medium of glass in addition to his ceramics prowess for which he was previously employed at the Casino di San Marco in Florence. For Neri, working at Sisti's glass house in Pisa played an important role in his glassmaking education. Sisti would serve three Medici grand dukes, Francesco I, Ferdinando I and Cosimo II. When work came to a stop at the Casino di San Marco, after Francesco’s death, Sisti may have opened his own factory in Florence for a short time, but then moved to a new facility in Pisa.

 In 1592, Grand Duke Ferdinando set up a glass shop in the central part of Pisa, along the north bank of the Arno River. This furnace was staffed by Muranese workers and was located in the city center, along the river. Archaeologists have unearthed its remains in the courtyard of what is now 43-44 Lungarno. The operation was capitalized with a loan of five hundred scudi made by Ferdinando I to Sisti, with a special mandate: he was to introduce new forms of pottery to the region. In addition to glass, the furnace at Pisa would produce soft-paste porcelain and majolica ceramics. These were both forms that Sisti had helped to develop when he worked in Florence at the Casino; he was involved in Francesco’s quest to duplicate Chinese porcelain.

In 1602, Neri was to be found working alongside Sisti at the Pisan furnace. According to his own account, this is where he worked on special colors, and collected river stones for glass frit. Here he made kermes based paints, enamels and used ferns as an alternative plant salt for glass. In all likelihood, he would have had access to the nearby botanical gardens and the small adjacent laboratory located just a few blocks from the glass furnace. 

Early in 1604, the priest would make his trip north to Antwerp to visit his friend Emmanuel Ximenes. During Neri's seven year absence, Sisti's projects included cristallo table service for the Vatican, and special glass for the lenses of Galileo's telescopes. Upon Neri's return from Flanders, we again find him working in Pisa, this time on alchemy. In a copy of his last known manuscript, a heading reads, "Techniques copied from an old book here in Pisa."  The university at Pisa was an intellectual center and a repository of technical knowledge. There, Neri had access to a wide range of materials in the libraries. The furnaces and laboratories provided him with hands-on experience, but there can be little doubt that he was a voracious reader as well. On the same page of this manuscript appears the date 26 January 1614. This is the last known specific information on the priest's whereabouts, since he would be dead within the year, at the age of thirty-eight.

*This post first appeared here in a shorter form on 18 October 2013.

Monday, May 22, 2017

A Deeper Accomplishment

From Antonio Neri, "Treasure of the World"
MS Ferguson 67, f. 22r.
For the past four centuries, Antonio Neri has been best known as the author of L'Arte Vetraria, the first printed book solely devoted to the art of glass formulation. It is a work committed to the subject of refining raw materials and combining them into a range of glasses, over a rainbow of colors. 'First into print' is a notable distinction, but one that Neri surpasses with ease by a deeper accomplishment. His book provides a rare glimpse of skilled practical knowledge. This was an era when prized techniques were frequently lost to subsequent generations; lost because artisans so often spared the pen. Their precious knowledge went purposely unrecorded, passing in strict confidence from master to apprentice working side by side. Neri preserved the old techniques like no other document has.

That 'first into print' is what we remember him for highlights an age-old problem that dogs historians. It is a simplification that puts a convenient handle on Neri, but at the same time, it de-emphasizes the fact that he was not working alone. It plays into a narrative that history, in general, happens in a parade of discrete jumps due to the brilliant discoveries of individuals working in isolation. This is reinforced by the mythology surrounding Neri – that he was a mysterious lone alchemist, wandering around Europe, evading those who would steal the secret of the philosopher’s stone. A similar narrative is applied to one historical figure after another, a form that is so appealing that it fills many history books of our schoolchildren and dictates the story lines of popular media productions (of a certain ilk) about the history of science and technology.

This is not to deny the limelight to anyone. Neri is a comparatively minor contributor and in my humble opinion definitely deserves recognition and even celebration. The danger is that by reducing history to a list of lone individuals making breakthrough discoveries, we distort the truth of how things are done and more to the point; we miss out on the far richer adventure of what really happens.

Never mind that Neri's book chronicles the work of hundreds or thousands of glassmakers that came before him or that he probably would have been far more grateful to be remembered for his work in alchemy and medicine. What sticks is 'first into print.' The reality is that he had the substantial resources of the Renaissance Medici court at his disposal. There is strong evidence based on his own manuscripts and drawings that he worked among a group of at least a dozen colleagues of both sexes, exchanging ideas, experimenting and urging each other on; a mode that no scientist would deny is far closer to the way discovery and innovation really happen.

This cultural defect in our perception of history is by no means a recent development. Even in Neri's own time, the early seventeenth century, the 'lone man' paradigm was well established. He and his contemporaries thought along similar lines about alchemists Arnold Villanova, Ramon Llull and Paracelsus. likewise for physicians that his father idolized like Galen and Dioscorides.

For the first time in history, we each have a tremendous chunk of the past at our fingertips in the form of the internet. It is a golden opportunity, not to be fed history, but to discover it for yourself and perhaps for the rest of us. There is no shortage of connections yet to be made and libraries around the world are availing their treasures freely to anyone with an interest. For a great adventure and an exercise in critical thinking, pick a discovery attributed to your favorite figure in history and ask the question "on whose shoulders was she standing?"



*This post first appeared here on 21 March 2014.

Friday, May 19, 2017

Alchemist's Assistant

Spine of volume 3 of Della Casa's notebooks,
Biblioteca Nationale Centrale Firenze.
At the turn of the seventeenth century, when Priest Antonio Neri was employed in Florence by the Medici prince Don Antonio, he worked closely with another alchemist by the name of Agnolo della Casa. Casa chronicled Neri's work and after his colleague's death in 1614, he undertook a special mission for Don Antonio to interview Neri's other associates and uncover the priest's recipe for the philosopher's stone. Don Antonio went as far as consulting a medium in Venice to contact Neri in the afterlife, but that is a story for another time. 

Thousands of pages of notes relating to Antonio Neri's work in Florence were recorded by fellow alchemist Agnolo della Casa. A significant portion of this nineteen-volume transcript is devoted to Neri's work on transmutation and specifically on the fabled philosopher's stone. The trouble is that he wrote much of it in obscure language, which renders it among the most cryptic in the entire canon of alchemy. Other sections of Della Casa's notebooks contain copies of the works of various adepts including Geber, Ramon Llull and Arnold Villanova. Neri took a keen interest in all of them.

In 1597, Prince Don Antonio de' Medici occupied the dormant Casino di San Marco and made it his new home. His father, the former grand duke, built this combination palace and laboratory on the north side of the city to indulge his own fascination with natural secrets. Don Antonio began to assemble a team that included Neri and Della Casa. The three men were all about the same age, in their early twenties, ready to do great things; ready to reveal nature and change the world.

In their time, it was reasonable to think that one metal could be 'purified' into another and that a single medicine could cure all disease or counteract any poison. These notions had been around since ancient times. In this realm, a skeptical eye was an absolute necessity, but there was no specific evidence that disproved the old stories. Don Antonio reportedly spent a fortune collecting recipes and testing them; he and his men worked to separate the real from the bogus. Swindlers and con men were in plentiful supply; they hawked miracle cures in public squares throughout Europe. Without a firm grasp of the underlying chemistry, the task of understanding a particular compound or chemical reaction could be quite difficult. Even to experienced, careful researchers, there was no guarantee that conclusions were correct.

Don Antonio was convinced that the glassmaking priest had indeed discovered the secret of transmutation. He put Della Casa to work interviewing Neri's acquaintances to see what could be learned. An expert gold refiner, Guido Antonio Milani, reported to Della Casa that in July 1596, Neri had performed before his eyes a transmutation of base metal into "twenty-four carat" gold. He said he pressed the 20-year-old, who in reluctance, confided that he had learned the secret from a German, who performed the gold transmutation with a "tablet of medicine." The German told Neri the medicine was nothing but the simple quintessence of green vitriol and the method to produce it was described by Paracelsus.

* This post first appeared here in a shorter form on 2 Sept 2013.

Wednesday, May 17, 2017

Diligence Among Craftsmen

"The Alchemist" Pieter Brughel the Younger
c. 1600 (detail)
In his 1612 landmark book about making glass from raw materials, there is a specific term that Antonio Neri uses repeatedly: "diligence." I count forty-two distinct instances spread throughout the book. Even so, in all of these occurrences, not once does our priest-alchemist uses this term in a casual manner; each appearance is in a critical step, in which he urges his readers to pay extremely close attention to what they are doing. 
If you want to have fine crystal, then in this you must exercise great diligence; when the frit is made with this careful attention, it will be white and pure like snow from heaven.
And
Then you must stir the glass with a paddle, but when the tinsel is calcined well and as directed, it swells so much that it could make all the glass go out of a large crucible. So use diligence in this.
And
All lead precipitating out of the glass must be removed with diligence, throwing it away, so that it does not make the bottom of the crucible break out, as can happen.
One might well ask, why so much attention to diligence? To be sure, there are many important aspects to the successful outcome of a batch of glass. Yet Neri singles out the seemingly simple act of paying attention. One reason is to avoid disasters. The last two quotes above imply that he has seen his share of these.

There is no question that glassmaking is a technically demanding process, where many things can go wrong. But there is more to it than that; Neri’s admonitions may have more to do with developing the proper attitude in a glassmaker. At first, it might seem that a recipe is a recipe is a recipe and as long as one follows it, mental state has no bearing on the situation. Yet as surprising as some may find it, this is definitely not the case. Materials and conditions vary in ways that cannot always be measured. What a recipe specifies is strictly limited by our perceptions and to quote the bard, "There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy."

Unlike some more intellectual pursuits, glassmaking falls into a category of activity in which there is no room for self-indulgence. It does not work to throw the ingredients into a furnace and walk away, assuming that they will react the way we anticipate. They will react, rather, according to the physical laws of nature. Diligence could make the difference between a minor correction and a disaster. For the headstrong, this can be a rude awakening. A would-be glassmaker is forced into a confrontation with stark, unforgiving reality. What one wants or expects has no bearing on the situation, only what one does, and when.

Neri makes clear that this philosophy of diligence is not only required by the novice, but also by the seasoned professional conciatore.
This entire exercise depends on the practice of being a worthy and diligent glass conciatore, because neither sure weight nor measure can be given.
And
The diligent furnace conciatore will meticulously remove any lead that has returned to its metallic state from inside the pot.
And
When working this glass, use the same diligence that the skilled masters use and in so doing you will make material that is perfectly true to the jasper, agate and chalcedony of the orient.


In the early seventeenth century, to be a glassmaker meant becoming a careful observer, ever mindful that Nature does not care a whit about the way you think things should work. 

Monday, May 15, 2017

Final Restingplace?

Entrance to the Neri Chapel,
Bprgo Pinti, Florence, Italy.
On the northeast side of Florence, there is a narrow, unassuming street called Borgo Pinti. Here there are two structures in particular which are of great interest in the study of seventeenth century glassmaker Antonio Neri. The first is the family’s residence at number 27, now a hotel, but largely intact and the second is the church located a few steps further north, now known as Santa Maria Maddalena dei Pazzi. 

In the sixteenth and early seventeenth century, the church was part of a Cistercian monastery known locally as “Cestello” It was attended by Antonio’s royal physician father Neri Neri, his grandfather, Jacopo and it is safe to assume, the rest of the family. This is where the medical doctor would later be buried. In 1598, he was laid to rest in the chapel that Poccetti and Passignano reworked to his specifications; both were well-respected fine artists of the time. One author would later refer to the space as “the famous Neri chapel.” The royal physician asked, in his will, that his remains never be moved outside of his beloved homeland. He provided money for what amounts to a complete restoration of the entire property. The work in the chapel and the main church was a top to bottom renovation and must have taken several years to complete; today it is considered Poccetti’s crowning achievement. In earlier times, the monks of Cestello had played a trusted role in pre-Medicean Florence, collecting and counting the beans used in votes of the Signoria (town council), and holding the keys to the Palazzo Vecchio.
The Vision of St Bernard, by Pietro Perugino (1448–1523)
The c. 1598 altarpiece that was commissioned 
for Cestello by Antonio Neri’s father

The chapel and the church still stand, but the occupants changed in 1628-29. Pope Urban VIII was seeking better accommodations for two of his nieces who were Carmelite nuns on the other side of the Arno River at San Frediano Monastery. He asked that the Cistercian brothers, against their protestations, exchange properties with the nuns, who brought with them the remains of Sister Maria Maddalena de’ Pazzi, the influential mystic who died in 1607. The church was renamed in her honor after canonization in 1669. 


The Cistercian’s archives record that:
In 1598 Doctor Neri remodeled in more honorable form the chapel which was originally built by Tommaso del Giglio, in the year 1505, which had since become occupied by the cobblers guild, who had begun to meet there and which he feared they wanted to usurp. Maestro Neri approached the Grand Duke [Ferdinando I] in order to have authority to free it from the hands of the cobblers and enlarge and redo it from the foundation and have it all painted in frescos by the hand of Bernardino Poccetti and dedicated to the honor of Saints Nereus and Achilleus.
Far more than the mere renovation of the chapel, the royal physician played a central role in the rehabilitation of an ancient and venerated church, a church that today continues as a testament to Poccetti’s great talent. Tommaso del Giglio, the former owner of Neri’s chapel and successful apothecary supplied Cestello as well as many Florentine hospitals with medicines and other staples. That the cobblers had occupied the chapel might seem strange. What possible claim could the band of shoe-makers have to this space? The simple answer is that Del Giglio was himself a member of their guild, perhaps the cobbler’s most famous member. About 1462 he moved his family to Florence from Montevarchi, where he was trained as an apothecary. For whatever reason he could not gain membership to the guild in Florence, so instead he joined the subordinate cobblers’ guild but retained his practice as an apothecary. He was still subject to the  rules, regulations and periodic inspections of the authorities. Eventually he attained the honor of apothecary to the ruling Medici family. A century after his death, it seems the chapel and the church itself was falling into disrepair; the cobblers, with the family’s blessing met there on a regular basis.

The Cestello monastery, of which the church was a part, served as an early home to the famed Accademia del Disegno (Florentine Academy of Design). The city’s greatest artists, sculptors and architects were all members, Giambologna not least among them. The rooms of the monastery were used to store artistic works and teach classes. For the members it served as a place to meet and plan projects for the city and royal family. A young Galileo Galilei would study mathematics here under Ostilio Ricci. 

It is unknown if the Neri chapel serves as the last resting place for the children of royal physician Neri Neri, among them his most famous son, glassmaker Antonio Neri, who died in 1614 at the age of thirty-eight.

* This post first appeared here in a considerably shorter form on 28 August 2013.

Sunday, May 14, 2017

Antonio Neri's Mother

Agnolo di Cosimo 'Bronzino',
"Portrait of Florentine Noblewoman"
(subject unknown , circa. 1540).
The mother of Antonio Neri, the 17th century glassmaker and alchemist,  was named Dianora Parenti. She was the oldest of six children: three girls and three boys. She was born in Florence, on 11 February 1552, with the given name of Dora listed in the city's baptistery register. In all probability by the age of eighteen she was quite accustomed to helping her mother with the other children; Caterina, the youngest, was born less than a year before Dianora's wedding.

Her father and grandfather were prominent lawyers; together they handled much of the personal business of famed artist Michelangelo. On the 20th day of August 1570, Francesco Parenti walked his eldest child down the aisle to be joined, in holy matrimony, to physician Neri Neri. Two years later, their first child Lessandra was born. 

Historians Luigi Zecchin and Enzo Settesoldi identified four of Antonio's brothers, two older and two younger. They were Jacopo (1573), Francesco (1575), a second Jacopo (1577) and Vincenzio (1579). In addition to these five boys, there were at least two more brothers born later, Emilio (1583) and Alessandro (1587). And there were at least three girls, the first-born child Lessandra (1572) and two younger sisters: Maria (1581) and Lucretia (1584). 

In all, there were ten births by Dianora recorded in Florence, occurring almost like clockwork on a fifteen-month schedule. As did many women of the period, she spent a significant portion of her adult life pregnant. In her case, it was a span of sixteen years, carrying one child after another with minimal interruption.

The birth of a child in Renaissance Florence was no small occasion. Patrician families went to considerable expense on decorations, on food and drink for guests and on gifts for the mother and godparents. "The woman who gave birth, like a bride at her wedding, occupied for a passing moment a position of unparalleled honor,"* more than that, while a wedding signaled the transition from daughter to wife, the birth celebration was a rare social recognition of a woman as an individual.

A genealogical record of the eighteenth century, held at the State Archives in Florence (ASF), confirms most of the Neri children's births. It also sets the date of death for their mother Dianora at 1594 when she would have been forty-two years old. This means Antonio lost his mother when he was eighteen and his youngest brother Alessandro was a mere seven.

* Margaret L. King, Women of the Renaissance (Chicago: University of Chicago Press, 1991), p. 4.

This post first appeared on 11 September 2013.

Friday, May 12, 2017

Dear Friends

The library of the University of Leiden (1610)
Christophe Plantin worked here from 1583 to 1585.
One day in July of 1601, in Florence, early in the morning, we imagine two men shaking hands, embracing and saying goodbye. Both knew it might well be the last time they saw each other. The older man climbs into a coach bound for his home in distant Antwerp and signals the driver to begin his journey. That man, Emmanuel Ximenes, had been in Florence to visit his sister, Beatrice, his brother, Niccolò, and several other relatives living in the area. Antonio Neri first met the wealthy banker at the home of Beatrice and her husband, Alamanno Bartolini. The priest lived there after his ordination and, according to nineteenth century historian Francesco Inghirami, functioned as house-master. Both men wished for more time together; they shared a fascination with alchemy and with the work of Swiss-born physician Paracelsus. They had become fast friends and formed a bond that would last until the end of their lives.

As soon as Ximenes arrived home in Flanders he wrote to Neri, on 17 August, 1601, "to the quite magnificent clergyman Mr.Antonio Neri, in the house of Mr. Alamanno Bartolini, in Florence, or where found." He expressed his great pleasure at receiving a booklet of recipes from Neri and declares him "molto caro" [most dear]. He goes on to warn his friend: "With your permission, I will not fail to bother you with my tiresome letters." Over the next two years, the men corresponded frequently. A set of twenty-seven letters written by Ximenes and one by his brother Eduardo, addressed to Neri, survive in the National Library of Florence. The two men discuss a wide variety of subjects including herbal remedies, glassmaking, enameling and in more careful language, the topic for which they were both most passionate: alchemy. They trade information on the results of their experiments and by 5 December, 1602, the banker wrote:

I have seen the tender affection which Your Lordship shows me and demonstrates with the hope to see me before death, which is no different from my own hope. I have desired this from the start… because if we were together, we could easily set to work on some small projects, being that our talents, if I am not deceiving myself, are very well suited...
Neri would ultimately make the journey to Antwerp, but not for another year. That winter he became quite ill in Pisa, postponing his planned visit. Finally, on 2 May, his friend wrote: "Praise God that your indisposition has ended." By the following spring the two men were reunited and Neri would spend the next seven years in a city that was in the eye of a storm. The low-countries (what today are the Netherlands and Belgium) were in the midst of a bloody civil war. The port of Antwerp was blockaded by the Dutch fleet and the countryside was being ravaged by troops from Spain and the Holy Roman Empire. The population of Antwerp was a shadow of its former self, but the city was left untouched by both sides, in an accord of political convenience. It had been burned and pillaged as recently as the 1570's, but by the early 1600's Antwerp was simply too valuable a jewel to be sacrificed.

Emmanuel's immediate family was among the wealthiest in Antwerp and strong patrons of the arts. He counted among his close friends humanist printers Christophe Plantin and Jan Moretus. Other branches of the Ximenes family topped the social ranks in Venice, Hamburg, Lisbon and Florence. Their ancient ancestors were kings of Pamplona, Navarre, Castile and Aragon. Emmanuel's father Rodrigo headed the prestigious Ximenes (Jiménez) Bank in Antwerp. By the end of his visit, Neri would present the prince of Orange with vessels of his chalcedony glass.


This post was first published here, on 6 September 2013.
For more on Ximenes, see http://ximenez.unibe.ch/

Wednesday, May 10, 2017

Casino di San Marco

The Casino di San Marco, Florence
Location of Antonio Neri's first glassmaking job
In 1612, Antonio Neri wrote the first book entirely devoted to making glass from raw materials. It was called L’Arte Vetraria, or in English, 'The Art of Glassmaking'. When Neri put pen to paper for his book, he had already been making glass for over a decade. He had the opportunity to learn his craft from some of the experts in the field. At the beginning, his first known experience in glassmaking was at the laboratory palace of Don Antonio de’ Medici, a prince from the ruling family of Tuscany. 

The Palace was called the Casino di San Marco. “Casino”, we might innocently guess indicated some kind of gambling hall, which it was not.  Instead, "Casino" was Italian parlance for a palace that was informally organized like a small country house with the living quarters on the ground floor. It was built by Don Antonio’s father, the former Grand Duke, as a place where Nature’s secrets would be discovered and new inventions would be made. Neri worked at the Casino for a couple of years before moving to Pisa and then to Antwerp, all the while making glass. He returned to Florence to publish his book, and thanked Don Antonio for his long patronage. 

Don Antonio's Casino was as much a grand concept as it was a physical space. Completed to his father’s specifications in 1574, it evolved into a prince's palace par excellence. Within its walls, grand dinners were held, productions were staged and poetry was read. In 1605 Michelangelo Buonarroti the younger staged a play there titled "The Christmas of Hercules." In its chambers, music was performed, philosophy debated and diplomacy conducted. In its laboratories, alchemy was nurtured, and glass was formulated. It was a sort of grand royal conservatory, melding together art, letters, drama, music and science. From its courtyard, hunters set forth into the Tuscan hills in search of unicorns, and within its workshops, artisans explored the territory of new materials and natural secrets.

The Royal Foundry, as it was also called, became a place of pride for Grand Duke Ferdinando. It was a place that visiting dignitaries specifically asked to see and tour. Behind the doors of the Casino di San Marco, Antonio Neri and his associates worked their magic. This is probably where he first learned the secrets of Venetian style glass composition and undoubtedly much more. He assisted the prince in his research, formulated herbal remedies and helped in the production of luxury gifts for visiting dignitaries.


This was the way that I made chalcedony in the year 1601, in Florence at the Casino, in the glass furnace there. At that time, the task of scheduling furnace-work fell to the outstanding Mr. Niccolò Landi, my close friend and a man of rare talent in enamel work at the oil lamp. I made many pots of chalcedony in the furnace there. I never deviated from the method stated above, I always prepared the materials well and it always came out beautifully in all my proofs.[1] 

[1] L'Arte VetrariaAntonio Neri 1612, p. 41.
* This post first appeared here in a shorter form on 12 August 2012.

Monday, May 8, 2017

Artificial Gems

Pastes (glass) set in silver openwork (Portugal c. 1750)
Victoria and Albert Museum, London.
Acq. nr. M.68-1962
In many ways, the story of artificial gems traces the story of glass technology itself. From ancient times, when glass could only be produced in very small quantities it was regarded and used as a type of stone that was made through art. Alchemists thought the bright colors produced by metallic pigments in glass were a key to the philosopher's stone, and the transmutation of base metals into gold. As the technical prowess of glassmakers expanded, so did the ability to simulate specific stones, most notably coveted gems. Glass went on to be used as material for utilitarian objects like goblets and as an indispensable part of scientific enquiry. All the while, artificial gems have continued to dazzle us with their beauty. 

In the fifth part of Antonio Neri's 1612 book, he teaches the secrets of making artificial gems "of so much grace, and beauty, that they will surpass the natural stones in everything except hardness." It is not a difficult argument to make that this section alone is responsible for much of the lasting popularity of L'Arte Vetraria. It is easy to see why enterprising artisans would want to make glass imitations that could pass for the real thing. It is also perhaps too tempting to jump to the conclusion that Neri intended his recipes to be used in deception, since there is no evidence whatsoever that this was the case.

Neri gives full credit for his innovative methods in paste gems to Dutch alchemist Isaac Hollandus. Hollandus is an enigmatic figure, whose writings survive, but not much is known of the man, his family, or even if he was living in Neri's time. What is known is that Antonio's dear friend Emmanuel Ximenes was the brother-in-law to Baron Simon Rodriguez d'Evora, a famous diamond dealer and jeweler of choice to royalty throughout Europe. He lived and worked on the same street in Antwerp as Ximenes' palace, only a few steps away from Neri's new temporary home. It was a common request of wealthy patrons to have duplicate jewelry made in paste for travel and security reasons. If a fake necklace or jewel could pass for the real thing, it was well worth the added expense, when the genuine article could remain safe under lock and key.

No artificial gem recipes have ever been found among Hollandus' writings, excepting one for ruby which is then crushed up as part of a prescription for the philosopher's stone. It is quite possible that Neri was applying a more general technique from the Dutchman. The basic material for all of Neri's paste gems is a fine lead crystal. The crux of his innovation lay in the form of lead used. Normally, metallic lead sheet was cut into small pieces, and roasted in a kiln such that it would oxidize into powder, but not melt. The powder was then added to the glass melt. In Neri's method the lead was chemically converted into a water-soluble form, which could then be filtered and purified to a much greater extent. The end result was a far better grade of crystal.


In 1697, Jean Haudicquer de Blancourt translated into French and greatly expanded Christopher Merrett's English edition of Neri. Blancourt gave no credit to the Italian for his work, and two years later, when it was translated back into English by Daniel Brown, the connection to Neri was completely lost, but the credit for paste gems remained with Hollandus. In the eighteenth and nineteenth centuries, numerous general encyclopedias of art and craft were published and the so-called 'Hollandus' paste gem recipes turned up many times. Meanwhile, a properly credited French version of L'Arte Vetraria was completed by Holbach in 1752. This edition was more suited to a scientific audience; he faithfully translated the Italian, but also incorporated the full comments of Merrett as well as those of Kunckel who issued his famous German version of Neri in 1679.

For more reading on Neri's artificial gems see Glass as Pasta and on the work of later investigators see Marieke Hendriksen at The Medicine Chest
*A shorter version of this post appeared here on 16 September 2003.

Friday, May 5, 2017

Scraping the Barrel

4th century BCE philosopher Diogenes
(supposedly lived in a wine barrel)
by Gaetano Gandolfi (1792)
To seventeenth century glassmaker Antonio Neri, "tartar" was a well-known byproduct of the winemaking process. If we chill wine or grape juice to below 50 degrees (10 deg. C.) crystals of tartar start to form and once they do, then tend not to dissolve back, even at room temperatures. Today, these crystals are commonly found in a powdered form, in kitchen cupboards as "cream of tartar." Bakers and cooks use it to stabilize whipped egg whites, and it has a number of other applications. 

Neri used it in his glass to add sparkle, a trick known to Venetian glassmakers as early as the 1400s. It was obtained from the dregs at the bottom of wine barrels. To understand how this works, it is useful to know that Florentines, Venetians and most southern Europeans made glass from crushed up quartz pebbles or sand mixed with a specific flux known as "glass salt." This salt was rich in sodium carbonates, which greatly reduced the melting point of the quartz. It allowed artisans to work the material at the temperatures easily achieved in their furnaces. Tartar turns out to be very similar, except that it is rich in potassium rather than sodium. 

Potassium atoms are bigger and heavier than sodium atoms and when light passes through a piece of potassium-fluxed glass, it bends and refracts more. This effect is not as pronounced as when adding the even heavier lead to form fine crystal, but it still adds noticeable sparkle to finished pieces. Using all tartar as a flux has the undesirable effect of reducing the workability of the hot glass. Outside the furnace, it becomes stiff quicker and artists have less time to create fancy shapes and forms. The solution to this dilemma is to use a mix of sodium and potassium fluxes together, which is exactly what Neri did. 

In his 1612 book L'Arte Vetraria, he shows how to prepare tartar and then adds it to a number of his glass recipes saying, "The tartar is the secret way to produce more salt and to make cristallo which is whiter and of rare beauty." Here is Neri’s prescription:


To make Purified Tartar Salt you should obtain tartar, which is also called gruma, from barrels of red wine in which it forms large lumps, however do not use powder. Roast it in earthenware pots amongst hot coals until it becomes calcined black and all its sliminess is roasted away. It then will begin to whiten, but do not let it become white, because if you do the salt will be no good.  
Calcine tartar this way: put it in large earthenware pans full of hot common water, or better yet in glazed earthenware pans then made to boil on a slow fire. You should do it in such a way that in two hours the level of the water will slowly decrease to one-quarter, at this point lift it from the fire and leave it to cool and to clarify. Now decant off the liquid, which will be strong lye and refill the pans containing the remains of the tartar with new common water. In the way stated above, boil as before and repeat the procedure until saltiness no longer charges the water. 
At this point, the [decanted] water is impregnated with all the salt. Filter the lye clear and put it in glass chamber pots to evaporate in the ash of the stove over a slow fire. In the bottom, white salt will remain. Dissolve this salt in new hot common water and leave it in the pans, letting it settle for two days. Then filter it and return it to chamber pots to evaporate over a slow fire. In the bottom, a much whiter salt will be left than the previous time. Now dissolve this salt in fresh hot common water and leave it to settle for two days. Evaporate, filter and repeat everything as before. Overall, repeat this procedure four times to dissolve, filter and evaporate the salt of tartar. This will make the salt whiter than snow and purified from the vast majority of its sediment.
When mixed with sifted polverino, or rocchetta, with its doses of tarso [quartz] or sand, this salt will make a frit that in crucibles will produce the most beautiful crystallino and common glass, which one cannot make without the accompaniment of tartar salt. Without it [tartar], good fine crystallino can be made, nevertheless with it, it will be the absolute most beautiful.

*This post first appeared here on 16 May 2014.

Wednesday, May 3, 2017

Pebbles from Pavia

A Bridge on the River Ticino, near Polleggio,
William Pars (1742‑1782).
In the sixteenth and seventeenth century, a type of glass known as 'cristallo' was the absolute pinnacle of the art. Its recipe was invented in Venice and guarded there as a state secret. Its name derived from the mineral it was designed to mimic: rock crystal. As clear as water, rock crystal was valued since ancient times for carving into cups, vessels and other objects of art. Today we know it as a form of quartz, but in Roman times it was thought to be a type of frozen or coagulated water.

In the early 1600s, when Antonio Neri started making glass in Florence, the grand duke's craftsmen were routinely carving this hard and brittle rock crystal into complex thin shapes, a process that took great skill and effort. Due to the expense involved in producing a piece, this art was the exclusive province of extremely wealthy individuals. Thus, objects made from rock crystal were considered markers of status. The recipe for cristallo was a very great secret indeed, but its real value lay in the specific materials used. Even if the recipe found its way out of Murano, which it inevitably did, the Venetian's tight trade network ensured a monopoly on many of the ingredients. It is said that even the furnace crucibles for cristallo were made from a specific clay gathered in Constantinople.

Cristallo was not only exceptionally clear, but for the artist it had working properties like no other glass. Thin, complex shapes were possible in cristallo that could never be duplicated in common glass. The secret for making cristallo came to Florence in the late 1560's, only a few years before the birth of Antonio Neri, who would learn the techniques and go on to publish the recipe for the first time anywhere.

 After protracted overtures, which involved diplomats, spies and the archbishop of Florence, Grand Duke Cosimo I managed to negotiate with the Venetian Doge and Senate for a Muranese master and two assistants to come to Florence and teach the way to make cristallo. It is likely that the raw materials were all purchased through the Venetians, at least initially. By the time Neri wrote his book, L'Arte Vetraria, in 1612, the Florentines were already finding alternate sources. In Venice, the ingredients of cristallo were prescribed and controlled by strict laws. The Florentines did not have this constraint and were free to experiment.

In the second recipe of Neri's book, he spills the beans on where the Venetians procured the single most important ingredient for cristallo, the pure quartz stones which account for the material's clarity. Notice in the following excerpt that Neri mistakenly thinks that the white river stones are a form of marble and also notice the alchemical language he uses to describe the process in which the stone is "transmuted" into glass.
When you want to a make cristallo that is beautiful and fully perfect, see that you have the very whitest tarso. At Murano they use pebbles from Ticino [Pavia], a stone abundant in the Ticino River. Tarso, then is a species of very white hard marble [quartz]. 
In Tuscany, it is found at the foot of Mount Veruca in Pisa, at Seravezza, at Massa near Carrara, and in the Arno River both above and below Florence. In other places as well, common stone is often recognized, which is seen to have the same qualities as tarso; it is very white and does not have dark veins, or the yellowish appearance of rust, but is spotless and pure. Take note that any stones that will spark with a piece of steel or strike plate, are apt to vitrify and will make glass and cristallo. All those stones that do not make sparks with a piece of steel or striker as above will never vitrify. This serves as advice for being able to distinguish stones that have the ability to transmute their form, from those that cannot be transmuted. 
Start with this same tarso, as fair and as white as possible. Grind it finely into powder in stone mortars. Do not use bronze or any other metal for this purpose or the stone will take in the color of the metal, which then would tinge the glass or cristallo, and make it imperfect. The pestle must be iron by necessity but at least the other materials will not have the possibility of causing any effect. Pulverize the tarso well and sift with a fine sieve. It is important that the tarso is ground as finely as flour, so that it will all pass through a fine sieve.
* This post first appeared here on 30 May 2014. 

Monday, May 1, 2017

Glass From Tinsel

From Diderot's Encyclopedia, machinery to hammer brass into thin sheets
Which were then used as decorative tinsel, in glassmaking and more 
(click image to enlarge).
To this day in the field of glassmaking, color is still a subject about which manufacturers hold their cards very close to the breast. It is very unusual to coax anyone in this trade to speak freely about exactly what materials are used to produce a specific color and for good reason – competitive advantage. In this respect, attitudes have not changed very much from the early seventeenth century when Antonio Neri blew the doors open with his 1612 book of glass recipes. L'Arte Vetraria, discussed, for the first time in print, a whole rainbow of different shades in terms of specific materials and amounts. 

Since then, a number of his formulations have become obsolete or fallen into disuse. This has happened for various reasons, typically because the raw ingredients he used fell out of favor. Many are not easily obtainable or reproducible today. Since the state of industrial chemistry is far ahead of where it was in his time, the basic metal oxides are now simply ordered from a catalog and mixed to produce the maker's specific color palate their customers expect. The result is that many of the shades of color Neri produced have not graced the end of a gaffer's blowpipe for centuries; they certainly could be duplicated today, but there is simply no call to do so.

One of the interesting raw ingredients that he used four hundred years ago is tinsel. Yes, this is the ancient relative of what we still use for holiday decoration. Neri advises, "Take orpiment, also known as tinsel and to save money purchase some that has already been used for decorative wreaths and garland." Tremolante is the specific word he uses; it has the same root as the English "tremulous" and "tremble." In modern Italian, it means to flicker or shimmer. The groundbreaking early dictionary first published by the Florentine Accademia della Crusca in the seventeenth century gives Neri credit for the first use of the term in this context, but if it was a common product, the word must certainly have been in use earlier. To confuse matters, Neri describes tinsel as a kind of "orpiment." (orpello) This term was also used to refer to arsenic sulfide, a highly toxic mineral used as a golden paint pigment, but in this recipe he uses the word only to refer to the golden color of tinsel.  

Neri's tinsel was made of brass, which is an alloy of copper and zinc. While zinc had been isolated as a pure metal, notably by Paracelsus, Neri knew it only by its oxide which he called zelamina. He cut the tinsel into tiny pieces with a scissors and then 'calcined' it, heating it in a covered crucible among live coals for four days. He was careful not to let it reach a temperature that will melt the metal. He removes it from the fire, grinds it into a black powder, then reheats it for another four days. By the end of Neri’s process both the metals would be oxidized. This product, he tells us, makes a blue color in glass reminiscent of the feathers of the "gazzera marina" bird, "holding the middle between aquamarine and the color of the sky when it is very clear and serene" There are several possibilities for the identity of the gazzera marina, the most likely seems to be the European Roller (Coracias garrulus). It is a species that is known for its striking appearance in flight; its brilliant blue breast contrasts against black flight feathers. 

In a second brass recipe (# 21), the snippings are mixed with powdered sulfur and heated in the live coals of the furnace firebox for a day. He then grinds it as before and reheats it for a protracted period of ten days in the hottest part of the furnace "near the eye." Neri advises that the product can be used for transparent red, yellow and in chalcedony glass. He uses calcined tinsel in two of his chalcedony recipes but we never see a further mention in the book for transparent red or yellow glass. In the first part of this recipe, the sulfur likely reacts with the zinc-copper alloy in the tinsel to form sulfides of the metals. In the second part, the sulfides are decomposed by the high heat to form oxides and most or all of the sulfur is driven off as noxious sulfur dioxide gas. This method could well produce better oxidation of the metals and therefore a better quality colorant. If the sulfides do not completely decompose, some interesting possibilities arise in the melt. Copper sulfides have the potential to be reduced to pure metal in a reheating maneuver done by the glass artist called 'striking.' This might produce the wonderful transparent red known as copper ruby glass. Zinc sulfides in glass, produces a white or opaline glass. The only way to know for sure what the old recipes would do is to make a batch and put it in the hands of an artist.

* This post first appeared here 23 May 2014.