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, August 30, 2013

We Were Trojans

Giovanni Domenico Tipeolo,
Procession of the Trojan Horse in Troy. 1773
In January of 1600, Antonio Neri finished an ambitious manuscript devoted to "all of alchemy." On the first page of text after the contents, above the first recipe, on the first line, written in Neri's own hand, are two solitary words, "fuimus troes"; a celebrated quote in Latin from Virgil’s epic poem, The Aeneid. The words translate to "We were Trojans" or "We Trojans are no more." They lament the fall of a city, sparked by the deception of the great wooden horse concealing enemy soldiers. These were words spoken in grief, in a charged, emotional scene, accepting defeat. We were once proud Trojans, but no more. While the intended significance in Neri’s manuscript may be lost, it is further affirmation of his academic grounding. What rings through the fog of history in these words, is the unmistakable passion behind them.
Tis come, the inevitable hour,
The supreme day of Darden power;
Our history’s ended: Troy’s no more,
And all her mighty glory o’er.
 
- Aneid 2,324.
(William King, trans.)

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

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

Wednesday, August 28, 2013

The Neri Chapel

Entrance to the Neri Chapel at S. Maria Maddalena dei Pazzi
A short walk from the Neri residence on Borgo Pinti in Florence is the church of Santa Maria Maddalena dei Pazzi. During Antonio Neri’s lifetime, it was part of a monastery known as Cestello. Although the family's parish church was the much grander San Pier Maggiore, for daily services, the Neri family attended the more intimate Cestello church. It was smaller, yes, but not without its own prestige. The Cistercian monks there hosted meetings of the famed Accademia delle Arti del Disegno, or "Academy of Drawing Arts." As a young boy, Galileo was taught there by court mathematician Ostilio Ricci, and back in the days of the Florentine republic, the monks were charged with responsibility to count votes taken by the city council (Signoria).

Women were not allowed inside the monastery church, but prayed in a separate chapel located just off the street. This chapel was owned by the Del Giglio family and had been built by apothecary Tommaso del Giglio. By the end of the sixteenth century, the family was having trouble maintaining the chapel, and it fell into danger of being taken over by the cobblers' guild, who were holding their meetings inside.

In the late 1590's Antonio Neri's father, the grand duke's personal physician, successfully petitioned to take over the space. He paid for a complete head-to-toe renovation of the chapel, but also of the church itself. While he did not live to see the work completed by artists Poccetti and Passignano, the chapel was renamed in his honor and became his final resting place. Historian Giuseppe Richa noted a plaque on the floor which read:

The mournful children have erected this AD 1598 for the highly celebrated doctor and philosopher Ner[i] Neri, who died with greatest honors in his fatherland.”
The final resting place of Glassmaker Antonio Neri is not known, but the Neri Chapel at Santa Maria Maddalena dei Pazzi stands at the top of the list of possibilities. 

Monday, August 26, 2013

From Beads to Belief

In L'Arte Vetraria, Antonio Neri makes sixteen distinct references to the production of glass for beads. In chapter 22 he gives a recipe for 200 to 300 pounds of aquamarine colored glass for beadmaking cane. 'Cane' is the term for thin rods of glass drawn out and cooled, to be used later over an oil lamp. The rods are heated in the flame and wound around a metal wire, forming individual "spiei" beads which can then be decorated with other canes of different colors. Neri says:
I demonstrated this method of making aquamarine in Florence in the year 1602, at the Casino, and I made many batches of it for beadmaking cane, which always resulted in a most beautiful color.
After cooling, the beads were removed from the wire, and often strung as rosaries. Using these beads in the recital of prayer dates back at least to the thirteenth century. In 1569, only a few years before Neri's birth, Pope Pius V officially established devotion to the rosary. As a priest, the production of glass for beads may have formed a part of Neri's ecclesiastical duties. 

In chapter 47, he describes a garnet colored glass which is appropriate for small "ferraccia," or pan-fired beads. For these, small lengths of cane were nipped off and pierced with a sharp metal point. A large number of these were then placed in an iron pan, in the furnace, and agitated in order to round them. Neri would supervise the production of beadmaking cane not only in Florence, but also in Pisa.

The praying of the rosary is sometimes started with a recital of the Apostles' Creed, and Neri makes use of that in the recipe for an emerald-green lead-glass in chapter 65:

…Mix the powders, and always give them to the glass in six portions, stirring the glass well. Set the interval from one portion to the next by reciting the creed.
Assuming he used the creed of Pius IV, adopted at the council of Trent in 1564, recitation takes a little under three minutes. Later in the book, in chapter 117, he uses Psalm 51(Have mercy upon me, oh God...) to time the extraction of kermes dye. At first blush, it might seem that religion would be at odds with alchemy and glassmaking. In reality, practical elements of Neri's religious life integrate seamlessly with his work at the furnace and in the laboratory.

Friday, August 23, 2013

Quotations

MS Ferguson 67, f. 14r.
University of Glasgow Special Col.
Throughout his book on glassmaking, Antonio Neri is able to give clear technical instructions, but here and there are passages that give us a deeper view into his life, his work and the poetry of making glass. From L’Arte Vetraria:

Always examine the colors to get to know them by eye, as I have always done, because in this matter I cannot give specific doses. Sometimes the powder will tint more, other times less, therefore you must practice with your eyes to understand the colors.-chap. 95.
Do not presuppose that I have described a way to make something ordinary, but rather a true treasure of nature, for the delight of kind and curious spirits.-chap. 133.
…Perform this operation under a large chimney and when the fumes begin to assault you, it is best to leave the room. This smoke is most injurious and could be deadly; therefore you should see that no one inhales it in any way, because it would do very great damage. When all fumes pass, you should nevertheless leave the crucibles in a low fire, until it goes out completely. -chap. 73.
When working this glass use the same diligence that the skilled masters use and in so doing you will make material that is perfectly true to the jasper, agate and chalcedony of the orient. It will be adorned with so many graceful and beautiful areas of undulations and enhanced with the play of diverse, lively, flaming colors, that truly it will seem nature cannot attain so great a height or grand a prize. -chap. 37.
If you want to have fine crystal, then in this you must exercise great diligence; when the frit is made with careful attention, it will be white and pure like snow from heaven. -chap. 2.
As the common proverb of the art of glassmaking says: a fine sieve and dry wood bring honor to the furnace. - chap. 8.
In closing, I say that the artisan who is diligent, practical and works step by step, as I describe, will find truth in the present work. - Preface

Wednesday, August 21, 2013

Gold-Ruby Glass

Gold ruby glass, at the Wittelsbacher in the Munich Residenz.
The glass with the lid is attributed to Johannes Kunckel.
What has become the most celebrated glass recipe in Neri's book is also one of the shortest. Chapter 129 is entitled "Transparent Red." In it, he describes his method for making gold-ruby glass. A deep red colored glass made with metallic gold. Because of the difficulty in making it, among later glassmakers, it became something of a holy grail. Here is Neri's recipe for gold-ruby glass in its entirety:
Calcine gold so that it becomes a red powder. This calcination is done repeatedly with aqua regis, pouring it over [the gold] five or six times. Then put this gold powder into a small earthen pan to calcine in the furnace until it becomes a red powder, which will take place after many days. Sprinkle this red powder of gold [gold chloride] over the fused glass. Use fine cristallo, thrown in water many times. This gold powder, given in proportion little by little, will make the transparent ruby red glass; but you must experiment in order to find it. 
To be blunt, by itself this recipe does not give enough information to reliably make the fabled red glass. Neri must have known this, as alluded to in the line "but you must experiment in order to find it." Neri's German translator Johannes Kunckel successfully made gold-ruby glass, but he too declined to disclose his method, although several beautiful examples of his do survive. Much later it became generally known that the addition of small amounts of tin will produce a dependable red color. It was not until the twentieth century that the underlying chemistry was understood. 

It appears that this color glass was produced even earlier by mosaic makers and enamellers, who routinely added tin to opacify the melt. The difference between their creations and transparent ruby glass was the amount of tin used. Deep transparent ruby glass requires only miniscule amounts of tin and gold. More tin makes the glass opaque and lightens the red color. There was one final secret necessary; the glass must be 'struck' in a special process. The freshly made glass object is cooled then reheated to bring out the deep red color. In 1568 Benvenuto Cellini clearly described the striking method for gold-ruby enamel.
 … when it has once more cooled you put it in [the kiln] again, but this time with a much weaker fire, until you see it little by little reddening, but take great heed that when it has got the good color you want, you draw it rapidly from the fire & cool it with the bellows, because too much firing will give it so strong a color as to make it almost black.
 Benvenuto Cellini, The Treatises Of Benvenuto Cellini On Goldsmithing And Sculpture, Charles Robert Ashbee, ed., tr. (New York: Dover, 1967), p. 20.

Monday, August 19, 2013

Salamander

If one can say that hot-glass workers have a mascot, it is without any doubt the salamander. Since ancient times, this lizard-like, poisonous skinned amphibian was ascribed to exist within fire, even to be born out of the flames. According to legend, its cold body allowed it to survive the heat. To see one in the flames of a furnace was considered good luck, but glassblowers who suddenly disappeared (to work elsewhere) were said to have been "eaten by the salamander." In his autobiography (1558-1567), Florentine artist Benvenuto Cellini offers this recollection:


When I was about five years old my father happened to be in a basement-chamber of our house, where they had been washing, and where a good fire of oak-logs was still burning; he had a viol in his hand, and was playing and singing alone beside the fire. The weather was very cold. Happening to look into the fire, he spied in the middle of those most burning flames a little creature like a lizard, which was sporting in the core of the intensest coals. Becoming instantly aware of what the thing was, he had my sister and me called, and pointing it out to us children, gave me a great box on the ears, which caused me to howl and weep with all my might. Then he pacified me good-humouredly, and spoke as follows: 'My dear little boy, I am not striking you for any wrong that you have done, but only to make you remember that that lizard which you see in the fire is a salamander, a creature which has never been seen before by anyone of whom we have credible information.' So saying he kissed me and gave me some pieces of money.

(Quotation from: J. Addington Symonds "Benvenuto Cellini's Autobiography" in Harvard Classics v. 31, Charles W. Elliot, ed. (New York: P. F. Collier & Son, 1910), p. 11 (book I, ch. V.))

Friday, August 16, 2013

Galleria

Giovanni Stradano  (Jan van der Straet) 
Alchemy Studio, 1571
In 1560, Cosimo I, Duke of Tuscany, commissioned Georgio Vassari to begin construction on the Uffizi Palace in Florence. Two wings of the structure frame a long, narrow courtyard leading out to banks of the Arno River. Today it houses one of Europe's premier art museums, but its original design was as the central administration of the Medici government. The lower floor held offices of the regional magistrates, and the upper floor of the west wing (above the mint) held a variety of workshops highlighting Tuscan industry. Cosimo built a glass furnace there, which he staffed with Muranese masters of the art. He won their expertise through long, hard negotiations with the doge of Venice. 

A 1571 painting by Giovanni Stradano is entitled the Alchemy Studio. It shows Cosmo's son, Francesco I, in the Uffizi surrounded by laboratory equipment and workers. Under the watchful eyes of a senior alchemist, he stirs a chemical preparation over a stove with intense concentration. The prolific glassware in this scene drives home the close relationship between glassmaking and scientific investigation.

By 1588 Francesco's brother, Ferdinando I de' Medici, formally declared this space the Galleria dei Lavori or 'gallery of the works'. There is no direct evidence that Antonio Neri gained his education in alchemy at this facility, but it makes a very attractive candidate. Of note to this story is that the German alchemist Leonhard Thurneysser passed through Florence in 1590, when Neri was fourteen-years-old and by several accounts preformed a transmutation of an iron 'chiodo' [nail] with a special oil. After the demonstration for Grand Duke Ferdinando, the nail remained on display for some time in the Galleria. Neri mentions the nail in his Discorso and Thurneysser is discussed in a 1601 letter to the priest from his friend Emanuel Ximenes.

Wednesday, August 14, 2013

Archiater

Antonio Neri's family arms.
In the late 1580s, approaching the age of fifty, Antonio Neri's father was appointed the personal physician to Grand Duke Ferdinando de' Medici. The son of a barber-surgeon, Neri di Jacopo Neri - or Neri Neri, as he was known - had parlayed a degree in medicine into a successful and prosperous career. His elevation to 'citizen' status, a decade earlier, gave him entree into the world of the patrician elite and his appointment as royal physician secured a place for his young family near the top of the Florentine social hierarchy.

The fact that Neri Neri gained citizenship at the age of forty and did so together with his father shows it was not a legacy, but perhaps their medical prowess that lead to the award. One requirement of citizenship was possession of a domicile within the city. The baptism register lists 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.

Baccio Valori was librarian, keeper of the royal herbal gardens and the godfather of Antonio Neri's older sister Lessandra. In 1587, Valori received a letter from Filippo Sassetti, sent from India. Filippo was a native Florentine, the nephew of Antonio Neri's godmother, Ginevra Sassetti. He attended university in Pisa with Valori and they became lifelong friends. In the letter, he notes that he has collected rare varieties of cinnamon in his travels along the Malibar coast. 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."

In the autumn of 1587, Grand Duke Francesco I de' Medici and his wife Bianca Cappello both became ill and died during a visit by the grand duke's younger brother Cardinal Ferdinando. Pernicious malaria was to blame and accounts by physicians on the scene described identical symptoms for husband and wife. The thirty-eight-year-old Cardinal Ferdinando relocated to Florence from Rome; he took charge and assumed power as the new grand duke of Tuscany. Shortly after, he appointed Neri Neri as his head physician.

Monday, August 12, 2013

Casino di San Marco

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

The Royal Foundry, as it was also called, became a place of pride for Grand Duke Ferdinando. It was a place that visiting dignitaries specifically asked to see and tour. Behind the doors of the Casino di San Marco, Antonio Neri and his associates worked their magic. This is probably where he first learned the secrets of Venetian style glass composition and undoubtedly much more. He assisted the prince in his research, formulated herbal remedies and helped in the production of luxury gifts for visiting dignitaries.
This was the way that I made chalcedony in the year 1601, in Florence at the Casino, in the glass furnace there. At that time, the task of scheduling furnace-work fell to the outstanding Mr. Niccolò Landi, my close friend and a man of rare talent in enamel work at the oil lamp. I made many pots of chalcedony in the furnace there. I never deviated from the method stated above, I always prepared the materials well and it always came out beautifully in all my proofs.
-Antonio Neri 1612, p. 41.

Friday, August 9, 2013

Bisextile

The day of Antonio's birth was leap year day, 29 February 1576, although his baptistery records indicate 1575. According to the old Tuscan calendar, the New Year would not be celebrated for another month, on 25 March, around the equinox. The Florentine calendar was aligned with the beginning of the planting season; swallows returning from Africa would sweep in the New Year, swirling over the city squares and proclaiming the impending arrival of spring. Soon enough the fragrant air would set farmers busy in the fields.

However, Antonio was born to a Florence still very much in the grip of February. He came into the world on a Thursday evening at 9:25 pm, (recorded as 3 and 5/12 hours past sunset). Of all the days to be born, 29 February was considered among the least auspicious. A dire Northern Italian folk proverb states "An bisesti, o la mama o 'l bambi", predicting that when a child is born on this day, by the end of the year either the infant or its mother will die. Indeed, the Italian word naming the day, bisestile, had become a synonym for misfortune or calamity, as is still the case for the French cognate bissêtre.  Whatever stock the family put into ancient superstitions, happily this prophesy did not come true for Dianora or her fourth child Antonio.

The baptistery record for Antonio Neri reads:
Thursday, 1 March 1575:  Antonio Lodovico was born to Mr. Neri Jacopo and Dianora di Francesco Parenti, residents of San Pier Maggiore parish. The time of birth was 29 February, at 3 hours 25 minutes past sunset. The godparents are Francesco di Girolamo Lenzoni, and Ginevra di Federigo Sassetti.

Wednesday, August 7, 2013

Laughing In the Fern

Fern ash is high in potassium carbonates. If carefully purified it can make an exceedingly clear glass, rivaling or even surpassing Venetian cristallo. It has the additional advantage of being physically tough, making it ideal for engraving or diamond-point work. On the other hand, once out of the furnace it stiffens quickly, giving it a short 'working life' for the hot glass artisan. This limits designs to simple basic forms. While soda-based glass was the norm for the Mediterranean region, throughout the Middle Ages and into the Renaissance, northern Europeans were more likely to be making potash-based glass. They utilized the potassium rich local trees and plants of the northern forests. In France, fern glass is called verre de fougère. In the considered opinion of some connoisseurs, wine tasted better when sipped from verre de fougère cups, hence the delightful expression 'le vin rit dans la fougère' [wine laughs (sparkles) in the fern].

Since the middle ages, fern glass became part of everyday life in northern Europe. It was familiar enough to find its way into literary verse on matters of the heart. There is a nice reference to fern glass by Geoffrey Chaucer, in The Squires Tale:
But notwithstanding, some said that it was
Wondrous to make fern-ashes into glass,
Since glass is nothing like the ash of fern;
But since long since of this thing men did learn,
Chaucer, in turn, borrowed this reference from an epic twenty-two thousand line French poem from the late thirteenth century, when the technique of making glass from ferns was already ancient.

Monday, August 5, 2013

Waxing Moon

In Chapter 5 of L'Arte Vetraria, Neri shows how to extract salt for glass from fern plants in an evocative recipe. Fern was and still is widely abundant in Tuscany. It presented a ready source material for glassmakers of the region. Neri directs that harvesting of the plants be done in the spring:

Cut this herb from the ground when it is green, between the end of the month of May and mid June. The moon should be waxing and close to its opposition with the sun, because at this point the plant is in its perfection and gives a lot of salt, more than it would at other times and of better nature, strength and whiteness.

At first, it is tempting to dismiss this lunar influence as the product of a fertile imagination, but let us take a closer look. Tidal forces of the moon do in fact subtly affect plants, fish and animals in ways that can be measured. A closer look at Neri’s advice reveals reasoning that is hard to dismiss as mere astrological superstition. When the moon is waxing, tides rise and so do water tables. According to folklore, this is when sap rises from the roots of plants into stems and leaves. Sap carries the dissolved mineral salts required for glass. Neri also stipulates that harvesting should take place during lunar opposition. When the moon is 'opposed' to the sun, it is on the opposite side of the earth from the sun. In opposition, the moon is near full and rises as the sun sets. Plants see more light at night, leading to increased photosynthesis and growth.

In contrast, violinmakers from Cremona valued high alpine spruce called moon wood. Trees were felled in the wintertime, when lunar tides were low. This minimized the amount of vibration deadening sap in the wood. In his Natural History, Pliny relates Cato’s advice on felling trees in accordance with the lunar cycle. In fact, centuries-old tradition specified lunar conditions for a host of needs from construction timbers to cheese boxes. 

Friday, August 2, 2013

Great Princes

Today, we recognize L'Arte Vetraria as the first printed book solely devoted to the art of glass formulation. It is a work committed to the subject of refining raw materials and combining them into a range of glasses, over a rainbow of colors. 'First in print' is a notable distinction, but one that is surpassed with ease by Neri's deeper accomplishment. His book provides a rare glimpse of skilled practical knowledge. This was an era when prized techniques were frequently lost to subsequent generations; lost because artisans so often spared the pen. Their precious knowledge went purposely unrecorded, passing in strict confidence from master to apprentice working side by side. In 1612, Neri published his expertise to the world, dedicating his book to Prince Don Antonio de' Medici the son of Grand Duke Francesco I:


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

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.

Thursday, August 1, 2013

Eyes of a Lynx


In 1614, the year of Antonio Neri's death, naturalist Prince Federico Cesi wrote to his good friend Galileo. He complains 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. Within a few months of Neri's death, his book was already on its way to making history.