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

Wednesday, March 30, 2016

Isaac Hollandus

J. Hollandus,
Chymische Schriften
(Vienna: 1773)
In early 1603, Glassmaker Antonio Neri traveled from Italy to Flanders, to visit his friend Emmanuel Ximenes. Neri would stay for seven years and in that time he worked on a number of glass related projects including the manufacture of artificial gems using lead crystal glass. An enduring mystery is that in his glass book L'Arte Vetraria, he gives credit to alchemist Isaac Hollandus for a "new chemical method never before used," yet no such recipe for artificial gems has ever been found in the writings of Hollandus.

Neri’s host Emmanuel Ximenes owned several titles by this somewhat obscure figure. Historians conjecture that there were actually two alchemists in the Hollandus family, Isaac and Johannes Isaac. Their relationship is not clear, although they are often assumed to be father and son. We know little about them; some authors date them as early as the fourteenth century. However, a preponderance of evidence point to about the time Neri lived. In his glass book, in the fifth part devoted to artificial gems, Neri writes:

Above all is this wonderful invention. A new way practiced by me, with the doctrine taken from Isaac Hollandus, in which paste jewels of so much grace, beauty and perfection are made, that they seem nearly impossible to describe and hard to believe.

In the 1679 German edition of L'Arte Vetraria, Johannes Kunckel implies that Isaac was dead before Neri came to Antwerp, writing "This is the manner to imitate precious stones, of Isaac Hollandus, (namely, from his posthumous writings) that I [Neri] learned in Flanders" (emphasis added). Yet, coinciding with Neri's visit, playwright Ben Jonson who had just returned to London from the war in Flanders, referenced the pair in his satirical work The Alchemist (1610). There he implies that the elder Hollandus was then dead but survived by "living Isaac." In 1644, the famous Flemish chemist Van Helmont identified Isaac Hollandus as a recent contemporary. In a 1716 treatise, Kunckel paid Hollandus a great compliment and at the same time took a swipe at Helmont saying "and the incomparable Hollandus had more of the fire-art in his little finger as Helmont in his whole body." In another reference, Sir Francis Bacon mentions Hollandus as "by far the greater part of the crowd of chemists."

One Hollandus title in Ximenes' Antwerp library was Opera Mineralia, first published in 1600. The subject of this volume is the philosopher's stone and its production. While there are no artificial gem recipes here per se, there are some intriguing connections between artificial gems and the philosopher's stone, both philosophical and practical. It was thought that the colors of metallic based glass pigments were an indication that the metals were "opened" and became susceptible to alchemical transmutation. Of special interest was the deep red ruby color made by adding gold to the glass melt. In the introduction to a 1797 French translation of Neri's book, artificial ruby or "vitrified gold," is equated to the bible's Electrum of Ezekiel —a red glow seen by the prophet in a vision.

By the mid-eighteenth century, Isaac Hollandus was lauded in industrial arts books as a genius of artificial gems. He may well have been, but the evidence does not support it. All of the specific recipes attributed to Hollandus seem to lead back to Neri's L'Arte Vetraria or its translations. A case can be made that Hollandus' reputation for artificial gems stems from a 1697 plagiarized version of Neri's book. A volume published in France by Haudicquer Blancourt that gives no credit to the priest. Blancourt used Christopher Merrett's English edition as his base and added to the recipes with his own embellishments. The chapter on artificial gems still lauds Hollandus, but its length was now doubled from the seventeen original recipes to thirty-five. The size of this one section jumped from thirteen to nearly two hundred pages, an increase in page-count larger than Neri's entire book. In 1699, Blancourt's version was then translated back into English, again without reference to Neri. There is no doubt that these two editions, with their expanded chapters on paste gems exerted a strong influence on later craftsmen. They may also be the source of the credit given to Hollandus' for paste gems in the eighteenth and nineteenth centuries.

A number of intriguing questions remain unanswered. Chief among them is the nature of Neri’s association with the Dutch alchemist(s). Was Hollandus or his son alive in the first decade of the seventeenth century and did Neri meet with either of them in person? We can only guess. The Hollandus men are notable, if not enigmatic, characters in the transition from alchemy to modern chemistry. Historians would very much like to know them better. Nevertheless, there can be no doubt of the strong impact Hollandus made on Neri. Isaac holds a singular honor as the one person named in Neri's book to whom he gives specific credit. As research on early modern science has progressed, the importance of communication between practitioners has emerged as a central theme. A meeting of the minds between Neri and Hollandus, if it ever occurred, would rank as a prime example of technology transfer with a definite impact.


For a comprehensive look at Hollandus see: Annelies van Gijsen, "Isaac Hollandus Revisited" in Chymia: science and nature in Medieval and early modern Europe, Miguel Lòpez-Pèrez, Dider Kahn; Mar Rey Bueno, eds., (Newcastle upon TyneUK: Cambridge Scholars, 2010), pp. 310–324.
*This post first appeared here 2 April 2014.

Monday, March 28, 2016

Aventurine

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

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

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

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

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

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

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


[1]  The earliest instance of this story in print that I can find is fairly late;  Faustino Corsi, Delle pietre antiche: libri quattro (Rome: Salviuccio e figlio, 1828)  pp. 166-167.  
[2] Cesare Moretti (†), Bernard Gratuze and Sandro Hreglich,  “Le verre aventurine (‘ avventurina ‘) : son histoire, les recettes, les analyses, sa fabrication”, ArcheoSciences, 37 | 2013, 135-154.
[3] For instance see  Giulio Salviati, “Venetian Glass” Journal of the Society of Arts (Proceedings), Volume 37 (7 June,1889), p. 630
[4] Neolithic Quartz Aventurine Pendant - 7 Cm/ 2. 76 ", green - 6500 To 2000 Bp – Sahara. Item Id: 106549,  Weight: 83 gm. Sahara - Mauritania - Tagant country.
http://ancientpoint.com/inf/106549-neolithic_quartz_aventurine_pendant___7_cm_2___76____6500_to_2000_bp___sahara.html
[5] Dizionario del cittadino, o sia Ristretto storico, teorico e ..., Volume 1 pp. 38-39.
[6] Antonio Neri, L'Arte Vetraria (Firenze: Giunti, 1612).
[7] Sauzay, A. (1870) Marvels of Glassmaking in All Ages. London, 1870 pp. 173 - 175.

Friday, March 25, 2016

Chalcedony Glass

17th century ribbed bottle,Brescia, Italy.
In hopeful anticipation of colorful flowers, the cusp of spring, seems the appropriate time to celebrate Antonio Neri's most colorful creation; chalcedony glass.[1] Through his clever technique, Neri managed to throw every color he knew into one glass pot and come up with, not mud, but the opposite—a swirly rainbow glass that defies verbal description. Somehow, he achieves a balance that blends a full range of colors in a way that seems natural and harmonious. While many glass creations survive from the seventeenth century, none is directly attributable to Neri's glass formulation. But, in my opinion, this piece from Brescia comes close to our alchemist's own description. 

Chalcedony is one of the more exotic varieties of glass described in Antonio Neri's book, L'Arte Vetraria. It is also one of the most labor intensive, exacting recipes and consequently a 'high stakes' risk for losing the entire batch after considerable work. Nevertheless, Neri assures us that the end result is worth the trouble; he describes it as:
Adorned with so many graceful and beautiful areas of undulations and enhanced with the play of diverse, lively, flaming colors.
Chalcedony is a natural mineral, known and admired since antiquity. It occurs in a variety of translucent colors and is most valued when swirls of many different colors are present together in the same piece. In the Roman Empire, it was prized for seals and signet rings; its fine-grained structure allowed intricate carving without fractures. Like many other rare natural materials, it was sometimes supposed to have mystical healing properties. 

Chemically, the mineral chalcedony is identical with quartz or silica, the main ingredient of glass. However, unlike the fabricated substance, the mineral is formed of networks of microscopic interlocking crystals that are responsible for its favorable properties. Small amounts of impurities between the crystal grains cause the swirls of color.

Neri presents three variations of chalcedony glass that span his career as a glassmaker. The first he describes as "the way that I made chalcedony in the year 1601, in Florence at the Casino, in the glass furnace there." The last was made "in the Flemish city of Antwerp, in January of the year 1611" where he presented "His Excellency, the Prince of Orange with two vessels of chalcedony [glass] which delighted him greatly."

His friend Emmanuel Ximenes was anxious to learn the secrets of this glass as early as July of 1603, when he wrote: 

The details of the last chalcedony [glass], which you promised to send to me, did not come in the letter: but I had to recant by the time I got to the end […] I see and understand, that Your Lordship is not at leisure, but in fact busy at work in the service of Christianity... 
Neri advises that in order to bring out the swirls of color, the glassblower must cool and reheat the piece several times, a process that today is known as 'striking'.

Unfortunately, there is also a dark side to this colorful creation.  It is strongly advised to avoid replication of Neri's chalcedony glass as described in his book of recipes; it contains a cocktail of extremely toxic ingredients. While these are relatively harmless once locked inside the glass, in preparation and especially in the hot molten glass melt, vapors of mercury and arsenic can be deadly. Moderate exposure can be expected to cause neurological and liver damage. (The term "mad as a hatter" comes from the unfortunate side effects of inhaled mercury vapors in the formation of felt hats.) In addition, Neri's extensive uses of strong acid reactions in these preparations make sudden eruptions and severe chemical burns a very real danger.


[1] At least in the northern hemisphere, lets say "autumn colors" in the south.
*This post first appeared here in a slightly different form on 27 September 2013.

Wednesday, March 23, 2016

Dyed In The Grain

Dyeing wool cloth, from "Des Proprietez des Choses"
Bartholomaeus Anglicus, 1482
British Library Royal MS 15.E.iii, folio 269
In his book on glassmaking, L'Arte Vetraria, Antonio Neri presents a number of recipes for paint pigments used to decorate finished glassware. One recipe (#119) is for crimson red, from kermes [kur-meez], prepared by a method of his own invention, which he developed while working in Pisa in 1602–1603.

Since antiquity, throughout Europe and the Near East, kermes was a highly valued red colorant because it formed a pigment that resisted sunlight, humidity and temperature. Kermes red can be found in prehistoric cave paintings, Egyptian scrolls and the robes of cardinals and kings. Words in many languages used to describe bright red, "crimson" and "carmine" among them, are derived from the name "kermes." The pigment is produced from the bodies and eggs of a small type of insect that feeds on the sap of evergreen oak trees throughout the Mediterranean region. In the spring, the female kermes insects and their eggs were harvested. The small eggs surrounding the edges of the insect body resemble kernels of grain, hence the expression "dyed in the grain." For medicinal purposes, kermes pastes were used to disinfect wounds and served as an effective contraceptive. 

To extract the color, Neri starts with a flask of "the very best grappa," which is a potent kind of liquor made by distilling the skins, seeds, stems and pulp of grapes, leftover from wine making. To this, he adds a pound of alum and one ounce of the dried kermes insects, ground finely and sifted. He agitates the mixture, at which point the grappa will "color beautifully" and then lets it sit. After four days, he adds four ounces of alum dissolved in water and pours the mixture into a stocking that has been sewn into the shape of a cone. The stocking hold most of the color, while letting the grappa pass through. 

Alum is another material used since antiquity. It was widely available in Neri's time as a mined mineral, which could actually be several different chemical species with similar properties. Today, chemists know it as a "flocculant"; it neutralizes the electrical charge of finely suspended particles in a liquid, allowing them to stick together and fall to the bottom. This is the secret to Neri's method, although he was not thinking in modern chemical terms, he did know that the alum precipitated the pigment from the liquid allowing it to be collected and dried.

Finally, he scoops the pigment onto pieces of linen stretched over newly fired terracotta tiles and lets it dry. He advises:
Do not spread it too thickly, because then it will not dry quickly. When there is too much moisture it will mildew, and make an ugly color. When a tile has absorbed a lot of moisture, take another new tile. In this manner, it will dry more quickly. When it is dry, remove the coating from the linens. This will be a good lake for painters, as I have made many times in Pisa. Take note that if the color is too strong you should use more roche alum and if it is too weak use less alum so that the color is according to your taste, and desire.
Through the fifteenth century, kermes was among the most sought after pigments, but by Antonio Neri's lifetime, its use was declining in favor of a new insect-based red called cochineal that Portuguese traders brought back from Mexico. Cochineal bugs inhabit the prickly pear cactus. They give a more intense color and eventually replaced kermes throughout Europe.

*This post first appeared here on 26 February 2014.

Monday, March 21, 2016

Carries The Palm

Entry into Jerusalem, Pietro Lorenzetti 1320
For Western Christians, this week began with "Palm Sunday," a feast day that falls on the Sunday before Easter and celebrates Jesus' entry into Jerusalem. His procession is said to have included his followers laying palm tree leaves before him along his path. The connection to seventeenth century priest and glassmaker Antonio Neri is this: In his book L'Arte Vetraria, Neri describes his very best green glass with a colloquial expression; saying the recipe "carries the palm" for all other greens.   


Saint Justina of Padua with a palm frond,
Bartolo Montagna 1490s
In his book, Neri presents a string of recipes for variations of green glass. Finally, in chapter 35, he presents his ultimate green, which he titles: "Another Green, Which 'Carries the Palm' for All Other Greens, Invented by Me." The phrase "carries the palm" alludes to the biblical story of Jesus entering Jerusalem, in which the people welcomed him by laying down cloth and palm branches on the ground in his path. Even before that, the palm branch served as a symbol of victory; in ancient Greece, palm fronds were awarded to victorious athletes. Later in history, Roman lawyers who won a case decorated their doors with palm leaves.


Copper Sulfate (vitriol of copper)
Cristallino was a mid-grade glass made with a soda based plant ash from the Levant which Neri called "rocchetta." For this recipe, he blends it with common glass, and adds red lead oxide to the mix, in effect forming an early version of what we now call lead crystal. He "cleans" the glass by using the well-established technique of flinging the molten glass into a large tub of clean water. This had the effect of "washing out" excess glass salt (flux). In addition, it provided the opportunity to sort through the fragments to remove any undissolved metallic lead. Lead that did not go into the glass had the tendency to collect at the bottom of the clay crucible as lumps of molten metal. It could then eat a hole in the vessel, resulting in a glass-shop disaster, as Neri warns: 
All lead precipitating out of the glass must be removed with diligence, throwing it away, so that it does not make the bottom of the crucible break out, as can happen. Return the glass that was thrown in water to the crucible and leave it to clarify for a day. Then add the color using the powder, made chemically by the dry distillation of vitriol of copper [chapter 31]. Also, add a little crocus of iron, but very little. The result will be a most marvelous beautiful green, the best that I ever made. It will seem just like an emerald of ancient oriental rock, and you can use it in every sort of job.
The "crocus of iron" mentioned above is simply iron oxide or 'rust' as it is more commonly known. The "vitriol of copper" he refers to is copper sulfate. Neri forms it in a laborious process that involves cutting copper sheet into small, coin-sized pieces, mixing it with sulfur, heating in the furnace and then reprocessing it several times. The result is then added to water and the soluble part is further processed, filtered and evaporated. The final product is a pure blue crystalline material that has uses for our alchemist that go far beyond glassmaking, as he alludes to in the final sentence of the book:
Although I have placed here the way to make this powder with much clarity, do not presuppose that I have described a way to make something ordinary, but rather a true treasure of nature, and this for the delight of kind and curious spirits.
*This post first appeared her in a slightly different form on 25 October 2013.

Friday, March 18, 2016

The Sisters of Antonio Neri

Portrait of the Egerton Sisters
(no relation to Neri)
English School,  c. 1601-1602
Among the ten children born to glassmaker Antonio Neri’s parents, three of them were girls; Lessandra, Maria, and Lucrezia. Because women were not allowed to legally own property, or sign contracts many of the usual sources of information are silent. Most of what we can learn about them is through their relationships with the men around them.

The Neri's were a patrician family, and the children enjoyed a very comfortable existence for the late sixteenth century. There is evidence that all three sisters survived into adulthood. Lessandra was the first-born, nine years older than Maria, and twelve years older than Lucrezia. 

When Lessandra was around age seventeen, her famous father, Neri Neri, was appointed as personal physician to the newly crowned Grand Duke Ferdinando de’ Medici. However, only a few short years later their mother Dianora died at age 42, of causes that are unknown, perhaps childbirth. The girls were 22, 13 and 10. A few short years later they lost both their father, and a brother.

Two information sources for the Neri sisters are their birth records kept at the Opera del Duomo and genealogy records for the family which are filed at the National Archives, both in Florence. The baptism records hold a wealth of indirect material through the names of their godparents. While these do not tell us anything specific about them, it does tell us who their influences were; who they looked to for strength and spiritual guidance, under the circumstances, this is the best we can do. 

Lessandra (b. 1572) claimed Baccio Valori as her godfather. The Valori family had a long, tragic history with the ruling Medici family. His father, grandfather and great-grandfather were all close Medici supporters, yet each ended up exiled, imprisoned, or executed after relationships soured. On one hand he was faithfully employed by the Medici, yet he reportedly spent a good deal of his time collecting letters and papers documenting his family’s close support of Girolamo Savonarola, the firebrand Dominican priest who lead Florence in the late 1490s, after the Medici had been temporarily expelled from the city.   

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

The genealogical records imply that Lessandra later took vows with the S. Agata monastery on the North end of Florence and took the name suor Emilia.

Maria’s (b. 1581) godfather was Monsignor Giovanni Alberti. Giovanni was the son of a Florentine senator. He served as protonotary apostolic for Pope Gregory XIII and as bishop of Cortona under Pope Clement VIII. A godfather serving in the papal inner chambers was a good family contact indeed. Also appearing for Maria was Pierfilippo Perini, a physician and lawyer. The Registri lists Maria Neri's godmother as Alessandra di Girolamo Pepi. Among the prominent Florentine republicans was Alessandra's father, Girolamo. He was tortured by Alessandro de' Medici in the 1530s, upon the family's regaining control of Florence after the siege.

The genealogy indicates that she married into the Boscoli family, but further work is needed to identify a specific individual.

Lucrezia (b. 1584), the youngest Neri girl, has a single godparent listed in the register, Montiglio degli Albizi. The Albizi family boasted powerful bankers and politicians. This was another case where deep divisions over Medici rule drove a family apart. Perhaps the best-recognized member of the Albizzi family was Eleonora degli Albizi. She was the young consort of grand duke Cosimo I. Folklore has it that in 1566, Cosimo intended to retire from public life and marry Albizi quietly, after the birth of a girl, but his regent son, Francesco I, forbade it to due to the inheritance complications that would ensue. The story is that Cosimo's long-time personal secretary, Sforza Almeni, leaked word of the clandestine marriage to the family. For his betrayal, an enraged Cosimo murdered Almeni in cold blood. Eleonora later gave birth to Don Giovanni de’ Medici, the uncle and friend of Don Antonio, Neri's sponsor. The specific Albizi family member we are interested in, Lucrezia's godfather, Montiglio degli Albizi, seems to have eluded history. Lucretia married into the Talenti family, but no further details are known.

Wednesday, March 16, 2016

Rise and Fall

"Merry Company," (1623)
Gerard van Honthorst
The first decade of the seventeenth century was a golden era for glass in Tuscany. The Venetian techniques brought to the region by Grand Duke Cosimo de' Medici in the 1570s had been assimilated. The pioneering work of his son, Francesco, in cross pollinating different crafts under one roof, was by now bearing fruit in unique items that included the handiwork of glass artisans. Grand Duke Ferdinando understood the value of glass as a source of prestige and was willing to invest in it. This was the environment in which Antonio Neri first learned to make glass. Delicate drinking glasses were the toast of the aristocracy throughout Europe. The material was critical to the advancement of chemistry, medicine and by the end of the decade astronomy. 

In 1602, Antonio Neri came to work in the shop of Niccolò Sisti in Pisa. While Sisti was making fancy glassware for the Medici court, the nearby Coscetti firm was supplying Pisa with everyday items. Coscetti made glassware for private homes, but also innkeepers, spice and perfume sellers, winemakers and a baker among others. Their wares included cruets for oil, saltcellars, carafes, drinking glasses, containers for holy water, reliquaries, gilded Venetian style cups and English style flasks. 

By the second decade, momentum started to shift and before long, the glass industry in Tuscany fell on hard times. Apparently the demand for glass could not support the number of factories that had started and the rapid succession of leadership in the duchy added uncertainty to patronage of the arts in general. 

Another factory in Pisa was run by Giovanbattista Guerrazzi, who had acquired the exclusive right to make Venetian style cristallo from Neri's old employer Sisti. In 1623, Guerrazzi had problems of a different sort, not directly related to the sales of glass. He appealed to Pisa’s Office of Rivers and Ditches, pleading with them to modify a recent ruling. He explained that he owned three houses next to his furnace, one for his family and the others functioning as sales space and housing for his workers. Since he was the exclusive maker of cristallo, he had employed a number of girls and women to decorate the delicate glassware, and a constant stream of the nobility showed up to watch the work being done. Guerrazzi's problem was that the Magistrate of Public Decency had recently published a list of seven places where women of "ill repute" were allowed to stay. One of these was located next door to his glassmaking operation. He begged for a change in the ruling, to move his new neighbors elsewhere.

The outcome of his appeal is not known, but Guerrazzi was succeeding in the glass business, and at the same time accelerating the demise of his competitors. He bought-out and demolished the furnaces of a number of other glassblowers and planned the same fate for the Coscetti operation, putting all the craftsmen there out of work. In the mid 1620s, after a quarter century of operation, the fires under Coscetti furnace were allowed to go out forever. Furnaces at Leghorn, Pistoia and Prato had shuttered, leaving only the one furnace in Pisa, two in Florence and two at the castle of Montaione. 

*This post first appeared here on 12 Dec 2013.

Monday, March 14, 2016

Kitchen Alchemy

Tesoro del Mondo, "Ars Preparatio Animalium"
Antonio Neri 1598-1600, f. 10r (MS Ferguson 67).
Between 1598 and 1600, Antonio Neri wrote a manuscript filled with alchemical recipes. He entitled it Tesoro del Mondo or "Treasure of the World" and stated that it was a book in draft form, intended for publication. It never did see the ink of a printer's press, but Neri's original did survive intact and today occupies a place of pride in the Ferguson Collection of the University of Glasgow Library. [1]

Tesoro is an ambitious work, devoted to "all of alchemy," containing numerous hand-drawn ink and watercolor illustrations; some of the pictures are allegorical, many others document practitioners working with equipment. Only passing reference is made in this manuscript to glass—its most notable appearance is as experimental vessels. 1598 was two or three years before Antonio's glassmaking career is thought to have started. His life was busy on other fronts. He had just been ordained as a Catholic Priest, undergoing the laying on of hands ceremony, probably by his neighbor on Borgo Pinti, the Florentine archbishop Alessandro Ottaviano de' Medici. 1598 was also a year of tragedy for the Neri family; by the summer, his father Neri Neri, personal physician to the grand duke, died of an unknown illness, but not before making arrangements for his family, which included a will. A court magistrate would oversee the now orphaned children's education, inheritance and dowries. They would soon suffer further tragedy in the unexpected death of a brother; sixteen year-old Emilio would leave them on Christmas day of the following year, in Castello outside Florence. 

The losses must have been devastating. In 1598, five of the nine children were still under the age of twenty. Without a mother or father, great responsibility must have fallen on the shoulders of the matriarch of the house, the children's elderly paternal grandmother Maddalena. [2] Even though the Neri's were a wealthy and quite well respected family, these events undoubtedly threw their lives into turmoil. It is in these circumstances that Antonio started his manuscript. The tragic events allude to the reasoning behind a cryptic Latin quote scribbled at the top of a page above the first recipe: "fuimus troes." It means, "We are Trojans no more" From Virgil's Aeneid, referring to the fall of Troy. [3] 

Early in the manuscript there is a series of four illustrations, each showing a different activity, In order, they are titled The Art of Preparation of Stones, Metals, Plants and Animals. [4] Each is filled with multiple workers engaged in various activities pertinent to the specific art. Each highlights interactions between the Aristotelian elements: air, water, earth and fire. There is no specific indication of where any of the four scenes take place, although some educated guesses can be taken. For instance, the stone workers, or lapidaries, almost certainly are an early incarnation of the famed 'Opificio delle pietre dure' working in the Uffizi's Galleria dei Lavori. But we will leave that discussion for another time. 

Of the four illustrations, "Preparing Animals" focuses on activity within a kitchen. (See above, click to enlarge). The scene is intriguing in that it appears to take place in a domestic setting. Labels call out the four Aristotelian elements; birds hanging from the rafters represent air, fish on a grilling rack represent water, a whole carcass on the spit represents earth and fire appears as itself in several locations. I would like to suggest that this setting is none other than the Neri family kitchen and that the practitioners of the art are three of Antonio's siblings. In the middle right, a young boy is engaged in turning the spit (in green). The best candidate would be then eleven year-old Alessandro, the eventual heir to the family, whose own son named Neri would carry on the family practice as a physician. Of the two young women pictured, the three family choices are fourteen year-old Lucretia, Sixteen year-old Maria and twenty-six year-old Lessandra.

In addition to preparing finished meals, seventeenth century kitchens were busy making more basic ingredients also; preserves, distillations, special salts, herbal extracts and so forth. In addition to foods, medicinal and hygienic products were produced, like syrups and soaps. There is another strong connection between the kitchen and alchemy that lives on today: the methodology of cooking. The process of combining raw ingredients and cooking them together, of experimentation and of iteratively refining a recipe to perfection, this is not so different from what Antonio Neri and his siblings were doing four hundred years ago.


[1] Neri 1598-1600.
[2] Maddalena di Bartolomeo di Niccolò Bartoloz[z]i, married Jacopo Neri, and they gave birth to Antonio’s father Neri Neri. (ASF 599).
[3] Fuimus Troes, fuit Ilium, et ingens Gloria Teucrorum. [We Trojans are at an end, Illium has ended and the vast glory of the Trojans], The Aeneid: Book 2, Line 325.  See also the post in this blog (Conciatore.org) dated 13 June 2014.
[4] Neri 1598-1600, ff. 7r, 8r, 9r, 10r.
* This post first appeared here on 27 August 2014,

Friday, March 11, 2016

Dianora Parenti

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

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

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

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

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

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

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

This post first appeared on 11 September 2013.

Wednesday, March 9, 2016

Sara Vincx

Still life with façon de Venise wineglass,
Alexander Adriaenssen (1587-1661)
Antwerp.
In the 1590s, after the death of her husband, Sara Vincx ran a successful glassmaking business in the city of Antwerp. In the midst of a major war, she presided over a furnace where craftsmen from Murano, Italy made fine cristallo glassware for the elite families in Flanders. Vinx is the first documented female owner of a glass furnace anywhere.

The Dutch Eighty Years' War for independence from Spain was heating up in Flanders; towns were being pillaged and burned to the ground throughout the Low Countries. Even so, Vincx ably managed a crew of expert glass artists and brought her company's wares to market. When competitors tried to duplicate her products, she successfully defended her shop in court. Later, she remarried to Filippo Gridolfi, one of her foremen at the furnace. The two went on to open a show-room on the Meir, the most prestigious sales district of the city. They also welcomed glassmaker Antonio Neri to work at their facility. Neri was living in the city on an extended seven year visit to his friend and fellow alchemical experimenter Emmanuel Ximenes. 

The seven years that Antonio Neri spent in Antwerp were arguably the most formative for his knowledge of glassmaking. While his first exposure to the art was in Italy, a large portion of the skills and recipes exhibited in his recipe book, L'Arte Vetraria, trace to his activities in the Low Countries. Neri writes "This will make a beautiful aquamarine so nice and marvelous, that you will be astonished, as I have done many times in Flanders in the city of Antwerp to the marvel of all those that saw it." On tinting rock crystal: "In Antwerp, I made quite a bit of this, some ranged in tint from an opal color that looked very beautiful, to a girasol, similarly nice." On equipment: "In Antwerp, I built a furnace that held twenty glass-pots of various colors and when fired for twenty-four hours everything fused and purified." He also speaks of chalcedony glass, paste gems  and ultramarine paint all crafted in Antwerp.

Neri was apparently on good terms with Vincx and Gridolfi, perhaps he was introduced through Ximenes, one of the wealthiest men in the city. In his book Neri describes Gridolfi as "a most courteous gentleman." Vincx and Gridolfi possessed exclusive rights in the region to produce cristallo glass in the Venetian style (façon de Venice) a type of glass that Neri was already quite familiar with from his time making glass in Florence and in Pisa. The license, or patent as it was called, passed down from previous owners, was quite a valuable part of the operation. Employed in their shop was a steady stream of craftsmen from Murano. They made the finest glassware for the upper classes of Antwerp and surrounding areas. Because these craftsmen were bringing the secret techniques with them, they worked outside of the guild system, which would have otherwise required them to share their techniques with other artisans. Through special arrangements with the local authorities, the Venetians were exempt from joining. 


Sara Vincx (or Vincks) was the widow of the former owner, Ambrogio de Mongarda. Gridolfi had previously worked in the shop under Mongarda, who had been in the business for twenty years. Vincx was pressed into service by unhappy circumstances. In 1594, Ambrogio returned alone to Venice to recuperate from gout, but by the following year he was dead, leaving Sara to both run the glass shop and care for at least eight young children. Sara Vincx carries a distinction as the first documented female owner of a glass furnace anywhere. She took an active role in the business as attested by lawsuits she filed, and won, against rival shops that violated her patent. Records show she also expanded the furnace and hired two new artisans to increase production.

Despite the war and the blockade of the Scheldt River, which shut down trade by sea for a number of years in Antwerp, the glass furnace there thrived and reached its zenith under Vincx and Gridolfi. Soon after their marriage, seventeen employees were counted working at the shop. They established their own retail presence on the Meir, selling high-end cristallo within steps of the Ximenes palace. Their glass operation enjoyed top-rung status, and no doubt, Antonio Neri's involvement must have bolstered the reputation of the firm even further.

*This post first appeared here in a shorter form on 4 October 2013.

Monday, March 7, 2016

Béguines of Malines

A Béguine of Antwerp,
from Pierre Hélyot,
L'Histoire des ordres monastiques… 1719 (v.8)
Five years into his stay in Antwerp, on 21 February 1608, Antonio Neri posted a letter to a friend in Florence. The letter was addressed to the house of Zanobi Bartolini—likely the son of Neri’s late former landlord Alamano, also the nephew of Emmanuel Ximenes, Neri’s host in Antwerp. The letter provides strong evidence that however much time Neri devoted to making glass, he also devoted considerable attention to his interest in medicine. 

In this letter, the priest describes his success with medicinal cures. He also references experiments he carried out in Brussels and at the Hospital of Malines, in Mechelen. In particular, he praised Paracelsus’ recipe for ‘theriac of mummy,’ and its superiority to Galen’s ‘theriac magna’. Theriac was an ancient medicinal remedy, often taking the form of a thick honey based syrup. It often contained numerous herbal ingredients. It was thought to be a cure for any poison and used as a way to stave off the plague. Mummy or mumia was a compound composed of just what one might think: the ground up flesh of ancient Egyptian bodies. 

The Hospital of Malines was an ancient one, started in the thirteenth century by a society of lay Catholic women called Béguines. In their 1907 book A History of Nursing, Dock and Nutting note:
Through the whole time of the active career of the Béguines, nursing remained an important branch of their work. One of their most beautiful settlements was at Malines, where there were over 1500 Sisters, not including their dependents. This would appear to have been a nursing center of importance, for Helyot says that the nursing in many hospitals was provided for by orders arising from the Béguines of Malines. […] The building were surrounded with extensive gardens and trees, and had an ample water supply. ‘The sick were nursed there’ he [Helyot] wrote ‘with all the skill, refinement and sweetness that might be expected from the appearance of the place. [1]
The Béguines were not nuns. They did live in communal housing, and did devote themselves to a pious lifestyle, but without formal cloister, without renouncing their possessions, and taking only a temporary vow of chastity, able to leave at any time, for instance to get married. They formed corporations throughout the Low Lands and into France and Germany that were self sustaining and largely independent of local control. These were huge organizations of women, working for themselves, under their own roofs and by their own rules. They produced crafts and textiles, they schooled nurses and they ran hospitals. Because they existed on the fringes of Church control, they were downplayed or even resented within the hierarchy. One result is that their achievements have largely been forgotten by history. When Mathias Hovius, the Archbishop of Mechelen, toured the facilities in 1601 he took the petty action of requiring Béguines who chose to keep lap-dogs to pay a fine to the Church. In 1630, Bishop Malderus of Antwerp defended the women in an extraordinary letter. He wrote,
The Order of the Béguines is truly not a religious order, but a pious society, and compared with the former complete consecration is as a preparatory school in which the piously inclined women of Belgium live after a pattern highly characteristic of the temper and mind and the character of the people. For this people is jealous of its liberty and will be led rather than driven. Although it is beyond a doubt more meritorious to devote one’s self to the service of heaven by vows of perpetual chastity, obedience, and poverty, and though there are many pious women in Belgium who are so disposed, yet most of them shrink from this irrevocable vow. They prefer to remain inviolably chaste rather than to promise to be so; they are willing to obey, but without formally binding themselves to obedience; to rather use their poverty in reasonable outlays for the poor than to give it at once up for good to all; rather voluntarily renounce daily the world than immure themselves once and forever.[2]
At the beginning of the seventeenth century, the hospital was used to treat wounded Spanish and Italian soldiers fighting in the war against the Dutch. By 1607, just before Antonio Neri wrote his letter, the staff at the hospital numbered fifty, “including seven doctors, eight surgeons, and three surgeon’s mates.”[3]

As the son of a grand duke’s personal physician and grandson of a surgeon, there can be little doubt that Neri had ample familiarity with medical procedure. It seems likely, given the circumstances, that in Mechelen he was lending his expertise to ease the ravages of war, helping to heal wounded soldiers.

[1] Lavinia L. Dock, Mary Adelaide Nutting, A History of Nursing (Putnam, 1907) v. 1, p. 268.
[2] Ibid, p. 269.[3] Geoffrey Parker, The Army of Flanders and the Spanish Road, 1567-1659 (Cambridge Univ. Press, 2004), p.141
[3] Ibid, Dock, Nutting 1907.
* This post first appeared here on 26 Mar 2014.

Friday, March 4, 2016

Women in Alchemy

Antonio Neri, 1598-1600,
MS Ferguson 67, f. 25r.
It is certain that women have participated in the practice of alchemy since its beginnings, but hard documentation is scant. Maria Prophetissima, also known as Mary the Jewess, is perhaps the best known female alchemist. None of her writings have survived, but she is thought to have lived around the third century. Legend tells that the "bain-marie" (double boiler) is named after her.

In the seventeenth century, One of Antonio Neri’s manuscripts, entitled Tesoro del Mondo (Treasure of the World) depicts three women running chemical equipment. It is possible that these were nuns, trained in the same Church sponsored educational system that produced Neri. Convents were often expected to be self-sufficient and many ran their own pharmacies. Neri had sisters as well as brothers and at least one sister entered a convent located on the north side of Florence, near the laboratory where Antonio practiced alchemy and made glass. The fact that specific names have not been associated with Neri’s three female co-workers should not deter us from celebrating their contribution to the birth of early modern science.

Within a year of his ordination in the Catholic Church, Antonio Neri began an ambitious treatise, illustrated in his own hand, devoted to "all of alchemy." Six of the illustrations in this manuscript, completed in 1600, show women tending equipment. It is not remarkable that some alchemists of the 16th century were women, what is remarkable is to find them in the historical record. Direct depiction of female participation in alchemy is otherwise extremely rare. 



Two pictures in the Neri manuscript show female alchemists at
Antonio Neri, 1598-1600, 
MS Ferguson 67, f. 35r.
work. In both cases, the technician stands behind a dedicated piece of apparatus, facing forward, giving the impression of propriety in an arranged portrait. In other words, Neri is drawing his co-workers at their stations, practicing their art. The first drawing depicts a furnace and vessels used to make liquid mercury from its ore. The other shows a different type of furnace with a 'tower,' used as an efficient way to cook ceruse (white lead oxide). These images are part of a larger set of two dozen similar drawings that each illustrate the equipment used to prepare a specific product, many include a furnace and glassware. Nine of these show a single individual, (or in one case two men) tending the equipment. Because the manuscript is a recipe book, it contains almost no personal information. However, the context of these illustrations indicated that like their male counterparts, the individuals depicted all have specific responsibilities and specializations within the workplace.


Three other illustrations in the manuscript are notable for their engagement of women. These pictures show details of kitchen and nursing work; what might be termed more traditional female roles in the sixteenth century. Two of these illustrations are devoted to the respective arts of preparing plants and animals. They show women working alongside men performing various tasks. A third illustration shows medicinal fogging tents tended by a woman. Inside one tent, a male patient sits naked on a bench, exposed and breathing fumes pumped in by a large vessel perched over a fire. Similar arrangements are known to have been used to treat skin lesions caused by leprosy and syphilis.
Antonio Neri, 1598-1600, 
MS Ferguson 67, f. 37r.
The circumstances in these images present other possibilities to Antonio Neri's work environment. One is that the scenes take place at the Neri household on Borgo Pinti in Florence. Antonio's father was the personal physician to Ferdinando de' Medici, the grand duke of Tuscany. He was also the head of the college of physicians, and presumably ran a thriving private practice. The women may be Neri's siblings or other family members. 

Another possibility is that we may be looking at operations inside the Casino di San Marco soon after prince Don Antonio de' Medici's occupation of the facility. This palace laboratory had a reputation for medical cures that extended throughout Europe. Don Antonio spent extravagant sums to learn alchemical and medicinal secrets. The glass furnace here, which had employed masters from Venice is where Neri began formulating glass. The presence of women among his colleagues indicates a social setting with a camaraderie not displayed in other alchemical works of the period. 

* This post first appeared here on 17 March 2013 in a slightly different form.

Wednesday, March 2, 2016

Caterina Sforza

Caterina Sforza, by Lorenzo di Credi
(now in the Museum of Forlì.)
Antonio Neri is remembered mostly for his book on glassmaking, L'Arte Vetraria. However, he considered himself first and foremost an alchemist. This interest can be traced to at least two generations before him; his father, Neri Neri, was an acclaimed physician – in fact, the personal physician to Grand Duke of Tuscany, Ferdinando I de’ Medici. Antonio's grandfather, Jacopo Neri, was a barber-surgeon. Both of these professions required an extensive knowledge of herbal distillation and other techniques which are shared by alchemists.

Antonio's benefactor, Don Antonio de' Medici, also followed a family passion for the chemical arts, in his case, traceable through an unbroken chain, to a female alchemist, his great-great-grandmother, Caterina Sforza, (c.1463–1509). After her death, over four hundred of her formulas were passed down to her son, Giovanni dalle Bande Nere, then to his son Grand Duke Cosimo I de' Medici, Grand Duke Francesco I, and finally to Don Antonio. 

Caterina was the illegitimate daughter of the Duke of Milan, Galeazzo Maria Sforza, but was still educated at court. At age fifteen, she was married to a nephew of Pope Sixtus. The pope granted her title of Countess of Forlì and Imola. After her territory was later taken and her husband murdered (by a faction of their own people), she escaped prison and retook the two cities. In 1495, when her second husband was assassinated, she launched a campaign which gutted the families of the murderers. Her third husband was Giovanni de' Medici, and their son, named after his father would become a brilliant military strategist, like his mother. His own son, Cosimo, would later become the first "Grand Duke" of Tuscany. 

Her chemical recipes were transcribed in 1525 by a captain in her son's army, Count Lucantonio Cuppano da Montefalco, and ultimately published as a book in 1893 (Passolini). Included are an assortment of formulas which range from cosmetics, to medical remedies, poisons and alchemical concoctions.
Researcher Jacqueline Spicer writes:
Lost among the romanticized military conquests is a thorough account [of] the project that occupied several years of her life—the manuscript of her alchemical and medical experiments and recipes titled Gli Experimenti de la Ex.ma S.r Caterina da Furlj Matre de lo inllux.mo S.r Giouanni de Medici, or Gli Experimenti. The text is an early example of what would later become the popular medical genre of "Books of Secrets", but is so early that it does not appear in most modern writing on such books. Furthermore, Gli Experimenti is unusual because it was written by a woman in an otherwise male dominated genre, and unique in that we know a great deal about the life of its author.[1]

Among the alchemical entries are "to convert pewter into silver of the finest quality and of standard alloy," a method "for giving to bars of brass a fine golden color" and another for "for multiplying silver." Also, there are ways described  to "make iron hard," "to dissolve pearls" and "to dissolve all metals." In the medicinal category, we find "for infirm lungs, an ointment is to be made of the blood of a hen, a duck, a pig, a goose, mixed with fresh butter and white wax." This was to be applied to the chest with a fox's skin.
Sandro Botticelli, Primavera (1498)
(detail - rightmost of the three graces)

Caterina Sforza was painted many times and often depicted as the Virgin Mary, a typical trope for the nobility at the time. She may have been immortalized  by Sandro Botticelli as the rightmost of the three graces in his Primavera and as the main subject in The Birth of Venus.[2] Reportedly, she was the subject of ballads and sonnets, although most have been lost. She is a topic of discussion in Niccolò Machiavelli's famous treatise The Prince

In the end she was captured, raped and imprisoned on the orders of Pope Alexander VI, who justified her incarceration, in the Vatican's  Sant'Angelo Castle, by claiming she tried to poison him. She survived the ordeal, but after release entered the convent of the Murate nuns in Florence, and died, in 1509, at the age of forty-seven. She was buried at the convent, in the same city where her future great-great-grandson, Don Antonio, along with Antonio Neri, would perform their own alchemical experiments and help usher in the age of  modern science.

[1]https://sites.eca.ed.ac.uk/renaissancecosmetics/cosmetics-recipes/caterina-sforzas-experimenti/ also see  http://edinburgh.academia.edu/JacquelineSpicer.
[2] Another possibility for the model of Venus was Simonetta Vespucci.
*This post first appeared here on 27 January 2014.