Dear Readers,

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

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

Paul Engle
6 March, 2021

Friday, January 29, 2021

Don Giovanni de' Medici


Don Giovanni di Cosimo I de' Medici
In July of 1621, a man lay dying in his bed, in his palazzo on Murano, the glassmaker's island in Venice. This fifty-four year old had recently become a father and his wife Livia was expecting a second child, but the tumor in his throat meant he would not see his two year-old son Gianfrancesco Maria grow up, nor would he live to hold his yet unborn daughter in his arms. His death would also trigger a series of unanticipated ugly events. Don Giovanni de' Medici was the son of Grand Duke Cosimo I and Eleonora degli Albizzi. He had been general of the Venetian army and before that led Tuscan troops in Flanders, France, Hungary and served as ambassador in Madrid. But he was far more than a soldier; he was an architect who helped design the Chapel of Princes in Florence, he was a strong patron of the arts and he was a devoted alchemist. He plays a somewhat tangential role in the life of glassmaker Antonio Neri, yet their paths cross repeatedly through common associates, interests and locations.

Don Giovanni's palazzo on Murano was the grandest on the island; previously owned by the father of Grand Duchess of Tuscany Bianca Cappello. She spent time at the palazzo as a child and was the mother of Antonio Neri's sponsor, Don Antonio de' Medici. King Henry III of France stayed there on his tour of glass factories on the island. Later, the palace would be the residence of the bishop of Torcello and ultimately, in 1861, became what it is today: the famous Museum of Glass (Museo del Vetro).[1]  If, in the winter of 1603-4, Neri followed the route through Venice to Antwerp suggested by his friend Emmanuel Ximenes, then a visit to this palazzo would have certainly been in order, although not yet occupied by Don Giovanni.

Early in his career, in the 1590s, Don Giovanni commanded troops against the Ottomans in Hungary and his young nephew Don Antonio was directly under his command. The two men would both set up alchemy laboratories in their respective Florentine residences; Don Antonio in the Casino di San Marco on the north side of town and Don Giovanni at his Casino del Parione (today the Palazzo Corsini al Parione) along the Arno River behind the Santa Trinita Church. Don Giovanni's was only steps away from Antonio Neri's residence, the palazzo Bartolini,  after his ordination. Santa Trinita was a Benedictine church and the office of yet another alchemy enthusiast: Vallombrosan Abbot-General Orazio Morandi. It is unknown if Neri had any association with this church, but Morandi wrote that times spent in Don Giovanni's laboratory were among his "most cherished memories." Much later, in 1630, Morandi gave testimony at court concerning a Simon Carlo Rondinelli, saying: 
I have known Signor Rondinelli for twenty years, from the time I was in Florence. I met him often there in the house of Alessandro de’ Neri. The said Rondinelli is very well versed in astrology.[2]
The timing places Morandi in the Neri family house when Antonio's younger brother, Alessandro (who had inherited the house), was twenty-one years old. It was shortly before Antonio's return from Antwerp.

While Neri was in Antwerp visiting his friend Emmanuel Ximenes, Don Antonio was leading Tuscan troops nearby, in Flanders, on the side of the Spanish against the Dutch independence movement. Nevertheless, he found time to submit his design for the Chapel of Princes in Florence, and to quarry marble for the project and have it shipped back to Tuscany. It is unknown if Neri and Don Giovanni ever shared a meal in Antwerp, but the decorated soldier/polymath did commission a series of paintings there, for the grand duke, to be hung in the new Medici villa 'La Ferdinanda' at Artemino in Prato. The interior decoration of the public spaces in this villa were being executed by artists Passignano and Poccetti, fresh from finishing their recent collaborative masterpieces; the Neri Chapel and Cestello church on Borgo Pinti, financed by Neri's late father.

[1] For a full  treatment of the history of the Palazzo, see Canal 1909 in the Bibliography (to the right).
[2] Translation by Brendan Dooley “Morandi's last prophecy and the end of Renaissance politics” (Princeton: Princeton Univ. Press, 2002), p. 22.
*This post first appeared here in a slightly different form on September 25, 2013.

Wednesday, January 27, 2021

Neri and the Kabbalah


Kabbalistic Sephiroth Tree,
from Portae Lucis, Paulus Ricius (Trans.)
Augsburg, 1516.
Kabbalah is a form of mysticism practiced within the Jewish tradition. In the early seventeenth century, there was a great deal of interest in Kabbalistic teachings among Catholic alchemists and natural philosophers. It was recognized that Christian alchemy had its roots in Hermetic and earlier Arabic societies, (the word "alchemy" itself is of Arabic origin.) It was thought that the Jewish Kabbalah was yet another branch of the same traditions of relaying secret knowledge by word of mouth. 

In early modern Florence, Italy, there were some interesting connections between the Kabbalah and glassmaker, alchemist and Catholic Priest Antonio Neri. Here is Neri’s own description, of Kabbalah in his 1613 manuscript Discorso: 
Some call it Kabbalah: in ancient times fathers communicated it to their children only by voice, preserving [this knowledge] for posterity, not for history, but as simple tradition. Others finally gave it the name of 'wisdom' [sapienza] because they rightly believed it was impossible, without this art, to know perfectly the nature and the qualities of natural bodies. In order to achieve the end they wanted, which was the perfection of the bodies, they separated the pure from the impure through various chemical operations, which can all be reduced to six principal phases.*
He goes on to describe basic chemical operations that were thought to be fundamental to purifying materials, and ultimately to the production of the Philosopher's Stone. These techniques are the same as practiced in Christian alchemy, and Neri uses them in his glassmaking recipes. Clearly, he had more than a passing knowledge of the subject, and it is interesting to speculate on how he might have come to learn about Jewish alchemical traditions. 

Early seventeenth century Florence contained a city within a city: the Jewish Ghetto. A walled perimeter encircled what is now the Piazza della Republica. This was the mandated home for all of Florence's Jewish population. Each night, entrance gates were closed and locked from the outside. Within the Ghetto, residents were allowed to live and warship freely, even maintaining a Synagogue. In the daytime, the gates were opened, and residents were allowed to go about their business and leave the city with special passes. Among the Ghetto's most prominent residents was the family of alchemist Benedetto Blanis (c.1580-1647.) Blanis served as librarian to Medici prince Don Giovanni. Giovanni maintained an alchemical laboratory in his residence, which was run by Blanis, located only a short distance from where Antonio Neri was living when he first worked at the Casino di San Marco.  

Don Giovanni maintained a close relationship with Neri’s benefactor Don Antonio de' Medici. So close, in fact that when two of  Blanis' relatives were implicated in a gambling scheme, Don Antonio hid them at his residence and then spirited them away, out of Florence, in his own coach until matters cooled off. Furthermore, Blanis came from a family of doctors who must have been known to Neri's father, royal physician to Grand Duke Ferdinando. Antonio Neri was probably a couple of years older than Blanis, if they did not meet through mutual connections with the Medici family, then perhaps they met on the street. The walk for Neri, between his living quarters near Santa Trinita, and the Casino laboratories would have passed around or through the Ghetto, and the walk for Blanis to Don Giovanni's palazzo on Via Parione took him past Neri's front door. The paths of the two men may have crossed, but there is not direct evidence.

Of course, in the absence of hard facts, there are many other possibilities of how Antonio Neri might have become acquainted with Kabbalistic tradition. By taking a look at Blanis and his connections to the Medici family, we can at least see an area of cooperation between Jewish and Christian alchemists in what we might otherwise assume to be an inviolable separation.** 

* “Discorso sopra la Chimica: The Paracelsian Philosophy of Antonio Neri”, M.G. Grazzini / Nuncius 27 (2012), p. 337.
For more on Blanis, see Edward L. Goldberg, The Secret World of Benedetto Blanis. (2011).
** This post first appeared here on 6 January 2014.

Monday, January 25, 2021

Knights of Malta


Fra Antonio Martelli, Knight of the Order of Malta,
Attrib. Caravaggio, c. 1608.
"Of me, Priest Antonio Neri, Florentine 1598." So starts the inscription on the first of 61 ink and watercolor illustrations in a manuscript titled "Tesoro del Mondo" [Treasure of the World]. It is the earliest manuscript known to exist by the respected glassmaker and alchemist, started when he was just twenty-two years old. Given the Church's rules and the typical length of training for ordination, twenty-two is about the youngest age possible for a priest. In fact, it is likely that the responsibility was granted to him mere months or weeks before the ambitious manuscript was begun, which he dedicates to the exposition of "all of alchemy." 

This scenario raises the intriguing question of which religious order would have taken on the sponsorship of educating a future priest as an alchemist; a mystery that remains unanswered to this day. Recently, we looked at two promising possibilities; the Canons Regular, and the Dominicans. Today we investigate a less conventional possibility: the Knights of Malta. The knights were ancient aristocratic military order that originated during the crusades and in Neri's time ran the papal navy. 

The Knights of Malta headed two churches in Florence and Neri can be connected to both. With the first, our priest has an indirect association. San Giovannino dei Cavalieri, (formerly called San Giovanni Decollato) is located a few steps from the Casino di San Marco, where Neri made glass at the beginning of the seventeenth century. His sponsor and owner of the Casino was Medici prince Don Antonio, whose daughter Maddalena later served as a nun at the associated convent. [1] The second church, San Jacopo in Campo Corbolini, is directly connected to Neri in a story recorded shortly after his lifetime. [2]

The following passage contains much that is contradicted by the facts, yet infused enough with the truth to make us wonder. Historian, courtier, genealogist and Florentine senator Monsignor Girolamo da Sommaia [3] recounted that:
M. Antonio who had died in Florence five or six years earlier and was from San Jacopo in Campo Corbolino,[4] said that he had the [philosophers] "stone," which he found in a pen-written book of secrets and took the paper and showed it to Casa (Agnolo Talducci della Casa, from the reign of Ferdinando I) who said what he was holding was sophistry, but that the cost was very little to try, so he tried it, and saying he succeeded, he told Casa and a goldsmith on the Ponte Vecchio, who did the first assay and later in his presence threw a bag of that powder into the Arno.[5]
A number of notebooks chronicle Neri's long working association with Della Casa at Don Antonio de' Medici's laboratory. These and other documents cast considerable doubt on the veracity of Sommia's story. Nevertheless, individual details do ring true. Of particular interest is the name of the church, San Jacopo in Campo Corbolini. It still stands today, a block west of the mercato centrale in Florence. The Knights Templar occupied it since 1256 and when that order died out, the Knights of Malta took it over. Neri's affiliation may have been through his work for Don Antonio, who belonged to the order. Another possibility is that Neri was attached to the knights through his father's connections at court. The order maintained a great deal of independence, reporting directly to the pope and curia. Their main presence was on Malta, Neri was not a knight but he could have occupied a place in their clergy.

The knights followed the rule of Augustine and enjoyed a close relationship with the Augustinians. The order traces its roots to the crusades [6] and has various associations with alchemy, notably George Ripley. [7] The fifteenth century English physician and alchemist was ordained into the Canons Regular of Saint Augustine, but he later joined the Carmelites. He is purported to have used gold produced through alchemy to help finance the Knights of Malta in the war with the Ottoman Empire. [8] Folklore maintains that Ripley learned transmutation as part of his Italian schooling in alchemy.

[1] Luti 2006, pp. 171, 172.
[2] See Targioni-Tozzetti 189.
[3] Girolamo da Sommaia (1573–1635). He served as provost of the university (studio) at Pisa and prior of the convent church of the Knights of Saint-Etienne in the years 1614–1636. He was also a friend and supporter of Galileo.
[4] Today, this church is called S. Jacopo in Campo Corbolini. It was founded in 1206.
[5] Related in Targioni-Tozzetti 189, thanks to Maria Grazzini for pointing me to this passage.
[6] Known variously through history as the Knights Hospitaller, the Knights of Rhodes, the Knights of St. John of Jerulsalem and the Knights of Malta.
[7] Sir George Ripley (ca. 1415–1490), Bridlington, York. Cf. Rampling 2008; McCallum 1996.
[8] Fuller 1840.

Friday, January 22, 2021

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:
I have considered dedicating this book to none other than you, most Illustrious Excellency; for you have always been my outstanding patron and you understand this and all other worthy and precious knowledge. In fact, you always practice all the arts requested of a true and generous Prince. I implore you therefore to accept if not my work, then my complete devotion to your great merit and virtue, Excellency. I pray that God will fill you with happiness.
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 Francesco de' neri and Bianca Capello 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 here on 12 May 2014.

Wednesday, January 20, 2021

Eyes of a Lynx


The seal of the Accademia dei Lincei.
In the spring of 1612, Florentine priest Antonio Neri published his book on glassmaking. L'Arte Vetraria was the first printed book devoted to the formulation of glass from raw materials, but unfortunately for him it did not exactly take the world by storm, at least not at first. Sales were such that a number of copies still exist from the initial printing; they remain in pristine condition, never bound. 

Initially, the book received scant attention, but it was noticed. In fact, within a couple of years word had reached Rome, where Prince Federico Cesi, the founder of a scientific society, asked a Pisan member of his group to obtain a copy. That other member would go on to become one of the most recognized scientists in history. Meanwhile, L'Arte Vetraria gained prestige and readers, slowly but steadily.  By the end of the century, Neri’s book would be translated into English, Latin, German, French and then back into English from the French. It became the bible of glassmakers throughout Europe. 

In 1614, the year of Antonio Neri's death, naturalist Prince Federico Cesi wrote to his good friend Galileo. He complained of the difficulties in getting material from the Roman libraries, urging the astronomer to send him a copy of Antonio Neri's book.
The poor management of these libraries in Rome makes me feel continually thirsty for good books that come to light, which I can use for my study of compositions. They are scarcely giving me the titles, and after a long wait, only a tenth of what I asked. […] now I hear that printed in Florence is L'Arte Vetraria by Priest Antonio Neri, and I think there is some good in it. Please, your lordship, send me a copy, and believe me that I will gladly give them trouble.
 Shortly after, having received the book the prince wrote,
I thank your lordship for the book on glass, which I find very rich in experiments and beautiful artistry.
In 1603, Cesi founded the Accademia dei Lincei (Society of the Lynxes), an early scientific society whose members (with eyes as sharp as a lynx's) eventually included both Galileo Galilei and Giambattista della Porta.[1] Within a few months of Neri's death, his book was already on its way to making history.

[1] In classical Greek mythology Lynceus was the grandson of Perseus, and had preternaturally keen eyesight. See Apollodorus, Bibliotheke I, viii, 2 & ix, 16; III, x, 3 & ix, 2.

* This post first appeared here in a shorter form on 1 August 2013.

Monday, January 18, 2021

The Glassmaker and The Astronomer


Portrait of Galileo Galilei, 1636 (detail),
by Justus Sustermans (1597-1681).
Galileo Galilei lived almost simultaneously with glassmaker and alchemist Antonio Neri. Both were employed by the Medici royal court in Tuscany and both spent considerable time in Florence and Pisa, possibly also in Venice and Rome. No direct contact is known to have occurred between the glassmaker and the astronomer, but their paths did cross many times, orbiting like two celestial bodies in the cosmos - albeit one with a bit more gravitas than the other. 

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

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

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

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

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

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

* This post first appeared here in a slightly different form on 18 Novenber 2013.

Friday, January 15, 2021

Aventurine Glass


Small amphora in aventurine glass,
Murano, Salviati.
With all its glitz and sparkle, aventurine (avventurina) stands out as a flamboyant extrovert among the varieties of glass. Developed and perfected on the Venetian island of Murano, also known as 'goldstone', it consists of a transparent base glass with myriad reflective crystalline "spangles" running throughout. The classical version is a deep golden brown with crystallites composed mainly of metallic copper, with a few related compounds as supporting cast. However, numerous colors have been developed, including red, orange, yellow, green, blue, violet, black and white. 

Folklore holds that aventurine was discovered by accident ("a venturi") when unknown monks inadvertently dropped copper or brass shavings into a glass melt as early as the thirteenth century. [1] However, more thorough investigations have recently identified 1620 as a likely date for the first appearance of aventurine glass. [2] No example or written account has been found that dates prior to the seventeenth century. An alternate story accounts for the name aventurine being derived from 'adventure'; referring to the difficulty and uncertainty involved in its production.[3] At first, the formula was a closely held secret among a few glassmakers and subsequently it was lost and then rediscovered not once but  twice.

To complicate matters, natural minerals with a similar appearance were named after the glass, leading to the misconception that they were also discovered after the glass was invented. This is clearly not the case. Early examples of mineral aventurine artifacts date to the Neolithic era [4] and can be found throughout history. First century Roman writer Pliny mentions a type of stone with silvery flecks, a passage that was well known when the glass was developed.  The compositions of these minerals were also identified early; either species of quartz that contain flecks of mica, or a type of feldspar (sunstone).[5] Mineral aventurine turns up as the eyes of Greek statues, in stonework mosaics and later in the 'pietre dure' art perfected by the Medici artisans in Florence around the time Antonio Neri started making glass there. The chances are good that examples of the mineral were known to Neri as well as to the glassmakers on Murano, but a recipe for the glass version does not turn up in Neri’s 1612 book; he was apparently too early by a decade.  

The story of aventurine's accidental discovery by monks may well be apocryphal; nevertheless, it is a great entrée to understanding how the formulation works. First, contrary to what the story implies, aventurine is not the result of dumping metallic confetti into glass. The reflective "spangles" (as early researchers were fond of calling them) are actually uniformly sized, mirror-like crystals that are grown in the glass. In truth, the formula is quite similar to recipes already in use by Neri and others; the difference was in proportions and in how the glass was treated after it was in the furnace. The formula for aventurine calls for the addition of copper, iron and tin oxides, to a base that was a hybrid of soda, potash and lead glass. Neri’s recipe #128 is titled "A Proven Way to Make Rosichiero" [6] and provides for all of these ingredients, albeit in lower concentrations. Rosichiero was a transparent tawny red colored glass that was a staple of furnaces throughout Italy. 

The secret to producing the reflective "spangles" was to mix the glass and heat it in the furnace in a normal way, but then to slowly reduce the heat while creating a low oxygen “reducing” atmosphere. The furnace draught was shut; the glass pot was fitted with a tight lid and then covered with ashes and allowed to cool very slowly.  

Initially, the batch is saturated with copper oxide. This means the glass has dissolved as much copper, iron and tin as it can and any further addition of these powders will simply float to the bottom of the pot.  The exact amount of powdered metals able to dissolve is a function of temperature; the hotter the glass the more that will dissolve and the cooler the glass the less that will dissolve. The key concept here is that as the glass slowly cools, the metals start to come out of solution and crystals start to form. There is some complex chemistry happening at the same time; the reducing atmosphere encourage the metals to stay in a pure un-oxidized form,  Furthermore any oxygen or sulfur  that happens to be present will preferentially combine with the iron, leaving the copper crystals pristine. Once cooled to room temperature, a successful batch would be broken away from the glass pot by workers and divided into smaller pieces. Glass artisans wanting to incorporate the aventurine into their work needed to work quickly. They carefully reheated an appropriate nugget and coated (encase) it in a layer of clear glass; once molten, direct exposure to the air would destroy the glittery effect. 

Over time, it was discovered that various colors could be produced with the addition of different chemicals, but the central principal of growing tiny metallic crystals is the same.

[1]  The earliest instance of this story in print that I can find is fairly late;  Faustino Corsi, Delle pietre antiche: libri quattro (Rome: Salviuccio e figlio, 1828)  pp. 166-167.  
[2] Cesare Moretti (†), Bernard Gratuze and Sandro Hreglich,  “Le verre aventurine (‘ avventurina ‘) : son histoire, les recettes, les analyses, sa fabrication”, ArcheoSciences, 37 | 2013, 135-154.
[3] For instance see  Giulio Salviati, “Venetian Glass” Journal of the Society of Arts (Proceedings), Volume 37 (7 June,1889), p. 630
[4] Neolithic Quartz Aventurine Pendant - 7 Cm/ 2. 76 ", green - 6500 To 2000 Bp – Sahara. Item Id: 106549,  Weight: 83 gm. Sahara - Mauritania - Tagant country.
[5] Dizionario del cittadino, o sia Ristretto storico, teorico e ..., Volume 1 pp. 38-39.
[6] Antonio Neri, L'Arte Vetraria (Firenze: Giunti, 1612).
[7] Sauzay, A. (1870) Marvels of Glassmaking in All Ages. London, 1870 pp. 173 - 175.

Wednesday, January 13, 2021

The Adventures of Adam Olearius


Adam Olearius
In the autumn of 1633, a trade mission heavily laden with gifts headed east from northern Germany. The great duke of Holstein was sending an ambassador to Moscow to request the czar’s permission for travel rights along the Volga River. Holstein was the northernmost tip of the Holy Roman Empire, in many ways more  closely tied to Scandinavia than to their Habsburg overlords. This expedition was part of an attempt to establish an inland silk-trade route between Europe and the Orient. Such a route would eliminate the circumnavigation of Africa, shortening the trip and reducing risk. After several years and initial high hopes, it became clear that the effort was doomed to failure. Czar Michael I of Russia was enthusiastic about the project, but at the southern end of the route, the king of Persia was not so receptive. Nevertheless, the expedition did become famous for a different reason: a written account of the adventures of the diplomats.

Upon the delegation’s return to Holstein, their secretary Adam Olearius (1599-1671) published a book that chronicled their travels. [1] As a mathematician, astronomer and general polymath, Olearius provides an uncommon perspective of the various cultures, practices and technologies encountered. Ultimately, he was appointed royal librarian and keeper of the duke’s cabinet of curiosities. The book proved so popular that more comprehensive editions soon followed, adding the contemporary accounts of another traveler, Johann Albrecht von Mandelslo. [2]

Glass is not the central theme of his adventures, yet this and related subjects are discussed in a number of different passages, giving us a unique insight into the material’s place in those societies.

In August of 1634, the group arrived in Moscow. Having been granted audience with the czar, Olearius describes the procession of the entourage and enumerates a long list of the gifts they brought. Among them was “a great looking-glass, being an ell and a quarter high and half an ell broad, in an ebony frame, with boughs and fruits carv'd thereon in silver, carried by two Muscovites.” [3] An ‘ell’ was the northern european equivalent of a cubit or about 25 inches, so the mirror measured about 12 inches wide by 30 inches tall, not enormous by current standards, but quite an achievement in the seventeenth century. Glass workers would have to blow a large cylindrical bubble, cut it open and lay it flat on a polished marble surface. To be usable, the sheet of glass would have to be made without waves or defects and it would have to be cooled slowly, over a period of many hours in order not to form cracks. Silvering the back was a whole other ordeal performed by an artisan schooled in alchemy.

Speaking of the chemical arts, gifts from the duke of Holstein to the czar of Russia also included “an ebony cabinet, garnish'd with gold, like a little apothecaries shop, with its boxes and vials of gold, enrich'd with precious stones, full of several excellent chymical extractions, carried by two Muscovites” [4]

While in Moscow, Olearius put on a demonstration of optics for some locals. “I shew’d them upon a wall of an obscure chamber, through a little hole I had made in the shutter of the window, by means of a piece of glass polish’d and cut for optics, all was done in the street, and men walking upon their heads: This wrought such an effect in them, that they could never after be otherwise persuaded than that I held a correspondence with the devil.” [5] Here he is describing a ‘camera obscura’ in which scenes from outside are projected upside-down onto the wall of a darkened room.

A couple of years later, after a return to Holstein to ratify a treaty with the czar, the delegation arrived in Persia. They were treated to a sumptuous meal by the king’s chancellor. “The walls were all set about with looking-glasses, to the number of above two hundred, of all sizes. So that when a man stood in the midst of the hall, he might see himself of all sides. We were told that in the king’s palace, in the apartment of his wives, there is also a hall done all about with looking-glasses, but far greater and much fairer than this.” [6]

“For the teaching of astronomy they have neither sphere nor globe, insomuch that they were not little astonished to see in my hands a thing which is so common in Europe. I asked them whether they had ever seen any such before. They told me they had not, but said that there was heretofore in Persia a very fair globe which they call ‘felek’, but that it was lost during the wars between them and the Turks. They haply meant that which Sapor, king of Persia, had caused to be made of glass, so large, that he could sit in the center of it, and observe the motions of the stars and must no doubt be like that of Archimedes, where of Claudian speaks in the Epigram which begins thus: Jupiter in parvo cum cerneret aehera vitro.” [7]

Olearius goes on to describe the Persian army in some detail, including this account of an early form of chemical warfare. “At the siege of Iran, in the year 1633, they had the invention of casting into the place with their arrows, small glasses full of poison, which so infected the air that the garrison was extremely incommodated thereby and made incapable of handling their arms for the defense of the place.” [8]

In 1637, near Tehran, Iran, he describes a royal tomb “adorn’d all about with glass of all sorts of colors, which are preserved by iron grates.” [9] And in the same area,

“At Kimas, in the province of Kilan, there was one of these mountebanks, who having found out the trick of setting cotton on fire by means of a crystal cut in half-round and held in the sun like a burning-glass, would have people persuaded that by operation, which he affirmed to be supernatural, that he was of the kindred of Mohammed. After our return to Holstein, I shew’d the Persians, whom Schach-Sefi [king of Persia] sent thither, that it was the easiest thing in the world to get fire from the sun, and I lighted paper in the very depth of winter by means of a crystal full of cold water, or a piece of ice, which I had made half round in a pewter dish. They were astonish’d at it, and said, that if I had done as much in Persia, I should have pass’d there for either a great saint, or a sorcerer.” [10]

As an addendum, in later editions of Olearius’ book, the recollections of Johan Albrecht de Mandelslo (1616–1644) were added. He accompanied an unrelated trade mission to Isfahan,Persia, and then split from his group to continue touring the region. He traveled through India, and then down the African coast. In 1639, the German traveler passed through Madagascar. He commented on the inferior quality of European glass trade-beads, compared to those of India, which he acquired earlier in the trip.

“The glass-bracelets, beads and agates, we had brought from the Indies [India] were incomparably beyond what they were laden with out of Europe; so that it was resolved ours should not be produced, till the others were sold. By this means, we bought every day four oxen for forty pair of glass bracelets, which the inhabitants call ‘rangus’; a sheep for two, and a calf for three ‘rangus’; and for a brass ring, ten or twelve inches about, a man might have an ox worth here six or seven pound.” [11]

Much has been made of the use of glass trade-beads by Europeans around the world.
In Madagascar and along the trade routes of the Indian Ocean, European traders were fairly late to the party. For a thousand years earlier, [12] beads had been used as the currency of choice among disparate cultures from Indonesia and China to India to Africa who did business with each other.[13] The above quote from Mandelslo’s diary provides a fascinating firsthand account of transactions with beads. The passage also hints at the superior quality of Indian glass beads. Today, glass beadmaking continues on an industrial scale there, and the glass bracelet industry still survives, notably in Firozabad, northern India.

[1] Adam Olearius: Beschreibung der muscowitischen und persischen Reise, (Schleswig: 1647).
[2] Adam Olearius, John Davies, Johann Albrecht von Mandelslo, Philipp Crusius, Otto Brüggemann: The Voyages and Travells of the Ambassadors Sent by Frederick Duke of Holstein, to the Great Duke of Muscovy, and the King of Persia... (London: John Starkey, and Thomas Basset, 1669).
[3] Ibid, p. 11.
[4] Ibid.
[5] Ibid, p. 58.
[6] Ibid, p. 212-213.
[7] Ibid, p.252. Jupiter in parvo quum cerneret æthera vitro [When Jove a heav’n of small glass did behold,] see Henry Vaughan: Silex scintillan, Hermetical physick, Thalia redivava, Translations, Pious thoughts and ejaculations. (Oxford: Clarendon Press, 1914) v. 2, p.635.
[8] Ibid, p. 271.
[9] Ibid, p 182.
[10] Ibid, p. 280-281.
[11] Ibid, p.204.
[12] For example warring states beads in China, see
[13] Carla Klehm has a nice post on the subject of trade beads used around the Indian Ocean; see “Trade Tales and Tiny Trails: Glass Beads in the Kalahari Desert” in The Appendix, Jan. 2014, v. 2, n. 1.

Monday, January 11, 2021

What Goes Around Comes Around


The German city of Ulm in the 16th century
Georg Braun, Franz Hogenberg 1570-78
(Click image to enlarge.)
In the spring and summer of 1525, peasants and farmers throughout German speaking Europe staged a popular revolt now called the Deutscher Bauernkrieg. [1] At the heart of the matter was an oppressive system of taxation run by the Roman Catholic Church, in which little or none of the revenue was used to improve life locally. Often, action was lead by Protestant clergy, but to little effect against the mercenary armies hired by the aristocracy. In the end, up to 100,000 of the poorly armed and organized peasants were slaughtered.

Along the banks of the Danube River in southern Germany lies the ancient city of Ulm. Besides being the birthplace of Albert Einstein, Ulm was, in the sixteenth century, near the center of the Peasant’s Revolt, which brings us to a curious story which traces the migration of a technical recipe from Ulm over the alps to Venice, then to Sienna and finally Florence. The recipe is for the metal alloy to make mirrors, and it is told from one friend to another while chatting amiably in Venice.
Among other things, he said that he had made one [concave mirror] almost half a braccio across [about 13 inches], which extended the clear rays of its brightness more than a quarter of a German league when he caught the sun with it. One day, when for amusement he was standing in a window to watch a review of armed men in the city of Ulm, he bore with the sphere of his mirror for a quarter of an hour on the back of the shoulder armor of one of those soldiers. This not only caused so much heat that it became almost unbearable to the soldier, but it inflamed so that it kindled his jacket  underneath and burned it for him, cooking his flesh to his very great torment. Since he did not understand who caused this, he said that God had miraculously sent that fire on him for his great sins. [2]
The story was told to Vannoccio Biringuccio, who recalls it in 1540 in his Pirotechnia, the first printed book devoted to metallurgy. Specifically, the recipe is a variant of what today we would call white bronze, which as Biringuccio states is similar to the metal used to cast bells. He recites ancient formulations that used three parts copper and one part tin. To this was added 1/18th part of antimony and optionally 1/24th part of fine silver to give it a neutral color. Indeed, other ancient formulations for what was known as speculum metal specify a 3:1 ratio of copper to tin. He continues,
But nowadays most of the masters who make them take three parts of tin and one of copper, and melt these together. When they are melted, for every pound of this material, they throw in one ounce of tartar and half an ounce of powdered arsenic, and let them fume and melt and incorporate well. 
Biringuccio’s version reverses the copper and tin ratio from the classical composition. Compare it with Antonio Neri’s prescription which appears half a century later, it is almost identical:
Have 3 lbs of well-purified tin, and 1 lb of copper also purified. Melt these two metals, first the copper, then the tin. When they fuse thoroughly, throw onto them 6 oz of just singed red wine tartar, and 1½ oz of saltpeter, then ¼ oz of alum, and 2 oz of arsenic. Leave these all to vaporize, and then cast [the metal] into the form of a sphere. You will have good material, which when you burnish and polish, will look most fine. This mixture is called acciaio and is used to make spherical mirrors.
To be clear, the tartar, saltpeter and alum act as a surface flux - they form a layer that floats on the liquid metal, preventing oxides from forming, which can foul the melt.  their addition does not change the base alloy composition.

The similarity of the two recipes alone is not enough to draw any conclusions. Biringuccio himself reports that the contemporary artisans favored the tin rich formulation. However, there are other details to consider. The Sienese born Biringuccio was something of a hero in Florence where Antonio Neri was raised. The famous metallurgist helped cast cannons, mortars and guns for the Florentines to defend themselves in the late 1520s, when the city was under siege, just a few years after Biringuccio’s conversation in Venice with his German friend from Ulm.

Neri was definitely familiar with Biringuccio’s book Pirotechnia. In fact, the introduction to Neri’s own book L’Arte Vetraria is patterned after the metallurgist’s survey of glassmaking.  In his chapter 14, book 2 Biringuccio wrote:
… it [glass] is one of the effects and real fruits of the art of fire, because every product found in the interior of the earth is either stone, metal, or one of the semi-minerals.  Glass is seen to resemble all of them, although in all respects it depends on art. [3]
And here is the opening to Neri’s introduction a half century later in 1612,
Without a doubt, glass is a true fruit of the art of fire, as it can so closely resemble all kinds of rocks and minerals, yet it is a compound, and made by art. [4]
Both passages go on to cover much of the same ground, albeit with a change in focus reflective of new thinking about chemistry and nature. In one sense, Neri is paying homage to his distinguished predecessor, and there can be little doubt that he read Biringuccio’s book and its technical recipes closely. 

Lastly, the story of the burning mirror itself mimics a widely known story about the Greek polymath Archimedes. About 200 BCE during the siege of Syracuse, he is said to have set invading Roman ships on fire with a concave mirror, which focused the radiation of the sun.

In fact a depiction of this scene was painted in Florence on the walls of the Uffizi Palace in 1600, when Neri was at the height of his employment for the ruling Medici family. This particular rendering would have been all but impossible for him to miss. 

Uffizi Gallery, Florence, Italy, Wall painting
showing the Greek mathematician Archimedes' mirror 
being used to burn Roman military ships. 
Painted in 1600 by Giulio Parigi.
In the years leading to the publication of Neri’s book, he left his home in Florence and traveled to visit a friend in Antwerp. If he had read the book on metallurgy early, perhaps as part of his education, then he was already familiar with the mirror alloy recipe. If he followed the route suggested by his friend, he would have taken the recipe back to Venice, and then over the Alps and likely through Ulm on his way north to the Low Countries, where he would spend the next seven years before returning to Italy. [5]

[1] For more on the German peasant wars of 1524-25 see
[2] Vannoccio Biringuccio, Pirotechnia. Ed., Tr. Cyril Stanley Smith, Martha Teach Gnudi (New York: Basic Books, 1959), pp. 385-390. (Original Italian published in 1540.)
[3] Antonio Neri, L’Arte Vetraria (Florence: Giunti, 1612). p. iv.
[4] Ibid,  p.126 (in original, ff.41r-44v).
[5] Special thanks to Jamie Hall (@PrimitiveMethod) for inspiring this post.

Friday, January 8, 2021

Reflections on the Mirror


Jan van Eyck
The Arnolfini Portrait (1434)
L’Arte Vetraria, Antonio Neri's 1612 book, would eventually become the glassmakers' bible throughout Europe. By 1900 it had been translated into five different languages besides the original Italian; English, Latin, German, French, and Spanish (and in this century Japanese). Because of its seminal importance in the spread of glass technology, often overlooked are a few recipes at the back of the book, which have only a tenuous connection to the main subject.

Among these is a metallurgical formula for making convex mirrors. Neri gives instructions for producing what we would now call a "white bronze" that may be cast into a rounded form and polished to take on a highly reflective surface finish. This "spherical" form of mirror was popular throughout the Renaissance. It reflected a wide-angle view of the space in which it was hung, but at the cost of distorting the image. Nevertheless, upon looking into such a mirror, objects are still quite recognizable. 

Here is Neri's prescription:
A Mixture to Make [Mirror] Spheres:
Have 3 lbs of well-purified tin, and 1 lb of copper also purified. Melt these two metals, first the copper, then the tin. When they fuse thoroughly, throw onto them 6 oz of just singed red wine tartar, and 1½ oz of saltpeter, then ¼ oz of alum, and 2 oz of arsenic. Leave these all to vaporize, and then cast [the metal] into the form of a sphere. You will have good material, which when you burnish and polish, will look most fine. This mixture is called acciaio and is used to make spherical mirrors.
Of note is the fact that the word Neri uses for this alloy, acciaio, translates to "steel." Over the intervening four centuries, the meaning of this term has been refined so that today it denotes not simply a hard white metal, but a specific range of alloys containing iron and carbon, which Neri's alloy does not. 

This recipe and a few others in the book show the breadth of Neri's experience in arts other than glassmaking. It is a conclusion greatly amplified by a perusal of his other manuscripts on alchemy and medicine. There is good evidence that our priest was a voracious reader, however he was also quite cautious about repeating techniques only after he had verified them personally. Besides, artisans never wrote down much of this knowledge – only passed in confidence between trusted parties – since, in a very concrete way, superior knowledge represented a competitive advantage over ones rivals. Even if Neri was in the business of divulging secrets, it is safe to assume that many of the artisans and craftsmen he interacted with were decidedly not. Apparently, Neri was not familiar with the process of mirroring glass directly with mercury/tin amalgam; a process for which Venetian glassmakers had already become famous for perfecting. It is an interesting omission from his book, since he almost certainly would have seen examples in Florence and in Antwerp.

Two centuries before Neri, the beginning of the fifteenth century saw the invention of moveable type printing in Germany, but also the mastery of perspective illustration in Italy. The contribution of printing to early modern science is well documented, less obvious is the role playerd by artists and perspective illustration. Moveable type made possible the mass production of books; what did get committed to paper now stood a much better chance of survival and transmission. Perspective illustration played a more nuanced role, one that ultimately brings the convex mirror back into the discussion.
Jan van Eyck
The Arnolfini Portrait (detail).

In Venice and especially in Florence (Neri's hometown), perspective drawing became the rage among artists, largely due to the Italian translation of a book entitled Deli Aspecti, or "Alhazen's Book of Optics." Suddenly, paintings were made to look three-dimensional, with a realistic sense of depth to them. The new techniques were largely kept in Italy, but interest spread across Europe. Patrons placed great value on work depicting scenes in correct perspective, and in excruciatingly accurate detail. 

In Flanders, in 1434, Jan van Eyck produced "The Arnolfini Portrait," (above). Behind the main subjects, hanging on the wall is a convex mirror. The reflection in the mirror shows the backs of the two subjects, but also two other figures further back, one of which is thought to be the artist himself, and beyond him a strong light source. The image in the mirror is distorted exactly as one would experience in real life. 

There is growing speculation that among the secrets of "realist" (or naturalist) painters was a growing arsenal of optical tools and lenses used to map out and understand the attributes of perspective. The mirror, in the Arnolfini Portrait was a sort of boast of the artist's proficiency in recreating reality on the canvas.

The point is that here is a case where art led science into new realms. Painters started to take great pains in reproducing reality "as it is" on canvas. Soon minor experimenters like Neri and major luminaries like Galileo were taking great pains to do the same. They strove to observe nature "as it is," not as was prescribed in ancient texts, or dictated by authority. Once that process started, awareness of the world grew and there was no turning back.

Finally, it is amusing to note that in his many manuscript illustrations, Antonio Neri himself never quite mastered perspective drawing, although he did try.

* This post first appeared here 17 January 2014.

Wednesday, January 6, 2021

A Band of Alchemists


"The Alchemist" 1558, Pieter Brugle the Elder.
Mention the word 'alchemist' and the images that spring to mind are likely the same ones that have been around for centuries. Perhaps you will imagine something like Pieter Brugle’s 1558 depiction; a fool, whose head is filled with fantasies of conjuring gold. He spends all his earnings on exotic chemicals while his children go shoe-less, the cupboard goes bare and his family starves. No? Then perhaps a more classical rendition; a white bearded mystic stirring a cauldron in a deserted castle, summoning unearthly forces, bending the will of nature.    

It is true that outlandish characters like these have existed, but as a fringe element at best.  For every secluded wizard or "get rich quick" schemer there were many more alchemists who lived otherwise unremarkable lives and went to work every day. They interacted with colleagues and used their knowledge to provide valuable services like making painter's pigments or medicines or refining metals. Seventeenth century glassmaker and Catholic priest Antonio Neri fell into the latter category. Another departure from the typical caricature of alchemy is that it was very much a plural endeavor; it was practiced not primarily in isolation but by well connected networks of people, at least in late sixteenth century Florence.
Anibal and Martin
Neri's "Tesoro del Mondo" 1598-1699

Neri's father was the chief physician to the grand duke of Tuscany, and as such probably had something to do with Antonio's education and with the position that he landed in Florence at the renowned "Casino di San Marco," the laboratory of Medici prince Don Antonio, inherited from his father grand duke Francesco. Even before his prestigious appointment, Neri wrote an illustrated manuscript in which he shows a number of young men and some women his own age working at the business of alchemy. A few of them are identified by name and must have been Antonio’s friends: Anibal, Martin, Hiroem and Pietro. [1] 
Female alchemist depicted in Neri's
"Tesoro del Mondo"

The female alchemists depicted in the manuscript are not specifically identified, but a strong possibility is that they were nuns from one of the nearby convents. These facilities often maintained their own pharmacies and ran cottage industries that produced and sold goods to raise funds. Alchemy practiced by women is an area of study which still needs much research, but it is known that convents used alchemical techniques to distill their own medicinal remedies and produced their own paint pigments. The famous painter Suor Plautilla Nelli resided in the Dominican convent across the street from the Medici's Casino laboratory. Sculptor Suor Caterina Eletta was a nun at the same convent around Neri's time and was the daughter of Stefano Rosselli, the royal apothecary, another profession steeped in alchemy. Her uncle Fra Anselmo ran the Dominican's apothecary at San Marco, literally a few steps from the laboratory's front door. Suor Caterina was surrounded by relatives deeply involved in alchemy, how could she not be familiar with the subject?

At Don Antonio's laboratory, the Casino di San Marco, or the Royal Foundry as it also became known, Neri worked closely with Agnolo della Casa, another Florentine of the same age. In fact, all three men, Neri, Della Casa and Don Antonio were all born within a year of each other around 1576. Della Casa took notes on Antonio Neri's experiments in Florence over a period that spanned more than a decade. He filled literally thousands of pages. Much of this material is devoted to transmutation and the philosophers stone, both were subjects dear to Don Antonio de' Medici, their boss. The notebooks also indicate a lively correspondence with other chemical experimenters around Italy and wider Europe. Neri himself carried on a correspondence with his friend Emmanuel Ximenes who lived in Antwerp, a city that would become Antonio's home for seven years. 

The network of alchemy in Florence reached outwards to other experimenters and it also reached forward in time. Knowledge was passed from one generation to the next by schooling children in the art. From another branch of Della Casa's family came two brothers, Ottavio (1596) and Jacinto (Giacinto) Talducci della Casa (1601).  As youngsters they were said to have learned alchemy at the knee of Don Antonio. A century later, historian Giovanni Targioni-Tozzetti chronicled that these boys would go on to serve Grand Duke Ferdinando II de' Medici  and continue the work by directing the Real Fonderia when, after Don Antonio's death, it was moved from the Casino to the Boboli Gardens. Ottavio would become director of the Royal Foundry. [2]  
Jacinto Talducci Della Casa

Jacinto became a parish priest a few kilometers east of Florence, but he was pressed back into service as an alchemist after his brother died. He succeeded Ottavio as director of the Royal Foundry under Francesco Redi. Little is known about Jacinto's contributions to chemistry, but it must have been a remarkable life. He saw the germ of experimentalism really take hold; it would continue to grow and become the basis of our own modern science. Jacinto died in 1700 at the age of 99, he was the last surviving member of Don Antonio's band of alchemists and quite likely the last living soul to have personally met Antonio Neri.

[1] Neri 1598-1600, ff. 22r, 23r, 24r.
[2] Targioni-Tozzetti 1780, p. 127. Don Antonio de' Medici died in 1621.
* This post first appeared here on 26 September 2014.

Monday, January 4, 2021

Art and Science


Jacopo Ligozzi,1518,  fanciful glass vessels,
ink and watercolor on paper.
Antonio Neri's writing on glassmaking and alchemy was distinguished from that of many contemporary authors in that his work was all deeply rooted in hands-on experience. He worked in the early 17th century, when art and science were different sides of the same endeavor to understand the world. His contemporaries were often content to repeat century's old teachings about the four Aristotelian elements; that chemical interactions could be explained through an analysis of the balance between hot and cold, dry and wet. But more and more, these notions were being discarded and replaced. It is common to cite the invention of instruments, and other technical developments; these factors certainly did contribute to advancement. But many different forces worked toward the emergence of early modern science, and one in particular is so obvious that it is easily overlooked: artists.

Working with hot glass was a profession in which attention to nature was essential: artists did not have the luxury of fanciful explanations of physical processes. They were obliged by their work to learn the ways glass mixed, moved and behaved in the furnace, not as they imagined it should, but as it actually did. The only way to achieve the complex forms and vessels for which master glassblowers were renowned was through long experience. Failure to understand the glass and predict its properties accurately resulted in failure of the piece.

Neri was immersed in this environment and the same principles applied to his own work in formulating the glass. Ancient theories had little value if they did not accurately predict nature. Like the glass artists, the way forward for Neri was careful attention and hands-on experience. He learned the value of starting with highly purified ingredients for his glass melts. He learned that too much glass salt resulted in a putrid 'gall' that would need to be skimmed off the molten surface. Substituting salts made from fern plants, for the Kali based ones from the Levant, produced a more lustrous glass, yet it stiffened more quickly for the glassblowers.

A glass artist's work also serves as a kind of narrative. For those familiar with the techniques, a finished piece of glass work can be 'read' like a story: The handles were put on last, before that, perhaps a thin bead of color was applied to the lip of the vessel. And the work started as a blown bubble of glass, shaped and opened with special tools. Each step is an insight into the artist's technique, but also into the way nature itself operates. Each motion was a well practiced negotiation between the artist and the properties of the material.

On one hand, an artist's job was to produce objects contemplated for their physical beauty and cultural significance. On the other hand, the act of producing these objects created an environment where accurate reasoning flourished. By collecting artists and employing them together, the Medici rulers of Tuscany were creating a cauldron effect where experiences collected, stewed and nature's secrets unraveled.

* This post first appeared here on 23 October 2013.