The Rise and Fall Reprise

"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. 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.

Francesco's Studiolo

The Studiolo of Francesco de' Medici,
Palazzo Vecchio, Florence.

In all likelihood, Antonio Neri started his glassmaking career around 1601 in the laboratory palace of Medici prince Don Antonio. The Casino di San Marco is located on the north side of Florence, not far from where the old city walls once stood. It was purpose-built as a laboratory by Don Antonio’s father, Grand Duke Francesco and stands on the former location of the sculptural school that Michelangelo attended as a boy. The Casino is a remarkable structure in the history of science, however, our subject today is not the laboratory but one of its primary inspirations, located across town in the Palazzo Vecchio; The Studiolo of Francesco de’ Medici.

Books of secrets, like Neri’s L’Arte Vetraria exposed methods to transform nature. Cabinets of curiosities, on the other hand, celebrated the finished products as well as nature’s ready-made treasures. These so-called cabinets were a sort of physical counterpart to books of secrets. Starting as small collections of exotic objects, princes and nobles strove to out-do each other and the largest examples encompassed entire rooms. In the early 1570s, at around age thirty, Francesco de’ Medici initiated a special project; he constructed a secret room in the Palazzo Vecchio. [1] Accessible through a concealed staircase in his bedroom, this small, but opulent, study chamber was devoted to natural curiosities and secrets. The “Studiolo” contained his collection of rare gems, exotic seashells, animal horns, chemicals, potions, scientific instruments and other strange and wonderful treasures collected from around the world. 

From floor to barrel-vaulted ceiling, paintings and niched sculptures covered the chamber walls. Celebrated artist Giorgio Vasari designed and constructed the secret room in partnership with Vincenzo Borghini, a Benedictine priest and close Medici advisor. [2]  In all, thirty-two of the city’s artists contributed to the project, although most had no idea where their work was destined to hang. Francesco organized paintings such that each wall was themed by one of the four Aristotelian elements: air, earth, water and fire. Behind nineteen of the lower paintings, cabinets housed the treasures of Francesco’s collection. From within the Studiolo two other secret passages were accessible from behind concealed panels. One leads to a smaller private treasury once used by Francesco’s father, Cosimo and another leads down a stairs to an unmarked outside door on the street. [3]

Part study and part museum, Francesco used the Studiolo to escape public life and explore the secrets of nature. This menagerie and ones like it were an outgrowth of the wunderkammer or “cabinet of curiosities.” Early in their evolution, they took the form of single pieces of furniture for the display of collections. Monarchs and nobles throughout Europe boasted collections of ever-increasing size and diversity. In a way, the Casino di San Marco was the next evolutionary step; from a cabinet of curiosities, to a study room, to an entire facility devoted to nature’s secrets. 

The paintings in Francesco’s Studiolo depict various religious, mythological, historical and industrial scenes. [4] Some of them show various royal workshops documenting activities as diverse as goldsmithing and wool dying. A 1571 painting by Giovanni Stradano [5] is entitled the Alchemy Studio. It shows Francesco I in the Uffizi surrounded by laboratory equipment and workers. 

[1] Constructed between 1567 and 1675, cf. Feinberg 2002, Edwards 2007.
[2] Giorgio Vasari (1511–1574), Vincenzo Borghini (1515–1580).
[3] Via della Nina.
[4] Feinberg 2002.
[5] Giovanni Stradano, also called Jan van der Straet (1523–1605).

Making Connections

Plaster Medallion of Neri,
La Specola  (Florentine Natural History Museum).

In the past few weeks, we have investigated the identity of the specific Catholic sect to which priest, alchemist and glassmaker Antonio Neri belonged. We have seen a glimpse of the number and diversity of possibilities but really only scratched the surface. Today, the Church is often portrayed as a tightly organized, monolithic organization. It is a misleading characterization now and it was even more so in Neri’s early seventeenth century Florence. Religious based organizations were as prolific as weeds and were the way things got done in all aspects of society. The trade guilds ran religious charities, monasteries ran schools, government offices were administered by churches, lay organizations ran hospitals and on and on. It is quite possible, even likely, that Neri was associated with more than one institution over his lifetime, which complicates the picture even more.

Until definitive records turn up—and they may never turn up—Antonio Neri’s religious training, and therefore his education in alchemy will be open to conjecture. Since archdiocese records from the period around his lifetime were destroyed in a fire, evidence is thin and scattered but that is no reason to abandon the search. In fact, getting down into the weeds is one of the best ways to learn about history, from individual characters.

Torbern Bergman, a famous Swedish naturalist who lived in the mid-eighteenth century wrote briefly but knowledgably about Neri and glass. It is interesting to note that Bergman, working with his student and friend Carl Scheele were the first to isolate Manganese in its metallic state. The two men are credited with the discovery and were well aware of its critical importance in glassmaking. This blog has explored Neri’s varied uses of manganese oxide (its main ore) for both coloring and decoloring glass. Bergman conducted extensive experiments trying to fuse various minerals with glass fluxes over an oil lamp with a blowpipe.

Bergman’s exposition on Neri appears in his History of Chemistry in The Middle Ages surveying developments in the chemical arts that had occurred over the previous few centuries. That work was translated into Italian by another interesting character named Giuseppe Tofani. [1] “Tofani,” it turns out, is a pseudonym for, Felice Fontana the man charged with beginning “La Specola,” the Florentine natural history museum, the first of its kind anywhere. To his translation of Bergman, Fontana adds extensive annotations, much of it about Neri. He quotes at least one manuscript, [2] that identifies our priest in several places as “R.P.D. A. Neri” implying [Reverend Priest Dominican*, Antonio Neri]. He also cites references that hint at the connection to the Canons Regular (through Neri’s confessor Benedetto Vanda) and the connection to the Knights of Malta through Neri’s benefactor Prince Don Antonio de’ Medici.

Hanging on the walls of the natural history museum today are a series of old plaster “medallions,” each showing a bas-relief likeness of an early Italian investigator in profile. The origins of some of these are not clear, including the one dedicated to Antonio Neri (see image above), yet it is clear that the museum’s founding director, Fontana, was thoroughly familiar with the alchemist-priest, his associates and his exploits.

One final connection. Fontana’s translation is dedicated to a Knight of Malta named Deodato Dolomieu. Neri’s sponsor, Don Antonio, was a fellow Knight and Neri is placed by one account at their primary church in Florence. Dolomieu was a colorful character. He was a French aristocrat, inducted into the Knights at the tender age of two. At eighteen, he killed a man in a duel and was sentenced to life in prison, a verdict that was commuted by the pope. He learned natural science from an apothecary whose daughter accepted his hand in marriage. He became a dedicated geologist and while on an expedition in the northern mountains of Italy, noticed a “form of limestone that is not attacked by acid,” the mineral and the mountain range are both now named “Dolomite” in his honor.

[1] Bergman, Tofani 1790.
[2] ibid, p. 106.
* 12/12/14 - actually RPD = "Reverendus Pater Dominus" [Lord Reverend Father], a title popular in the Canons Regular.

Royal Apothecary Reprise

Fresco, early 16th century speziale,Castello di  Issogne, lower Aosta Valley, Italy.

As physician to the Medici royal family, Antonio Neri’s father (Neri Neri) worked closely with the other medical professionals in Florence. Among them was Stefano Rosselli, the royal pharmacist, who owned the Speziale al Giglio in the center of town.  We would readily recognize this shop today; rows of labeled jars lined the walls holding exotic remedies and ingredients from around the world. Freshly made sweets, cakes and other confections sat on the counter to entice customers. 

One of several such shops located around the city, ‘speziali’ dealt with medicines and herbal remedies, but also a wide variety of other needs, from pigments for artists, to the distillation of spirits, to the rental of funerary equipment, to raw materials for alchemists. Each shop had its own specialty to distinguish itself from the others. To some extent, they also competed with private operations run by convents and monasteries. Rosselli’s shop was famous for catering to the Medici family and courtiers, and as such he could command premium prices. But the function of these shops was not all business; they also proved popular meeting places for the local intelligentsia. Poetry, literary and other groups with various interests often congregated in the back rooms of the speziali.

Stefano Rosselli came from a family that was a mixture of artists and pharmacists. His father Romollo, with a degree from the university at Pisa, was a specialist in herbal remedies (simples). His brother Antonio (Fra Anslemo) worked at the pharmacy of San Marco, directly across the street from the Casino where Antonio Neri would later make glass. Their grandfather Bernardo Rosselli was a painter, a favorite of Michelangelo. Stefano’s daughter Fiametta joined the Dominicans as a nun, and became the famous sculptress Suor Caterina Eletta. A distant cousin was Cosimo Rosselli, who returned from Rome with a small fortune, earned painting for the pope. Biographer Giorgio Vasari noted that Cosimo could have lived comfortably on those earnings had the passion for alchemy not overtaken him. 

Stefano proudly maintained a proprietary list of treasured recipes gathered over a lifetime of experience. Some were given to him directly by Grand Duke Cosimo de’ Medici, his son Francesco and daughter Isabella. Between 1589 and 1593 when Rosselli was in his late sixties, he started to compile these into three notebooks, which he eventually passed down to his sons and today have survived the ravages of time. The three books are devoted to medicines, perfumes and confections. Antonio Neri was a teenager in this period, and it is easy to imagine an occasional visit to the Speziale al Giglio for a piece of something sweet, perhaps one of Rosselli’s excellent pistachio calissons.

For a transcription and French translation of the recipes see: Rodrigo de Zayas, Mes Secrets, à Florence au temps des Médicis 1593 (Paris: Jean-Michel Place, 1996).

This post first appeared here on 4 December 2013.

Yellow Glass

Yellow Neon Chandelier, 1995
Dale Chihuly.
(Columbus, Indiana Visitors Center). 

Very few people know how to make colors like golden yellow and solid red well. These are difficult and troublesome in the art of glassmaking, since in making them you must stick precisely to the doses, the timing, the details and the materials as prescribed. The smallest error will cause everything to be ruined, and the colors to be irreparably spoiled. Therefore, you must be on guard not to make mistakes. [1]

So says Antonio Neri in his groundbreaking 1612 book of glass recipes, L’Arte Vetraria. Elsewhere he warns in several places not to add “tartar” to any glass destined for yellow pigmentation. Tartar was a common additive to boost the ‘sparkle’ of a glass because it contained a high level of potassium carbonates. These converted to potassium oxide in the melt, which has a higher refractive index than the usual glass flux, sodium oxide. 

However, the reason for the mismatch is not clear, since Neri also says of his “fern glass,” which is entirely potassium based:

…This frit can be given a wonderful golden yellow color provided there is no tartar salt within, as described in the caution, because then golden yellow will not emerge. This crystal is given to a golden yellow that is far more beautiful and pleasant than can be achieved in cristallo made with Levantine polverino salt and with this crystal unlike the other, every kind of job can be done. [2]

“Polverino” was a sodium based plant product used in many of Neri’s glass recipes, which he says was derived from the Kali plant grown in the Levant. The plot thickens when, for yellow, he recommends substituting ‘rocchetta’ another soda based Kali derivative. 

His primary recipe for golden yellow is #46, in which he reveals two ingredients responsible for the color: “For every 100 pounds of [glass], add 1 pound of tartar from the dregs of red wine. Use large pieces well vitrified naturally in bottles of wine, because the powder is no good. Crush these raw dregs well, and pass them through a fine sieve. For every 1 pound of these dregs, add 1 pound of prepared Piedmont manganese…” [3] To this he adds the advice that “the powder is always given in parts and given [to the frit], not to the fused glass, because then it will not tint.”

He also offers advice to add more or less pigment depending on the intended use of the glass: more for thin items, less for heavier ones. “For larger [thick] spit beads, it is said that at Murano they reduce the dose of [wine] dregs and manganese by nearly half.”

For Neri’s lead glass, he uses a different combination, this time pairing copper sulfate with iron oxide: “Take 16 pounds of cristallo frit and 16 pounds of lead calx. Mix them well and pass them through a sieve. To this material, add 6 ounces of thrice cooked copper, made with flakes of the kettle-smiths [chapter 28], and 2 pennyweight of iron crocus made with vinegar [chapter 17].” He goes on to advise, “If it leans toward greenishness, add a little iron crocus, which will remove the greenishness and will bring out a yellow color of the most beautiful gold.

Yellow is one of several colors that iron oxide can form in glass, and is used frequently in low-fire pottery glazes. In that realm, it has a reputation as a difficult, unstable color, as Neri alludes to in his warnings. But in modern, higher temperature borosilicate glass, iron oxide is relied on for a nice yellow. In modern soda-lime glass, cadmium, titanium or the exotic praseodymium are more likely choices. They produced bright reliable color that is stable at the higher temperatures of modern operations. In lead glass, selenium is the modern favorite for yellow.

[1] Neri 1612, ch. 45.
[2] ibid, ch 5.
[3] ibid, ch 46.

The Knights

Fra Antonio Martelli, Knight of the Order of Malta,
Attrib. Caravaggio, c. 1608.

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

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

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

The following passage contains much that is contradicted by the facts, yet infused enough with the truth to make us wonder. Historian, courtier, genealogist and Florentine senator Monsignor Girolamo da Sommaia [3] recounted that:

M. Antonio who had died in Florence five or six years earlier and was from San Jacopo in Campo Corbolino,[4] said that he had the [philosophers] "stone," which he found in a pen-written book of secrets and took the paper and showed it to Casa (Agnolo Talducci della Casa, from the reign of Ferdinando I) who said what he was holding was sophistry, but that the cost was very little to try, so he tried it, and saying he succeeded, he told Casa and a goldsmith on the Ponte Vecchio, who did the first assay and later in his presence threw a bag of that powder into the Arno.[5]

A number of notebooks chronicle Neri's long working association with Della Casa at Don Antonio de' Medici's laboratory. These and other documents cast considerable doubt on the veracity of Sommia's story. Nevertheless, individual details do ring true. Of particular interest is the name of the church, San Jacopo in Campo Corbolini. It still stands today, a block west of the mercato centrale in Florence. The Knights Templar occupied it since 1256 and when that order died out, the Knights of Malta took it over. Neri's affiliation may have been through his work for Don Antonio, who belonged to the order. Another possibility is that Neri was attached to the knights through his father's connections at court. The order maintained a great deal of independence, reporting directly to the pope and curia. Their main presence was on Malta, Neri was not a knight but he could have occupied a place in their clergy.

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

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

Metal Veins Reprise

Antonio Neri, "The Mineral Gold"
Neri 1598-2000 (Ferguson 67), f. 5r.

Over a decade before Antonio Neri wrote L’Arte Vetraria, the book on glassmaking for which he would become famous, he wrote an illustrated manuscript on the subject of alchemy. Begun around 1598 and completed in 1600, this is Neri's earliest known work, written very shortly after he was ordained as a Catholic priest. 

The illustrations are divided between technical depictions of chemical apparatus and allegorical images meant to show philosophical relationships within the natural world. Two of Neri's pictures from this latter group, respectively, show veins of gold and silver growing in the earth. The veins are depicted exactly like the arteries of an animal. In both pictures, they radiate out around a fiery hole in the ground. Overhead the sun shines down on the gold and the moon over the silver. Further up in the sky, Neri shows the constellations associated with each metal; Leo the lion for gold and Cancer the crab for silver (his rendition looking more like a lobster).

It was no flight of fancy that mined metal and ore deposits were depicted as literal veins. It was widely thought these were living structures, which carried the earth’s nutrients. In one of Neri's final works, his 1613 manuscript Discorso, he explains the ancient theory that gold could occur as immature seed material, left over from the primordial creation. If properly nourished, this seed would mature and grow into the precious metal, and with the appropriate knowledge this natural process could be restarted, or accelerated and the gold could be brought to perfection by artificial means. 

Antonio Neri, "The Mineral Silver"
Neri 1598-2000 (Ferguson 67), f. 6r.

The idea that mined mineral deposits could regenerate naturally, if left to rest, is an ancient concept, one that persisted long past Neri’s era. In 1814, writing about tin mining in "On the Veins of Cornwall," William Phillips complained to the Geological Society of London, that armed with some current scientific knowledge, "nor would many miners […] believe, even to this day, in the regeneration of metals." Phillips quoted from an 1811 survey by

Tonkin, in Carew's survey of Cornwall: "Whether tin doth grow again, and fill up places which have been formerly wrought away, or whether it only seperateth itself from the consumed offal, hath been much controverted, and is not to this day decided." And  "whether—dead lodes—that have not one grain of tin in them—may not hereafter be impregnated,  matured,  and prove a future supply to the country, when the present lodes are exhausted, I think well deserves our highest consideration."  

At base, this is not superstition nor wild speculation, but rather considered judgments of thoughtful men making careful observations. Mines were often attended by acidic or other caustic liquids, either produced naturally or by washing operations, which leached out and dissolved various solubles. These liquids could sometimes dissolve metal out of ore and redeposit it elsewhere. Abandoned mines, it was noticed, could exhibit new crystal growth after a period of years or centuries. Today, the redeposition of minerals is a well accepted phenomenon, however, where it does occur it takes place not on a human time scale, but on a geological one, over millions of years.

*This post first appeared here on 2 December 2013.