Dear Readers,

As you may have seen elsewhere, in mid February my wife and I suffered the loss of our home in a fire, in the hills of central Massachusetts. The good news is that we got out safely and had no animals in our care at the time. The fire crews were able to contain the fire from spreading, in what turned into a 3-alarm, 5-hour-long ordeal in subzero temperatures; they did amazing work, and no one was injured. The bad news is that all of my physical historical materials and research of 30 years have gone up in smoke. As a result I have decided to suspend this blog for the time being. It will remain online as a resource for those interested in the history of glass and glassmaking in the seventeenth century and beyond. I do intend to resume writing when I can, but for now my time and energy are required in getting us back on our feet.

Friends are providing temporary shelter for us nearby and our intention is to rebuild as soon as possible. To those who have reached out with a steady hand, to those who have opened their wallets, and offered advice in our time of need, we thank you from the bottom of our hearts. In what are already difficult times for all of us, you have made a huge difference in our lives.

Paul Engle
6 March, 2021

Monday, December 30, 2013

The Golden Sun

The Sun, Robert Fludd
from Utriusque Cosmi (1617),v. 2, p. 19.
Today, Antonio Neri is best known for his 1612 book, L'Arte Vetraria, in which he exposes the secrets of the art of making glass. In publishing his volume, he helped to fuel new discoveries in chemistry and medicine simply by making glass apparatus more available to experimenters. A 1662 translation of his book into English was one of the first acts undertaken by the newly formed Royal Society in London. Neri himself lived for only two years after his book went to press, in his native Florence, and never saw the seeds of his labor come to fruition. If he had lived, he might well be surprised that his legacy is in glassmaking, and not in the subjects that he himself held most dear.

In his death at the age of thirty-eight, Neri missed a rapid advancement in our basic understanding of nature. In the space of only a few decades the face of science and medicine would start to change irrevocably. Soon, experimenters were finding new chemical elements and began to map out the periodic table, often with apparatus made of glass. For centuries, the ancient Aristotelian concept of air, earth, water and fire as the basic building blocks of the universe had endured. By the end of the seventeenth century, the inadequacies of the old model were becoming clear. 

But Neri was not privy to any of this. In his time, any cracks in the Aristotelian model were minor. Like his sponsor, Medici prince Don Antonio, Neri was an adherent of new doctrines of the physician Paracelsus, who rebelled against the old system, but was still very much a product of it. First and foremost, Neri thought of himself as an alchemist. While history has not generally been kind to his ilk, a true understanding of early modern science rests on the methods and reasoning developed by alchemists like Neri. 

Although alchemy covered a wide range of activities, it will forever be associated most closely with the mistaken notion that base metals such as lead or iron could be transmuted into gold. Once science had established this idea as specious, the race was on to separate "new science" from the old. It became fashionable to cast alchemists into the mold of charlatans, tricksters and self-deceived fools. While many such characters did exist, Neri was not one of them; his work was based on careful reasoning and experimentation. The final irony is that through the kind of advancements that he himself helped to pioneer, the majority of his life's work has fallen by the wayside. What has endured the test of modern science is his treatise on glassmaking.

As early as the age of twenty, Neri was demonstrating transmutation to expert gold refiners. As late as the year before his death he was writing authoritatively and coherently on the subject. To understand how this is possible – to be rational and methodical, and at the same time completely wrong – is to get a sense of the true difficulties involved in science. Based on what he was taught, what he read, and his own experimentation, Neri thought metals and other materials "matured" over time. He thought that more "imperfect" metals like lead and iron were part of a continuum that ended with the "perfect" metal gold. Furthermore, he thought that primordial "seeds of gold" left over from the creation of the earth could be mined and isolated. Like wheat and other plants, given the correct nurturing, and conditions, this seed material could be encouraged to mature into vast quantities of gold. Writing in his 1613 manuscript Discorso, he says,
The response is that the chemical art lets the gold proceed from that present and immediate cause, because this is the seed of gold, which acts naturally when art cooperates. The chemist does nothing but extract the seed from gold and apply it to suitable bodies, with which it is united to render the fruit multiplied in the same way that the farmer does. He does not produce the fruit, but provides and prepares the earth and the seed, uniting them in such a way so that they bear fruit.*
Neri thought that ultimately, for gold transmutation to be successful one needed the blessing of the Creator. He documented his process in a heavily coded (and incomprehensible) recipe he called "Donum Dei" (the most precious gift of God). This name traces to alchemical writings from as early as the fifteenth century. He maintained that those who might harm society with this knowledge or wished to profit personally or swindle others would be denied the blessing and therefore be unsuccessful. 

The remarkable thing here is that Neri's understanding of chemistry was supported at every turn by experimentation. His recorded methods, for transforming lesser metals into one-another, were repeatable and stood the test of scrutiny by contemporary experts. In the light of modern chemistry, these transformations depended on subtle physical processes and chemical reactions that would not be understood for another century or more. By performing these experiments under controlled conditions, he was taking the first steps in what would become modern science. Eventually, it would be understood that while chemical compounds can be created and destroyed by various manipulations, individual elements cannot. Today we know that iron, lead and gold were formed in the cores of ancient stars, not too different from our sun. Lighter elements are successively transformed into heavier ones under a star's "nurturing" conditions. While he lived in a period in which he had no chance of getting the particular details correct, in a poetic sense Neri was not far from the truth.

* See Maria Grazia Grazzini, “Discorso sopra la Chimica: The Paracelsian Philosophy of Antonio Neri” Nuncius 27 (2012) 311–367.

Friday, December 27, 2013

Scientific Glassware

Antonio Neri (1598-1600),
"Libro intitulato Il tesoro del mondo" f. 38.
In the introduction of L’Arte Vetraria, his 1612 book on glassmaking, Antonio Neri discusses the technical and scientific uses of glass. He rattles off an impressive list of items, many of which are still in everyday use in chemistry and medicine:
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 very useful to the arts of distillation and spagyrics, 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;   cucurbits,  alembics,  receivers,  pelicans,  lenses, retorts, antenitors,  condenser coils, vials, tiles, pouring-vessels (nasse),  ampules, philosophic eggs  and balls. Countless other types of glass 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 aqua fortis and aqua regia, which are so essential for refiners (partitori) and masters of the prince’s mints 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.

The glass book, as it was published by Neri, did not contain any illustrations. If we hunt around in the alchemical literature and in museums, we can find examples of the apparatus and vessels on his list, but still, we might feel disappointed at not seeing the specific pieces with which our glassmaker was referencing. As it happens, we actually can see a number of these pieces, exactly as Neri experienced them. Over a decade before writing  the glass book, when he had just completed Catholic seminary and become an ordained priest, Antonio Neri wrote a manuscript devoted to "all of alchemy" in which he shows us many of the same glass vessels. Here he lists and shows us (in the illustration, from left to right, top to bottom) a double vase, a urinal (yes, that kind of urinal), a pair of Florence flasks (the Italians now call this a pallone di Kjeldahl), a philosophic egg, another flask which Neri calls a “bozza longa”, an alembic (or still-head), a retort, a bottle,  mouth-to-mouth urinals, a receiver (for a still or retort), a saucer, and assorted cups and ampules. Since many of these terms changed from place to place and over time, we can use this chart to get a much better idea of exactly what Neri was doing in his recipes. The use of urinals in his chemistry kit shows simple practicality; these were standard items made by glass factories. If a low-cost, readily available item could be used in the laboratory, so much the better.

Many of the items Neri lists were used in distillation, which was a basic technique of alchemists. A still could be set up in any number of variations, depending on the intended product, which could range from alcoholic spirits to powerful acids and other reagents. The "athanor" was a stove specially engineered to gently heat a large flask, called the "cucurbit," which contained whatever was to be distilled. The apparatus would include an "alembic"; a cap that fits on top of the cucurbit with a snout-like tube running downward from its top. The idea was that volatile ingredients would evaporate inside the cucurbit, rise up, condense in the alembic and run down its snout, to be collected in a "receiver" vessel. Sometimes, for convenience, all three pieces (cucurbit, alembic and receiver) are together referred to as the alembic. The process could be sped up significantly by adding a condenser coil, what Neri calls a "serpentine." As steam built up in the cucurbit, it was routed through its snout to a coiled tube that might be submerged in cold water. This way, the steam would condense more rapidly, sending more liquid to the receiver. Neri uses this method to produce acids in order to dissolve metal pigments for his glass, but the same basic technique is still applied today in producing industrial chemicals, medicines, perfumes and alcoholic drinks such as moonshine, brandy, vodka, rum and whisky. However, in the distillation of alcohol, metal (usually copper) containers are preferred. Neri was often producing chemicals that would react with metal, glass provided a very good solution to this problem but as he discusses at length, great pains must be taken to ensure that the glass vessels do not crack or break when heated or cooled too suddenly.

Wednesday, December 25, 2013

Buon Natale

In early modern Florence, on Christmas day, most shops closed for business as they do today. However, let us imagine that the royal apothecary, Stefano Rosselli, kept his Speziale al Giglio opened for a few hours in order that his customers could pick up bundles of his specialty sweets; his pistachio calissons. Around 1590 Rosselli started a recipe book which in time was handed down to his sons, who inherited the shop. There were actually three volumes, one for cakes and sweets, one for perfumes, and a third for medicinal remedies. 

Calissons are small confections which have been traditional sweets in the Provence region of France for centuries. Their modern incarnation usually takes shape of an almond, and consists of a candied fruit and almond paste base, frosted with royal icing. Here is Rosselli's version of pistachio calissons, recipe number forty-six from the first manuscript.
Take marzipan paste: Lay it on the plates as you would for calissons, but with the dough thin in the middle. On the edges all around, make a round hem, half a finger thick, and sculpt as it is done for scallop-embellished cakes [torte ricamate], with a knife, small scissors or tweezers. Baking is like for calissons. Once cooked, you will need some dough made with pistachios mixed with a bit of musk, and you must drop it into the hollow and fill so that we can see only the hem, the rest is covered by the pistachios. Do not bake (the pistachio paste); otherwise it loses its color. These are nice things.
To update the recipe, I started with a package of almond paste (Odense, 7oz/200g) from the grocery. This marzipan is made specifically for baking. It comes as a cylinder of paste which I cut into quarter inch slices (1/2cm), for a total of about twenty calissons. I arranged them on a baking sheet, on aluminum foil, and sculpted them into 1-1/2 inch / 4cm discs with a depression in the middle of each, building a low wall around their edges. I baked them in a 350deg F/ 175C oven, watching carefully, and pulled them out when they started to turn golden brown (8-10 minutes). The centers puffed up in the oven, so I gently poked them down with a spoon. Let them cool fully and they should peel off the aluminum foil easily.

For the filling I start with a 6oz/170g bag of shelled pistachios, (roasted and salted). This is more than enough for twenty calissons. The pistachios used by Rosselli were undoubtedly Italian which have a dark green color, as opposed to mine which were a paler brown-green. Reserve a ¼ cup/60cc of whole pistachios for use as decoration later. I used a large mortar and pestle to grind the pistachios into a smooth paste. Later I tried a food mill (clean coffee bean grinder) and that worked well also. Grinding will first make a powder, but continue until a paste forms with the consistency and appearance of peanut butter. Work with smaller batches of about ¼ cup/ 60cc at a time until everything is made into paste. 

Musk is an aromatic product used in perfume, but also in baking (do not confuse one with the other; the perfume is not edible). In Australia musk is a popular addition to candies and buttercream frosting. I couldn’t find it in my area (Boston), so I substituted honey and rosewater, both popular flavoring used in early modern Florence. Add 2 tablespoons/ 30ml of rosewater and one tablespoon of honey to the ground pistachios and mix thoroughly. Gently spread the filling into the marzipan calissons with a butter knife. Add a pair of whole pistachios (reserved earlier) to the top of each calisson as decoration. Serve and enjoy.

Of course, it is impossible to duplicate the exact ingredients used in the late sixteenth century. Beyond that, it is impossible for us to taste food as our ancestors did. Our likes and dislikes are influenced by the wider culture; the foods that we were brought up on are significantly different from the ones enjoyed by Rosselli and his patrons. Marzipan, by itself, can be overpowering but the pistachio takes the intense flavor down a notch. In my version, the lightly salted pistachios acted as a nice counterpoint to the sweetness of the marzipan. Even though this is not an exact duplication of the Renaissance era treat, this recipe is an enjoyable insight into some unusual flavor combinations of the past. Buon Natale.

Monday, December 23, 2013

Enamels

Enameled Pendant, Pope Gregory IX
Attr. Italian, mid 17th  c.
In the sixth part of his book, L'Arte Vetraria, Antonio Neri presents his recipes for enamels. These are a form of glass meant to be applied in thin layers like paint, and fired quickly. In the early seventeenth century, enamels were used to decorate both glass and gold. Neri does not present any methods specifically for enameling technique, but he does praise the talent of a good friend, who worked on glass in 1601, at the Casino di San Marco in Florence.  "At that time, the task of scheduling furnace work fell to the outstanding Mr. Nicolò Landi, my close friend and a man of rare talent in enamel work at the oil lamp."

The recipes Neri does present in his book are geared towards metalwork, as he says, "In which I show the way to make all of the goldsmiths' enamels to fire over gold in various colors. Included are the rules, the colorant materials and the methods to make the fires for such enamels with exquisite diligence. I present the demonstrations as clearly as possible for this subject." He continues,

Now, this is not only a difficult art but also necessary. We see ornate enameled metals in many colors, and they make a pleasant and noble sight; they entice others to look and take notice. In addition, enameling is one of the main segments of the glass field, and quite necessary. It seems to me to cause universal gratitude and pleasure, so I will endeavor to describe many ways to make all sorts of enamels, which are special materials in the art of glassmaking. They form one of its noble domains, not common, but a particular niche, and because this work is not lacking in substance, and is pleasant, useful, and necessary, I have made this present sixth book, for the satisfaction and benefit of everyone.
Neri's interest in enamels seems to start with  Nicolò Landi. Within a couple of years, in 1603, the glassmaker’s friend Emmanuel Ximenes wrote from Antwerp to Neri in Pisa about the suitability of an enamel he had received from the priest, purposefully overloaded with color. "As far as the red glass, […] I am doing a test in enameling gold, because having such a thin layer of enamel, if it is not very full of pigment it would remain a pale color. […] If it will not grieve Your lordship, I would love to find out the composition."

The implication is that Ximenes was working with his brother in law Baron Simon Rodriguez d'Evora, a famous jeweler and diamond dealer. Soon, Neri would join them in Antwerp, however, the evidence points to a working relationship with goldsmiths before his visit.  "In Pisa, I made them [enamels] without [measuring] weights, but by rough estimate." In fact, Neri mentions goldsmiths in virtually every enamel recipe in the book, and unlike other chapters, he makes no mention of Antwerp, but only of Pisa.

As in all his endeavors, Neri pays close attention to ground truth; he is not as interested in presenting a tidy cut-and-dried recipe as he is in describing what is actually happening with the materials.
You should add the material in four doses, stirring [the melt] thoroughly each time, and leaving the glass to incorporate the powder. The way to check that the color pleases you is by proofing it, and watching to see if it is sufficiently loaded. Stop adding powder and proceed to make a goldsmith's proof [on metal]; always examine the colors to get to know them by eye, as I have always done, because in this matter, I cannot give specific doses. Sometimes the powder will tint more, other times less, therefore you must practice with your eyes to understand the colors.

Friday, December 20, 2013

Don Antonio and the “French Disease”

Venus and Mercury with Cupid
Nicolas Chaperon (1612-1655)
A short time after finishing the seminary, newly ordained Catholic priest Antonio Neri entered employment with Don Antonio de' Medici at the Casino di San Marco. It was the beginning of a new century, and the beginning of what would become a lifelong accord between the two men. For the prince, the Casino also represented a new chapter in his own life. This was the palace that his father, Grand Duke Francesco, had built for himself, and after standing dormant for more than a decade it was now Don Antonio's. By renovating the Casino to his own taste, and restarting the alchemical and glass operations there, he was setting the stage for his adult life; what would turn out to be a difficult and physically painful life. In the seventeenth century, there were short term treatments for syphilis, but not a cure. Once contracted, the sexually transmitted bacterial infection would slowly, inexorably wind its way through the flesh and bones of its victim, savaging as it went. 

Don Antonio and Antonio Neri were both born in 1576. It is widely assumed by historians that the prince contracted the disease in his late teens, as a soldier and diplomat fighting the Ottoman encroachment into Hungary in the 1590s. What is not widely known is that he was sexually active as early as age fifteen. Crossed out and marked "in error" is a curious entry in the Florentine baptism register. Lines dated 31 October 1592, All Hallows Eve, record a male child, also named Antonio, born to the Medici Prince of Capestrano by the widow Madonna Isabella Casini. The following year, he was given a military commission and shipped to the front.

During his service, he was plagued by illness; he did participate in several battles, but was then reassigned to diplomatic duty. Upon return to Florence, the prince was ill for most of the ensuing year, running a fever that lasted for many weeks, keeping him bedridden for the entire summer. Later in the year, he suffered what was described as a terrible attack of "arthritic pain," leaving him immobile. These symptoms later resolved into "horrible diabetes," causing paralysis of the left side. It is difficult to imagine that the severity of Don Antonio's illness would not garner the full attention of the medical staff associated with the royal household. The symptoms described above are all consistent with syphilis.

Antonio Neri's father, Neri Neri, was physician to the royal family and must have been involved to a greater or lesser extent in Don Antonio's treatment. Dr. Neri’s 1585 treatise on left-side paralysis indicates he was considered an expert on the matter. Furthermore, it is easy to imagine that the doctor's alchemist son, the same age as the prince, might take an interest. While it is very possible they were already acquainted, perhaps this period was an opportunity for a bond to cement between the two Antonios.

This infection, which the Italians referred to as the "French disease" and the French as the "Italian disease" was elsewhere attributed to the Spanish, Germans and the Polish. Current research is still undecided if Spanish explorers brought the bacterium back with them from South America. The first recorded epidemics of syphilis occurred soon after Christopher Columbus’ return to Europe in the late 1400s.

Calamine and mercury were both effective at closing the open ulcers that were associated with advanced syphilis. Hence the expression "A night with Venus and a lifetime with Mercury." While illness in the royal court was generally kept a closely guarded secret, Don Antonio did develop a very public reputation for spending lavish sums to acquire natural secrets and recipes. It would be foolish to deny that his medical condition played a role in his devotion to discovering new medicines and in his pursuit of the philosopher's stone, which according to legend could cure all disease.

In the first decade of the 1600s, while Antonio Neri was in Flanders, the prince's condition deteriorated. But as soon as Grand Duke Ferdinando was dead, a baby girl was born to Don Antonio's handmaid and  then three boys to another woman he employed as a music teacher. While it would be easy to jump to conclusions about promiscuity, the evidence is that as each birth became known, the royal family mobilized to break-up Don Antonio's relationships. As the son of Grand Duke Francesco, and arguably the rightful heirs to the throne, Don Antonio's children were a vexing issue for his uncle's family, who currently enjoyed power.

As the second decade of the seventeenth century wore on, Don Antonio gave up horseback riding, and then travels all together. By 1620, he was confined to his bed. On 2 May 1621, he died at the age of forty-five. An account of his funeral procession tells that his lower body was so ravaged, that blankets were used to cover the carnage.

Wednesday, December 18, 2013

Prince Rupert's Drops

Prince Rupert's Drop
Christopher Merrett, The Art of Glass, 1662, p. 354
In 1612, Antonio Neri wrote the first book devoted entirely to the formulation of glass. Titled L'Arte Vetraria, it covers a wide range of glass recipes, colors, enamels and artificial gems. Neri died two years after its publication. The book was recognized by artisans and scientists, but by mid century it had become something of a rarity. Finally, in 1661 the book was reprinted in Florence, in a smaller format (octavo), with some grammatical revisions but otherwise in its original form. The following year, London physician, naturalist and member of the Royal Society, Christopher Merrett, published an English language translation of Neri's book. Toward the end of the volume, Merrett adds his own observations, and includes a section devoted to "Prince Rupert's drops," as had been recently demonstrated to the Royal Society.

Also known as "Dutch tears" these are glass novelties, usually made about three or four inches long, shaped like a tadpole; round and bulbous at one end, tapering to a narrow point at the other. They are formed by dripping hot molten glass into a bucket of cold water. Once a drop cools to a solid, the bulbous end can easily endure a moderate hammer blow, yet if even the smallest piece of the tail is broken off, the entire object will immediately explode into a hail of tiny glass fragments. The explanation is that when the glass is forced to cool rapidly in the water, the outer layer contracts like a tight skin, holding the interior under great compression. Like a balloon, it remains stable as long as the skin is not compromised. When the tail is snapped off, a shock wave of cracks advances and encompasses the entire object. Once the compressive forces of the skin are released, the glass interior shatters.


Prince Rupert of the Rhine
The glass drops were introduced to England by German Prince Rupert of the Rhine. He was a noted military and naval leader as well as a scientist and artist. His mother Elizabeth was the oldest daughter of King James I of England, making Rupert the nephew of Charles II, who chartered the Royal Society. In fact, Rupert was one of its founding members, along with Robert Boyle, Christopher Merrett and others. The drops were apparently invented after Neri’s death, in northern Germany or possibly Holland, where the method of manufacture was kept a secret, as the objects became popular party novelties throughout Europe. Finally the secret was revealed by Rupert to the society. A year after publication of Merrett’s translation of L'Arte Vetraria, in 1663, the drops were immortalized in a stanza of the "Ballad of Gresham College," which is where the society met regularly:

And that which makes their Fame ring louder,
With much adoe they shew'd the King
To make glasse Buttons turn to powder,
If off the[m] their tayles you doe but wring.
How this was donne by soe small Force
Did cost the Colledg a Month's discourse.


As mentioned, there is no direct connection between the glass drops and glassmaker Antonio Neri, but there is at least one interesting association. When Neri was in Antwerp for seven years visiting his friend Emmanuel Ximenes, the city was not exactly under siege, but a nasty civil war did rage all around (the eighty years war). The Dutch to the north wanted independence from Spanish-Hapsburg rule, and Catholic Antwerp was caught in the middle.

As a teenager, Rupert fought on the Dutch side, but this was long after Neri had returned to Florence from Antwerp. Before Neri left, he presented Maurice, the Prince of Orange with two vessels made from his best chalcedony glass, "which delighted him greatly." Rupert fought under Maurice's much younger brother, Frederick Henry. A third brother had courted his mother when she was young, as the two families enjoyed close ties. It is an open question whether Rupert saw or held any of Neri’s work in the Dutch royal households, but he clearly did take a keen interest in glass.

Monday, December 16, 2013

A Wee Bit Stroppy

Christopher Merrett
George Perfect Harding, (c.1820-50)
Antonio Neri's first translator was a London physician named Christopher Merrett. He was an early member of the Royal Society and completed several projects for them. Besides Neri's book, he compiled several volumes on flora, fauna and minerals. He published work on herbs and flowers, which was criticized as derivative, and he made some important contributions to the invention of carbonated wine (champagne). At the behest of physicist Robert Boyle, one of the founding members of the society, he spent considerable effort on the translation of L'Arte Vetraria into English in 1662. He sought out glassmakers, observed work in progress and tried, unsuccessfully, to find out something about the author himself. Nevertheless, he seems to have disliked Neri, or at least was very annoyed by him. Most notably, in the book, he complains about Neri's "nauseating repetitions" and decides to reorganize the structure of the volume. Dispensing with many of Neri's personal remarks, he congratulates himself on his "ingenious" changes to the text.

Merrett was also the first official librarian for the Royal College of Physicians. Through his dealings with them, we can see his ornery streak more clearly. In the 1666 great fire of London, the library and much of the college had burnt to the ground. He personally saved about a tenth of the 1300 volumes. Nevertheless, with the library, college and much of London gone, Merrett demanded his usual salary from the college and when they refused, he sued them in court. Later he got into a rather nasty public dispute with apothecaries over how to fill prescriptions. He was incensed at the practice of occasionally substituting unavailable ingredients for others that were at hand. In the end he was expelled from the College of Physicians, and to this day remains the only member ever to be banned for life. He retreated to his private practice and retired in obscurity.

Merrett's translation appeared a year after Neri's original was reprinted for the first time, in Florence, and a year before another edition printed in Venice. For the most part, Merrett's version of Neri is accurate, although he does go off the rails in a few places. He translates the Italian term for beadmaking "conteria" as “counting houses” rendering several passages completely nonsensical. As mentioned above, he decided to collect repetitious information at the beginning of sections, which does condense the text, but at the same time makes the book very difficult for any craftsman to actually use. On the other hand, he did introduce Neri's recipes to the English speaking world for the first time and he added extensive remarks and annotations, starting a tradition that would continue in later translations into French and German. The next translation after Merrett was into Latin, in Amsterdam in 1668. This version pays homage to Merrett but reverts to the original Italian for translation purposes, restoring Neri's format. 


The 1666 Great Fire of London
"Ludgate in Flames" (c. 1670)
Attrib. Unknown
Only fifty years after Neri’s death, Merrett stated that “Concerning our author, and this work, I find no other mention of him” (aside from two minor references). It is a shame that the physician did not have contacts in Florence, because he would have certainly found Neri’s nephew, living in the family palazzo on Borgo Pinti, practicing medicine himself. Antonio Neri was celebrated locally, in Italy; the Accademia della Crusca had adopted a number of his glassmaking terms for their groundbreaking dictionary. But it was Boyle and Merrett who put Neri on the path to greater notoriety throughout Europe. The book was translated and reprinted dozens of times, yet the life of the author remained largely a mystery. Neri was remembered briefly in the eighteenth century by Florentine historian Targioni-Tozzetti and again in the nineteenth century by Inghirami, Poggendorff, and in numerous short entries of other biographical dictionaries. By then, his book had become a classic text on glassmaking, yet still almost nothing of the author’s life was written. 

Regardless of Merrett’s difficulties with the College of Physicians, the apothecaries and his apparent dislike of Neri, it cannot be said that he was entirely humorless, even if on the dry side:
Glass is one of the fruits of the fire. Which is most true, for it is a thing wholly of Art, not of Nature, and not to be produced without strong fires. I have heard a singular Artist, merrily to this purpose say, that their profession would be the last in the world: for when God should consume with fire the Universe, that then all things therein would vitrifie and turn to glass. Which would be true upon supposition of a proportionable mixture of fit Salts, and Sand or Stone.

Friday, December 13, 2013

Ultramarine


Cappella Scrovegni (Arena Chapel), Padua
Frescos and ultramarine ceiling, Giotto 1306
In his fifteenth century handbook for painters, Cennino Cennini said, "Ultramarine blue is a color illustrious, beautiful and most perfect, beyond all other colors; one could not say anything about it, or do anything with it, that its quality would not still surpass." The ancient Egyptians used ultramarine to decorate the sarcophaguses of their pharos. Later, Marco Polo reported that it was made at a lapis lazuli mine in Afghanistan. Its name alludes to these far-flung origins: ultra-marine="beyond the sea." Venetians were probably the first in Italy to learn the extraction technique and import the raw lapis. Producing the rich blue pigment from the rock was no simple task; success required an elaborate set of steps. Because of the difficulty, for a time, an ounce of ultramarine was valued more highly than an ounce of pure gold. In the legal contracts drawn up for commissioned paintings, patrons often stipulated exact amounts of the precious material for the artist to use. Beyond its beauty, its presence in a painting signaled the wealth of its owner.

In the last part of his book, L'Arte Vetraria, Antonio Neri presents his recipes for a variety of paints, including one for ultramarine. In glassmaking, drinking goblets adorned with delicate paint-work raised their value and elevated them into the realm of art. Unlike enamels, which fired into the glass, most paint, including ultramarine could not survive the furnace, requiring application only after a piece was finished. The number of different paint and lake recipes in the book indicates Neri's familiarity with the craft. This, combined with his willingness to use other painter’s materials like "smalt" in his glass formulations, hints at a still unknown chapter in the alchemist's life. Perhaps, for a period in Antwerp, he worked directly with fine artists. Here is Neri’s ultramarine:

Take fragments of lapis lazuli, which you can find plentifully in Venice and at low prices. Get fragments that are nicely tinted a pretty celestial color and remove any poorly tinted fragments. Cull the nicely colored fragments into a pot and put it amongst hot coals to calcine. When they are inflamed throw them in fresh water and repeat this twice. Then grind them on a porphyry stone most impalpably to become like sifted grain flour. 

Take equal amounts, three ounces each, of pine pitch, black tar, mastic, new wax and turpentine, add one ounce each, of linseed oil and frankincense. I put these things in a clay bowl to warm on the fire until I see them dissolve and with a stirring rod, I mix and incorporate them thoroughly. This done, I throw them into fresh water, so they will combine into one mass for my needs. 

For every pound of finely powdered lapis lazuli, ground as described above, take ten ounces of the above gum cake. In a bowl over a slow fire, melt the gum, and when it is well-liquified throw into it, little by little, the finely powdered lapis lazuli. Incorporate it thoroughly into the paste with a stirring rod.

Cast the hot incorporated material into a vessel of fresh water and, with hands bathed in linseed oil, form a round cake, proportionately round and tall. You should make one or more other of these cakes from the quantity of the material. Then soak these cakes for fifteen days in a large vessel full of fresh water, changing the water every two days. In a kettle, you should boil clear common water and put the cakes in a well-cleaned, glazed earthen basin. Pour warm water over them and then leave them until the water has cooled.

Empty out the water and pour new warm water over them. When it has cooled, pour again, replenishing the warmth. Repeat this many times over, so that the cakes unbind from the heat of the water. Now add new warm water and you will see that the water will take on a celestial color. Decant the water into a clean glazed pan, pour new [warm] water over the cake and let it color [the water].

When it is colored, decant it and pass it through a sieve into a glazed basin. Pour warm water over the cake, repeatedly until it is no longer colored. Make sure that the water is not too hot, but only lukewarm because too much heat will cause the blue to darken, hence this warning, which is very important.

Pass all this colored water through a sieve into the basin. It still has the unctuosity of the gum, so leave it to stand and rest for twenty-four hours; all the color will go to the bottom. Then gently decant off the water with its unctuosity, pour clear water over it and pass it through a fine sieve into a clean basin.

Pass the fresh water through the sieve with the color stirred-up so that this color still passes through and therefore a great part of the filth and unctuosity will remain in the sieve. Wash the sieve well and with new water again pass the color through. Repeat these steps three times, which ordinarily leaves all the filth on the blue resting in the sieve. Always wash the sieve each time, cleaning it of all contamination. Put the blue in a clean pan. Gently decant off the water and then leave it to dry. You will have a most beautiful ultramarine, as I have made many times in Antwerp.

The amount per pound of lapis lazuli will vary. It depends on whether the lapis has more or less charge of color and on the beauty of its color. Grind it exceedingly fine on the porphyry stone, as described above and you will succeed beautifully. 

For a quite beautiful and sightly biadetto blue that mimics ultramarine blue, take ordinary blue enamel and grind it exceedingly fine over the porphyry stone, as above. Incorporate it into the gum cake with the dose described above and hold it in digestion in fresh water for fifteen days as with the lapis lazuli. Follow the directions for the lapis lazuli, in all and for all, until the end. These blues are not only useful to painters, but they also serve in order to tint glasses par excellence.

Wednesday, December 11, 2013

Faux Pearls

Johannes Vermeer
"Girl with a pearl earring" (1665-6)
Natural pearls, found inside various seashells, have been prized and worn as jewelry since antiquity. The pearl is formed as a secretion of the mollusk; it is the animal's response to an irritant, perhaps a sharp grain of sand, which has become lodged in its tissue. The secretion, called "nacre" is the same material from which the mollusk builds and enlarges its shell. Natural pearls are rare; large, well formed ones are even more so. A famous legend claims that Cleopatra used pearls to win a bet with Marc Antony: that she could spend ten million sesterces on a single meal. She literally drank pearls that had been ground up and dissolved in wine. Because of the difficulty in obtaining pearls, and their high demand among the wealthy, it is not surprising that like artificial gems, artificial pearls have enjoyed a brisk trade throughout history. 

In Antonio Neri's era, a number of recipes used glue, egg whites or other organic materials to simulate pearls. These had the obvious disadvantage of being susceptible to degradation by moisture and physical handling. Another alternative was to simulate pearls with glass, and on this count, Neri does not disappoint. Recipe number sixty in his book L'Arte Vetraria gives his prescription for artificial pearls. Here it is in its entirety:
 In fused and clarified cristallo, add three or four portions of tartar from wine dregs. You must thoroughly calcine this tartar to a white color. Stir it thoroughly into the glass, and continue to add more tartar, also well calcined until it is white. Add four to six more portions, always stirring the glass thoroughly, continuing thus until the cristallo takes on a pearl color. In this recipe, I cannot give exact rules, because it is a matter of experience, which is gained through experimentation. Once obtained, you must work the color quickly, because it will dissipate. I have practiced and experimented with this method many times.
"Cristallo" is the exceptionally clear glass the Venetians developed, perfected and were renowned for throughout Europe. "Tartar" is a crystalline growth that forms on the inside of wine casks, what we now know as "cream of tartar." Occasionally, one might spot crystals at the bottom of bottles of wine. They are a rich source of potassium. Neri, the Venetians and others had used tartar as a glass flux over a period of centuries. Here, however, he is not using it as a flux, but as a colorant to give the glass the pearl's shimmering appearance. His claim to making many batches of this glass implies large numbers of artificial pearls were in circulation. Our glassmaker presents a second recipe, which does not make any mention of pearls, but oddly may have much more to do with the evolution of reproducing these treasures of the sea. Recipe number 114 is entitled "The Way to Tint Glass Balls, and Others Vessels of Clear Glass, From the Inside, In All Kinds of Colors, So They Will Imitate Natural Stones." Here, Neri spreads fish-glue on the inside surface of a blown globe of clear glass, followed by various pigments.

Even in his time, artificial pearls found their way into royal courts and onto the canvasses of master painters. The fashion-setting monarchs of France and Britan, Catherine de' Medici and Elizabeth I were famous for their extravagant love of pearls. Elizabeth famously purchased faux pearls from Venetian glassmakers to adorn her garments. She commissioned many portraits donning her pearl studded creations. Referring to the famous painting by Johannes Vermeer, Lloyd Schwartz recently observed, "[T]he scholarship on Girl with a Pearl Earring reveals that the pearl isn't really a pearl […] the famous pearl is probably just glass painted to look like a pearl."*  It is interesting to note that the painting was executed in 1665-6, within five years after three reprints of Neri’s book, two in Italian one in English, and only a couple of years before a Latin edition printed in Vermeer's own country.

Around 1680, a Parisian maker of rosary beads invented a type of artificial pearl consisting of a small hollow glass bead, painted on the inside with the iridescent discharge of fish scales mixed with glue. He then filled the beads with wax. Jacquin had apparently rediscovered the shimmering pearly residue of a specific fish. His innovation fueled a new industry; he called the precious pigment "essence d'orient." But the material had already been employed in eastern France in 1656 and according to other reports as early as the reign of Henry IV of France (1572–1610), which closely coincides with Antonio Neri's own lifetime. By 1716, scientists were investigating essence d'orient under a microscope. Rene Antoine Ferchault de Reaumur reported tiny, perfectly formed rectangular plates that reflect the light to cause the shimmering.**

Perhaps more interesting than who discovered what, is the exchange of ideas and the overlap of interest between an Italian alchemist, a British queen, a Dutch painter, a French jeweler and a biologist.

* Also see Anthony Bailey, A View of Delft: Vermeer Then and Now (London: Chatto & Windus, 2001), p. 123, 124.
** For an English summary see The Edinburgh Philosophical Journal October 1839-April 1840 (Edinburgh: Adam & Charles Black, 1840), v. 28, p. 114, 115.

Monday, December 9, 2013

Glass Salt

Diderot & d'Alembert, L'Encyclopédie (1772)
Raking Out Baked Frit
Making glass from raw materials involves several steps. In his 1612 book on glassmaking, L'Arte Vetraria, Antonio Neri breaks the process down into parts so that, "given a bit of experience and practice, as long as you do not purposely foul-up, it will be impossible to fail." Pure white sand, or preferably quartz river stones which Neri calls "tarso" is broken up and pulverized into a fine powder. The initial work can be done by heating the stones in a furnace, then dropping them into a vat of clean cold water, where they will fracture due to the thermal shock. The process was often repeated multiple times. From there, the pieces are pulverized in a stone mortar and pestle. Stone, because metal tools would contaminate the quartz, and in the end tint the glass. Finally, a powder is obtained by grinding with a stone tool on a flat granite "porphyry stone." This powdered quartz is the main ingredient of glass.

The second critical ingredient is the flux, what Neri calls "glass salt" or "soda." This can be obtained from mineral sources, but European glassmakers in the seventeenth century extracted all their salt from certain plants. The powdered quartz was mixed with the salt and a third ingredient, which is critical, lime. Lime is simply calcium oxide used by builders to make cement. It is nothing more than pulverized seashells roasted to a high temperature. Neri advises using two pounds of lime for every hundred pounds of salt. He specifies that it should be added to all his frit recipes, but it is not clear that he understood its critical importance; without lime, the glass would be subject to attack by mere water, eventually decomposing. This mixture of soda, lime and silica when heated in a kiln would chemically react forming "frit." The combined materials were raked around in a kiln for a long period (many hours) and finally formed nut sized pieces. It was cooled and heaped into piles in dry cellars where it was aged for a time. This is where some real "magic" in glassmaking takes place. The glass salt or soda dramatically lowers the melting temperature of the quartz, all the way down to a point that was easily achieved in a wood fired furnace. When a batch of glass was made, the aged frit was then melted in furnace crucibles and skimmed to remove excess salt, which floated on the surface; it could foul the glass, and smelled terrible. The melted glass, now ready to work, was sometimes colored and finally made into objects by gaffers. 

Neri obtained his glass salt from products shipped by traders from the Levant (eastern Mediterranean). It was supplied as the dried, partially charred remains of special plants that grow in arid seaside conditions. Shipping them this way cut down on weight and volume, and prevented rotting. These Soda and Kali plants contain large amounts of sodium carbonates. This is a white powder, chemically identical to what we know as "washing soda." He advises, 
In buying either of these make sure it is richly salted. This may be determined by touching it with the tongue in order to taste its saltiness; but the surest way of all is to do a test in a crucible and to see if it contains much sand or stones, a thing common in this art and very well known by glass conciatori.
He crushes any large pieces of the product in a stone mortar, and sifts the result through a fine screen, ensuring that most of what remains is salt.  
As the common proverb of the art of glassmaking says: a fine sieve and dry wood bring honor to the furnace. Then with any of these sodas, 100 pounds of soda ordinarily requires 85 to 90 pounds of tarso.
Neri sets up large cauldrons of clean water over brickwork stoves, adds the plant product and boils the water. He strains the insoluble parts out and reduces the liquid by evaporation until crystals of the salt start to form on the surface. He skims these off and continues the process. Finally he carefully dries the product. Our glassmaker describes several variations of this process, including one in which he takes extreme measures to ensure the purity of the salt and clarity of the finished glass. In all, this is a task that could easily take several weeks to perform for the amount of frit to fill a single pot for the gaffer to work.

Not content with the established materials, our glassmaker experimented extensively with other plants: 
[U]se the husks and stalks of fava beans after the farmhands have thrashed and shelled them. With the rules and diligence prescribed for the Levantine polverino salt, extract the salt from this ash, which will be marvelous, and from which a frit can be made using well-sifted white tarso, as is described throughout this work. A very noble frit will result, which in the crucible will make a crystal of all beauty. The same may be made from the ashes of cabbages, or a thorn bush that bears small fruit, called the blackberry, even from millet, rush, marsh reeds, and from many other plants that will relinquish their salt. *
*These other plants produce potassium carbonate salts with similar properties to sodium carbonate.

Friday, December 6, 2013

The Rise and Fall

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

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

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

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

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

Wednesday, December 4, 2013

Royal Apothecary

Fresco, early 16th century speziale,
Castello di  Issogne, lower Aosta Valley, Italy.
As physician to the Medici royal family, Antonio Neri’s father (Neri Neri) worked closely with the other medical professionals in Florence. Among them was Stefano Rosselli, the royal pharmacist, who owned the Speziale al Giglio in the center of town.  We would readily recognize this shop today; rows of labeled jars lined the walls holding exotic remedies and ingredients from around the world. Freshly made sweets, cakes and other confections sat on the counter to entice customers. 

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

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

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

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



Monday, December 2, 2013

Metal Veins of the Earth


Antonio Neri, "The Mineral Gold"
Ferguson 67, f. 5r.
Over a decade before Antonio Neri wrote L’Arte Vetraria, the book on glassmaking for which he would become famous, he wrote an illustrated manuscript on the subject of alchemy. Begun around 1598 and completed in 1600, this is Neri's earliest known work, written very shortly after he was ordained as a Catholic priest. 

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


Antonio Neri, "The Mineral Silver"
Ferguson 67, f. 6r.
It was no flight of fancy that mined metal and ore deposits were depicted as literal veins. It was widely thought these were living structures, which carried the earth’s nutrients. In one of Neri's final works, his 1613 manuscript Discorso, he explains the ancient theory that gold could occur as immature seed material, left over from the primordial creation. If properly nourished, this seed would mature and grow into the precious metal, and with the appropriate knowledge this natural process could be restarted, or accelerated and the gold could be brought to perfection by artificial means. 

The idea that mined mineral deposits could regenerate naturally, if left to rest, is an ancient concept, one that persisted long past Neri’s era. In 1814, writing about tin mining in "On the Veins of Cornwall," William Phillips complained to the Geological Society of London, that armed with some current scientific knowledge, "nor would many miners […] believe, even to this day, in the regeneration of metals." Phillips quoted from an 1811 survey by Tonkin, in Carew's survey of Cornwall: "Whether tin doth grow again, and fill up places which have been formerly wrought away, or whether it only seperateth itself from the consumed offal, hath been much controverted, and is not to this day decided." And  "whether—dead lodes—that have not one grain of tin in them—may not hereafter be impregnated,  matured,  and prove a future supply to the country, when the present lodes are exhausted, I think well deserves our highest consideration."  

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

Friday, November 29, 2013

A Matter of Plagiarism

Francesco Lana Terzi (1631-1687)
The seventeenth century Jesuit scientist Francesco Lana Terzi (1631-1687) is famous for his design of a "flying boat"; he has been immortalized as the father of aeronautical engineering. What is not generally known is that he plagiarized the entire text of Antonio Neri's manuscript Discorso.

The original was never published by Neri, perhaps due to his premature death, but even as a manuscript, it must have circulated widely. It would be interesting to know the history of its diffusion, in order to understand how it became the subject of plagiarism. Lana Terzi, well known in the Italian Academia of the late seventeenth century, published his Prodromo in 1670. The entire chapter 20 is an exact reproduction of Neri's Discorso. Lana Terzi was fascinated by experimentation and manual arts. The Jesuit order refused their members permission to write about magic and alchemy; Jesuits with such esoteric interests could never write books directly devoted to these subjects, however, they could write works on the different aspects of natural philosophy. In this broader context chemical philosophy could be admitted. 
Title page of Lana Terzi's Prodromo

Neri was popular in his own time for his glassmaking knowledge. L'Arte Vetraria was widely read and its reprints and translations appeared over the centuries. Nevertheless, Neri enjoyed a considerable reputation among his contemporaries also for his 'chemical philosophy'. Discorso is a complete treatise on the subjects of chemistry and philosophy, to all appearance not different from many others written during the sixteenth century. It holds a similar structure, with an introduction defining the subject and the description of procedures. The final part lists possible objections raised against the validity of chemistry and gives Neri's timely responses. In this sense Discorso belongs to the alchemical traditions and Neri shows his deep knowledge of the Paracelsian doctrine and literature. Even so, the main features of the new 'scientific' mindset are present in Neri's treatise: the study of "the great book of nature" and the value of experimental practice. The traditional reliance on the authority of ancient wisdom loses its legitimacy. "We should not so easily give credence to all the histories," Neri claims, but we should "prove the possibility of this art of transmutation with certain […] experiences". Knowledge is acquired "with the practice of many experiences." It does not come from a divine revelation or from the study of many books.

There is no contradiction between the alchemist Neri and the glass-conciatore Neri; the will of gaining a deep knowledge of nature, based on the observation and experimentation, is common to both. Neri is always 'the technician' and never 'the philosopher'. Alchemy, the "Great Art," is the result of a deep study of nature and its aim is not to give an imitation of nature, but to make it perfect.

The 'modernity' of Neri can also be understood in his way of talking about chemical philosophy. He does not pretend to teach eternal truths, but only to indicate the way to achieve greater knowledge, by "understanding the modus operandi of nature." Consequently, the writer does not use the form of a dogmatic essay, but that of a conversational chat, or 'discourse'.

It would be interesting to discover how Lana Terzi came into possession of Neri's manuscript. Perhaps he was attracted by the mixture of old and new which was also a predominant theme of his time, when different models of knowledge coexisted and intertwined. Discorso offered him the chance of introducing the topic of alchemy without being accused of magism.

-M. G. Grazzini
Conciatore is pleased to welcome our first guest writer, independent researcher Maria Grazzini. Maria holds a Ph.D. in Philosophy from the University of Florence, where she studied Antonio Neri under the late Prof. Paolo Rossi, philosopher and historian of science. Recently, she published an annotated English translation of Neri's manuscript Discorso in the journal Nuncius. By day, she runs the hotel Albergo Natucci, in Montecatini Terme, with her husband Vincenzo. Please join me in welcoming Maria to Conciatore:

Wednesday, November 27, 2013

Cardinal del Monte

Portrait of Francesco Maria del Monte.Ottavio Leoni (1578–1630)
In the early seventeenth century, Cardinal Francesco Maria del Monte was the unofficial Florentine cultural ambassador in Rome. He regularly entertained visiting dignitaries and represented the Medici family's interests within the Vatican. He was an avid art collector, glass enthusiast and amateur alchemist.  He was a patron to the artist Caravaggio, to the astronomer Galileo and a dear friend to Neri's employer Don Antonio de' Medici.

There is a chance that he met Glassmaker Antonio Neri in person; in 1602 he visited the Casino di San Marco, where the glass foundry was located and returned in 1608, although by then Neri was in Antwerp. The strong bond of affection between Don Antonio and Cardinal Del Monte is clear from their extensive correspondence and gifts to each other.  In addition to their passion for alchemy, the two shared a strong interest in glassmaking technology.

Del Monte collaborated with Niccolò Sisti, the grand duke's glass foundry master at Pisa, where Neri also worked for a time. Sisti often provided Del Monte with glassware for Medici customers within the College of Cardinals in Rome. Thanks to the cardinal's patronage, many glassmakers in Rome were brought to the appreciation of the papal court.  

There are indications in Neri's 1600 manuscript that he visited Rome. If so, it is hard to imagine him not seeking an audience with the cardinal, either at his villa on the Pincio,  overlooking the city or at the Palazzo Madama, now offices of the Italian Senate. The palazzo was Del Monte's main residence near the center of Rome, appointed in fabulous luxury and arranged to accommodate a constant flow of dignitaries from around the world. The villa, on the other hand, was where his alchemy laboratory was located. This was a more secluded retreat where the cardinal could entertain guests with more discretion.


The Portland Vase
Del Monte's will shows that at the palazzo he maintained an entire room, "gabinetto dei vetri" [cabinet of glasswork] that housed five hundred pieces of glassware. It cannot go without mention that he was also the proud owner of what has become one of most celebrated pieces of ancient glass, now referred to as the Portland Vase.

Monday, November 25, 2013

Tin into Silver

The Alchymist, (Joseph Wright of Derby, 1771)
In Discorso sopra la chimica, a manuscript written by Antonio Neri in 1613, he discusses his philosophy of chemistry and gives several examples of recipes for the transmutation of metals. An instructive example is his conversion of tin into silver. He starts with a ball of pure English tin. He encases it in lute—clay that can withstand high temperatures—and then forces it below the surface of a bath of molten silver. After a time, the ball is removed and cooled. The clay is then cracked away to reveal that the tin inside is now silver. Neri explains that the "spirit" of the silver has penetrated the clay ball and its noble properties have converted the tin. 

In the light of current knowledge it is not hard to assign a more accurate understanding of what was taking place. Tin is a much less dense metal than silver and melts at a lower temperature. By forcing the luted ball down into the liquid silver, the tin inside quickly melts and its buoyancy forces it out of any small holes or cracks in the clay, even if microscopic in size. Much the same way as a sealed rubber balloon filled with helium deflates over time. As tin escapes the rigid ball it is replaced by silver from the surrounding melt, pushing inward. Once the tin escapes the clay, it will rise to the surface, but it also mixes, diffusing into the silver. Depending on the quantities and the temperature of the melt, a thin layer of alloyed silver-tin might form on the surface and some would evaporate into the air. Neri describes this as "malignant fumes" of the tin and goes on to say anyone discovering something "that would repress these vapors would have a very great secret."

Even though the clay encasement might appear to be a solid barrier, buoyancy forces cause much of the tin to escape the ball and to be replaced by silver. If the process of mixing were allowed to complete, the comparatively small amount of tin in the ball would disperse throughout the much larger silver melt. An assay would reveal a high silver content in the luted metal. Given the historical lore of alchemy and the level of scientific knowledge at the time, this was a very persuasive argument in favor of transmutation, even for seasoned experts. A valid criticism of Neri's explanation is that he was simply not skeptical enough; the presence of silver inside the sealed ball does not, in itself, prove transmutation. Indeed, a careful accounting of all the materials involved would have revealed to him that the total amount of silver had not changed in the experiment. 

For the viewers of such a demonstration there are other considerations. There was an unmistakable theatrical flair to these events. Audiences often included princes and other royals. Even before the demonstration begins, there is an air of anticipation, the expectation to witness something extraordinary. It is not hard to imagine the same sort of performance atmosphere for Neri's demonstration that was and is still a critical part of legerdemain and conjuring acts. Even if not intentional, this charged setting leads to a suspension of disbelief. It can have a powerful effect on our perceptions. The same state of mind that allows us to be amazed by a "magic act" can blind us to seeing nature as it is in truth. Despite his interpretation, Neri’s experiment does involve repeatable chemistry, conducted without trickery that has a legitimate explanation, even if not the same one advanced in the early seventeenth century.

For further reading, see M. G. Grazzini 2012, p. 351.