Vitrum Flexile

Roman Emperor Tiberius - Glass paste cameo
 c 20ACE by "Herophilos, Son of Dioskurides"

In the first century CE, references appear in the literature for a malleable form of glass --that is to say flexible-- the method for which is reported as lost. This 'vitrum flexile' was a material that supposedly could be worked with a hammer like metal; not brittle but plastic, yet retaining the other favorable properties of glass. In the ancient world, historians Strabo (c. 63 BCE–24 CE), Pliny (c. 23–79 CE), Petronius (c. 27–66 CE) and others recount the story of a hapless artisan who brought his great discovery to Roman emperor Tiberius. Fearing the devaluation of his wealth, the emperor had the glassmaker executed on the spot and his workshop destroyed. The implication being that the inestimable value of a malleable glass would crash the markets for gold and silver. [1]

Since then, the legend has resurfaced in various forms, notably at periods in history of technological upheaval; times when innovative knowledge threatened to 'disrupt' the established order. One incarnation has the sophy of Persia gifting a set of malleable drinking glasses to the king of Spain, Philip III, around 1610. Just then, new trade deals with the Middle East rattled the European economy and Venetian glass craftsmen fanned out through Europe, disrupting local glass furnaces and guilds with their superior techniques. [2] Another version tells of a French sculptor bringing his malleable glass-work to Cardinal Richelieu (1585-1642), of Dumas' Three Musketeers fame. According to the story, that particular artisan’s reward was life in prison. The tale takes place in a tumultuous political period in French history and appears in print at the dawn of the so-called industrial revolution. [3]

Chronologically, this last story aligns nicely with the publication, in southern France, of a Latin book of alchemical recipes by royal physician Pierre-Jean Fabre (1588-1658). Contained in his volume is a prescription for a malleable form of glass, presumably the fabled vitrum flexile. Fabre's book was titled Palladium Spagyricum, 1624. [4] Spagyricum is a reference to spagyrics, the specific brand of chemistry practiced by sixteenth century alchemist-physician Paracelsus. Palladium translates to 'protector' or 'savior'. As an aside, it is interesting to note that Fabre developed an elaborate philosophy which integrated chemistry as a 'sacrament' to Catholic theology, but that is a story for another day.

In 1685, Fabre's recipes were nicely translated into English and tucked into the end of a book otherwise devoted to the art of drawing, by William Salmon [5]. Here is the full recipe "To Make Malleable Glass" as rendered in Salmon's book:

I.        Take oyl of Luna, twenty drachms: oyl of Mercury, or its water seven times rectified, one pound: mix them together and distill them.

II.      Repeat this distillation till the oleum Lunae rises with the water of Mercury in distillation. 

III.     Distill this water again until it is fixed, and converted into a fixed oyl, and this repeat four times. 

IV.     In the fourth time the oyl of Luna is fixed with the oyl of Mercury, so that they render glass malleable; for so great is the viscosity in your oyls, that it removes the brittleness of the glass, and so leaves it of a malleable temper. 

V.      The reason is, because that the radical moisture of the glass is multiplied by the radical moisture of the metals. Which is plentiful and turgent or swelling in the oyls of Luna and Mercury. 

VI.     And if [in] this oyl made volatile, diamonds should be dissolved, and then digested into a fixt oyl, it would transmute all glass into diamonds, only by projecting this oyl onto melted glass. 

VII.   There are also other precious stones comprehended within this oyl, when it is made volatile, and digested, and fixed again by digestion continually for the space of a year. 

VIII.  Also this oyl can turn glass into precious stones of any kind whatsoever, if therein (being made volatile) precious stones of the same kind have been dissolved, and digested with it into a fixed oyl. 

IX.     For as metals are included in their fixed oyls: so are precious stones in theirs, as Raymundus Lullius doth witness in many places; the which thing we shall teach you in the following chapter. 

 Elsewhere in the book, it is explained that 'oyl of Luna' is silver dissolved in acid, and 'oyl of Mercury' is a sublimation of mercury and saltpeter. [6] From a purely technical standpoint, the formula is credible in that both mercury and silver were successfully used as additives to glass and they do integrate into the matrix. Notably, Antonio Neri used both of them in his chalcedony glass. In Neri's case he was using these metals to produce color, although he does not attribute a specific tint to these ingredients. Under some circumstances, silver is known to produce an attractive blue. It should also be noted that Renaissance glassmakers used similar silver-mercury formulas to produce a reflective layer on finished glass mirrors, in a process that resembled gilding. They formed what was known as "mercury glass." It is not beyond the pale to speculate that experiments would be conducted to add such concoctions directly to the glass melt. In the end, though, there is no indication that these additives would produce a malleable glass.

As far as I am aware, this is the first example of a specific recipe for malleable glass uncovered in the literature. If nothing else, it is an important marker for further research into the history of glassmaking.

[1] Strabo: Geography, v. 8; Pliny: Naturalis Historia XXXVI.lxvi.195; Petronius: Satyricon 50.7; Also recounted by Casius Dio (c.150–235 CE): Historia Romana 57.21.7; Isidore of Seville (c. 560–636 CE): Etymologiae XVI.16.6, ‘De vitro’; Suetonius; Ibn Abd Alhokin; John of Sailsbury.

[2] Knolles, Grimstone, Johnson: Richard Knolles' The General Historie of the Turkes (London: Adam Islip, 1621).

[3] Neri 1697 (Introduction). A French translation of Florentine glassmaker Antonio Neri’s 1612 book L’Arte Vetraria [The art of making glass] by Jean Haudicquer de Blancourt. Also see my earlier post here http://www.conciatore.org/2014/07/flexible-glass-reprise.html .

[4] Pierre-Jean Fabre: Palladium spagyricum Petri Ioannis Fabri doctoris medici Monspeliensis ... (Toulouse: Bosc, 1624), p. 276. Later translated into several English editions, see note [5].

[5] William Salmon: Polygraphice: Or the Arts of Drawing, Engraving, Etching, Limming, Painting … (London: T. Passenger & T. Sawbridge, 1685), pp. 598, 599.

[6] To more adventurous readers: DO NOT TRY THIS AT HOME, or anywhere else, ever. Vaporized mercury is a powerful neurotoxin. Small amounts can cause permanent brain damage and multiple organ failure. Furthermore, this recipe uses powerful acids and nitrates, which are extremely dangerous even in a controlled laboratory setting. Even if you have little regard for your own health and safety, consider those around you; this includes loved ones, family, children, pets, neighbors and the emergency workers who will inevitably be left to clean up your mess.

The Material of All Enamels

Léonard Limosin, Allegory of Catherine de' Medici as Juno,

French, 1573, Polychrome enamel  on copper and silver.

In L'Arte Vetraria, Antonio Neri's recipe book on glassmaking, he devotes the sixth chapter to making enamel. For Neri, this was a tinted form of opaque glass favored by jewelers and goldsmiths. The material was ground into a fine powder, added to a binder and painted onto glass or metals, usually copper, gold or silver. Once dry, the item was fired over a flame or in a kiln so the enamel would fuse to form a durable glossy coating. Talented workers could use various colors to paint entire scenes.

“We see ornate enameled metals in many colors and they make a pleasant and noble sight; they entice others to look and take notice.”

Neri begins by showing how to produce what he calls “the material to make all enamels.” This is a neutral-white base to which he then adds various metal oxide pigments to produce color.

He starts by mixing together thirty pounds of pure lead and thirty-three pounds of pure tin, both in a finely divided state. He heats them in a low temperature kiln that has a wide, accessible hearth. He roasts or "calcines" the metals, raking the powders around with special iron tools for many hours. This has the effect of oxidizing the metals without melting them.

He sifts the mixture and boils it in a kettle of pure clean water. The kettle is removed from the heat and the contents are allowed to settle for a while. The water is then carefully poured off, carrying with it only the finest particles still in suspension. This liquid is saved, while the sediment at the bottom of the kettle is sent back for reprocessing in the kiln. He repeats the "decanting" procedure many times, and then carefully evaporates the accumulated liquid over a low fire. What remains is an extremely fine powdered tin and lead oxide mixture.

Neri tells us that fifty pounds of this oxide is to be mixed with an equal weight of powdered cristallo frit. Cristallo was the coveted glass perfected by the Venetians on the island of Murano. "Frit" is the granulated glass before it is put into the furnace and melted. The recipe for cristallo had remained a state secret for over a century. It was the clearest, finest glass that money could buy and items made from it commanded top dollar among the richest families in Europe. Even after production methods became known to outsiders, Venice still controlled many of the raw materials through exclusive trade agreements around the Mediterranean. Neri was first to actually publish the recipes for making cristallo, in this very same book. It was made with pure white quartz pebbles from Pavia, mixed with purified salts derived from the Levantine kali plant, and decolorized with manganese from Piedmont.

In order to complete the enamel base material, Neri adds eight ounces of white tartar salt (made from the dregs of wine), sifts the mix and carefully heats it in terracotta pots for ten hours. The result is ground again and stored in a in a dry place, in a sealed container for future use.

The rest of the chapter is devoted to coloring this enamel base material; he always starts with a batch of either four or six pounds. He uses a large furnace pot to melt the enamel because even though the amount is relatively small, some of the pigments cause the batch to froth and swell violently. After adding the pigments, he lets the glass cook for a while, adjusts the color as necessary and then "washes" it several times. In this process, he throws ladlefuls of molten glass from the furnace-pot into large vats of cold clean water. The effect is to remove excess plant salts from the glass, which would ultimately foul the enamel. Finally, he forms the glass into individual dollops of about five ounces each; a size to which the goldsmiths were accustomed.

For green enamel, Neri uses copper and iron oxides in various proportions, for blues he uses "zaffer," which is a cobalt oxide. He mixes green and blue pigments to obtain turquoise colors. Manganese produced a red wine color, for yellow, he adds the unrefined dregs of red wine (potassium) with a pinch of manganese. Violet is a mix of manganese and copper oxides.

Finally, a word to the wise: Do not attempt to duplicate these recipes; fine lead powder is dangerous enough, molten lead enamel will evolve fumes that cause heavy metal poisoning. Remember that Antonio Neri was dead by age thirty-eight.

* This post first appeared here 11 July 2014.

True Colors

The European Roller [Pica Marina]

Antonio Neri's book, L'Arte Vetraria, is devoted to making glass from raw ingredients found in nature. Many of his finished creations were intended to also resemble the natural world. A number of colors are meant to mimic the appearance of gems and minerals, others are named after plants and animals. Some are easily recognized today, even if they are not as familiar as they were in the seventeenth century. One of his recipes will make "a wonderful pimpernel green," while others evoke peach and orange blossoms. An entire section of the book is focused on paints that are named after the flowers from which the colors are extracted. Many of these plants have remained common: poppies, irises, violets, lilies, carnations and red roses. Others are less so: the mallow, pomegranate, broom and borage flowers.

In addition to flora, the fauna make a few notable appearances in Neri's book. In chapter 16, in the preparation of iron oxide pigments, he advises that after fifteen days in the furnace, the product will be finished when it takes on the purple color of the peacock. In chapter 73 he gives a method for "tinting rock crystal the color of a viper" and chapter 121 is the method for a glass which is "red like blood."

Named in several chapters is a shade of 'celestial blue,' which Neri likens to the color of the "gazzera marina." Common bird names pose a special challenge for translation in that they, like the birds themselves, never seem to settle in space or time for very long. Vernacular names of a species can change from one century to the next, one region to another, even between adjacent valleys and several species can share the same name. It is with this admonition that we attempt to flush out the elusive gazzera marina.

Consulting a modern Italian dictionary draws the eye to the similar sounding 'gazza marina' (alca torda), known in English as the razorbill. This sea bird inhabits coastal cliffs, but alas, as a close relative of the penguin, it dons only black and white formal attire. Digging deeper we find poet Gabriele d'Annunzio, "At Dawn" carefully tracking the gazzera marina across a salty marsh, in his Halcyon. This time the poet himself throws us off the trail with his description, since no bird sports five digits but the chicken. Turning to etymology, we find another potential match in the magpie (pica pica); it is a credible but unconvincing fit with its blue and white plumage.

Aldrovandi's pica marina

Combing the references of Neri's own sixteenth century, we find the best candidate is the roller (pica marina). This bird was described by naturalist Ulisse Aldrovandi, a friend of Don Antonio de' Medici's father and guest at the Casino di San Marco, where Neri later worked. Other contemporary authors list the gazzera marina as a synonym to Aldrovandi's pica marina. Neri's Latin translator Frisius (1668) and his German translator Geissler (1678) agreed, both sighting the "Pica Marina" in their works.

This post first appeared here on 13 Sept 2013.

Neri & The Portland Vase

The Portland Vase
(British Museum)

286 years ago this month, (12 July 1730) marks the birth of Charles Darwin's grandfather, English potter Josiah Wedgewood. He founded the company that still bears his name, a name that has become synonymous with the iconic blue with white bas-relief cameo-themed jasperware pottery.  

What is less well known is that the style was developed over several years by Wedgewood in an attempt to copy a particular ancient glass object, now called the Portland Vase. This piece was and still is regarded by many as the pinnacle of ancient glass art. The vase was made around the time of the birth of Christ and shortly after the invention of glassblowing. The prevailing theory states a dark, cobalt blue vase was blown and then coated in a second thin layer of white glass. The piece was then carefully sculpted, probably by a gem carver, by grinding the white over-coat glass into various mythological scenes. The figures stand on dark blue ground that was revealed by completely grinding away areas of white, leaving only the under-layer. 

Wedgwood's Sydney Cove Medallion

Alternate thinking has the piece cast or blown into a mold which contains powdered white glass in the appropriate areas. [1] 
Both theories have their points, and the wide differences only serve to emphasize how little we actually know about ancient methods and technology. Having said that, the alternate theory, it seems to me, has an up-hill battle to gain acceptance over the prevailing one.

What is especially revered by aficionados, and gave Wedgewood the most trouble in replicating, is the delicate carving of the white glass. The figures depicted around the vase in various scenes are not monochromatic, but expertly shadowed just like a fine painting. This, it is commonly thought, was achieved by grinding the white glass so thin that the dark blue under-layer starts to show through, making gradations of lighter and darker features. A face or a hand was shaded by making the white glass slightly thinner on shadowed areas. Wedgewood's solution was to subtlety tint the white clay he used, which was then applied to a blue clay vessel and fired in a kiln. One of his early successes, owned by Darwin, can be viewed at the Victoria and Albert Museum in London.

Today the original Portland Vase can be viewed at the British Museum where it has taken a place of pride almost since the museum’s inception. A series of unfortunate accidents and one act of intentional destruction have broken the vase several times, but it has been painstakingly pieced back together and restored so that cracks are minimized. One of these events occurred during the Roman Empire, when the bottom of the vase was replace by a circular medallion of the same style cameo glass. In modern times, the vase was the subject of a nineteenth century contest, with a prize of 1000 pounds, to make an accurate reproduction in glass. The winners of that contest were glass blower Philip Pargeter and engraver John Northwood. Their piece is on display in the Corning Museum of Glass in New York.

The vase was uncovered in the late sixteenth century during an excavation, when the hunt for ancient tombs around Rome was in full swing. It was presumably used as a funerary urn in what, at the time was thought be the tomb of Emperor Alexander Severus. It's first owner after discovery was none other than Cardinal Francesco Maria del Monte, patron of the arts, alchemist, glass collector and Medici family confidant, of whom I have written here before. The cardinal was a lifelong advisor to Don Antonio de' Medici, who was in turn, the patron of glassmaker Antonio Neri. There is every chance that Neri and Del Monte knew each other, although no such record has yet been found. Del Monte is known to have visited the Casino di San Marco in Florence at the time that Neri was making glass there and Neri is conjectured to have visited Rome a couple of years earlier. 

If Neri the priest was ever granted audience with the cardinal in Rome at his main residence, the Palazzo Madama (now occupied by the Italian Senate), it is easy to imagine a tour of the cardinal’s extensive glass collection, which he displayed in a special room dedicated to the purpose. Such a tour would not be complete without an examination of what would become the most famous piece of glass in history, the Portland Vase, by the man who would become the most famous glassmaker in history, Antonio Neri. "Go ahead, take it – hold it up to the light."

[1] For more on this see http://rosemarie-lierke.de/English/Cameo_glass/cameo_glass.html

The Cardinal's Ceiling

From "Tesoro del Mondo" (Treasure of the World)
Antonio Neri 1598-1600

In the years 1598-1600, newly ordained Florentine priest and alchemist Antonio Neri was hard at work on a manuscript which he titled Tesoro del Mondo (Treasure of the World). [1]  One illustration near the front shows an allegorical map in which six roads all lead to the Vatican at its center. A Latin inscription translates as, "The different ways to Rome" followed by "Qui pot[est] capere capiat" or 'He that can take, let him take it.' Taken in context, this Biblical reference ( Matthew 19:12) apparently refers to the various alchemical 'paths' leading to the philosopher's stone, but the choice of imagery suggests that Neri spent time in the city of seven hills. [2] It is a tantalizing clue to his travels, although there is no direct confirmation. 

If Rome did figure in the young Neri's itinerary, a visit to Cardinal Francisco Maria Del Monte would have been de rigueur. The Medici family ruled Neri's home region of Tuscany and Cardinal Del Monte was the Medici's informal ambassador in Rome. He was a dedicated patron of the arts, an amateur alchemist, a collector of glass and a trusted successor to Grand Duke Ferdinando in the College of Cardinals. More significantly, he was a close friend and advisor to Neri's sponsor Don Antonio de' Medici ever since that prince was a child.  Del Monte's biographer Zygmunt Waźbiński offers, "It is very likely that Cardinal Del Monte, with his interest in glass, had known then (in 1598) the [future] author [Neri] of L'Arte Vetraria." [3]

Michelangelo Caravaggio, c. 1597
Casino Ludovisi.

As the sixteenth century ended and a new one dawned, Del Monte sheltered the rough-and-tumble painter Michelangelo Caravaggio, whom he set up with an in-house studio and an allowance. However, in 1606, the master of Realism fled Rome after reportedly murdering a tavern waiter over a tennis wager, but not before executing his only known fresco on the vaulted ceiling of Del Monte's own alchemy laboratory. Looking out over Rome, on the panoramic Pincio, in the Villa that later became the Casino Ludovisi and is now known as the Casino dell'Aurora, Caravaggio put his brush to work. According to early biographer of artists, Gian Pietro Bellori, he executed the oil painting on the vaulted ceiling of the small alchemical laboratory (now a corridor) sometime between 1597 and 1600. [4] Depicted in the mural are the three brothers Jupiter, Neptune and Pluto: the masters of the universe. The image is a double allegory of the three basic chemical substances of Paracelsus (salt sulfur and mercury) and the four Aristotelian elements (air, earth, water and fire). Jupiter with the eagle stands for sulfur and air, Neptune with the seahorse stands for mercury and water and Pluto with the three-headed dog Cerberus stands for salt and earth. Jupiter is reaching out to move the central celestial sphere in which the sun (fire) revolves around the earth. [5] 

The villa was a relatively secluded retreat where the Cardinal could entertain guests discretely, including his friend Galileo–Del Monte and his older brother Guidobaldo helped land Galileo the chair of mathematics at the university in Pisa. It would be interesting to hear the astronomer’s comments on Caravaggio's tribute to heliocentrism.


[1] Neri 1598-1600, f.xxviii-v.  (see bibliography).
[2] For more on the alchemical interpretation of this illustration see Grazzini 2012.
[3] Neri 1612.
[4] Bellori 1672, pp. 197-216.
[5] Wallach 1975, pp. 101-112.

* this post first appeared in a slightly different form on 4 July 2014.

Old Post Road

A coach of the middle of the seventeenth century:
 from an engraving by John Dunstall.

In the winter of 1603-1604, Antonio Neri left Italy to visit his friend Emmanuel Ximenes in Antwerp. There is no way to know the exact path he took, but based on the advice in Ximenes' letters and on well-established trade routes; a good estimation can be made. It is likely that Neri was starting from Pisa. The path  suggested by his friend took the priest first back east to Florence, then perhaps through Bologna, Ferrara and Padua to Venice. Ximenes offered to make arrangements for Neri to travel from Venice with traders headed to the Frankfurt fair held at mid-lent. There would have been plenty of time for him to celebrate Advent in Florence and Christmas in Venice before his caravan headed north. The group could have left as late as the end of January.

Ximenes suggested that Neri travel with the courier from Florence to Venice. He was referring to the system of coaches that delivered the mail throughout Habsburg Europe, run since the early 1500s by the De Taxis family. While the Medici and other heads of state maintained their own fast couriers for diplomatic and military messaging, the De Taxis had a monopoly on almost every other piece of correspondence, a privilege for the family that was later extended to other parts of the world by the Holy Roman Emperor. They ran an efficient system well into the eighteenth century. An elaborate series of 'posts' were set up at intervals, where tired horses were watered and swapped for fresh steeds and riders so that the journey could continue uninterrupted. Independent travelers could partake in the system for a fee based on equipment required and the weight of luggage. In Neri's time, accounts were settled at each post and travelers could elect to stay over in a town and pick up a later expedition. On well-established popular routes like between Florence and Rome, travelers could pay a flat rate that included lodging and meals. If Neri had traveled light and spoke some German, he might have completed the entire journey in as little as ten days; the time letters from Venice to Flanders took to arrive. However Ximenes advice suggests a longer excursion.

I would recommend that you should go with the courier from Florence to Venice, arriving in Venice in time that you would be able to accompany the merchants who come to the fair held in Frankfurt at mid Lent;  you  will stay there the length of the fair for fifteen days, which will not displease you for having seen it. After that, you would go in the company of other merchants to Cologne, and then with them or others, by land or sea to Holland, ending up at this city. This sea, however, is nothing more than rivers. I recently went by land to Basel and from there by water ending here. But for Your Lordship,  who does not speak the German and Flemish languages, I would consider better the way that I say, with merchants from Venice to Frankfurt and then with others by water to arrive here. 

On Embarking from Venice, the party of traders would head west, back to Padua, on to Verona and then north along the ancient trade route through Bolzano to the Brenner Pass. The journey from Venice to Frankfurt was about 600 miles (950 km). Traveling an average of 30 miles per day, they would be on the road for three weeks. Depending on their itinerary, the journey could have varied by a week in either direction. The start of the fair was mid-lent, the date of the traditional feast held three weeks before Easter. In 1604 mid-lent Sunday fell on 28 March.

Brenner is the lowest pass across the central Alps, connecting Bolzano on one side to Innsbruck on the other and was passable year round. The distance of this, most difficult part of the journey, was about 75 miles (120 km), with a vertical climb of 4,495 ft (1,370 m), almost a full mile, but all below the tree line. Assuming a slow pace for pack animals, this segment could still be completed in less than a week, stopping in Bressanone, (Brixen), then at the alpine city of Vipiteno (Sterzing), where perhaps some extra time was taken to rest and view the nearby silver mines. Gries am Brenner was just over the pass on the Austrian side. With the majestic Wipp valley (Wipptal) at their backs, the remaining journey was down hill from there. From Innsbruck, the traders would head towards Augsburg, perhaps with an excursion through Munich, which was then the capital of Bavaria. The route from Augsburg through Wurzburg to Frankfurt was riddled with small towns accustomed to hosting traders since Roman times. After a few weeks on the road, the fair at Frankfurt would have come as a welcome diversion.

At the end of the fair, a week before Easter, Neri would start the final 250 miles (400 km) of his journey. First, he would travel over land with merchants or the Ximenes family servant to the walled city of Cologne on the Rhine River. Next, he would move by water toward the sea. The northern route, along the Rhine, avoided the military conflicts between the Dutch Republic and the Hapsburg Empire. The most dangerous were between Liege and Antwerp. From Rotterdam, the inland waterways led south to Antwerp. Priest Neri may well have arrived in time for Easter Vigil.

This post first appeared in a shorter form on 21 October 2013.

Galleria dei Lavori

Giovanni Stradano  (Jan van der Straet) 

Alchemy Studio, 1571
(Inside the Uffizi Galleria dei Lavori)

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. Grand Duke Cosimo de' Medici 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 a demonstration was performed for Ferdinando de' Medici that purported to turn half of an iron nail into gold; the work of German alchemist Leonhard Thurneysser. In the 1590s, when Neri was being schooled, several accounts describe that the nail (chiodo) 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.

This post first appeared on 16 August 2013.