The Importance of Being Diligent

Fennec fox pup, 2008
Everland Zoo, South Korea.

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. 

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.

Rosichiero Glass

Sunset over Venice

The most famous recipe in Antonio Neri’s book, L'Arte Vetraria, is “#129 Transparent Red.” The reason for its notoriety is, of course, the pure gold used as a pigment. Gold-ruby, or “rubino” is a devilishly difficult color to produce, and was not reliably duplicated until many years after Neri’s death, although pieces made in ancient times have been unearthed.  

Even though gold rubino is Neri's most well known recipe and certainly his most famous red glass, this recipe does not exist in isolation. In fact, it fits in the middle of a group of eleven recipes (120–130) devoted to transparent, or at least translucent red glass, enamel and related preparations. 

120 Transparent Red in Glass.
121 Red Like Blood.
122 Balas Color.
123 To extract the Spirit of Saturn, Which Serves Many Uses in Enamels and Glasses.
124 Rosichiero to Enamel Gold.
125 Rosichiero for Gold by Another Method.
126 How to Fix Sulfur for the Above Described Work.
127 A Glass as Red as Blood, Which Can Serve as Rosichiero.
128 A Proven Way to Make Rosichiero.
129 Transparent Red.
130 The Way to Fix Sulfur for Rosichiero to Enamel Gold.

A particular shade that was popular at the time was known in Italian as "rosichiero." Our glassmaker presents four different recipes and two more on “fixing” sulfur which some of the preparations require. Most dictionaries cite Neri as the first to use of the word 'rosichiero' in print, but we know it was a common term of art among glassmakers much earlier. The French equivalent is "rouge clair." The Spanish edition of L'Arte Vetraria notes that in that language the term is “rosicler,” which is still used today to describe the intense rosy twilight color of a nice sunset.

The red glasses of this group all call for the addition of copper as a colorant and copper has remained a popular pigment up to the present. For instance, red traffic lights that are made of glass are typically tinted with copper. But that is not the entire story; some of Neri's rosichieros also include the addition of sulfur and some require hematite or iron oxide, red lead oxide, manganese oxide, or wine tartar. In his recipe #125 for rosichiero, he starts with four pounds of high quality cristallo glass. To this adds equal parts of tin and lead oxides, mixed together: 

[A]dd this calx little by little, ½ oz at a time, let it incorporate, and watch for when the glass becomes an ash gray color, at which point it will be good. Do not add too much calx because if you overload it, the glass will become white in color, which is not good.When it turns the said gray color, do not add more calx but leave it to clarify. Then have 2 oz fine minium [red lead oxide], add this to the glass, and let it incorporate well, and clarify. When it clarifies well, throw into water, return it to the crucible and leave it for 8 hours [in the furnace]. 

Have ½ oz of calcined copper, that is to say red copper and ½ oz of raw white [wine] tartar. Throw these materials in, and stir them well. Now add a dram of hematite, which the sword makers use for burnishing, and 1 dram of fixed sulfur. Stir and incorporate these powders, and watch. If it is over-colored, give it a little manganese to dilute it. If it is clear of color, add more of the fixed sulfur, hematite, a little red copper and a little white wine tartar at your discretion so it becomes the desired color.

None of these ingredients excepting copper is common in color glass production today; in fact, sulfur is usually considered an undesirable contaminant. Hematite is a naturally occurring mineral form of iron oxide. It is so named because if abraded in water it tints the water red, appearing to bleed. Hematite is not currently used as a red pigment in glass, but it is commonly used in some pottery glazes. 

From a chemistry standpoint, a good guess is that sulfur added to the glass would react with the copper and iron to produce various sulfide compounds. How those compounds affect the color and texture of the glass is an open question. Here is where we get into uncharted territory; four hundred years after Neri’s book was first published, predicting colors based on chemistry is no easier for us than it was for him. The science of color in general remains a difficult nut to crack. However, the fact that there is still much that we do not understand does not prevent us from enjoying the brilliant reds inspired by a good sunset.

* For the technically minded, the University of Oslo has a wonderful presentation on the state of color physics. For the non-technical, take a look – a series of fascinating images that spans the sense of sight and beyond. There is a link address in the "picture credits" for this post.

** This post first appeared here on 24 April 2014.

Don Antonio de' Medici

Don Antonio de' Medici
Frontispiece from Pierfilippo Covoni 1892

In 1612, Priest Antonio Neri published his book of glassmaking recipes. L’Arte Vetraria went on to become a primary reference for glass artisans throughout Europe. He dedicated his book to Prince Don Antonio de' Medici the son of Grand Duke Francesco I:

In all consideration, it is my proud duty to dedicate this book to none other than you, most Illustrious Excellency; for you have always been my outstanding patron. You are a gifted leader in this and in all other noble and worthy developments made continually in all the arts.

As an eleven year-old, Don Antonio was slated to succeed his father as the next Grand Duke of Tuscany, but that situation changed quickly. In the autumn of 1587 the young prince lost both of his parents in the space of a few days. They both fell extremely ill and died within a short time of each other. Rumors flew that they had been poisoned, but forensic investigators have found pernicious malaria pathogens in Francesco’s remains, a disease with symptoms consistent with the reports of physicians on the scene. Historians trace their infection to an outing in the damp forest a few days earlier, where they had probably been bitten by mosquitoes carrying the disease. 

The boy’s uncle, Cardinal Ferdinando took charge, consolidated power and excluded Don Antonio from the royal succession, although he was given a prominent place at court as a diplomat. As part of a deal that he would never marry, he was allowed to keep the title of Prince of Capestrano, to which was added Grand Prior of Pisa, in the Knights of Malta. The deal also gave him possession of the laboratory facility that his father had built and several other properties. That laboratory, the Casino di San Marco would become the prince’s residence and the place where Antonio Neri would learn about glass formulation.

Poor health attended Don Antonio from his first months through the end of his life. Doctors and medical examinations were to become a regular part of his routine; they may well have inspired his later pursuit of medicinal cures, as well as his foray into alchemy, which also involved Antonio Neri. At some point, probably as a teenager, Don Antonio contracted syphilis, a condition that may well have been treated by Antonio Neri’s father who was physician to the royal family.

The prince had played a major part in Neri's life, elevating him into the upper stratum of Florentine craftsmen and to the forefront of alchemical research in Europe. However, in another manuscript, Discorso, we see a different side of Neri. On the subject of turning base metals into gold, the priest was less forthcoming:

I would add that God's providence over human affairs must not easily allow many to acquire this art, particularly not the great princes. It should not be made clear and common to the vulgar, because in this way, gold and silver and consequently coins lose their value, so that the good order of human trade will be disrupted and we should go back to the ancient barter of things that are necessary to a civil life, creating great disruption and confusion.

Although never allowed to marry, over his lifetime Don Antonio managed to have a number of children; his last three sons were ultimately legitimized by the pope as Medici heirs. In the end, it was the slow, progressive ravages of syphilis that brought him down. He died in 1621, at the age of forty-five, unable to leave his bed. He was given a proper funeral, and interred at the Medici chapel of princes in Florence.

*This post first appeared on 12 May 2014.

The Casino di San Marco

The Casino di San Marco, Florence

Antonio Neri wrote the first book entirely devoted to making glass from raw materials. L’Arte Vetraria, or in English, 'The Art of Glassmaking', did not get written in a vacuum. When Neri put pen to paper for his book, he had been making glass for over a decade. He had the opportunity to learn his craft from some of the experts in the field. 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” not because it was a gambling hall (which it was not) but because this was the name 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 Vetraria, Antonio Neri 1612, p. 41.

* This post first appeared here in a shorter form on 12 August 2012.

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 confirmed 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 television 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. Physicians like his father idolized 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.

The Neri Chapel

The Vision of St Bernard, by Pietro Perugino (1448–1523)

The c. 1598 altarpiece that was commissioned 

for Cestello by Antonio Neri’s father

On a narrow unassuming street called Borgo Pinti on the northeast side of Florence, 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 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.

The Neri Godparents III

Portrait of Alessandro Gondi as a child (1569)
(Later became godfather of Emilio & Allesandro Neri)
by Anguissola Sofonisba.

This is the third and final part of an examination of the godparents of seventeenth century glassmaker Antonio Neri and his brothers and sisters. In early modern Florence, the families of godparents formed tight alliances, helping each other with business opportunities and social contacts. The Neri family was no exception; their godparents formed a very well connected group. Margherita Ardinghelli appeared as godmother to Antonio's brother Jacopo Neri. Eight years later, her husband Braccio's first cousin, Monsignor Giovanni Alberti, appeared as younger sister Maria Neri’s godfather. Giovanni was also the son of a Florentine senator. He served as protonotary apostolic for Pope Gregory XIII and as bishop of Cortona under Pope Clement VIII. A godfather serving in the papal inner chambers was a good family contact indeed. Also appearing for Maria was Pierfilippo Perini, a physician. Other records indicate Perini was also a lawyer, apparently part of the Ricci household. The Registri lists Maria Neri's godmother as Alessandra di Girolamo Pepi. Among the prominent Florentine republicans was Alessandra's father, Girolamo. He was tortured by Alessandro de' Medici in the 1530s, upon the family's regaining control of Florence after the siege. 

Emilio's two godfathers were Alessandro Gondi (pictured) and Gondi's own father, Giovanbatista. At the time, they were 20 and 66 years-old respectively. The Gondi's ancient Florentine roots trace back to the rule of Charlemagne, who first established the heraldic nobility system in Florence in the year 800. The Gondi's were bankers and landholders in the Mugello region between Florence and Bologna, where the Medici family originated. A branch of the Gondi family became heavily involved in the French court under Catherine de' Medici. Giovanbatista had appeared two decades earlier, in 1564, as godfather for Bianca Cappello's first child Pellegrina. Bianca was the controversial Venetian lover of Grand Duke Francesco de' Medici who later became his wife and Grand Duchess. Giovanbatista's brother Piero was friends with Michelangelo. The artist once gave him the keys to the New Sacristy in the San Lorenzo Basilica in order to hide family belongings during the sack of Rome. In Antonio Neri's time, members of the Gondi family were intermarried with the Ardinghelli and Ricci families. They all supplied godparents to Antonio's siblings, the children of Neri Neri and Dianora. In addition to standing for Emilio Neri, Alessandro Gondi appears again four years later in 1587 as a godparent for Alessandro Neri, the eventual heir to the Neri family's fortunes. 

Lucrezia, the youngest Neri girl, has a single godparent listed in the register, Montiglio degli Albizi. The Albizi family boasted powerful bankers and politicians. This was another case where deep divisions over Medici rule drove a family apart and eventually into near extinction. Luca degli Albizi headed the pro-Medici faction in Florence in the latter half of the sixteenth century. This branch of the family thrived, living in a series of palazzi just a few steps to the west of the Neri's parish church, San Pier Maggiore, close to the Neri home. They resided alongside properties owned by the Altoviti and Valori families. Today, perhaps the best-recognized member of the Albizzi family was Eleonora degli Albizi the young consort of Cosimo I after the death of his first wife, also named Eleonora. Folklore has it that in 1566, Cosimo intended to retire from public life and marry Albizi quietly, after the birth of a girl, but his regent son, Francesco I, forbade it to due to the inheritance complications that would ensue. The story is that Cosimo's long-time personal secretary, Sforza Almeni, leaked word of the clandestine marriage to the family. For his betrayal, an enraged Cosimo murdered Almeni in cold blood.  Eleonora later gave birth to Don Giovanni de’ Medici, the uncle and friend of Don Antonio, Neri's sponsor. The specific Albizi family member we are interested in, Lucrezia's godfather, Montiglio degli Albizi, seems to have eluded history, although the first name ‘Montiglio’ is almost certainly a moniker for an immigrant to Florence from Italy's Piedmont region.

Like his older brother Francesco, Alessandro Neri boasted a godfather from a powerful banking family, this time the Ricci clan. Godfather Federico de' Ricci, was a very famous name indeed. Federico was named for his father's first cousin, who ran the influential Federigo de' Ricci and Partners public bank and helped to finance Cosimo I in the war for Siena. Together, the Ricci and Acciaiuoli families controlled the Tuscan treasury for the Medici. (Giovanni Acciaiuoli was Francesco Neri's godfather). Alessandro Neri's godfather was closely related to the venerated holy-woman Catherine de' Ricci later canonized as Saint Catherine. His second godfather, Alessandro Ginori, was a Benedictine monk at the Badia Fiorentina, taking the name of Don Gregorio. He descended from a long line of Florentine merchants, bankers and republican leaders. Four years after the baptism in 1591, the monastery elected Ginori as their abbot. Distinguished for great learning, his peers considered him one of the leading writers of his day. Five years later, he moved to the abbey of San Paolo d'Aragon in the territory of Bergamo, where he died in 1598. The same year saw the death of Neri Neri, Antonio's father.

*This post first appeared here on 23 April 2014.

The Neri Godparents II

Opening lines of Piero della Stufa’s MS.

Translating Luca della Robbia from Latin to Italian.

In early seventeenth century Florence, the honor and responsibilities of being a child's godparent was a serious affair. There were the ceremonial aspects of taking part in the baptism, but that was just the beginning. A godparent pledged responsibility to the Church for overseeing the spiritual upbringing of their charge. Beyond the realm of religion, they later brought a child into the family’s web of social, business and political contacts. In the family of Neri Neri and Dianora Parenti, there were ten children. Their fourth child, Antonio, would go on to write the first book devoted to glassmaking formulas called L'Arte Vetraria. Each sibling with one, two or even three named godparents, made in total a list of eighteen family associates. These eighteen had families of their own, and soon the list becomes formidable. The genealogy is interesting; many of these families are intermarried, and a number of the godparents are related directly or have common family ties. However, even glossing over these specifics, a remarkable aspect of the list emerges that demands notice. This is the striking prominence of the names; almost all of the Neri godparents are known to history. They were lawyers, bankers, politicians, ambassadors, courtiers and high church officials.

Continuing where we left off, Francesco Neri was the third child. Francesco's only godparent was Giovanni Acciaiuoli. He was from one of the two influential banking families that managed the Tuscan treasury for Grand Duke Cosimo I. Giovanni had been one of five special administrators charged with the construction of the new seat of the Medici government, the Uffizi palace, on the banks of the Arno River. 

Antonio Neri's godparents were Francesco Lenzone  and Ginevra Sassetti. Lenzone was a Florentine lawyer and notary like Dianora's father. By 1590, he was ambassador to Spain for Ferdinando I. The wealthy Sassetti family was part of the early Medici banking empire. In the sixteenth century, the family continued as close allies of the Medici. They ran a trading operation within India through Pisa and Lisbon. Ginevra's nephew, Filippo Sassetti, was a correspondent with the circle of friends to which Antonio's father belonged. He sent medicinal samples back to Florence from his base in Goa India. 

Loyalist Jacopo di Alamanno Salviati (1537-1586) enlisted as the godparent of Jacopo, the Neri's second son so named. He was both friend and first cousin to Cosimo I. He was also the first cousin of Alessandro Ottaviano de' Medici, who at the time was Bishop of Pistoia and later rose to Archbishop of Florence. He would go on to become a Cardinal, and in 1605, his peers elected him pope, taking the name Leo XI.

Appearing in the register as godfather for Antonio's younger brother Vincenzio was Piero della Stufa, a church canon. The Della Stufa family has a long and venerable history in service to the Medici. Piero translated a book from Latin written a century earlier by famed sculptor Luca della Robbia. In 1570, the same year that Antonio's parents were married, he was named as will executor and administrator to the estate of mannerist sculptor Benvenuto Cellini. Other members of the Della Stufa family had come to the legal and financial aid of the colorful and somewhat volatile sculptor at various times in his life. Cellini himself wrote a book on goldsmithing and sculpture, in which he devotes a chapter to the art of enameling. He does not give specific recipes, but he does discuss transparent gold ruby enamel and the procedure for ‘striking’ the fabled color in the furnace. Striking is the special reheating process required to bring out the deep ruby red color. Neri would later discuss red enamel in letters to his friend Emanuel Ximenes and ultimately publish a short recipe for gold ruby glass in his own book. There is no indication if Neri was familiar with Cellini's 1568 publication, but this is entirely possible, especially in light of the family connection. 

* This post first appeared here on 18 April 2014.

The Neri Godparents

Guido Reni (1575–1642)

St Joseph with the Infant Jesus (c. 1635)

Not too long ago, the life of seventeenth century Florentine glassmaker Antonio Neri was regarded as a blank slate, an enigma of history. Some reports described him as a poor itinerant, assuming (perhaps correctly) a vow of poverty in connection with a mendicant order of the Catholic Church; he was, after all a self-described priest. Recent research has begun to bring him into sharper focus.

We now know that he was born into a patrician family, and probably enjoyed a very comfortable childhood. When Antonio was around age thirteen, his famous father, Neri Neri, was appointed personal physician to the newly crowned Grand Duke Ferdinando de’ Medici. His grandfather was a close friend to historian and poet Lodovico Domenichi. (In fact, Antonio’s second given name is Lodovico). 

Even with all the new material that has come to light, there is still much that is unknown about Antonio Neri, his family and their daily life. A window of sorts into that life can be opened by looking at some of the characters chosen as godparents for Antonio and his siblings, details that have been preserved in the city baptistery records.

The first-born child of Neri Neri and Dianora Parenti was Antonio’s older sister Lessandra. She claimed Baccio Valori as her godfather. The Valori family had a long, tragic history with the Medici. His father, grandfather and great-grandfather were all close Medici supporters, yet each ended up exiled, imprisoned, or executed after relationships soured. On one hand he was faithfully employed by the Medici, yet he reportedly spent a good deal of his time collecting letters and papers documenting his family’s close support of Girolamo Savonarola, the firebrand Dominican priest who lead Florence in the late 1490s, after the Medici had been temporarily expelled from the city.   

Lessandra’s godmother was Marietta Gaetani, also from a noble family, which included dukes, cardinals and popes. They played prominent roles in the politics of Pisa, Rome and Naples for several centuries. Marietta’s father owned the house from whose tower Galileo showed the moons of Jupiter to Grand Duke Cosimo II in 1610. 

Antonio’s oldest brother was Jacopo, named after his still living grandfather, barber-surgeon Jacopo Neri. His godmother, Margherita di Braccio Alberti, (née Margherita di Neri Ardinghelli) was the wife of a Florentine senator and the niece of a Cardinal.  

Of all the Neri godparents, Jacopo’s godfather was perhaps the most notable. Antonio Altoviti was the very controversial archbishop of Florence. It is an understatement to say that the relationship was tense between him and the first Grand Duke, Cosimo I de’ Medici. Nevertheless, he did eventually gain the trust of Cosimo’s inner circle; in 1567 Altoviti was involved in negotiations to bring Venetian glass workers to Tuscany, an agreement the grand duke very much wanted. 

It is impossible to gain full appreciation of a man through a single anecdote, but we can get a flavor. In 1569, shortly after occupying his post for the first time, Altoviti introduced a new ritual to the Florentine Church. On Holy Thursday, the Bishop would wash the feet of twelve of the city’s poor residents rather than of twelve canons (as done previously) and he would give them generous alms. On 13 December 1573, Altoviti became godparent to Jacopo. But Jacopo would never learn what it was like to have the Archbishop as his spiritual guide. Two weeks after his birth, on the 28th of that month, Altoviti convened a special post-Christmas meeting of regional bishops. It was during this synod that he suddenly and unexpectedly died at the age of fifty-two. Within a few years, the boy would join him.

While these names do not tell us anything directly about the Neri family, they certainly provide us with insight into the people they befriended and trusted. In the next post we will take a look at a few more of the Neri children’s godparents.

* This post first appeared here in a slightly different form on 16 April 2014.

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 Tesino [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. 

Glass from Tinsel

From Diderot's Encyclopedia, machinery to hammer brass into thin sheets.

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 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.

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.