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 31, 2020

Glass Pearls

Johannes Vermeer
"Girl with a pearl earring" (1665-6)
Natural pearls, found inside various seashells, have been prized and worn as jewelry since antiquity. The pearl is formed as a secretion of the mollusk; it is the animal's response to an irritant, perhaps a sharp grain of sand, which has become lodged in its tissue. The secretion, called "nacre" is the same material from which the mollusk builds and enlarges its shell. Natural pearls are rare; large, well formed ones are even more so. A famous legend claims that Cleopatra used pearls to win a bet with Marc Antony: that she could spend ten million sesterces on a single meal. She literally drank pearls that had been ground up and dissolved in wine. Because of the difficulty in obtaining pearls, and their high demand among the wealthy, it is not surprising that like artificial gems, artificial pearls have enjoyed a brisk trade throughout history.

In Antonio Neri's era, the early seventeenth century, a number of recipes used glue, egg whites or other organic materials to simulate pearls. These had the obvious disadvantage of being susceptible to degradation by moisture and physical handling. Another alternative was to simulate pearls with glass, and on this count, Neri does not disappoint. Recipe number sixty in his 1612 book L'Arte Vetraria gives his prescription for artificial pearls. Here it is in its entirety:



In fused and clarified cristallo, add three or four portions of tartar from wine dregs. You must thoroughly calcine this tartar to a white color. Stir it thoroughly into the glass, and continue to add more tartar, also well calcined until it is white. Add four to six more portions, always stirring the glass thoroughly, continuing thus until the cristallo takes on a pearl color. In this recipe, I cannot give exact rules, because it is a matter of experience, which is gained through experimentation. Once obtained, you must work the color quickly, because it will dissipate. I have practiced and experimented with this method many times.

"Cristallo" is the exceptionally clear glass the Venetians developed, perfected and were renowned for throughout Europe. "Tartar" is a crystalline growth that forms on the inside of wine casks, what we now know as "cream of tartar." Occasionally, one might spot crystals at the bottom of bottles of wine. They are a rich source of potassium. Neri, the Venetians and others had used tartar as a glass flux over a period of centuries. Here, however, he is not using it as a flux, but as a colorant to give the glass the pearl's shimmering appearance. His claim to making many batches of this glass implies large numbers of artificial pearls were in circulation. Our glassmaker presents a second recipe, which does not make any mention of pearls, but oddly may have much more to do with the evolution of reproducing these treasures of the sea. Recipe number 114 is entitled "The Way to Tint Glass Balls, and Others Vessels of Clear Glass, From the Inside, In All Kinds of Colors, So They Will Imitate Natural Stones." Here, Neri spreads fish-glue on the inside surface of a blown globe of clear glass, followed by various pigments.

Even in his time, artificial pearls found their way into royal courts and onto the canvasses of master painters. The fashion-setting monarchs of France and Britain Catherine de' Medici and Elizabeth I were famous for their extravagant love of pearls. Elizabeth famously purchased faux pearls from Venetian glassmakers to adorn her garments. She commissioned many portraits donning her pearl studded creations. Referring to the famous painting by Johannes Vermeer, Lloyd Schwartz recently observed, "[T]he scholarship on Girl with a Pearl Earring reveals that the pearl isn't really a pearl […] the famous pearl is probably just glass painted to look like a pearl."* It is interesting to note that Vermeer's famous painting was executed in 1665-6, within five years after three reprints of Neri’s book, two in Italian one in English, and only a couple of years before a Latin edition printed in Vermeer's own country.

Around 1680, a Parisian maker of rosary beads invented a type of artificial pearl consisting of a small hollow glass bead, painted on the inside with the iridescent discharge of fish scales mixed with glue. He then filled the beads with wax. Jacquin had apparently rediscovered the shimmering pearly residue of a specific fish. His innovation fueled a new industry; he called the precious pigment "essence d'orient." But the material had already been employed in eastern France in 1656 and according to other reports as early as the reign of Henry IV of France (1572–1610), which closely coincides with Antonio Neri's own lifetime. By 1716, scientists were investigating essence d'orient under a microscope. Rene Antoine Ferchault de Reaumur reported tiny, perfectly formed rectangular plates that reflect the light to cause the shimmering.**

Perhaps more interesting than who discovered what, is the exchange of ideas and the overlap of interest between an Italian alchemist, a British queen, a Dutch painter, a French jeweler and a biologist.


* Also see Anthony Bailey, A View of Delft: Vermeer Then and Now (London: Chatto & Windus, 2001), p. 123, 124.
** For an English summary see The Edinburgh Philosophical Journal October 1839-April 1840 (Edinburgh: Adam & Charles Black, 1840), v. 28, p. 114, 115.

Wednesday, January 29, 2020

Lakes of Flowers

'The Miracle of the Immobility of Santa Lucia'
Leandro Bassano, painted using Florentine lakes.
In the final part of Antonio Neri's 1612 book on glassmaking, [1] he presents several recipes that are devoted to pigments for painting. His intention for including them is for their application on glass objects, but these were the same materials used in general by fine artists in the early seventeenth century. 

In his recipe #110, the Florentine priest gives a wonderfully simple method to extract the color from common flowers. The term for these pigments is "lakes." Once obtained, the pigments were often used to dye a powdered carrier material in order to give them more body and behave like other paint. From there they might be mixed into egg-tempera, varnish or oil depending on the application. It is likely that Neri used similar pigments for the illustrations in his 1598 manuscript.[2] Here is his recipe in its entirety: 


A Way to Extract the Lake [3] and Color for Painting, from Orange Blossoms, Red Poppies, Blue Irises, Ordinary Violets, Red Violets, Carnations, Red Roses, Borage Flowers, Day Lilies, Irises, and From Flowers of Any Desired Color and the Greens of the Mallow, the Pimpernel and All the Plants. 
Take whichever flower you want, of any color you want, or even a [green] plant. If it will rub green from a leaf onto white paper staining it with color, then it will be good. The plants and flowers that do not show this effect are no-good. Put ordinary aqua vitae into a glass urinal, with a cappello [alembic cap] for its cover, making sure the said crystallo cap is as wide as possible. 
Into this cap, pack the leaves [or petals] of any flower or plant from which you want to release and extract the tincture. Now lute the mouth joint of the cap. Fit a receiver to its snout and lute that joint. Give it a moderated fire so that the volatile part [alcohol] of the aqua vitae rises into the alembic, and falls down into its volume upon the petals of the flowers, extracting the tincture. 
In time, drops will run down the snout of the cap into the receiver, colored and charged with the tincture. Once all of the volatile part of the aqua vitae passes and becomes colored, distill this colored volatile part of the aqua vitae in a glass vessel. [The alcohol] will pass white and will be useable three more times. The dye will remain in the bottom, which you should not allow to dry too much, but just moderately. Then you will have the very best tincture or lake for painting from an abundance of flowers and plants.

The "aqua vitae" he refers to is simply a distilled alcohol such as grappa. The important point here is that it is a potent solution of ethanol and water; a well-known modern equivalent would be vodka. The chemical apparatus he describes is about as simple as it got for alchemists. It has three parts; the first is a base consisting of (in this case) a urinal—an inexpensive and convenient glass container with a wide mouth. The second piece is what Neri calls a "cappello"; it is a special glass cap featuring a long tubular snout leading from the top, angled slightly downward. When the cap is affixed to the base with the materials inside and gently heated, vapor will condense in the cap and run down the snout for collection in the third piece, a "receiver" vessel. 

The material he uses to seal the pieces together was called "lute," a mixture of mud, cloth fibers, egg and some other materials that stick to the glass and withstand the heat of the fire. Its only purpose was to keep the glassware sealed until the procedure was complete. [4] 

In the mid nineteenth century, Mary Merrifield made an extensive survey of Italian manuscripts with recipes for artists. She included this comment about Neri's home town:
Florentine lake must have had considerable reputation in Venice, since Leandro Bassano contracted to employ it in his picture of the 'Combat of the Angles,' painted for the church of S. Giorgio Maggiore at Venice in 1597. [5]
Today, this painting is known as 'The Miracle of the immobility of Santa Lucia' and is shown at the top of this post.

[1] L'Arte Vetraria, Neri 1612.
[2] Discorso, Neri 1598-1600.
[3] Neri uses the word "lacca," the equivalent of "lacha" in other manuscripts. For a specific reference to Neri in this regard, see Merrifield 1849, v. 1, p. clxxxi.
[4] A word to the wise: high proof alcohol in a confined glass container near an open flame is a good way to cause a minor explosion and a fireball featuring glass shrapnel.
[5] Merrifield 1849, v.1, p. clxxxiii. She references Cicogna  1824–1858, v. 4, p. 349 for this information. 
* This post first appeared here on 14 Oct 2014.

Monday, January 27, 2020

Neri's Other Ruby Glass

Rhodochrosite, from the Sweet Home Mine, Colorado.
Antonio Neri is widely recognized for publishing a recipe for the coveted and difficult gold ruby glass. "Rubino," as it is sometimes called, achieves a deep ruby red color utilizing only powdered metallic gold as a colorant. Perhaps because of the notoriety of that prescription, Neri’s other transparent red glass is hardly known. His recipe #120 describes a deep red pigment based on manganese. Today manganese takes its place on the periodic table as an elemental metal, but in the early seventeenth century it had not been isolated from its mineral ore. What Neri calls manganese was actually its oxide, which occurs as a black powdery material. Its effects in glass have been known since the early Egyptian dynasties and before that, as a pottery glaze. By itself the oxide produces a tint often likened to violet or amethyst. In small quantities, it is used to neutralize the slight green tint introduced by iron impurities in clear glass. 

To make his ruby red pigment, Neri starts with high quality manganese oxide from Piedmont and processes it through several alchemical operations. I will not be delving into the chemistry in detail here, suffice it to say that he comes close to synthesizing a highly unstable explosive, the likes of which was not "discovered" for another two centuries. It is a striking illustration of how technical ability can be in place long before theory catches up, in this case thankfully so. 

The pigment he did succeed in making is for now a mystery. Manganese carbonate, which can form ruby red crystals might fit the bill, except that it decomposes at the temperatures of molten glass. It occurs in nature as the mineral rhodochrosite as seen above. [1] Below is Neri's recipe for "Transparent Red in Glass" from his 1612 book L’Arte Vetraria. Most of the terminology is straightforward, with the exception of a few terms. 'Porphyry' is a hard granite used for grinding stones. 'Reverberation' is indirect radiation in a furnace, where the heat is reflected from the walls. 'Sublimation' is when certain materials vaporize directly from a solid form and recondense without passing through a liquid phase.
Grind manganese impalpably, then mix it with an equal amount of refined saltpeter and put it into a clay pan set to the fire, reverberating and calcining it for 24 hours. Take it then and wash its saltiness away with warm common water. Once separated from the salt, let it dry. It will be a ruby-red color. With this, mix an equal weight of sal ammoniac and grind them together over porphyry stone with distilled vinegar, which they will soak up. Leave this alone to dry and then put it in a retort with a wide body and a long neck. Heat it in sand for 12 hours to sublimate. 
Then break up the glass. Take all the deposits in the neck and body of the retort and mix it with the residual remains in the bottom. Weigh it and combine it all with as much sal ammoniac as was lost in the first sublimation. Grind everything together over the porphyry stone, with distilled vinegar for it to soak up. Then put it in a retort to sublimate as above. Repeat this sublimation, in this manner, many times until in the end, the manganese will all remain fusible in the bottom. 
This is the medicine that tints crystal and pastes in a diaphanous red color and a ruby red as well. Use 20 oz of this medicine per ounce of cristallo or glass, but more or less may be used accordingly to govern the color. The manganese should be the very best from Piedmont, so that it will have the effect of tinting the glass a beautiful ruby color and be a sight of wonderment.
[1] Manganese carbonate, MnCO3.

Friday, January 24, 2020

Descendants of an Alchemist

Ecce Homo by Titian, circa 1570-1576
Antonio Neri was the son of a royal physician and the grandson of a well respected barber-surgeon. At the turn of the seventeenth century he pursued a career as a priest in the Catholic Church, but with the rare distinction of alchemy as his specialty. He is best remembered for his book on glassmaking, but he also wrote on the subjects of chemistry and medicine; an area of study that his family had embraced and would continue to practice  for several generations. 

According to Florentine genealogy records, Antonio's mother died in 1594, at the age of 42. She had given birth to ten children; Alessandro was the youngest, born in 1587. The same year as her death, the family would loose, Antonio's grandfather Jacopo, the barber surgeon. He had moved the family back to Florence after the turbulent 1520s; the years of what would be the final attempt to re-establish a self governing republic.  In 1598, just as Antonio finished seminary his father died leaving his ten children orphaned. A year later fifteen year old Emilio died on Christmas day.  Details of how the family survived this series of calamities may never be known, but in the end it was the youngest child, Alessandro who inherited the family house and fortune. Only eleven years old at the time of his father's death, an administrator was appointed by the court to oversee his and his siblings interests until they were of age. By all indications, the Neri children were well cared for; the list of godparents reads like a who's-who of the Florentine elite, including wealthy bankers, lawyers, senators and curia officials at the Vatican.

Alessandro would become the royal physician’s main heir. We might expect this honor to fall to the eldest son, and how the youngest of the seven brothers could end up in this position is a matter ripe for conjecture. Antonio and perhaps Francesco were in the clergy and therefore ineligible. We can surmise that the first of the sons named Jacopo died in infancy and if the second Jacopo survived he along with Vincenzio were somehow also out of consideration. One compelling scenario passes the family inheritance to fifteen-year-old Emilio, who would also die within a year leaving the mantle to Alessandro. Not yet of legal age, the family assets would have been held in trust, perhaps by his mother’s brother, notary Agostino Parenti.

Future research will likely uncover more details about the family after Antonio's death in 1614, however, a nice outline is already in place. In 1620, Alessandro inherited a second house from his uncle Agostino. It was located outside the city walls in a wealthy neighborhood, just to the southeast of Florence. It was along the old road called Via del Ponte a Ema.

In a 1630 court case in Rome, Orazio Morandi, abbot general of the Vallombrosans gave testimony. One  incidental remark he made indicates he was a Neri family friend; he told prosecutors that when he lived in Florence he often saw fellow astrologer Simon Carlo Rondinelli at the home of Alessandro de’ Neri. [1]

Although the exact date is not clear, Alessandro would marry Caterina di Becci and have three children; Neri, Dianora and Filippo. We can speculate, the first two were named after their grandparents, and the third after distant cousin Saint Philip Neri, canonized in 1622. Dianora was married to Ottaviano Buonaccorsi and had a son named Alessandro.

The bloodline would continue for another generation through Alessandro's son Neri, who would enroll in the medical program at Pisa and become a physician in his own right, taking a degree in 1646, where his diploma is still on file. [2] He in turn would marry Margherita Scalandroni who gave birth to Ottaviano. Alessandro, Francesco and Caterina.

At the end of the seventeenth century, historian Giovanni Cinelli wrote about our glassmaker’s nephew, who at the time had been practicing medicine for twenty years:
Succeeding M. Neri Neri, is a grandson [Neri di Alessandro], alive today, [1677] a man of good taste, who is delighted by pictures and sculpture, who has imitated his grandfather Neri, by [collecting] many paintings and gallant statues by talented artists. Two small bronze horses by Giambologna, many works of [Simone] Pignoni and others, among which are two marvelous holdings; a waist-up Ecce Homo by Titian and a Satyr of beautiful ancient bronze which is wonderfully captivating; it is of the Greek manner and expresses an attitude of prompt movement that recalls liveliness, the muscles are very well prepared. Finally, a statue of Cupid flanked in marble in the best Greek style. [3]
The elder Alessandro’s daughter, Dianora, would marry Ottaviano di Camillo Buonaccorsi, who gave birth to seven children. Her son named Francesco would marry into the Medici Family, coupling with Aurelia de’ Medici, daughter of Luigi di Francesco.

In 1768, historian Domenico Maria Manni wrote about the family. [4] In a short pamphlet about ancient Christian tombstones, he reports on the lineage of his patron, Girolamo Neri, a Camaldolese abbot. It traces the family back through two centuries, back to our doctor Neri Neri and to Antonio the glassmaker. Manni connects Girolamo to the family through the elder Antonio, the brother of Jacopo Neri, the barber surgeon.

Although further work is needed, all indications are that our glassmaker’s branch of the family died out by the end of the eighteenth century. [5] The family arms do not appear in use again, nor is there any evidence of a Neri tracing his heritage to the noble family of physicians. It seems finality is provided by Manni. He references a court judgment which awarded inheritance of the property of the extinct branch to Girolamo Neri’s kin. 


[1] Dooley 2002, p. 32. Dooley states that Alessandro is not related to Antonio Neri, but I feel otherwise; the name, timing, and circumstances are a perfect fit. His conclusion may be based on the scant family history available to him. Cf. ASR 1630.
[2] Mazzatinti 1917, p. 44, n. 549.
[3] Cinelli 1677. 
[4] Domenico Maria Manni, a member of the Messina scientific society known as the Accademia Pericolante. Manni was a prolific historian, although has on occasion been accused of careless work. For instance, he misidentifies Antonio’s mother as ‘Dianora di Ser Agostino di Ser Francesco Parenti’ Manni 1763, p. i-vi.
[5] Mecatti 1754, p. 77; Manni 1763, p. v.
*This post first appeared here on  29 Oct 2014.

Wednesday, January 22, 2020

The Purse of Envy

Antonio Neri, "The Mineral Gold" Tesoro del Mondo,
(MS Ferguson 67, GB 0247,
Glasgow University Library, Special Collections,
1598-1600), f. 5r.
As a young alchemist, Antonio Neri faced a decision that had confronted virtually all accomplished artisans since the dawn of time and continues to do so today; whether or not to freely share hard-won technical knowledge with others. The indications are that Neri's thinking on the subject evolved over his lifetime. Testimony given by Florentine metals refiner Guido Melani indicate that as a twenty-year-old, Neri was willing to share his most precious secrets, albeit reluctantly.

Melani reported that in July 1596, Neri performed a transmutation of base metal into "twenty-four carat" gold. Upon being pressed, Neri confided that he had learned the secret from a German, who performed the gold transmutation with a "tablet of medicine." The German told him the medicine was nothing but the simple quintessence of green vitriol and the method to produce it was described by Paracelsus.[1] (In reality, an ion exchange reaction that we now know takes up iron and deposits copper in its place).

The motivations for keeping techniques secret are obvious; potential monetary reward and personal prestige. Aside from the immediate gratitude of confidants, the motivation for sharing technical secrets can be more subtle; the satisfaction of serving a greater good by advancing the art. It is indeed an ancient and very human dilemma. Five centuries before Neri, in the early 1100s a glassmaking Benedictine monk wrote on the subject. In Hesse, Germany, Theophilus Presbyter penned these lines in his De Diversis Artibus [On Various Arts]. "Do not hide His [God's] gifts in the purse of envy, nor conceal them in the storeroom of a selfish heart" and "Do not hide away the talent given to you by God, but, working and teaching openly and with humility, … faithfully reveal it to those who desire to learn."[2] Although it is doubtful that this particular writing was ever seen by Neri, his access to the most extensive libraries in Italy, along with his knowledge of Latin and the writings of other alchemists ensured a comprehensive understanding of his subject and the politics surrounding it.

Two centuries after Neri's death, historian Francesco Inghirami published details of an incident, which if true, might have contributed to a change of heart with our priest:
He [Neri] claimed he had found the secret of making the famous philosopher's stone and it was said he had discovered it among some of his confidants.  Some thugs learnt of this and attacked him at night, in order to obtain the secret by force. He shrewdly gave them a certain recipe he had in his pocket and explained the figures written on it, claiming it to be the secret oil required. But that night, Neri left Florence and traveled to various parts of Europe.[3]
Nevertheless, in his travels to Antwerp it is clear that Priest Neri continued to share his knowledge of glassmaking, in the shop of Filippo Gridolfi, and of course, upon his return to Florence seven years later in the publication of his famous book, L' Arte Vetraria.[4] In contrast, on the subject of transmuting gold and silver, Neri had decided to take his secrets with him to the grave, a decision that he justifies in a manuscript, Discorso, which he completed shortly before his death:
We must also consider the danger to its possessor if it became known to others and particularly to the princes. For that reason even if someone knows and practices this art, he is obliged to keep it hidden and to conceal it; and I know of what I speak.[5]
Neri outlines his fears that such a momentous discovery, if generally known could lead to abuse of power, a collapse of the monetary system, and general chaos in society. In spite of his deep reservations, we see a final glimmer of his innate desire to share. He did, in fact, leave behind his recipe for the philosopher's stone, but in coded, obscure language that has never to this day been deciphered. As he put it: "I wrote the words so strangers will not understand." 

[1]  Galluzzi 1982, p. 53; Grazzini 1983, pp. 214–216. 
[2]  For modern English translation see Theophilus 1979. 
[3]  Inghirami 1841–44, v. 13, pp. 457–458. 
[4]  Neri 1612.
[5]  Grazzini 2012, pp. 329, 356.
*This post first appeared here on 6 November 2013.

Monday, January 20, 2020

Neri and the Inquisition

Insignia of the Inquisition, 1574.
The mandate of the Catholic Church's inquisition was to stamp out heresy. Although empowered to impose sanctions that included torture and execution, such extreme measures were not imposed casually. Typically, they operated within communities as an extra layer of bureaucracy.  Nevertheless, the Holy Office of the Inquisition  was not an organization with which to trifle. In 1600, just over a decade before Antonio Neri's glassmaking book was printed, former Dominican friar Giordano Bruno was convicted of heresy and burned at the stake in Rome's Campo de' Fiori market, albeit after nearly a decade of confinement and numerous opportunities to recant. Shortly before that, the inquisition ordered Neapolitan polymath Giambattista della Porta to disband his group of scientific investigators and to cease all publication without special written permission from the Church, an order with which he readily complied. Famous French essayist Michel de Montaigne complained of having books confiscated upon entering Rome, although in Florence he was welcomed with open arms by Francesco de' Medici at the Casino di San Marco, where Antonio Neri would later work.

The Inquisition paid special attention to books and pamphlets because they carried the potential to 'corrupt' large numbers of people over a wide geographic area. In the Church's view, heresy was considered a disease of the mind, the devil's work. Books were seen to be a potential source to spread the infection, especially books from the Protestant quarters of Europe, but also from the 'misguided' notions of early scientific investigators. Antonio Neri was an alchemist with deep knowledge of materials that, to the unsophisticated, could easily be viewed as "magical" and therefore heretical.

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

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

Writing perceived to defy the Church's teaching was a serious concern for authors in Italy, even those under the protection of the liberal Medici family. Although not overtly heretical, Neri's other manuscripts could have easily fallen into this category. Thankfully for our alchemist and glassmaker, upon reading Neri's book, Vigiani stated "I have not found anything repugnant to the Christian conscience and good customs, but [a book] full of things and natural secrets, no less useful than curious." Neri's book went on to become known throughout Europe. Over the next two centuries, it was translated into English, Latin, German, French and Spanish. L'Arte Vetraria became an indispensable reference for scientific, artistic, and practical glassmakers everywhere. 

This post is based on one that originally appeared here in a slightly different form on 13 November 2013.

Friday, January 17, 2020

Pirates!

Sea fight with Barbary corsairs, c. 1581
Lorenzo Castro.
In the early seventeenth century, shipping goods and travelers around the world was big business; life on the high seas was an excellent way to find adventure, make a fortune or even become famous. On the other hand, it was also an excellent way to lose one's freedom, lose a fortune or lose one's life. International trade affected Florentine glassmaker Antonio Neri in at least two major ways; first as a consumer of exotic materials and second as a traveler. Land routes were plagued by highway robbers, corrupt officials and a host of other problems that included keeping perishables viable over long journeys, keeping pack animals in good health and navigating unreliable roads. Transport by sea promised a potentially quick journey, but at the risk of bad weather, water damage and the dreaded scourge of pirates. Aye.

In early 1604, Neri traveled to Antwerp to visit his friend Emmanuel Ximenes, who as it happens was himself an international banker; he provided the financial backing for trade expeditions to the Far East, Brazil and Africa. His extended family ran what today would be recognized as a vertically integrated corporation. The control of raw materials, to the supply chain, through to finished products was under the common management of the family. It is an open question if the Ximenes supplied Neri with materials for his work in Florence, but it is undoubtedly the case for his seven year long visit to Flanders. 

With Ximenes extensive shipping connections one might well ask why Neri did not take a boat from the Medici’s port of Livorno near Pisa, sail to one of the Spanish or Portuguese ports, where Ximenes had family and then on to Antwerp which was, after all a Spanish domain. It would be faster and one might think safer, weighed against the very real perils of violence, highway robbery and a host of other dangers when traveling by land. 

The sea route, however, was in fact far more problematic and dangerous. The Mediterranean was teeming with pirates and privateers. Privateers were state sponsored raiding parties, who commandeered the trade ships of their enemies and split their bounty with the government, often stranding the crew or selling them into slavery; it was a very lucrative enterprise, even if often short lived. Pirates, on the other hand, were independent operators, commonly they were former navy men who had lost their commission or otherwise ran afoul of their sovereigns. Basic equipment for any pirate was a chest of flags of the various nations. For any ship encountering another vessel on the high seas running under the same flag, the very first order of business was to ascertain if it was a friend as presented or a foe in disguise. An elaborate series of secret signals would follow. To complicate matters, the signals were sometimes compromised or changed without notice.  For the Spanish treasure ships returning from South America, evading pirates in the Caribbean at the start of a journey was matched by similar perils the last few days before making port in Spain. Tuscan and Venetian ships were in conflict with the Ottomans, but did conduct trade with them through intermediaries. The Dutch were undercutting Spanish deals in the Far East, while the Spanish paid cash bounties for any ship caught trading south of the equator. Meanwhile, the English were at war with the Spanish, trading with the Ottomans, but amicable with the grand duke and Tuscany.

The Barbary Coast in Tunisia, a short distance from Italy,  was a popular haven for pirates. Infamous at the time was Captain Jack Ward, [1] an Englishman who found shelter with the Ottomans through the local governor [2] to whom he paid ten percent of his bounty. Ward with his crew had converted to Islam and caused no end of grief to all European shipping. This included traders from Spain, the Netherlands, Britain, France, Tuscany and Venice. Ward had amassed a fleet of his own based on the African coast in Tunis. From here he conducted operations as far north as Ireland, running them under the Tuscan flag as well as numerous others.

Despite all these issues, for Neri, the biggest impediment by far to traveling by sea or by land was that he was heading into a war zone. Antwerp was the calm at the center of a bloody conflict that thrashed and destroyed the surrounding countryside. The Dutch fleet had blocked the city port on the Scheldt River and opposing armies clashed in a great ring around the Low Countries. This is what Emmanuel Ximenes was alluding to in his letter of December 1602 when he said “the lack of peace in these countries prevents me from recommending them for you to come or not” [3] The northern Netherlands were in the midst of a war for independence against Spain and the Holy Roman Empire.  These two superpowers of Europe were governed by the same tightly-knit Habsburg family, who at the time controlled what are now Portugal, Spain, Southern Italy and Flanders on one side of the family; Germany, Austria, Hungary and Transylvania, on the other. At the same time, the region had become a haven for formerly Jewish "New Christians" (like the Ximenes family) after their expulsion from Spain. [4] The city was blocked from sea trade by their Dutch neighbors to the north and armed confrontations with imperial troops from the south demolished surrounding towns. The conflict threatened to spill into the city for which Neri was bound.

The other way that international trade affected Neri was through the materials so necessary to glassmaking, to medicine and to his other alchemical activities. As our priest makes clear in his book, the quality of ingredients must always be tested and assayed before purchase or use. Unscrupulous merchants could and did mix or dilute expensive materials with inexpensive fillers and made unreported substitutions. The level of mistrust over imported ingredients can be better appreciated through an understanding of just how chaotic life was on the high seas. Even generally honest traders might turn to deceptive or otherwise questionable business practices when faced with the staggering losses of an entire ship and its contents. 

As the first decade of the seventeenth century unfolded, the pirating of trade ships turned into a well-organized and quite profitable occupation. Operations blanketed the entire Mediterranean and the eastern Atlantic from the Canary Islands to Ireland, which as we have seen complicated Neri’s travel arrangements in the region. Captain John (Jack) Ward was based in the Algerian and Tunisian Barbary Coast and commanded a formidable armada. Dutch born Zymen Danseker (Simon the Dancer) specialized in raiding Spanish and Portuguese trade ships. Much to Spain’s dismay, the Dutch set up outposts in India, Africa, Asia and the Americas circumventing the Habsburg’s previous monopoly.

As pirating became endemic, friction started to build between competing interests. The British and the Florentines clashed often in the Mediterranean. The grand duke employed English mercenaries to harass Turkish (Ottoman) vessels. The Ottomans were valued trading partners to the London based Levant Company. The Ottomans, upon seeing a ship manned with Englishmen, did not know whether to extend a welcome or to prepare for a fight.  Meanwhile, from his Barbary base of operations, Captain Ward continued to take British ships, strand crews and reap the rewards. All the while, he seemed to enjoy an indifferent if not outright amicable relationship with Grand Duke Ferdinando. This “understanding” developed after the sound thrashing Ward received, in 1607, at the hands of the Knights of Malta and the Knights of Saint Stephen. Once a pecking order was established with Florence, Ward did very well for himself. In June of 1608, the following description was given at court in London and then repeated to the Venetian senate through their ambassador. 
John [Jack] Ward, commonly called Captain Ward, is about 55 years of age. Very short, with little hair and that quite white; bald in front; swarthy face and beard. Speaks little and almost always swearing. Drunk from morn till night. Most prodigal and plucky. Sleeps a great deal and often on board when in port. The habits of a thorough "salt." A fool and an idiot out of his trade. [5]
This "idiot" outlived many of his detractors, evading capture and sleeping late until the ripe old age of seventy. For a man of his occupation this was a remarkable accomplishment. Reports claim he succumbed not to the sword of a British officer, but to the ravages of the plague in 1622.

[1] Jack (alias John, Birdy) Ward (c.1553–1622),Also known as Siemen Danziger, Zymen Danseker, Simon de Danser, Danziker, Dansker, Danser and later after conversion to Islam, Yusef Re’is or Reis.
[2] Uthman Bey.
[3] Ximenes 1601–11, 5 Decembre 1602.
[4] For an excellent synopsis of the historical events leading up to the 80 years war see Christman 2005.
[5] Brown 1904, (no.268 ), 23 June 1608; see also (no. 2), 6 June 1607; (no. 7), 11 June 1607; (no. 33), 21 July 1607; (no 34), 25 July 1607; (no. 112), 15 Nov 1607; (no 319), 4 September 1608.
* This post first appeared here 24 Oct 2014.

Wednesday, January 15, 2020

Top Physician

Frontispiece from Ricettario Fiorentino 1597 ed.
In 1580, when Antonio Neri was four years old, just after the birth of his brother Vincenzio, both his father and grandfather were together granted full Florentine citizenship by Grand Duke Francesco I de' Medici. In Tuscany, citizen status was an honor conferred to a small fraction of the population and often through inheritance at around the age of thirty. The fact that Neri Neri gained citizenship at the age of forty and did so together with his father, Jacopo, shows it was not legacy, but perhaps their medical prowess that lead to the award. Antonio's father was a celebrated physician, and his grandfather was a well regarded barber surgeon. This period also corresponds to the first appearance of the unique coat of arms that distinguish this branch of the family. The same arms adorn the central panel of the vestibule ceiling at the Neri's residence. Citizen status bestowed the advantage of direct representation in the government and the right to hold public office. It also carried responsibilities to the city, to its leaders and to the Church. One requirement of citizenship was possession of a domicile within Florence. The baptism register listed Antonio and all of his siblings as residents of San Pier Maggiore parish long before the citizenship grant. However, it is in the 1580s that we see the first reference to Neri Neri's ownership of the palazzo at what is now 27 Borgo Pinti. 

Within a few years, Antonio's father's work on cures for paralysis were published. By the end of the decade he was appointed personal physician to the new grand duke, Ferdinando de' Medici, and to the royal family. The 1590's saw Antonio taking vows, and beginning his career in the Church. The road to priesthood ran on a parallel track to an apprenticeship in a trade. The completion of a trial period led to becoming a novice at the age of sixteen, then deacon and finally priest at around twenty-two. Meanwhile, Antonio's father, along with another doctor and two apothecaries was chosen by the entire Florentine College of Physicians to revise and update the famed Ricettario Fiorentino.[1] This book was the gold standard of doctors and pharmacists in Tuscany and throughout much of Europe. The Ricettario was an official reference for medicinal cures and prescriptions. The law required every apothecary to own a copy and to supply its listed formulas to customers. Many regard this volume as the first European pharmacopoeia. It was a systematic standardization of drug recipes and dosages. Throughout the Medici reign, updated editions appeared as knowledge progressed. The book is a major landmark in the history of medicine. The edition authored by Neri's father and colleagues, in 1597, proved so popular that in 1621 it was reissued without change.

There can be no doubt that Antonio's father and his work had a profound influence on the priest. In the introduction to his book on glassmaking, L'Arte Vetraria,[2] he proclaims his desire to publish his own work on chemical and medical [spagyric] arts, saying "I believe there is no greater thing in nature in the service of humanity." In his recipes he uses the terminology of physicians; adding chemicals in 'doses' and measuring 'ana' (in equal parts). In a 1608 letter to a friend, [3] Antonio describes his great success with medicinal cures of Paracelsus, "to the great wonderment of Antwerp." The priest also references experiments he carried out in Brussels and at the Hospital of Malines. Following in the footsteps of his father and grandfather, medicine would continue to be practiced in the Neri family for generations to come. 

[1] Neri, Benadù, Rosselli, Galletti 1597.
[2]Neri 1612.
[3]Neri 1608.
This post was first published here in a slightly different form on 16 October 2013.

Monday, January 13, 2020

The Neighbors

"Portrait of Giambologna"by Hendrick Goltzius
In Florence, directly across the street from the Palazzo Neri, where glassmaker Antonio Neri spent his youth (now the Marzichi-Lenzi), was the residence and workshop of famed sculptor Giambologna. This two-building compound was a 'gift' to the artist from the newly crowned Grand Duke Ferdinando de' Medici, in 1587. It was intended to settle debts incurred for the artist's work by the previous grand duke, Francesco. The dwelling, at 26 Borgo Pinti, was located on the same street that was formerly inhabited by the likes of Michelangelo, Perugino, Pontormo and Cellini.
Neri's father, the royal physician, had collected art. According to historian Giovanni Cinelli, in 1677, when Antonio Neri's nephew owned the property, among the pieces in the house were:
Two small bronze horses by Giambologna, many works of [Simone] Pignoni and others, among which are two marvelous holdings; a waist-up Ecce Homo by Titian and a Satyr of beautiful ancient bronze which is wonderfully captivating; it is of the Greek manner and expresses an attitude of prompt movement that recalls liveliness, the muscles are very well prepared. Finally, a statue of Cupid flanked in marble in the best Greek style.
Giambologna had a strong influence on Florentine art and his work was to be found throughout the city, from the courtyard of the Palazzo Vecchio, to the gardens of the Casino di San Marco, where Neri made glass. The sculptor was well known for the fine surface finishes he achieved on marble and for his ability to resolve the technical challenges of portraying multiple figures, especially those involving a complex intertwining of limbs and bodies. The Rape of the Sabine Women, completed when Neri was a boy, is considered his crowning achievement.

Giambologna was born in Douai, Flanders, now in France, as Jean Boulogne. He landed in Florence in 1553, after a period working in Rome for Pope Pius IV among others. The Medici never allowed him to leave Tuscany for fear that once out of their reach, he would be enticed to go to work for another of the European sovereigns, never to return. It is reasonable to speculate that before his own trip to Flanders in 1604, Antonio Neri offered to relay messages or other effects to the family of his seventy-five year old former neighbor. Neri spent seven years with his friend Emmanuel Ximenes in Antwerp. Before his return to Tuscany, in 1611, both Grand Duke Ferdinando and Giambologna had already gone to meet their maker.


Neri had left Florence in his twenties, and returned in his thirties to a very different city. He settled down to write the book for which he will forever be remembered, L'Arte Vetraria, the first printed book devoted to the formulation of glass.

This post first appeared here on 20 Sept. 2013.

Friday, January 10, 2020

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.

Wednesday, January 8, 2020

Filippo Sassetti

Goa, India 1509
Later distinguished as a renowned glassmaker and alchemist, Antonio Neri was born into a patrician household. In the Florentine baptism records, his entry was made on a Thursday, the first of March, 1576. He was born the previous evening, to Dianora Parenti and Neri Neri. His godmother is listed in the document as Ginevra Sassetti. Not a great amount is known about her; she was from a prominent family, at the time in her late fifties. However, there are indications that other members of her family interacted with the Neri's. Her nephew Filippo mentions Antonio's father favorably several times in letters, providing a fascinating glimpse into the way disease was diagnosed and treated.

When Antonio was born, his father Neri Neri was in his early thirties, and already a highly regarded physician. Baccio Valori was director of the famed Laurentian Library in Florence and steward of the Medici's simples (medicinal herbs) garden. He was friend to Neri Neri and godfather to Antonio's oldest sister Lessandra. Between 1583 and 1588, Valori received letters from a mutual friend, Filippo Sassetti, who was living in Goa and Cochin – trading settlements in India. Filippo was a native Florentine; he attended university in Pisa with Valori and they became lifelong friends. After Sassetti's father was forced to sell the family home to pay off a debt. Filippo moved to Lisbon and became a spice trader. Not suited for a desk job, he soon set sail seeking adventure in the orient. 

In a 1586 letter to his old friend Valori, Sassetti discusses an Indian remedy against the plague, with a substance called bezoar. The bezoar stone is a mass that develops and becomes trapped in the digestive systems of certain animals. It often resembles a smooth rock. Some thought ground bezoar to be a universal antidote to any poison. Sassetti was puzzled about how the grindings of bezoar could work to cure the plague. Its Aristotelian elemental properties would not be a match for correcting the imbalance of humors in the body. "This is a principle," he explains, taught to him by Neri Neri. "I have thought about it and I can not understand how it works, because the plague is of the same corruption and this is a lack of heat inherent in the humidity. And the stones, if I recall correctly, they have a cold and dry complexion, hence may not precede the restoration of heat. Messer Neri one time did me the favor of telling me." 

In another letter to Baccio Valori, Sassetti notes that he has collected rare varieties of cinnamon in his travels along the Malibar coast in India. His intention was to rediscover the species thought to be a powerful cure of disease by the ancients. He planned to send a parcel of seeds of these and other medicinal plants. "If it pleases God, in the coming year, I will send this to you, so that you may see it all, together with our Messer Neri Neri, who graces my memories." Later he writes that he is sending Baccio the discourse on cinnamon, which he has compiled, along with some plants. These, it later turned out, were water damaged in the journey. He had hoped for some help from Neri Neri on the question of whether the cinnamon he collected from the island of Zeilan [Ceylon], is the same thing as the curative cinnamon of Mantua described by the ancients. Valori was an authority on these matters in his own right. As librarian for the Medici's imposing collection of books and manuscripts, he had vast academic access. As keeper of the simples garden, he had first hand experience in horticulture and its derivative medicinal cures. 

The principles of "humorism" were passed down from celebrated physicians of the ancient world, like Galen, Hippocrates and Dioscorides. It was thought that the cure of disease was dependent on the restoration of balance between four substances in the body: blood, phlegm, black bile and yellow bile. In turn, each of these was associated with one of the Aristotelian elements: air, water, earth and fire respectively. Each was further associated with specific symptoms and characteristic traits of the patient, even their psychological outlook and physical complexion. This system formed the foundation of Western medicine and was taught and practiced well into the nineteenth century. Although, within Antonio Neri's lifetime newer experimentally based methods did start to take hold. A decade after his father's death, in a 1609 letter, Antonio boasts about his success in curing disease in Antwerp using the methods of the medical upstart Paracelsus. It is unlikely that his father would have approved.

*This post first appeared here 13 August 2014.

Monday, January 6, 2020

Report from Parnassus

Rafael - El Parnaso (Vatican, Rome, 1511)
Apollo on Parnassus, (fresco detail). 
In the spring of 1612, Italian glassmaker Antonio Neri finished writing L’Arte Vetraria, and the Holy Office of the Inquisition approved it for publication. The book of glass technical recipes passed the Church’s censors despite it containing a large number of alchemy related methods. Contrary to what we might imagine, they did not have any problems with Neri’s work; in fact, one bureaucrat commented that the book was full of useful information. Remember, this was at the same time that so-called sorcerers and witches were being tortured and executed around Europe. One big difference in this case was intent, or rather the perceived intent of Neri's writing. Another factor was his personal connections. The truth is that alchemy was something of a fad among the wealthy nobility, who used the equipment for everything from making rosewater, to distilling liquor, to quietly trying their hand at transmutation. 

To form a better sense of the public image of the chemical arts in the early seventeenth century, we can turn to the satirical critic Traiano Boccalini, who published a book of his own the same year as Neri. Ragguagli di Parnaso [Reports from Parnassus] was an immediate hit. In fact, it became so popular that he and his sharp tongue were forced to leave Rome for the comparative safety of Venice soon after its completion, and soon after that friends found him dead under suspicious circumstances. Initially, Boccalini had been on good terms with Church officials, but perhaps he had seen a bit too much of the institution's inner workingsEventually, he became bitterly disillusioned and wrote Ragguagli as a collection of fictitious news-sheets. These were patterned after the letters that circulated widely as the forerunners of modern newspapers. His reports took place in the mythical state of “Parnassus,” which struck an uncanny resemblance to contemporary Rome. Its monarch, Apollo, struck an uncanny resemblance to the pope, as the princes of Parnassus did to cardinals, bishops and curia officials. Report LXXXIX is illustrative of what were the more practical fears over alchemy, in this case, some creative wealth building among the clergy. It gives a sense of alchemy’s public persona. Apparently, in real life, there was a crackdown by the Church on chemical apparatus, under the guise of concern for public health. Our author slyly suggests, in the very last line, that it may have had more to do with putting an end to clergy lining their own pockets. 
Apollo [the pope] Prohibits the Princes from the Use of Distillers or Alembics At Home: 
In the past few months here, various ailments have emerged in this state of Parnassus, which have caused in some an extraordinary fatigue with frequent agitation: in many a tenacious fever, a faint pulse and a monstrous appetite: in others an intense stomach ache with an ardent thirst.  
The doctors cannot find a single remedy. However, the true cause of these maladies, by decree of Apollo, was revealed before a recent meeting of the grand Asclepius [Society] of prominent Greek, Latin and Arabic doctors, where it was the subject of long and erudite debate. Because neither the enemies of the grand princes nor other eminent gentlemen were spared, it was doubted whether the sickness was caused artificially by powerful poisons. Furthermore, it is clear these troubles were not only happening nearby.  
And we see several modern princes put great study in their most excellent facilities to prepare in their alembics things other than rose water. They conceal subjects dangerous and heinous with their hidden machinations of poison. This cannot be allowed to be covered up; such a scandal must be exposed with the violence of a dagger.  
His Majesty, concurring with the opinion of the congregation, yesterday morning made a public speech, to issue a strict edict, which forbids princes of any color, from ever keeping distillation or alembic operations at home or outside. However, he allowed similar exercises in the hands of experimenters and herbalists. A thing being extremely foul is the minting of counterfeit money in the night and then by day covering so treacherous a crime by running shops openly making medals for the crown. 

In this piece, Boccalini crystallizes the complex social stigma carried by alchemy. Of all the practical tasks that could be performed in this art, the most notoriety by far was derived from the concept of turning base metals into gold. 

In a 1613 ms, Neri openly expressed his fear that true transmutation, in the hands of the masses was likely to collapse the economy. The Vatican’s concerns were more immediate: financial gluttony within the Church. Anyone with enough alchemical knowledge could produce convincing counterfeit money. Turning lead into gold was a theoretical issue; dealing with rogue counterfeiters was a real and immediate one. 

[1] Antonio Neri, Manuscript, Biblioteca Nazionale Centrale di Firenze: Ms. Conv. Soppr., B.3.16. Discorso sopra la chimica (che cosa sia, e sue Operazioni del R.[everendo] P.[rete] Antonio Neri Sacerdote Fio.o) (1613).
*This post first appeared here on 8 August 2014.

Friday, January 3, 2020

Glassware of an Alchemist

Antonio Neri (1598-1600),
"Libro intitulato Il tesoro del mondo" f. 38
In the introduction of L'Arte Vetraria, his 1612 book on glassmaking, Antonio Neri discusses the technical and scientific uses of glass. He rattles off an impressive list of items, many of which are still in everyday use in chemistry and medicine:
Beyond the ease and low cost with which it is made, and the fact that it can be made anywhere, glass is more delicate, clean, and attractive  than any material currently known to the world. It is very useful to the arts of distillation and spagyrics, not to mention indispensable to the preparation of medicines for man that would be nearly impossible to make without glass. Furthermore, many kinds of vessels and instruments are produced with it;   cucurbits,  alembics,  receivers,  pelicans,  lenses, retorts, antenitors,  condenser coils, vials, tiles, pouring-vessels (nasse),  ampules, philosophic eggs  and balls. Countless other types of glass vessels are invented every day to compose and produce elixirs, secret potions, quintessences, salts, sulfurs, vitriols, mercuries, tinctures, elemental separations, all metallic things, and many others that are discovered daily. Also, glass containers are made for aqua fortis and aqua regia, which are so essential for refiners (partitori) and masters of the prince’s mints to purify gold and silver and to bring them to perfection. So many benefits for the service of humanity come from glass, which seem nearly impossible to make without it.
The glass book, as it was published by Neri, did not contain any illustrations. If we hunt around in the alchemical literature and in museums, we can find examples of the apparatus and vessels on his list, but still, we might feel disappointed at not seeing the specific pieces with which our glassmaker was referencing. As it happens, we actually can see a number of these pieces, exactly as Neri experienced them. Over a decade before writing  the glass book, when he had just completed Catholic seminary and become an ordained priest, Antonio Neri wrote a manuscript devoted to "all of alchemy" in which he shows us many of the same glass vessels. Here he lists and shows us (in the illustration, from left to right, top to bottom) a double vase, a urinal (yes, that kind of urinal), a pair of Florence flasks (the Italians now call this a pallone di Kjeldahl), a philosophic egg, another flask which Neri calls a "bozza longa," an alembic (or still-head), a retort, a bottle,  mouth-to-mouth urinals, a receiver (for a still or retort), a saucer, and assorted cups and ampules. Since many of these terms changed from place to place and over time, we can use this chart to get a much better idea of exactly what Neri was doing in his recipes. The use of urinals in his chemistry kit shows simple practicality; these were standard items made by glass factories. If a low-cost, readily available item could be used in the laboratory, so much the better.

Many of the items Neri lists were used in distillation, which was a basic technique of alchemists. A still could be set up in any number of variations, depending on the intended product, which could range from alcoholic spirits to powerful acids and other reagents. The "athanor" was a stove specially engineered to gently heat a large flask, called the "cucurbit," which contained whatever was to be distilled. The apparatus would include an "alembic"; a cap that fits on top of the cucurbit with a snout-like tube running downward from its top. The idea was that volatile ingredients would evaporate inside the cucurbit, rise up, condense in the alembic and run down its snout, to be collected in a "receiver" vessel. Sometimes, for convenience, all three pieces (cucurbit, alembic and receiver) are together referred to as the alembic. The process could be sped up significantly by adding a condenser coil, what Neri calls a "serpentine." As steam built up in the cucurbit, it was routed through its snout to a coiled tube that might be submerged in cold water. This way, the steam would condense more rapidly, sending more liquid to the receiver. Neri uses this method to produce acids in order to dissolve metal pigments for his glass, but the same basic technique is still applied today in producing industrial chemicals, medicines, perfumes and alcoholic drinks such as moonshine, grappa, brandy, vodka, rum and whisky. However, in the distillation of alcohol, metal (usually copper) containers are preferred. Neri was often producing chemicals that would react with metal, glass provided a very good solution to this problem but as he discusses at length, great pains must be taken to ensure that the glass vessels do not crack or break when heated or cooled too suddenly.

* This post first appeared here on 27 December 2015.

Wednesday, January 1, 2020

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 endeavour 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.