Friday, August 29, 2014

Neri's Cabinet #3

Crystals of Copper Sulfate Pentahydrate
(Vitriol of Venus)
Vitriol of Venus was one of the most cherished items in Antonio Neri’s chemical library. In his book, L'Arte Vetraria, he describes its effect in glass this way:
To your great contentment, you will be astonished at what you see. I do not know of anybody else who has tried it this way and I Priest Antonio Neri trying it found it most marvelous, as said above, and it is of my own invention. [1]
He is so proud of his creation that he spreads the description of his method over four full chapters of the book, going into a level of meticulous detail that is extreme, even for Neri. Rest assured, dear readers, that I have taken the liberty of distilling said description down to a more manageable form for your reading pleasure. Nevertheless, our priest-alchemist clearly puts great stock in this preparation, going so far as to drop hints that this material has uses that go far beyond glassmaking: "Many things could be said here, which are omitted as not being pertinent to the art of glassmaking, which perhaps upon another occasion you will be able to judge." [2]

Before starting, he gives some general advice:
You should make the sulfurs, vitriols, ammoniac salts, and similar materials slowly, over a low fire, so they are well prepared and well opened, because a violent fire will cause great damage to them.[3]
To begin, Neri cuts thin copper sheet into small pieces half the size of a small coin. filling a crucible, he layers the copper pieces with common sulfur (known as brimstone).  He cements the vessel shut with a lid and then buries it in the hot coals of a drafted furnace for two hours.

The dark purple contents are then ground and sifted through a fine screen, mixed with six ounces of pulverized sulfur per pound and then heated in a round terracotta pan, which is sitting in the hot coals. When the sulfur starts to burn, he stirs the mixture, rolling it into balls with an iron hook so it does not stick to the pan, continuing until it stops smoking. He removes the mixture from the heat, grinds it finely, adds more sulfur and repeats the entire process three times.

Neri grinds the resulting reddish tawny colored material into powder, putting a pound of it into a large glass vessel containing six pounds of clean water and gently evaporate away a third of the water. The liquid is carefully poured off and saved. The residual solids are dried and recycled in the process. Now more solids are allowed to settle out of the "beautiful blue" liquid over a two-day period and then the liquid is filtered through a felt cone.

He heats the liquid again, this time evaporating two thirds and then puts the remaining third into glazed terracotta pans, and leaves them in a cold damp place overnight. "You will find the vitriol of copper has formed into crystalline points that mimic true oriental emeralds." The crystals are removed, dried and the liquid is further evaporated in order to obtain more crystals. To the chemist, this material is copper sulfate pentahydrate [4]; today it is sold inexpensively as a fungicide for swimming pools. One reason it was so valuable to alchemists is that when gently heated or added to water this chemical forms a sulfuric acid solution. 
This is the true flaming azure blue [tincture], with which marvelous things are made. It is most potent, and as sharp as anything known in nature today, as can easily be perceived from its odor.
However important this was in other areas of alchemy, those applications do not have any particular relevance to the blue-green tint it imparts to glass, which he does make use of throughout the book. The full recipe was so long that he continued it several times and finished as the final chapter of L'Arte Vetraria. Here are the closing words to 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.[5]
[1] Neri 1612, ch. 31.
[2] Ibid, ch. 133.
[3] Ibid, ch. 37.
[4] CuSO4•5H2O
[5] Ibid, ch 133.

Wednesday, August 27, 2014

Alchemy in the Kitchen

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, was dead of an unknown illness. The now orphaned children 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. 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 Allesandro, 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.

Since I am already out on a limb, I will also suggest that the methodology of alchemy lives-on today in kitchens around the world. 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 ( dated 13 June 2014.
[4] Neri 1598-1600, ff. 7r, 8r, 9r, 10r.

Monday, August 25, 2014

Manganese from Piedmont Reprise

The green tint from iron contamination
is neutralized by magenta from manganese.
For Antonio Neri, contaminants, especially metallic contaminants were the bane of producing crystal clear glass. Great care needed to be taken to ensure the purity of each ingredient at each step of the glass making process. The greatest threat of all was iron. Even small amounts will tint glass green and for Renaissance era glassmakers, nemesis iron was everywhere. It is common in quartz, the main ingredient of glass, showing up as yellow "rust stains" both in sand and stones. It turned up in the plant salts as a trace-element and finally it was in the tools. Iron was in the mortars and pestles, in the pots and kettles, in the frit rakes, in the ladles, the stirring rods and in the blowpipes. A mistake at any step could easily tint the batch, even at the final stages. Neri admonishes glass workers:
Make sure never to return the neck, where the rod attaches to the glass, into the crucible of cristallo, because there are always remains of the iron that will cause it to become dark ... 
The antidote to iron is manganese or more specifically manganese oxide, a mineral mined throughout Italy. However, Neri cautions: 
… you must always use manganese of Piedmont the way it is made for Murano, because the manganese of Tuscany and Liguria has more rust, which always make the melt dark. 
This color correction technique was known as early as the late 14th century and by Neri’s time it was a widely practiced technique in the glassmaker’s toolbox. Manganese oxide was known as a pigment in antiquity; the Magnesia region in Thessaly, central Greece was an ancient source for the black mineral. Around the year 1450, a clear crystal-like glass suitable for working into thin elaborate forms was developed in Venice. The glass was called cristallo and Murano glassmaker Angelo Barovier is often given credit. He may well be responsible for bringing together several existing techniques—manganese color correction among them — but these techniques individually were all available and utilized by glassmakers at least fifty years earlier. Barovier’s innovation would become a tradition that would become synonymous with the finest glass made anywhere, carried on by countless glassmakers and ultimately by our Florentine priest more than a century and a half later.

Removing the green tint of iron contamination with manganese is a clever trick. The manganese imparts a magenta tint to glass. As the complementary color to green, it effectively "cancels out" the green tint. The trade-off is that the glass is slightly darkened, even if neutral in color. In terms of what light does, when it passes through glass tinted by iron, green light is unaffected, while red and violet light is dampened. In effect, the green is enhanced. Now, adding manganese to the glass dampens only green light and brings the spectrum back into balance. The overall effect is that all the colors of light are slightly dampened, but by the same amount. In Neri's case, minor contamination from iron would produce only a small green tinge and the problem was corrected with a small dose of manganese. The resulting grey would hardly be noticed, especially in the thin, delicate pieces so popular at the time. To the eye of all but the most experienced expert, this decolorized glass had perfect crystal clarity.

This post first appeared here in a slightly shorter form on 14 October 2013.

Friday, August 22, 2014

Neri’s Cabinet #2

Alchemical symbols used to denote sal ammoniac.
Today we will examine "sal ammoniac," a common alchemical ingredient used by Antonio Neri in many of his preparations. In its pure form, it is a colorless crystalline material and is known to chemists as ammonium chloride. It does occur as a (rare) natural mineral, but it was also manufactured as early as the thirteenth century, as noted by alchemist Albertus Magnus in his De alchymia.[1] Neither he nor Neri provides a recipe for sal ammoniac, but other sources indicate that it was made by allowing urine to putrefy with common salt. French investigators documented another method used in Egypt in the eighteenth century. This scheme involved burning the dung of animals who fed on spring grasses and then sublimating the ammoniac out of the resulting soot. Sublimation occurs when a heated material goes directly from a solid to a gaseous state without ever becoming liquid. Sal ammoniac has this property; when heated it turns to a gas and upon cooling, turns back to a solid.

The usefulness of sal ammoniac in alchemy stems from the fact that when dissolved in water, which it does easily, it immediately dissociates into equal parts of ammonia and hydrochloric acid, which in turn will dissolve some metals, including tin, zinc, iron and (reluctantly) lead. Its most famous use was as an additive to the stronger acid aqua fortis (nitric acid). Together the two formed aqua regis which was strong enough to dissolve gold. At the time that Neri was working, the only known way to dissolve the most 'noble' of metals (gold) was with the 'king' of acids (aqua regis). Neri puts this knowledge to use in his recipe for ruby-red colored glass made with pure gold. His description is light on details, but he does clearly direct the reader to dissolve the precious metal in aqua regis, then gently evaporate away the acid to obtain the red pigment.

Elsewhere in Neri's glassmaking book, L'Arte Vetraria,[2] he uses sal ammoniac in the production of "alemagna blue" paint and in the tinting of natural rock crystal. 

Another of Neri's creations requiring sal ammoniac was Chalcedony glass. It had swirls of every color the glassmaker could produce. He achieved this feat by making extensive use of aqua regis to dissolve a long list of metals. He then gently evaporated off the acid, leaving ultrafine powdered metals, which he added as pigments to the glass melt. 
With this powder, I made a chalcedony in a glass furnace in Antwerp that was then run by a most courteous gentleman; Mr. Filippo Gridolfi. This chalcedony gave rise to work so nice and graceful, that it emulated true oriental agate, and in beauty and delightful colors by far exceeded it.
Today, chemical factories produce vast quantities of the materials used by Neri in his glassmaking exploits and in far higher purities. Having unlimited quantities of every conceivable chemical compound at our fingertips makes it difficult to appreciate the physical labor involved by seventeenth century alchemists, both in the preparation of the glass and in the production of the individual ingredients. The chalcedony glass recipe cited above must have taken workers many, many hours to produce and must have cost a small fortune. 

[1] Magnus 1958.
[2] Neri 1612.
[3] Glauber and others used the term 'sal ammoniac' to describe a related chemical (NH4)2SO4. When mixed with aqua fortis this forms a nitric-sulfuric acid solution, which does not form aqua regis, and does not dissolve gold.

Wednesday, August 20, 2014

The Dregs

"the struggle of fixed and volatile"
allegorical illustration from
Splendor solis [detail] 16th C.
"Dregs" were otherwise known to Antonio Neri as, terra, gruma, immondita, terrestreità and my favorite:  sporchezza. It was the "filth" and sediment left in the bottom of vessels after useful material was extracted from a preparation. These often foul-smelling substances were sometimes discarded:
Then filter out the dregs of the vitriol impregnated water; that which is yellowish you should throw away. –L’Arte Vetraria, chap. 38.
Other times, dregs were further refined A notable example was the potassium rich muck left at the bottom of aged wine barrels. This was Neri's secret ingredient in producing a fine, sparkling cristallo glass. To understand the distinction between the useful and the useless forms of dregs, we must dig deeper into Neri's philosophy.

It might be surprising to some that these lowliest of materials could play an important role in the theory of transmutation—the alchemists' ultimate quest—, which was to turn base metals into gold and silver. The idea was that a natural evolutionary process occurred in which  primordial material from the creation of the universe would, over time, mature through the lesser metals into pure gold. It was thought that this maturation was prompted by "seeds" of gold contained in the material. In Neri's view, this could be interrupted by various natural circumstances and could be restarted or sped-up through alchemical manipulation.

If one was to "purify" lesser metals into gold, it was advisable to know what needed to be removed. In his manuscript Discorso, Neri carefully explains five categories of impurity, which he then breaks down further into two sub-groups:
It should be noted in general, that in dealing with the [Aristotelian] elements in accordance with chemical philosophy, we can say that all mixed bodies in this art are discovered to contain five kinds of impure substances, which are completely dead and without any virtue or properties effective to [alchemical] operations. Two are from impure substances and three from pure substances, where all the strength, effectiveness and virtue are located specific to each mixture. Of the two [derived from the impure] one is called 'phlegm', which is to say a watery substance with no odor or taste and the other is called 'dead body' [corpo morto] or 'damned earth' [terra dannata], an earthy substance that is equally tasteless and without virtue.[1]
Indeed, in Neri's chemical philosophy, the above two useless forms of impurity (phlegm and corpo morto) are complemented by three useful forms (salt, oil or true sulfur and spirit or mercury), which are present in so-called pure materials. Researcher Maria Grazzini notes in her annotations to the manuscript that: "The chemical philosophy to which Neri refers is Paracelsian, which in addition to the four Aristotelian elements introduces the principal triad (tria prima) of salt, sulfur, and mercury. References to sulfur and mercury were already present in Arabic alchemy." [2] 
Of the other three [derived from the pure] one is called 'salt' and it is the so-called most fixed substance because it is resistant to the violence of fire; it does not flee or vanish into the air. The second is called 'oil' or 'true sulfur' because of the similarity to it, fatty and viscous. The third is called 'spirit' because it is more spiritual and volatile than all the others and even the slightest heat will cause it to dissipate into the air if it has not been bound to the salt, which is the component fixed by the oil. By its tenacious, slimy nature, [oil] acts to bind the volatile to the fixed. These three types are those of the pure substances, which are called by many other names; 'body', 'soul' [anima], 'spirit'; 'bitter', 'sweet', 'acid'; 'salt', 'sulfur', 'mercury' etc.
In them alone are placed all of the virtue and effectiveness of the minerals, the vegetables and the animals, even if the quantity of pure substance is very small in comparison with the impure in any kind of mixed body. These [three] are found in each mixed quantity of pure substance, in comparison with the ineffectual found in the impure. [3] 
In his view, it is these last three forms of impurity that hold the key to transmutation, which tends to puts dregs in a whole new light.

[1] Grazzini 2012, p. 339.
[2] Ibid, note 45, p. 339.
[3] Ibid, p. 340.

Monday, August 18, 2014

Don Giovanni

Don Giovanni di Cosimo I de' Medici
In July of 1621, a man lay dying in his bed, in his palazzo on Murano, the glassmaker's island in Venice. This fifty-four year old had recently become a father and his wife Livia was expecting a second child, but the tumor in his throat meant he would not see his two year-old son Gianfrancesco Maria grow up, nor would he live to hold his yet unborn daughter in his arms. His death would also trigger a series of unanticipated ugly events. Don Giovanni de' Medici was the son of Grand Duke Cosimo I and Eleonora degli Albizzi. He had been general of the Venetian army and before that lead Tuscan troops in Flanders, France, Hungary and served as ambassador in Madrid. But he was far more than a soldier; he was an architect who helped design the Chapel of Princes in Florence, he was a strong patron of the arts and he was a devoted alchemist. He plays a somewhat tangential role in the life of glassmaker Antonio Neri, yet their paths cross repeatedly through common associates, interests and locations.

Don Giovanni's palazzo on Murano was the grandest on the island; previously owned by the father of Grand Duchess of Tuscany Bianca Cappello. She spent time at the palazzo as a child and was the mother of Antonio Neri's sponsor, Don Antonio de' Medici. King Henry III of France stayed there on his tour of glass factories on the island. Later, the palace would be the residence of the bishop of Torcello and ultimately, in 1861, became what it is today: the famous Museum of Glass (Museo del Vetro).  If, in the winter of 1603-4, Neri followed the route through Venice to Antwerp suggested by his friend Emmanuel Ximenes, then a visit to this palazzo would have certainly been in order, although not yet occupied by Don Giovanni.

Early in his career, in the 1590s, Don Giovanni commanded troops against the Ottomans in Hungary and his young nephew Don Antonio was directly under his command. The two men would both set up alchemy laboratories in their respective Florentine residences; Don Antonio in the Casino di San Marco on the north side of town and Don Giovanni at his Casino del Parione (today the Palazzo Corsini al Parione) along the Arno River behind the Santa Trinita Church. Don Giovanni's was only steps away from the palazzo Bartolini, Antonio Neri's residence after his ordination, located in front of the church. Santa Trinita was a Benedictine church and the office of Vallombrosan Abbot-General Orazio Morandi. It is unknown if Neri had any association with the church, but Morandi also held a strong fascination with alchemy and wrote that times spent in Don Giovanni's laboratory were among his "most cherished memories." Much later, in 1630, Morandi gave testimony at court concerning a Simon Carlo Rondinelli, saying: 
I have known Signor Rondinelli for twenty years, from the time I was in Florence. I met him often there in the house of Alessandro de’ Neri. The said Rondinelli is very well versed in astrology.*
The timing places Morandi in the Neri family house when Antonio's younger brother, Alessandro (who had inherited the house), was twenty-one years old. It was shortly before Antonio's return from Antwerp.

While Neri was in Antwerp visiting his friend Emmanuel Ximenes, Don Antonio was leading Tuscan troops nearby, in Flanders, on the side of the Spanish against the Dutch independence movement. Nevertheless, he found time to submit his design for the Chapel of Princes in Florence, and to quarry marble for the project and have it shipped back to Tuscany. It is unknown if Neri and Don Giovanni ever shared a meal in Antwerp, but the decorated soldier/polymath did commission a series of paintings there, for the grand duke, to be hung in the new Medici villa 'La Ferdinanda' at Artemino in Prato. The interior decoration of the public spaces in this villa were being executed by artists Passignano and Poccetti, fresh from finishing their recent collaborative masterpieces; the Neri Chapel and Cestello church on Borgo Pinti, financed by Neri's late father.

* Translation by Brendan Dooley “Morandi's last prophecy and the end of Renaissance politics” (Princeton: Princeton Univ. Press, 2002), p. 22.

This post first appeared here in a slightly different form on September 25, 2013.

Friday, August 15, 2014

Neri’s Cabinet, Part 1

The many alchemical symbols used to denote crocus martis.
In addition to the usual eclectic mix of Antonio Neri related material that I bring to this space, I have decided to start a regular series of posts dedicated specifically to his chemical repertoire. 

A first encounter with the technical aspects of sixteenth and seventeenth century alchemy can be confusing, frustrating and more than a little disorienting. There is no shortage of records, letters, manuscripts and recipe books; the challenge lays in making sense of them in a way that relates to our current view of the world. It is understandable that alchemical materials and compounds had unfamiliar names; but the real difficulties arise with the realization that any given name might describe several different chemicals, and in fact, there may be several different interchangeable synonyms/symbols for any given name. As it happens, there were good reasons for this state of affairs and taking the time to understand them really opens up a window onto a strange and wonderful landscape of history. 

Antonio Neri considered himself an alchemist first and glassmaker second. Because of this "crossover," his work can help us to navigate details in both fields that might otherwise go without explanation. His writing broadly divides into two categories: one intended for generally curious readers and another intended only for those familiar with the arcane coded language of alchemy. We have examples of both styles by Neri and all within the period of about fifteen years. By comparing one group against the other, we can start to decode some of his more arcane passages and at the same time gain considerable confidence in his technical abilities. In the introduction to his famous book on glassmaking, L'Arte Vetraria, he wrote, "I have described every last detail clearly and distinctly in this work, I am sure that if you do not purposely foul up, it will be impossible to fail, after having acquired experience and practice.” Yet, in 1870, in the journal Nature, George Rodwell commented on another of his works, pronouncing him a “sensible chemist” on one hand, but on the other, noting that Neri had used “no less than thirty-five different names, and twenty-two symbols" to denote a single material, the metal mercury. 

We will start with his glass book, where his materials and methods are detailed with special consideration for those not familiar with the art. Then perhaps we can build on that and make sense of his more esoteric material.

In L'Arte Vetraria, Neri gives four different methods to make crocus martis. He explains: 
Crocus martis is nothing other that a refinement and calcination of iron. A means by which its pigment, which in glass is a deep rutty red, is opened and imparted to the glass. It not only manifests itself but makes all the other metallic colors as well, which ordinarily hide and are dead in the glass, dance in resplendent apparition. Since this is the way to make the hidden metallic colors appear, I have put down four ways to make it.
In the first method, Neri mixes iron filings with sulfur and then heats the mixture in the furnace for a long period. We can guess that the result is a mix of iron oxide and iron sulfide. These are the constituents of a popular red pigment of the same name (crocus martis) used in pottery glazes. In the second method, he takes the iron and sulfur mixture and sprinkles it with vinegar and leaves it in the sun for many days. The third method uses aqua fortis (nitric acid) for better effect. In the fourth and final method, Neri uses aqua regis, an even stronger acid. 

In all four cases the predominant result will be iron oxide and sulfide, but alas, chemistry is not that simple; there will be minor concentrations of other compounds depending on the acid used. We must consider that vinegar and the other acids in the seventeenth century were significantly different from those products today. They were made by different methods and contained a variety of impurities that would never be found in the current products. As Neri notes, each method produces different effects in the glass and therefore we must conclude that each, to some extent, differs in chemistry as well. In a number of green glass recipes he uses crocus made with vinegar, yet in chapter 71 he uses it to diminish the green in yellow lead crystal. In 124 he uses crocus made with aqua fortis for red glass. The lesson here is that the name of a material tells us only the basics, how it was made is at least as important if not more so. 

Wednesday, August 13, 2014

Filippo Sassetti

Goa, India 1509
In the Florentine baptism records, the entry for Antonio Neri was made on a Thursday, the first of March, 1576. He was born the previous evening, to Dianora Parenti and Neri Neri. His godmother is listed in the document as Ginevra Sassetti. Not a great amount is known about her; she was from a prominent family, at the time in her late fifties. However, there are indications that other members of her family interacted with the Neri's. Her nephew Filippo mentions Antonio's father favorably several times in letters, providing a fascinating glimpse into the way disease was diagnosed and treated.

When Antonio was born, Neri Neri was in his early thirties, and already a highly regarded physician. Baccio Valori was director of the famed Laurentian Library in Florence and steward of the Medici's simples (medicinal herbs) garden. He was friend to Neri Neri and godfather to Antonio's oldest sister Lessandra. Between 1583 and 1588, Valori received letters from a mutual friend, Filippo Sassetti, who was living in Goa and Cochin – trading settlements in India. Filippo was a native Florentine; he attended university in Pisa with Valori and they became lifelong friends. After Sassetti's father was forced to sell the family home to pay off a debt. Filippo moved to Lisbon and became a spice trader. Not suited for a desk job, he soon set sail seeking adventure in the orient. 

In a 1586 letter to his old friend, Sassetti discusses an Indian remedy against the plague, with a substance called bezoar. The bezoar stone is a mass that develops and becomes trapped in the digestive systems of certain animals. It often resembles a smooth rock. Some thought ground bezoar to be a universal antidote to any poison. Sassetti was puzzled about how the grindings of bezoar could work to cure the plague. Its Aristotelian elemental properties would not be a match for correcting the imbalance of humors in the body. This is a principle, he explains, taught to him by Neri Neri. "I have thought about it and I can not understand how it works, because the plague is of the same corruption and this is a lack of heat inherent in the humidity. And the stones, if I recall correctly, they have a cold and dry complexion, hence may not precede the restoration of heat. Messer Neri one time did me the favor of telling me." 

In another letter to Baccio Valori, Sassetti notes that he has collected rare varieties of cinnamon in his travels along the Malibar coast in India. His intention was to rediscover the species thought to be a powerful cure of disease by the ancients. He planned to send a parcel of seeds of these and other medicinal plants. "If it pleases God, in the coming year, I will send this to you, so that you may see it all, together with our Messer Neri Neri, who graces my memories." Later he writes that he is sending Baccio the discourse on cinnamon, which he has compiled, along with some plants. These, it later turned out, were water damaged in the journey. He had hoped for some help from Neri Neri on the question of whether the cinnamon he collected from the island of Zeilan [Ceylon], is the same thing as the curative cinnamon of Mantua described by the ancients. Valori was an authority on these matters in his own right. As librarian for the Medici's imposing collection of books and manuscripts, he had vast academic access. As keeper of the simples garden, he had first hand experience in horticulture and its derivative medicinal cures. 

The principles of "humorism" were passed down from celebrated physicians of the ancient world, like Galen and Hippocrates. It was thought that the cure of disease was dependent on the restoration of balance between four substances in the body: blood, phlegm, black bile and yellow bile. In turn, each of these was associated with one of the Aristotelian elements: air, water, earth and fire respectively. Each was further associated with specific symptoms and characteristic traits of the patient, even their psychological outlook and physical complexion. This system formed the foundation of Western medicine and was taught and practiced well into the nineteenth century. Although, within Antonio Neri's lifetime newer experimentally based methods did start to take hold. A decade after his father's death, in a 1609 letter, Antonio boasts about his success in curing disease in Antwerp using the methods of the medical upstart Paracelsus. It is unlikely that his father would have approved.

Monday, August 11, 2014

Alchemy School Reprise

Frontispiece woodcut from
 De Chemia Senioris, by Zadith ben Hamuel, 1566
A common notion holds that alchemists were eccentrics, lone practitioners working in dingy basements, cut off from the rest of the world. This was a myth already well established in Antonio Neri's time, but far from the whole truth. In the early seventeenth century, alchemy was practiced in medicine and pharmacy, in precious metals refining and even in the preparation of artists' supplies. Where Antonio Neri received his training is unknown, but there are intriguing clues.

We turn first to Antonio's own father, Neri Neri, the royal physician to the Medici family. According to historian Giulio Negri, he received his medical degree at the prestigious Studio Fiorentino, the forerunner of today's University of Florence. At the time, it had already been in operation for two centuries, having been granted a charter in 1348 by Holy Roman Emperor Charles IV. The charter was a response to a personal appeal by Archbishop Piero Corsini. Antonio Neri's own distant relative, Ser Giovanni Neri, later became Corsini's secretary, so a family legacy of attendance is not out of the question. That our priest might attend his father's alma mater is pure speculation, but it seems foolish to doubt that he started his alchemy education at his father's knee, in his own home.

The manuscript entitled Treasure of the World that Antonio devoted to "all of alchemy" was completed in 1600, but started two years earlier. On a page near the beginning, dated 1598, the twenty-two year-old clearly identifies himself as a "priest." Church rules forbade anyone from becoming a novice before the age of sixteen, which for Neri would have been in the spring of 1592. Full ordination as a Catholic priest typically took six years, meaning in 1598 Neri only recently underwent the 'laying on of hands' ceremony by the archbishop, confirming his title. The inescapable conclusion is that Neri learned his craft while in seminary and the Church sponsored his education. 

The identity of Neri’s order is a mystery, but the few scattered pieces of the puzzle that we do have allow for some interesting speculation. The list of candidates having some connection to the priest and the means to support, if not supply an education is not long. The five names that stand out are the Dominicans, the Carmelites, the Augustinians, the Knights of Malta and the Benedictines. The Dominicans were noted for their scholarship and ran two apothecaries in Florence. The Carmelites are named in the deposition notes taken by Agnolo della Casa, which identify Neri’s confessor as such. The Augustinians counted a Francesco Neri as abbot of their San Clemente monastery who worked for Don Antonio de’ Medici at the Casino in 1619. Antonio’s aunt, Faustina, apparently entered an Augustinian convent after the death of her husband.  Also, though Neri’s confessor was a Carmelite, he also served as the parish priest of an abbey run by the Canons Regular of the Lateran—an independent Augustinian congregation. The Knights of Malta ran two churches in Florence and Neri can be connected to both.  The knights followed the rule of Augustine and enjoyed a close relationship with the Augustinians. The order traces its roots to the crusades  and has various associations with alchemy such as George Ripley. Their main presence was on Malta, though in 1565 they suffered a devastating defeat there to the Ottomans. Neri was not a knight, but he could have occupied a place in their clergy. In Florence, any resources for schooling in alchemy by the knights would have been overseen by its most prominent local official; that official was Neri’s benefactor Don Antonio de’ Medici, Grand Prior of Pisa. The Benedictines were also associated with Neri’s family and had the means to provide him with an education in alchemy. He was born in the parish district of Benedictine church, San Pier Maggiore. His father was buried in the Cistercian (reformed Benedictine) church of Cestello. His sister  committed to a Benedictine order (the Camaldolese). After his ordination, in 1601, Priest Antonio Neri lived across the street from the Vallombrosan (Benedictine) mother church, Santa Trinita.

In any case, as royal physician Neri's father was an esteemed member of the court and Antonio would have enjoyed rare access to its inner sanctum. The grand duke's own laboratory at the Galleria dei Lavori certainly would have been a familiar haunt for our alchemist-priest.

This post first appeared here in a shorter form on 2 October, 2013.

Friday, August 8, 2014

Reports from Parnassus

Rafael - El Parnaso (Vatican, Rome, 1511)
Apollo on Parnassus, (fresco detail). 
In the spring of 1612, Antonio Neri finished writing L’Arte Vetraria, and the Holy Office of the Inquisition approved it for publication. The Glassmaking book passed the Church’s censors despite it containing a large number of alchemy related methods. Contrary to what we might imagine, they did not have any problems with Neri’s work; in fact, one bureaucrat commented that the book was full of useful information. Remember, this was at the same time that so-called sorcerers and witches were being tortured and executed around Europe. One big difference was intent, or rather perceived intent. Another was personal connections. The truth is that alchemy was something of a fad among the wealthy nobility, who used the equipment for everything from making rosewater, to distilling liquor. 

To form a better sense of the public image of the chemical arts in the early seventeenth century, we can turn to the satirical critic Traiano Boccalini, who published a book of his own the same year as Neri. Ragguagli di Parnaso [Reports from Parnassus] was an immediate hit. In fact, it became so popular that he and his sharp tongue were forced to leave Rome for the comparative safety of Venice soon after its completion, and soon after that friends found him dead. Initially, Boccalini had been on good terms with Church officials. Eventually, he became bitterly disillusioned and wrote Ragguagli as a collection of fictitious newssheets. These were patterned after the letters that circulated widely as the forerunners of modern newspapers. The reports took place in the mythical state of “Parnassus,” which struck an uncanny resemblance to contemporary Rome. Its monarch, Apollo, struck an uncanny resemblance to the pope, as the princes of Parnassus did to cardinals, bishops and curia officials. Report LXXXIX is illustrative of what were the more practical fears over alchemy, in this case, some creative wealth building among the clergy. It gives a sense of alchemy’s public persona. Apparently, there was a crackdown on chemical apparatus, under the guise of concern for public health. Our author slyly suggests, in the very last line, that it may have had more to do with putting an end to clergy lining their own pockets. 
Apollo [the pope] Prohibits the Princes from the Use of Distillers or Alembics At Home: 
In the past few months here, various ailments have emerged in this state of Parnassus, which have caused in some an extraordinary fatigue with frequent agitation: in many a tenacious fever, a faint pulse and a monstrous appetite: in others an intense stomach ache with an ardent thirst.  
The doctors cannot find a single remedy. However, the true cause of these maladies, by decree of Apollo, was revealed before a recent meeting of the grand Asclepius [Society] of prominent Greek, Latin and Arabic doctors, where it was the subject of long and erudite debate. Because neither the enemies of the grand princes nor other eminent gentlemen were spared, it was doubted whether the sickness was caused artificially by powerful poisons. Furthermore, it is clear these troubles were not only happening nearby.  
And we see several modern princes put great study in their most excellent facilities to prepare in their alembics things other than rose water. They conceal subjects dangerous and heinous with their hidden machinations of poison. This cannot be allowed to be covered up; such a scandal must be exposed with the violence of a dagger.  
His Majesty, concurring with the opinion of the congregation, yesterday morning made a public speech, to issue a strict edict, which forbids princes of any color, from ever keeping distillation or alembic operations at home or outside. However, he allowed similar exercises in the hands of experimenters and herbalists. A thing being extremely foul is the minting of counterfeit money in the night and then by day covering so treacherous a crime by running shops openly making medals for the crown. 
In this piece, Boccalini crystallizes the complex social stigma carried by alchemy. Of all the practical tasks that could be performed in this art, more notoriety by far was derived from the concept of turning base metals into gold. Neri feared that transmutation in the hands of the masses was likely to collapse the economy. The Vatican’s concerns were more immediate: financial gluttony within the Church. Anyone with enough alchemical knowledge could possess the skills to produce convincing counterfeit money. Turning lead into gold was a theoretical issue; dealing with rogue counterfeiters was a more immediate one. 

Wednesday, August 6, 2014

The Curious Reader

An unknown early modern reader with spectacles.
Church of San Pedro y San Pablo Teposcolula,
High Mixteca Region, Oaxaca, Mexico, 16th century fresco. 
In my last post ("The Art of Fire Reprise"), I discussed Priest Antonio Neri’s familiarity with Biringuccio’s Pirotechnia and the allusions he makes to it in the introduction of his own book on glassmaking, L’Arte Vetraria. The entire introduction is relatively short and well worth reading for a fascinating glimpse into the state of the art four hundred years ago. It also outlines Neri’s thoughts on the earliest origins of glass; he recounts the prevailing stories of the day and adds his observations, but as a careful historian, he lets us decide for ourselves how much is truth and how much is myth. Here is the introduction to L’Arte Vetraria in its entirety, addressed to "The Curious Reader":

Without a doubt, glass is a true fruit of the art of fire, as it can so closely resemble all kinds of rocks and minerals, yet it is a compound and made by art. In the fire, it fuses and becomes imperishable. Indeed, like the perfect shining metal gold, the fire refines it, polishes it and makes it beautiful. 

Clearly, its use in drinking vessels and in other utilitarian objects is far more graceful, appealing and noble than any metal or stone suited for such creations. Beyond the ease and low cost with which it is made, and the fact that it can be made anywhere, glass is more delicate, clean and attractive than any material currently known to the world. It is so useful to the distillation and spagyric arts, not to mention indispensable to the preparation of medicines for man that would be nearly impossible to make without glass. Furthermore, many kinds of vessels and instruments are produced with it; boccie [cucurbits,] cappelli [alembics,] recipienti [receivers,] pellicani [pelicans,] leuti [lenses,] storte [retorts,] antenitorij [antenitors,] serpentine [coils,] fiale [vials,] nasse [nasse,] quadretti [tesserae,] ampolle [ampules,] oui filisofici [philosophic eggs]  and palle [balls].*

Countless other types of vessels are invented every day to compose and produce elixirs, secret potions, quintessences, salts, sulfurs, vitriols, mercuries, tinctures, elemental separations, all metallic things and many others that are discovered daily. Also, glass containers are made for acque forti and acque regie,** which are so essential for refiners and partitori [masters in royal mint] to purify gold and silver and to bring them to perfection. So many benefits for the service of humanity come from glass, which seem nearly impossible to make without it. We can see in it and in any other thing the great providence of God that has put glassmaking materials so abundantly in every place and region, so that something of such great use to humanity can be made with such facility for all. Glass is also a great ornament to God's churches since, among other things, many beautiful windows are made adorned with graceful paintings in which the metallic colors are so intense and vivid that they seem like so many oriental gems. In the furnaces, glasses of many colors are formed with so much beauty and perfection that it seems no material like it can be found on earth. 

We can suppose the invention of glass is very ancient since the Holy Scripture says in The Book of Job [28:17], "gold and glass shall not be equal to it [wisdom]…", which gives clear evidence that glass was invented in antiquity. Saint Jerome held that Job descended from Abraham, and was the son of Zanech, who descended from Esau and therefore was only fifth from Abraham. There are many who attribute the invention of glass, and perhaps with some reason, to the alchemists; wanting to imitate jewels, they discovered glass. This may not be too far from the truth; I show clearly in book five of the present work, methods to imitate all the jewels, in which we see the vitrification of stones that never could fuse and vitrify by themselves. Pliny indicates that glass was discovered by chance, in Syria [now Israel], at the mouth of the Bellus [now Na'aman] river by certain merchants pushed off course at the whim of the sea. They were forced to stop there and set up camp. In order to eat they built fires on the beach, where there was a large amount of that kind of herb that many call kali, whose ashes make soda and rocchetta. This burned in the fire, its ashes and salt reacted with the sand and with the stones suitable to vitrify; these materials changed into glass. This event illuminated the mind of man on the means and manner to make not only glass, but cristallo, cristallino and many other beautiful things made with glass. Also, it is taught that in the time of the Roman Emperor Tiberius, a way of making glass malleable was invented, a thing that was subsequently lost and today is hidden to all. Indeed, if such a thing were to be known today, without any doubt it would be more valued than silver or gold for its beauty and incorruptibility, since glass does not give rise to rust or taste or smell or any other [adverse] quality. Furthermore, it provides great value to humanity in the use of reading spectacles and [reflecting] spheres. Even though the former may also be made of natural rock crystal, also known as mountain crystal and the latter with the alloy known as steel [bronze], a composition made of copper and tin, nevertheless, in the one as well as the other, glass is better suited, not nearly as expensive, more desirable and more effective, especially with [reflecting] spheres. Beyond the difficulty and expense in making them, they do not image as vividly as the glass and what is worse, in a brief time they fade, not reflecting anything at all.

For these and many other reasons, we can easily conclude, glass is one of the most noble things on earth that humanity has today for its use. Since I have labored in the craft of glassmaking for a long time and seen many things, I am moved to report to the world part of that which I have seen and done in it. Although the methods to make salts, bollitos [salts for cristallo] and frits are well known to many, it still seems to me that this is a matter requiring clear and distinct treatment, which I do with observations and diligence. Moreover, if my work is well considered it will not be judged altogether useless, indeed, perhaps even necessary and enlightening. Besides, with my particular method of extracting salts to make the noblest cristallo, the artisan who is diligent in doing things the way I, with clear demonstrations, reveal and teach, will make things as worthy, appealing and noble perhaps as anything made today or that can be made in any other way. In this and every other matter that I deal with in the present work, the diligent and careful craftsman will find that I have written and shown the truth, not as I was told or persuaded by any person whatsoever, but as I actually did and experienced many times with my own hands.

I have always possessed the resolve to write and to speak the truth. If anyone trying my recipes and methods to make the colors, pastes and tinctures does not succeed in making what I have described, do not reject my work or think I have written lies, but reflect upon where he may have erred. Especially those who have never before handled such things, because it is impossible on the first try to have the ability to be a master. That being the case, repeat the work so that it will continuously improve and ultimately be perfect as I describe it. Be warned in particular to give careful consideration to the colors for which exact and determined amounts cannot be given. Indeed, with experience and due practice learn and with the eye and judgment know when a glass is colored sufficiently and appropriately for the work at hand. With paste made for the imitation of jewels, in determining the size that you want to make, bear in mind that those to be set in gold with foils as for rings and other similar applications should always be more transparent. Those that are also set in gold, but are intended to hang in the air, as earrings and similar items, require a greater charge of color. All of this is nearly impossible to teach, but must be left to the judgment of the careful artisan. Keep in mind also to be meticulous so the materials and colors that you make are well prepared and well ground. To ensure that materials slated for exquisite work are beyond question, prepare and make the colors personally the same way as I teach and to that end you can be confident of good work that will come to fruition happily. 

The fire in this art is of notable importance. Indeed, this is what perfects everything and without which nothing can be done, therefore give it in a proportionate way. In particular, use hard dry wood, being careful of harmful smoke, which always causes damage, especially in the furnaces, where pots and pans stand open and the glass could become imbedded with specks causing imperfections and notable ugliness. 

In closing, I say that the artisan who is or becomes diligent, practical and works step by step, as I describe, will find truth in the present work. He will find that I have published and given to the world only as much as I have proven and personally verified through experiment. 

If the world acknowledges my arduous efforts, as I hope, I will perhaps also be encouraged to publish the experience of my endeavors over many years, working in various parts of the world, in the chemical and spagyric arts. Known and perfected in the ancient times, I believe there is no greater thing in nature in the service of humanity. Men who became experts in these arts were thought to be gods and were esteemed and revered. 

I will not enlarge on this matter [glass] since I have described every last detail clearly and distinctly in this work. I am sure that if you do not purposely foul up, it will be impossible to fail, after having acquired experience and practice. Therefore take what I have to offer in good course, as I have candidly written this work, first for the glory of God and then for the delight, benefit and utility of all.

* A more detailed treatment of the translation of these terms can be found in the post dated 27 December 2013.
** 'Aqua fortis' and 'aqua regis' Neri uses the plural forms, so I have kept his italian.

Monday, August 4, 2014

The Art of Fire Reprise

Antonio Neri, MS Fergusin 67, 1598-1600,ink and water color.
In L'Arte Vetraria, Antonio Neri describes glass as "a fruit of the art of fire." He apparently liked this evocative phrase enough that he borrowed the words from an earlier volume written in the first half of the sixteenth century by Vannoccio Biringuccio. Biringuccio's De la Pirotechnia was a sort of bible for metal workers, refiners and miners. The author was in charge of an iron mine near Siena and in the late 1520's he became something of a local hero for casting cannons to help Florence defend itself in the great siege.

Neri’s opening line reads:
“Without a doubt, glass is a true fruit of the art of fire, as it can so closely resemble all kinds of rocks and minerals, yet it is a compound, and made by art.”
And here is Biringuccio, half a century earlier in 1540:
“… it [glass] is one of the effects and real fruits of the art of fire, because every product found in the interior of the earth is either stone, metal, or one of the semi-minerals.  Glass is seen to resemble all of them, although in all respects it depends on art.”
In one sense, Neri is paying homage to his distinguished predecessor, but he is also lending a new meaning to Biringuccio's words. The mining expert's short chapter on glass is a survey and a great deal of it is spent on the debate of whether glass should be classified as a 'semi-mineral' because of its similarity to rocks and gems, or as a metal because of its molten properties in the furnace. Neri puts a different spin on the fruits of glassmaking. He is not as worried about classification as he is excited about the material's many uses. He composes a formidable list for us, one that ranges from drinking glasses, to optical lenses, to church windows, to laboratory equipment.

Neri uses Biringuccio's chapter as a format for his own introduction; they both cover much of the same ground, but with a telling difference in tone. Biringuccio is very much 'old school.' His main concerns are taxonomy of the material and the construction of the equipment. For him, the finished products of glassmaking are more ornamental curiosities. He trumpets that glass objects hold more beauty than their metal counterparts, but he warns that we should not give them too much love because they are fragile and therefore, like life itself, ephemeral. Neri, on the other hand, agrees that glass can be beautiful, but he is all about the chemistry and the innovative things that can be done with this versatile material.

The differences in emphasis between the two men nicely illustrate a shift that was taking place throughout society in general. For hundreds of years, the focus of scholars and craftsmen had been on rehabilitating ancient knowledge. Europeans very much saw themselves as recovering from the long slow decline of medieval times. To learn the secrets of a craft, one looked backward, not forward, and the farther back the better. Ancient texts were prized and coveted because they were seen to contain purer wisdom, uncorrupted by centuries in the dark. Both men discuss the ancient origins of glass, recounting that it is mentioned in the Bible and by scholars of the Roman Empire like Pliny. The difference is that Neri's gaze is turning; instead of looking back so much, his eyes are shifting to the present. Biringuccio's Pirotechnia and books like it created a platform from which Neri and his generation could then build on. 

There are many definitions possible for the beginning of modern science. One that is compelling from a broad, non-technical point of view is that modern science began when we spent less time looking backward for answers and more time learning from the world as it is.
This post first appeared here in a slightly different form on 7 October 2013.

Friday, August 1, 2014


An ancient oil lamp (replica),
the first tool used to make glass beads.
Today, the first day of August, exactly marks the one-year anniversary of the start of this blog, Conciatore. I did not know what I was doing when it began and a good case can be made that the situation has not changed all that much in the intervening months. At first, I thought I might have enough material to keep it going for about six months and I was happy with that. It would be a sort of test to see if I had the chops to crank out a regular column on deadline, sweat the details, and get my facts correct. I never thought of myself as any kind of journalist, but as writing became more of an avocation for me, the question did pose itself. I thought there might be a small groundswell of enthusiasm to learn about Neri, an obscure seventeenth century Florentine priest who was also a glassmaker and an alchemist. After that I expected interest to trickle off and I could comfortably fade into obscurity and shut down the blog without anyone noticing; that is not what happened.

In fact, very little has gone according to plan, but that is ok with me. The realization that a backlog of posts was not going to happen was quickly replaced by continual panic about what I was going to write about next. Somehow, new subjects keep coming and I have learned to relax a little. Right now, for instance, I am only a few hours from post time. 

The biggest surprise, for me, has nothing—or maybe everything—to do with writing; it is the fantastic group of people who have collected around Conciatore. Thank you; thank you for making my life richer for knowing you, even if only through an occasional comment. Now that I am hooked, I can not imagine shutting down the blog, although I also have no idea what I will write about for another year, let alone next week.

Since today’s theme seems to be gratitude, I think it might be a nice idea to share the dedication page from Neri's 1612 book L'Arte Vetraria. In case you do not know, this was the first printed book in history devoted to the subject of making glass from raw materials. It became the bible of glassmakers for the better part of three centuries. It was translated into numerous languages, annotated, plagiarized and re-translated. Don Antonio de' Medici, to whom the book is dedicated, was the son of the second grand duke of Tuscany, Francesco I, who was instrumental in bringing Venetian glassmaking techniques to Florence. Don Antonio continued the tradition of this style of glassmaking in the laboratory-palace he inherited from his father. Around 1600, Antonio Neri would come to be employed there. A decade later, after a long visit to Antwerp, he returned to the city of his birth to publish the famous book. Here is the dedication in its entirety:

Priest Antonio Neri.
Since I spent many years of my youth laboring around the glassmaking craft and experimenting with many fine and marvelous effects, I have now drawn up a treatise with the greatest clarity of which I am capable, in order to publish it to the world to help and delight, as much as I will be able, those who know this craft. I have made many things of my own invention and  I have tested other recipes of skilled craftsmen, verified as true; since they were hidden I want to reveal them for the reasons stated above and if successful, I will be encouraged to publish the remaining part of my hard work on the subjects of chemistry and medicine as well. I have experienced, in both of them, many useful effects, which are believable and commendable only by those men who know these subjects. In all consideration, I dedicate this book to none other than you, most illustrious Excellency, for you have always been my outstanding patron and you also understand this and all other worthy and precious knowledge. In fact, you practice all of the arts required of a true and generous Prince. I implore you therefore to accept if not my work, then my complete devotion to your great merit and virtue, Excellency. I pray that God will fill you with happiness. 
From Florence 
January 6, 1612