The Duke's Mouthwash

Ferdinando de’ Medici (1549-1609),

Scipione Pulzone (1544 - 1598), Private collection.

Antonio Neri's father, Neri Neri, was royal physician to the family of Grand Duke Ferdinando de' Medici. As such, he regularly interacted with other members of court, ranging from the archbishop of Florence, to his colleagues in medicine, including the royal apothecary (speziale), Stefano Rosselli. Rosselli shared more than a professional relationship with Neri Neri. They both admired the work of an ancient Greek physician named Dioscorides; Rosselli was something of an authority on his methods. In addition, he ran the 'Speziale al Giglio' shop, once owned by Tommaso del Giglio, who's chapel Neri Neri took over at Cestello church. Rosselli's son, Francesco, and Neri Neri were among the four chosen to revise and update the famed 

On 21 September 1589, Rosselli started to compile his own book of recipes to pass down to his two sons, Francesco and Vincenzo, who would go on to continue the pharmacy.[2] The book begins with a poison remedy credited to none other than Cosimo de' Medici. Recipe no. 9 is the grand duke’s antispasmodic oil, presented by Niccolò Sisti, with whom Antonio Neri would later work at the glass house in Pisa. No. 20 is the duke's oil for deafness, also presented by Sisti. No. 41 is a poison antidote revealed to Francesco de' Medici by the Archduke of Austria. It was tested on a prisoner at the Bargello prison, a "volunteer" who was intentionally poisoned as part of the experiment, then revived with the antidote in the presence of Stefano Rosselli and Baccio Baldini, the long time physician to Cosimo I. Supposedly, the prisoner's reward for surviving was early release.

Recipe No. 30 carries perhaps a bit less risk; it is titled "Acqua da gengie di messer Nerj Nerj" (Mouth wash of Neri Neri):

Take a quarter of a bushel of mastic buds,a quarter of a bushel of myrtle buds, a quarter of a bushel of red roses, three ounces of alum, a half ounce of salt and a quarter ounce of hard rose honey. Mash the herbs with a mortar and pestle and put them in nine pounds of Greek wine for twenty-four hours, then boil in a bain-marie and reduce to two-thirds. In this, we bathe the gums: it makes them dry and firm.

Mastic
Myrtle
Alum
Rose Honey
Greek Wine

The date that Stefano Rosselli started his book of secrets is interesting because it is the same day that Neri Neri, with the grand duke's two other physicians, Cini and Da Barga, were busy making medicinal wine based on Dioscorides' ancient recipes. Perhaps they all met that day at Rosselli's shop, for his advice. 

[1] Neri, Benadù, Rosselli, Galletti 1597.
[2] Rosselli 1996; an Italian transcription and French translation of Rosselli's recipes, with a very entertaining introduction.

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

Rosichiero Glass

Sunset over Venice
(click image to enlarge)

The most famous glass recipe in Antonio Neri’s 1612 book, L'Arte Vetraria, is “#129 Transparent Red.” The reason for its notoriety is, of course, the pure gold used as a pigment. Gold-ruby, or “rubino” is a devilishly difficult color to produce in glass and was not reliably duplicated until many years after Neri’s death, although pieces made in ancient times have been unearthed.  

Even though gold rubino is Neri's most well known recipe and certainly his most famous red glass, this recipe does not exist in isolation. In fact, it fits in the middle of a group of eleven recipes (120–130) devoted to transparent, or at least translucent red glass, enamel and related preparations. 

120 Transparent Red in Glass.
121 Red Like Blood.
122 Balas Color.
123 To extract the Spirit of Saturn, Which Serves Many Uses in Enamels and Glasses.
124 Rosichiero to Enamel Gold.
125 Rosichiero for Gold by Another Method.
126 How to Fix Sulfur for the Above Described Work.
127 A Glass as Red as Blood, Which Can Serve as Rosichiero.
128 A Proven Way to Make Rosichiero.
129 Transparent Red.
130 The Way to Fix Sulfur for Rosichiero to Enamel Gold.

A particular shade that was popular at the time was known in Italian as "rosichiero." Our glassmaker presents four different recipes and two more on “fixing” sulfur, which some of the preparations require. Most dictionaries cite Neri as the first to use of the word 'rosichiero' in print, but we know it was a common term of art among glassmakers much earlier. The French equivalent is "rouge clair." The Spanish edition of L'Arte Vetraria notes that in that language the term is “rosicler,” which is still used today to describe the intense rosy twilight color of a nice sunset.

The red glasses of this group all call for the addition of copper as a colorant and copper has remained a popular pigment up to the present. For instance, red traffic lights that are made of glass are typically tinted with copper. But that is not the entire story; some of Neri's rosichieros also include the addition of sulfur and some require hematite or iron oxide, red lead oxide, manganese oxide, or wine tartar. In his recipe #125 for rosichiero, he starts with four pounds of high quality cristallo glass. To this adds equal parts of tin and lead oxides, mixed together: 

[A]dd this calx little by little, ½ oz at a time, let it incorporate, and watch for when the glass becomes an ash gray color, at which point it will be good. Do not add too much calx because if you overload it, the glass will become white in color, which is not good.When it turns the said gray color, do not add more calx but leave it to clarify. Then have 2 oz fine minium [red lead oxide], add this to the glass, and let it incorporate well, and clarify. When it clarifies well, throw into water, return it to the crucible and leave it for 8 hours [in the furnace]. 

Have ½ oz of calcined copper, that is to say red copper and ½ oz of raw white [wine] tartar. Throw these materials in, and stir them well. Now add a dram of hematite, which the sword makers use for burnishing, and 1 dram of fixed sulfur. Stir and incorporate these powders, and watch. If it is over-colored, give it a little manganese to dilute it. If it is clear of color, add more of the fixed sulfur, hematite, a little red copper and a little white wine tartar at your discretion so it becomes the desired color.

Many of these ingredients are no longer common in color glass production today; in fact, free sulfur is usually considered an undesirable contaminant. Hematite is a naturally occurring mineral form of iron oxide. It is so named because if abraded in water it tints the water red, appearing to bleed. Hematite is not currently used as a red pigment in glass because of its temperature sensitivity, but it is used in some pottery glazes. 

From a chemistry standpoint, a good guess is that sulfur added to the glass would react with the copper and iron to produce various sulfide compounds. How those compounds affect the color and texture of the glass is an open question. Here is where we get into uncharted territory; four hundred years after Neri’s book was first published, predicting colors based on specific chemistry is not as easy for us as it might seem. The science of color in general remains a difficult nut to crack. However, the fact that there is still much that we do not understand does not prevent us from enjoying the brilliant reds inspired by a good sunset.

* For the technically minded, the University of Oslo has a wonderful presentation on the state of color physics. For the non-technical, take a look – a series of fascinating images that spans the sense of sight and beyond. There is a link address in the "picture credits" for this post.

** This post first appeared here on 24 April 2014.

Arminia Vivarini

Nef Ewer, Late 16th century, Murano Italy.
Courtesy Milwaukee Art Museum

On the afternoon of Friday, 22 March 1521, The Venetian Senate - then called the ‘Pregadi’ - reconvened after lunch. Senator Marino Sanuto (the Younger) recorded in his now famous diary that among the afternoon business was the granting of a ten year exclusive license to Arminia, the daughter of painter ‘Alvise da Muran’ (Luigi Vivarini). She was granted this privilege to produce the ornamental glass galley ships she had recently devised. [1,2] Once called 'Navicella' (little ships) these ewers, probably most used to serve wine, are now known as ‘nefs’. A pour spout was situated at the ship's bow, and often a handle astern. These objects soon became iconic symbols of the island-nation’s long dominance in trade, and regularly appeared on sideboards and elaborate dinner table settings, not only in the lagoon, but in Florence, Rome and far beyond.

In their Objects of Virtue: Art in Renaissance Italy, Syson and Thornton write,

“It was not only the use of coloured canes in complex patterns embedded into clear glass that typified Venetian glass from the 1520s, but also the manipulation of cristallo into ever more fantastic forms. Novelties were first displayed at the Ascension Day Fair, which, like visits to the glasshouses in Murano itself, was firmly on the tourist map by about 1500. The Venetian diarist Marino Sanuto mentions the work displayed at three booths at the fair in 1525, those of Barovier, Serena and Ballarin workshops ‘among other things, a galley and a very beautiful ship were to be seen.’”

Syson and Thornton continue, “Leandro Alberti singled out just this kind of glass in his famous description of the marvels of Murano in his Description of All Italy of 1550: ‘I saw there (among other things made of glass) a scaled-down model of a galley, one braccia long and with all its rigging and equipment, so perfectly in scale that it seemed impossible to model such things accurately in such a medium.” [3]

Scholar and science investigator, Georgius Agricola, described a vessel in the form of a ship in his De re metallica published in Basel in 1556,

“The glass-makers make diverse things, such as goblets, cups [...] and ships, all of which excellent and wonderful works I have seen when I spent two whole years in Venice some time ago. Especially at the time of the Feast of the Ascension they were on sale at M[u]rano, where are located the most celebrated glass-works. These I saw on other occasions, and when, for a certain reason, I visited Andrea Naugerio in his house which he had there, and conversed with him and Francisco Asulano.” [4]

Arminia Vivarini’s father was a painter of some renown, but her family is also among the earliest recorded glassmakers on Murano. Her third-great grandfather, named Vivarino, arrived from Padua, just ahead of the plague in 1346. [5] The family seems to have been involved in the craft on the island from then on. She clearly had access to a furnace, perhaps one owned by an uncle or a cousin. In any event, she exemplified the qualities of the very best glass artisans throughout history: a clear design sense coupled with technical expertise and the opportunity to put them both into practice.

Her very existence also forces us to more closely examine the well worn narrative that hot-shops were exclusively male domains, from which women were strictly excluded. In such a highly competitive arena, it is perfectly reasonable that a family would promote its best talent, regardless of gender. In many ways, we owe homage to Vivarini for her success with this style of novelty glass object; it started the genre that continues in popularity today, five centuries later, with works of art prized by collectors and in museums around the world. [6]

[1] Arminia  (Armenia, Ermonia) Vivarini (1490-1569). See Luigi Zecchin: Vetro e Vetrai di Murano, 3 vols. (Venezia: Arsenale, 1987-9) v.3, p. 194.

[2] Marino Sanudo: I diarii di Marino Sanuto (1466-1536)  v.30. Eds., F. Stefani, G. Berchet, N. Barozzi (Venezia: Fratelli Visentini, 1891) col. 45. Also see Zecchin 1987-9, v.2, p.276.
[3] Luke Syson, Dora Thornton: Objects of Virtue: Art in Renaissance Italy (Los Angeles: J. Paul Getty Museum, 2001), p. 197.

[4]  Georgius Agricola (Georg Bauer): De Re Metallica: Tr. from the 1st Latin Ed. of 1556… trns: Herbert Hoover, Lou Henry Hoover. (Princeton: Mining Magazine, 1912), p. 592 (Book XII.)

[5] op. Cit. Zecchin 1987-9, v.3, p194-5.
[6] Thanks to Sophie Small‏ @sophieesmall for inspiring the subject of this post.

Reticello Glass

Reticello by Aaron Tate (detail),

Photo by David Lindes.

In fine art of the early twentieth century, ‘cubist’ painters and sculptors caused a sensation by pioneering a style that was fluid and emotional yet rigorously geometric. Earlier still, eighteenth century Baroque musicians thrilled audiences with ‘counterpoint’; music that was melodic and harmonious yet structured with an almost mathematical precision. The recurrence of similar themes in widely differing arts is perhaps not so surprising. When successful, these are themes that resonate deeply within us; they amplify what is common to our nature and remind us that we are in the world together. 

In sixteenth century Venice, a form of glasswork emerged that anticipated these juxtapositions to similar popular acclaim. In fact, the technique of ‘reticello’ went on to become an enduring trademark of Murano technical skill and artistry. To this day, well executed pieces of reticello glass are coveted by collectors and displayed with great pride. 

The form is characterized by a transparent glass base which is embedded with a network of crisscrossing threads of opaque glass, forming a lattice of diamond shaped pockets. Classically, white 'latimo' glass was used in a clear 'cristallo' base.The overall effect is reminiscent of fine lace or of fishing net, both of which are strongly evocative in Venetian culture. When executed in the classical technique of the island’s glassblowers, each diamond in the pattern contains a single bubble of trapped air, perfectly centered and uniformly sized. 

In general, the latticework theme in art traces to much earlier times. It is common in Hellenistic and Islamic art. To an extent it is a natural consequence of mosaic making. However the application of the pattern in glassblowing requires a completely different approach and a complex series of steps. First a ‘filigrana’ bubble is formed. To accomplish this, a series of pencil thin glass rods called ‘canes’ are laid side by side, touching each-other, in a pan ('piera' in Venetian, 'pietra'=stone in Italian) and partially fused together in the furnace.[1] Each cane is made of transparent glass with a core of opaque glass (a thread) running its entire length. Glass artist Emilio Santini writes:

On Murano, the "piera" is coated with a thin layer of clay from the laguna marshes. This is rich in salt and does not stick too much on the glass even if overheated. Then they preheat the, piera (called a 'plate' in the US) to dry the clay. While it is still hot but not scorching they lay down the canes so they are partially warmed before they go in the furnace. Remember that they are not annealed [and could easily shatter from thermal shock]. Then two little square metal pieces are placed at the two ends to hold the cane in place. These are called fereti (V) ferretti (I) . Some of these same terms are also used in the US by skillful glass blowers.[2]

On the end of an iron blowpipe, the fused mat of glass rods is wrapped around into a hollow cylinder. Next the open end is gently worked closed. This forms a sealed bubble of glass that can be manipulated by standard glassblowing techniques. Soft from the heat of the furnace, the glass can be given a twist so the parallel threads form a loose spiral. This piece is stored in a ‘garage’ kiln while a second bubble is formed in the same way but with the spiral running in the opposite direction. The first bubble is opened wide at one end, removed from its iron rod and placed in a cradle on the floor which holds it upright. The second bubble is carefully lowered into the open end of the first bubble. The glass artist stands above, with the second bubble inside the first and blows, inflating the inner glass until it comes in contact with the outer bubble. Watch master Dante Maroni at work in this video  http://www.youtube.com/watch?v=WJ3DDon23Lc

Because both glass bubbles are formed with canes, they have a ribbed texture both inside and outside. When the two glass bubbles contact each other, the high-points of the ribs meet first, which is where the threads of the two bubbles cross. The valleys of the ribs are where one cane is fused to the next; these areas cross between the bubbles at the center of each diamond in the pattern. The two bubbles fuse together trapping air in the valleys. As the glass is worked and heated these regions form small, perfectly round air bubbles trapped inside the glass. You can see this for yourself by taking two or three fingers of each hand and crossing them against each other. Imagine the threads of opaque glass running down the center of each finger. The air bubbles are trapped where you can see light between your fingers.

Reticello ("fillacello") style flamework pendant,
by Adam Reetz 2015.

The distinctive diamond pattern of reticello has been successfully achieved with other glassmaking techniques. In flameworking, glass is manipulated using only a torch and handtools. The torch is fixed to a bench where the artist either stands or sits. In general, this is a more accessible technique because it does not require a glass furnace. Here, the reticello pattern is accomplished by starting with glass tubing. The crisscross pattern is ‘painted’ onto the outside of the tubing, one line at a time; with very thin rods of glass known as “stringers.” In one version, evenly spaced straight parallel lines are drawn along the length of the tube. The tube is then reheated in the flame and twisted. Next, a second set of lines are drawn twisting in the other direction, forming the diamonds. The ends of the tube are drawn down and one end can be mounted to a rod or tube of glass and further manipulated in the flame. 

In a testament to the continued popularity of reticello, a new colorful variation of the flamework technique has emerged within the past decade, among American flameworkers. [3] This has been playfully dubbed “fillacello.” After painting the fishnet pattern on tubing, and further working the glass, the individual diamonds are “filled” with various colors using stringers. The resulting effect recalls mosaics and the ancient inspirations of reticello.

[1] The iron tool used to move the 'piera' of filigrana cane in and out of the furnace is called a 'pasorale' (V), 'pastorale' (I) = pastoral, named after the staff carried by the pope. It consists of a straight rod with a U-shaped fork in the end. Thanks to Emilio Santini for his kind assistance with Muranese terminology and knowledge of hotshop technique.
[2] Private correspondence, March 2015. Here is a video of the reticello technique as executed by American glass artist Dante Maroni. http://www.youtube.com/watch?v=WJ3DDon23Lc
[3] My research point to the first examples of this technique emerging on the west coat of the United States around 2005-07. (Further information on its origin would be greatly appreciated).

Filigrana Glass

Mezza Filigrana footed vase, circa 1950s,

by Dino Martens (for Aureliano Toso).

Filigrana is a classical glassmaking technique developed in the sixteenth century on the Venetian island of Murano. In the broadest sense, a piece of filigrana -- let's say a vessel -- is composed of transparent glass with very fine vertical threads of color running through it. Traditionally, these threads were opaque white lattimo (milk) glass, running through a colorless high quality product known as cristallo. Because of this, the technique was originally known as “latticino,” a term still in use, but now falling out of favor and being replaced by filigrana (filigree), a name that does not imply any particular color. 

Over the centuries, this and closely related techniques became a kind of trademark for the Murano glass industry. Parallel threads in a loose spiral winding around a vessel from top to bottom form what is perhaps the most basic application of the method. This is known as mezza filigrana (half filigree). The reason for the “half” becomes apparent when we consider its far more famous cousin reticello. With this technique, two sets of threads are used winding in opposite directions to form a fishnet pattern of  diamonds. The name recalls reticella, a traditional Venetian lace. When the work is done properly, tiny air bubbles are trapped inside the glass, one in the center of each diamond of the fishnet pattern.

Even more exotic variations have been developed, which we will discuss another time. First, let's explore how the glass artisan is able to achieve these fine threads in the glass, so perfectly spaced. I should hasten to say that I am not a glassblower and this description is not an instructional, but simply a window into some of the fabulous artistry that takes place in a glass shop. These techniques take hundreds or thousands of hours of practice to master. Even a shallow understanding of the steps that go into a piece of filigrana lead to a far richer appreciation than simply being able to identify it by name.

 “Cane” is a general term for long straight rods of glass. They have many uses in glass artistry and the method by which they are made can be surprising the first time you see it done. It is the same method as was practiced a thousand years ago. A gob of molten glass is removed from the furnace on the end of an iron rod. A second rod is attached by another artisan, with the lump of molten glass between the two rods. They start to pull in opposite directions, slowly at first. They swing and manipulate the hot glass as it cools, forming a mass of relatively uniform diameter. They continue to walk away from each other, the glass pulling thinner as they go. Practiced artisans can end up with a uniform pencil thin straight rod of glass that extends for many meters. It is laid on spaced wooden slats on the floor, allowed to cool and then snapped at regular intervals to form smaller rods.

In the case of filigrana cane, the artisan starts with a smaller gob of opaque glass; let us say lattimo (white). This gob is then dipped into clear glass, which encases it in a heavy transparent layer. When the cane is pulled, the result is a clear rod with a filament of opaque white glass running down the center. Short lengths of cane are laid side by side in a pan. The pan is heated so that adjacent rods start to fuse together into a mat. The glass artist will again take a gather of glass from the furnace around the end of an iron blowpipe and flatten it into a disk, leaving the blowhole unobstructed. The disk, known as a "collar"[2] is touched to the mat of canes at one end and rolled so that the canes wrap around and form a cylinder. The open end of the cylinder is then closed down, in effect forming a bubble on the end of the pipe. The glassblower can then treat this as if it were a bubble formed straight out of the furnace, but of course, this bubble has the threads of lattimo glass running through it. The bubble is then manipulated into a finished piece. [2]

Miniature flameworked vessels (aprox. 3cm tall)
in the style of filigrana, by Emilio Santini. 

Outside of the hot shop, there are methods that use only a torch to duplicate the appearance of filigrana and reticello on a smaller scale. This involves starting with glass tubing and "painting" the threads on using thin "stringers" of glass. It is a completely different technique which requires an entirely different set of skills. In the right hands, the results can be strikingly similar. Now that we have the basics down, we can discuss the more spectacular variations that have been developed, which we will talk about next time.


[1] "Colletto"(Italian) "Coeto" (Venetian), means narrow neck or little neck.
[2] The following Youtube video shows American glass artist William Gudenrath, assisted by Harry Siemens pulling filigrana cane and executing a reticello vase at the Corning Museum of Glass. http://www.youtube.com/watch?v=xCrdewFgObc

Incalmo Glass

Incalmo vessels by Tapio Wirkkala for Venini.

In this post, we will explore one of the classical techniques of glass art. Along with filigrana, latticino, reticello and pezzato, incalmo is a classical Venetian technique well established in the art, even if poorly understood by many outsiders.

‘Incalmo’, in Venetian dialect literally means “graft” as in joining two plants. That is a pretty good description of how this effect is achieved; think of a vase whose bottom-half is one color and top is another. The glass artist blows two separate bubbles of glass, opens them and joins them together to form a single bubble. It is a difficult operation because the two open lips must be exactly the same size to join properly. The process can be continued to add more colors; virtuoso pieces may include several sections, each a different color. In addition, the position of the iron rod that the artist uses to hold the bubble can be changed while the piece is under construction, leading to asymmetrical effects.

16th century incalmo plate,
unknown artist.

The above description is the classical way of achieving incalmo, but modern materials and equipment allow artists to achieve a similar effect with considerably less skill. For instance, precise diameter glass tubing is now available in a wide variety of colors. This can be cut into rings with a saw, then stacked in a kiln and fused together. From there, this “prefabricated incalmo tube can be worked by traditional methods. Whether or not this meets the definition of true incalmo depends entirely on whether one focuses on the method or on the end result.

9-10th century incalmo vase,
Syria or Iraq.

The name ‘incalmo’, was applied to glass in the first half of the twentieth century by the Venini factory on Murano, in Venice. [1] However, both the word and the method are much older. The Venini artisans revived the technique to great acclaim, but Venetian examples date from the sixteenth century and Islamic examples from ninth century Syria have also survived. It is not hard to imagine that this joining technique was experimented with shortly after glassblowing became common around the first century BCE. However, what is truly amazing is that any of these early examples survived to be sold to customers without breaking in the cooling process. The reason for this is a technical issue that we have not discussed yet.

All glass expands a little when it is heated and shrinks when it cools. Different formulations of glass generally expand by differing amounts. When a single piece incorporates more than one type of glass, and the thermal expansions differ significantly, the result is disaster. After the piece is finished it is placed in a kiln where it slowly cools back to room temperature. Because of the mismatch, one area wants to shrink more than the adjacent area and the glass cracks along the join. The expansion and contraction is microscopic, but it is enough to ruin hours and hours of work, leading to much gnashing of teeth the morning after, when the finished work is inspected. 

The Venini glass masters had the benefit of this knowledge, but for earlier artisans, trial and error must have played a big role in determining which formulas were compatible. Different colors mean different metallic additives and to match expansion other ingredients would need to be adjusted. Today, manufacturers produce glass in a series based on expansion; artists can be relatively sure that two different colors from the same series can be “grafted” and not self-destruct when cooled.

[1] I have not absolutely confirmed this, but authoritative secondary references credit Venini, and I can find no mention to "incalmo" as a glass technique prior to the twentieth century.

Primordial Matter

16th century Mining practices, 

from Agricola, De Re Metallica

In the early seventeenth century, Florentine priest Antonio Neri wrote the first printed book devoted to formulating glass from raw materials. His work is called L'Arte Vetraria, which translates to "the art of glassmaking." The book became quite famous and this is what he is remembered for today, yet he considered himself first and foremost an alchemist. In previous posts, we have explored the commonalities between glassmaking, medicine and the apothecary's trade. Another field closely connected to alchemy was mining. 

In the seventeenth century, the earth was considered a living entity; metals were found to occur in "veins" which were thought to grow and once mined, regenerated over time. The metals themselves were thought to undergo a maturation process. The thinking was that primordial material left over from the creation of the world exerted its influence deep in the ground. Nurtured by the earth, under the influence of the suns rays, a process took place that eventually turned base metals into the more noble silver and gold. As far as Neri was concerned, alchemy was the art of imitating and enhancing natural processes that were already at work. In his manuscript Discorso, he writes:

I feel that the more perfect the art the most simple it is; so the authors [of alchemy] most unanimously agree that the ‘primordial material’ [prima materia] of the [philosopher’s] stone is something vile [base] and not bought with money, but easy to find. Moreover, the manner of work must imitate nature, which in order to produce gold makes use of the singular or simple material, which is the seed of gold, of a single vessel, which is the ‘womb of the earth’ [seno della terra] and of a single natural and vital fire, which is the sun.*

Elsewhere in the manuscript, Neri discusses several specific mines. He discusses the use of "vitriol" water that flowed in certain mines and how it could be used to transmute iron into copper. He discusses an unidentified mine "some distance from Leiden" (possibly in Limburg) and another in Slovakia in the town of Smolnik. It is reasonable to think that Neri visited these places himself. A third location, which he purposely keeps under wraps, is where he obtained "immature" gold that he was able to "multiply" through alchemical manipulation. With a certain disappointment, he writes "To this day I have never found another mine like it, and therefore suitable for this purpose." Clearly, he spent a significant portion of his time looking. He advises:

The gold mines are not all in the same condition, which is well understood for those of silver and all the other [metals]. Some are already perfect, in which nature has done what it could do and reduced the gold to its maturity, while other [mines] are still imperfect and in their infancy*

In his work for Medici prince Don Antonio in Florence, Neri's assistant/disciple was Agnolo della Casa. Della Casa took copious notes of Neri's experiments, and literally filled thousands of pages in notebooks that are today held by the National Library in Florence. Much of this material dealt with the transmutation of metals, and as we have seen Neri was not only concerned with materials, but with their specific place of origin. His first manuscript was titled "Treasure of the World, By Priest Antonio Neri – which [covers] the whole of alchemy with various illustrations, not only of the furnaces, vessels and chemical instruments but with other illustrations concerning the mining of all the metals." For he and his colleagues, mining and alchemy shared theoretical connections but also familial ones. Della Casa had a relative named Filippo Talducci della Casa (1543- c.1615), who was a celebrated alchemist and mining engineer, working in Prague and Krakow for the Holy Roman Emperor. Last but not least, there was also a practical connection. Mining provided many of the raw materials used in Antonio Neri’s glassmaking activities.  

* For a full discussion of Neri’s Discorso, see M. G. Grazzini, “Discorso sopra la Chimica: The Paracelsian Philosophy of Antonio Neri”, Nuncius 27, pp. 411-467.

** This post first appeared here 30 April 2014.