Wednesday, July 31, 2019

A Reluctant Glassmaker

The Sun, Robert Fludd
from Utriusque Cosmi (1617),v. 2, p. 19.
(alchemical symbol for gold)
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. In fact, chemistry and medicine were areas for which he expressed the highest regard. A 1662 translation of his book into English at the behest of Robert Boyle 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 he 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 presenting  transmutation experiments 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, Neri 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 series of chemical transformations traces to alchemical writings from as early as the fifteenth century. Neri 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 little 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.

Monday, July 29, 2019

Neri and the Kabbalah

Kabbalistic Sephiroth Tree,
from Portae Lucis, Paulus Ricius (Trans.)
Augsburg, 1516.
Kabbalah is a form of mysticism practiced within the Jewish tradition. In the early seventeenth century, there was a great deal of interest in Kabbalistic teachings among Catholic alchemists and natural philosophers. It was recognized that Christian alchemy had its roots in Hermetic and earlier Arabic societies, (the word "alchemy" itself is of Arabic origin.) It was thought that the Jewish Kabbalah was yet another branch of the same traditions of relaying secret knowledge by word of mouth. 

In early modern Florence, Italy, there were some interesting connections between the Kabbalah and glassmaker, alchemist and Catholic Priest Antonio Neri. Here is Neri’s own description, of Kabbalah in his 1613 manuscript Discorso: 
Some call it Kabbalah: in ancient times fathers communicated it to their children only by voice, preserving [this knowledge] for posterity, not for history, but as simple tradition. Others finally gave it the name of 'wisdom' [sapienza] because they rightly believed it was impossible, without this art, to know perfectly the nature and the qualities of natural bodies. In order to achieve the end they wanted, which was the perfection of the bodies, they separated the pure from the impure through various chemical operations, which can all be reduced to six principal phases.*
He goes on to describe basic chemical operations that were thought to be fundamental to purifying materials, and ultimately to the production of the Philosopher's Stone. These techniques are the same as practiced in Christian alchemy, and Neri uses them in his glassmaking recipes. Clearly, he had more than a passing knowledge of the subject, and it is interesting to speculate on how he might have come to learn about Jewish alchemical traditions. 

Early seventeenth century Florence contained a city within a city: the Jewish Ghetto. A walled perimeter encircled what is now the Piazza della Republica. This was the mandated home for all of Florence's Jewish population. Each night, entrance gates were closed and locked from the outside. Within the Ghetto, residents were allowed to live and warship freely, even maintaining a Synagogue. In the daytime, the gates were opened, and residents were allowed to go about their business and leave the city with special passes. Among the Ghetto's most prominent residents was the family of alchemist Benedetto Blanis (c.1580-1647.) Blanis served as librarian to Medici prince Don Giovanni. Giovanni maintained an alchemical laboratory in his residence, which was run by Blanis, located only a short distance from where Antonio Neri was living when he first worked at the Casino di San Marco.  

Don Giovanni maintained a close relationship with Neri’s benefactor Don Antonio de' Medici. So close, in fact that when two of  Blanis' relatives were implicated in a gambling scheme, Don Antonio hid them at his residence and then spirited them away, out of Florence, in his own coach until matters cooled off. Furthermore, Blanis came from a family of doctors who must have been known to Neri's father, royal physician to Grand Duke Ferdinando. Antonio Neri was probably a couple of years older than Blanis, if they did not meet through mutual connections with the Medici family, then perhaps they met on the street. The walk for Neri, between his living quarters near Santa Trinita, and the Casino laboratories would have passed around or through the Ghetto, and the walk for Blanis to Don Giovanni's palazzo on Via Parione took him past Neri's front door. The paths of the two men may have crossed, but there is not direct evidence.

Of course, in the absence of hard facts, there are many other possibilities of how Antonio Neri might have become acquainted with Kabbalistic tradition. By taking a look at Blanis and his connections to the Medici family, we can at least see an area of cooperation between Jewish and Christian alchemists in what we might otherwise assume to be an inviolable separation.** 

* “Discorso sopra la Chimica: The Paracelsian Philosophy of Antonio Neri”, M.G. Grazzini / Nuncius 27 (2012), p. 337.
For more on Blanis, see Edward L. Goldberg, The Secret World of Benedetto Blanis. (2011).
** This post first appeared here on 6 January 2014.

Friday, July 26, 2019

Ultramarine Blue

Scrovegni  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, July 24, 2019

Early Modern Aleppo

Aleppo, 1764
Antonio Neri is famous for  his 1612 book on making glass, [1] but in the late sixteenth century his father was also famous; Neri Neri, as he was called, was a graduate of  the esteemed 'Studio Fiorentino', head of the Florentine physicians and apothecaries guild, and royal physician to the grand duke of Tuscany, Ferdinando I de’ Medici.  

In those days, one of the best connections a physician could have was a reliable associate who could procure the exotic herbs and remedies prepared in the Orient. To have such a contact in one's family was even better, but perhaps best of all was an older brother who was a merchant living in the fabled city of Aleppo, located in Syria at the very end of the Silk Road. The brother of Neri Neri was named Francesco or "Franco" [2] for short and Aleppo was no ordinary city; it was a sort of international crossroads for traders connecting north and south, east and west. It was where silk and cotton were traded for wool and metals, where gold and silver changed hands for rubies and lapis, and where exotic spices and medicinal preparations could be found and exported to places like Venice and  Florence. [3] In 1583, Englishman John Eldred passed through Aleppo and recorded this:
[W]e passed forward with camels three dayes more untill we came to Aleppo, where we arrived the 21 of May. This is the greatest place of traffique for a dry towne that is in all those parts: for hither resort Jews, Tartarians, Persians, Armenians, Egyptians, Indians, and many sorts of Christians, and enjoy freedome of their  consciences, and bring thither many kinds of rich merchandises. In the middest of this towne also standeth a goodly castle raised on high, with a garrison of foure or five hundred Janisaries [Sultan’s guard]. Within foure miles round about are goodly gardens and vineyards and trees, which beare goodly fruit neere unto the river side, which is but small; the walls are about three English miles in compasse, but the suburbs are almost as much more. The towne is greatly peopled. [4]
Aleppo has been in continuous occupation since prehistoric times; at least as far back as 5000 BCE, according to archaeologists. Stones were laid there before there was paper or written language or glass for that matter. There is a legend that the Arabic name for Aleppo, 'Halab' once meant "gave out milk" and was a reference to when Abraham gave milk from his white cows to travelers as they passed through the area. 

1563, when Franco Neri was still a young man of twenty-six, living in Aleppo, both he and his father were referenced in a couple of documents.  They are still held in the grand ducal archives in Florence, written in the reign of Cosimo I de' Medici. [5] This indicates, at the very least that the Neri family was in service to the leaders of Florence three full decades before Antonio Neri would make glass for Prince Don Antonio de' Medici.

In the sixteenth century the Christians in Aleppo lived in a tightly knit neighborhood that developed as a result of an Ottoman invasion around 1400. There were four churches standing side by side in the Jdeydeh quarter, only the old Maronite Church of Saint Elias was associated with the  Roman Catholic Church. If Franco Neri was in town when the above John Eldred passed through with his two companions, it is not impossible that they could have attended mass in the same church one Sunday in late May of 1583. 

Two decades later, the Emir (prince) of Aleppo, Fakhr-al-Din II forged an alliance with Tuscany, which apparently involved both economic and military provisions. He was attempting to break free of the Ottoman Empire and is considered by some to be the father of the Lebanese independence movement. He would go on to spend a number of years visiting Italy and Florence in particular, where he formed a friendship with then Grand Duke Cosimo II. 

Today, the beautiful, ancient city of Aleppo stands mostly deserted and partly demolished by war. Some news stories sight the determination and character of the current independence movement by quoting a poet, al-Mutanabbi, who lived in the mid tenth century. He spent the better part of a decade at the royal court of Aleppo, where it is said he did his best work. His most quoted lines are from a piece sometimes called "the poem that killed the poet." A legend tells that one night he was cornered by his enemies. Ready to flee, he was reminded of his own words by a servant, which caused him to stay and fight. The poem closes this way:

The desert knows me well, the night and the mounted men. 
The battle and the sword, the paper and the pen. [6]

[1] Neri, L’Arte Vetraria. (Firenze: Giunti, 1614).

[2] Registri Battesimali Firenze, reg. 10, f. 71v.  3 Feb., 1537, born to Jacopo Neri, barber [and surgeon] from dicomano, in the parish of San Ambrogio, Florence. (A couple of blocks from the Borgo Pinti childhood home of Antonio Neri.)

[3] Gian Pietro Vieusseux, Archivio storico italiano,  vol. 141, Issues 517-518 (Firenze, Leo S. Olschki, 1983), p. 370. “His correspondence also makes several references to the activity carried out by the Venetian court who had often had occasion to attend to solicit the interests of friends or acquaintances as Francesco Neri of Aleppo, the Capponi and Rinuccini [families].” 

[4] Richard Hakluyt, A selection of curious, rare and early voyages ..., (London: R. H. Evans, 1810)v. 2,  p. 403. “The voyage of M. John Eldred to Tripolis in Syria by sea, and from thence by land and river to Babylon and Balsara. 1583”

[5] Carteggio universale di Cosimo I de Medici /XI Archivio di Stato di Firenze Inventario XI (1560 – 1564) Mediceo del Principato Filze 489-499°, pp. 162, 206; /XII (1562-1565) Filze 500-514 p. 60.

[6] al-Mutanabbi (915-965 AD). He is thought to have spent nine years in Aleppo where he composed some of his best work,  See also 

Translated into German by Friedrich Dieterici, ed, tr. Mutanabbii carmina cum Commentario Wfthidii, (Berlin, 1858-1861), pp. 481-4. vv. 1-22, then into English by Nicholson, who wrote of Mutanabbi, “Although the verbal legerdemain which is so conspicuous in his poetry cannot be reproduced in another language, the lines translated below may be taken as a favorable and sufficiently characteristic specimen of his style.” Reynold A. Nicholson, A Literary History of the Arabs (Unwin, 1907).p. 307. Subsequently Nicholson published the present version in Reynold A. Nicholson, Translations of Eastern Poetry and Prose (Cambridge: Cambridge U. Press, 1922), p. 80. 

Monday, July 22, 2019

Glassware of an Alchemist

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.

* This post first appeared here on 27 December 2015.

Friday, July 19, 2019

Torricelli and Glass

Evangelista Torricelli
by Lorenzo Lippi, circa 1647
Evangelista Torricelli (1608–1647) is remembered as the inventor of the mercury barometer. Lesser known are a number of significant contributions he made to mathematics, astronomy and physics. There is no direct connection to the Florentine alchemist and glassmaker Antonio Neri—Torricelli was only a boy of six when Neri died—yet there are unmistakable echoes left by Neri that are amplified when we examine Torricelli’s time in Florence.   

In 1632, Torricelli wrote a letter to Galileo, which began a friendship that lasted until the famous astronomer died a decade later. In fact, Galileo invited Torricelli to stay at his house where they spent the last three months of Galileo’s life working together. If Torricelli had not heard of Neri before, perhaps he became acquainted through the copy of his book, L’Arte Vetraria that Galileo had on his bookshelf. Afterward, while preparing to return to Rome, Torricelli was intercepted by the Grand Duke of Tuscany, Ferdinando II de' Medici, who asked him to succeed Galileo as the chair of mathematics at Pisa. He was given a good salary and quarters at the fabulous palace in the center of Florence, that is now called the Medici-Riccardi.  

Historian Mario Gliozzi writes: “Torricelli remained in Florence until his death; these years, the happiest of his life, were filled with the greatest scientific activity. Esteemed for his polished, brilliant, and witty conversation, he soon formed friendships with the outstanding representatives of Florentine culture.” [1]  The ancient palace itself was largely empty in this period, inhabited by a handful of relatives, officials, intellectuals and artists connected with the Grand Ducal court. [2]

Among Torricelli’s companions at the palace were the three sons of Don Antonio de’ Medici, Antonio Neri’s long time benefactor. The boys, Paolo (1616-1656), Giulio (1617-1670) and Antonfrancesco (1618-1659) moved there in 1646. None of the brothers had personally met Neri, as they were all born shortly after his death, but they must have heard plenty about him growing up. As children, they had the run of the Casino di San Marco, the palace where Neri had made glass and pursued the secrets of alchemy. After Neri’s death, their father, Don Antonio spent significant time trying to hunt down Neri’s secret recipe for transmutation. Years later, when Giulio died in 1670, among his possessions were found a box of elixirs and “a booklet, entitled: Material of all the compounds of Priest Antonio Neri; there is a red dustcover, which says ‘experiments.’” [3] The materials were handed over to Jacinto Talducci, the Grand Duke’s chief chemist, and master of the new glassworks established in the Boboli Gardens, a man whom Torricelli depended on for glass. Talducci was also a veteran of the Casino di San Marco Laboratory; according to legend, as a boy he personally witnessed Neri’s transmutation of gold. Curiously, at Giulio’s death he was listed as living on Borgo Pinti in Florence, the same street on which Antonio Neri grew up. Also the same street where Galileo was tutored in  mathematics as a boy -- at the monastery where Neri's family attended church.

While in Florence, Torricelli took a great interest in optics. Again quoting Gliozzi:
[T]here is very good evidence of his technical ability in working telescope lenses, a skill almost certainly acquired during his stay in Florence. By the autumn of 1642 he was already capable of making lenses that were in no way mediocre, although they did not attain the excellence of those made by Francesco Fontana, at that time the most renowned Italian telescope maker. Torricelli had set out to emulate and surpass Fontana. By 1643 he was already able to obtain lenses equal to Fontana’s or perhaps even better, but above all he had come to understand that what is really important for the efficiency of a lens is the perfectly spherical machining of the surface, which he carried out with refined techniques. The efficiency of Torricelli’s lenses was recognized by the grand duke, who in 1644 presented Torricelli with a gold necklace bearing a medal with the motto “Virtutis praemia.” 
The fame of Torricelli’s excellent lenses quickly became widespread and he received many requests, which he fulfilled at a good profit. He attributed the efficiency of telescopes fitted with his lenses to a machining process that was kept secret at the time but was described in certain papers passed at Torricelli’s death to the grand duke, who gave them to Viviani, after which they were lost.
Gliozzi continues to describe that in 1924 one of Torricelli’s lenses was examined optically using the diffraction grating. “It was found to be of exquisite workmanship, so much so that one face was seen to have been machined better than the mirror taken as reference surface, and was constructed with the most advanced technique of the period.”

In addition to precision glass for lenses, Torricelli depended on Talducci and the grand duke’s furnace for scientific glassware; his experiments that demonstrated the measurement of air pressure required glass tubes, sealed at one end, two ‘cubits’ long (about four feet). They needed to be strong enough to be filled with mercury (which is very heavy) without breaking. It took his colleague Mersenne a couple of years (until 1646) to match the Florentines and obtain an acceptable tube from the French glassworks. 

Torricelli worked with former employees of the Casino di San Marco laboratory who knew Neri, he lived with Don Antonio’s three sons and he took a keen interest in glass; it seems impossible for him to be unaware of Neri and the echoes of his work in Florence.

[1] Mario Gliozzi "Torricelli, Evangelista" in Complete Dictionary of Scientific Biography. 2008.

[2] 1609-1659 - The last inhabitants of Palazzo Medici

[3] Covoni 1892, p. 193.

Wednesday, July 17, 2019

Sal Ammoniac

Ammoniac crystals, Fan-yagnobskoe coal mine, Tadjikistan,
Photo (c) A. A. Evseev.
Here we will examine "sal ammoniac," a common alchemical ingredient used by Antonio Neri in many of his early seventeenth century 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.
*This post first appeared here 22 August 2014.

Monday, July 15, 2019

Michel Montaigne

Michel Montaigne
Anonymous (17th century).
Michel Montaigne (1533–1592) was the proprietor of a vineyard and later a mayor of Bordeaux, France. However, his claim to fame in history is as popularizer of the writing form known as the essay. In 1580, a few months after publishing his first collection, he embarked on a grand tour of Italy by way of Austria, ending in Rome. He did this despite suffering from painful kidney stones or perhaps partly because of it; in addition to the usual tourist stops, he also sought out spas and purveyors of medicinal cures to help with his condition. Montaigne kept a travel diary, which he dictated to a servant accompanying him on the journey. 

Among his stops was a visit to Florence, where he dined with Grand Duke Francesco I de’ Medici and Bianca Cappello at the palace laboratory known as the Casino di San Marco. At the time, their son Don Antonio was a four year old toddler as was, 
in another quarter of the city, future glassmaker Antonio Neri. Within a few years both Francesco and Bianca would be dead, both stricken with pernicious malaria. Don Antonio would be sidelined as the future grand duke by his uncle, Cardinal Ferdinando de’ Medici. Don Antonio would inherit the laboratory complex and devote his time to the secrets of nature, where Antonio Neri would be employed as an alchemist and glassmaker.

What makes Montaigne’s journal remarkable is his clear, direct observation; his account is an unapologetic window into the thoughts and observations of a sixteenth century traveler. Here some excerpts from his account: 

Florence, seventeen miles, a place smaller than Ferrara, situated in a valley, surrounded by richly cultivated hills. The river Arno passes through the town, and is crossed by several bridges. We saw no fosse round the walls. Today he (Montaigne) passed two stones, and a quantity of gravel, without having had any other notice of it than a slight pain in the lower part of his stomach. The same day we went to see the Grand Duke's stables, which are very large, with arched roofs; there are very few horses of any value here: at least, there were not, when we went over them. We were shown a sheep of a very strange form; together with a camel, several lions and bears, and an animal as big as a large mastiff, but of the form of a cat, all striped black and white, which they called a tiger.  
We looked over the church of St. Lawrence, where the flags are still hanging, which we lost under Marshal Strozzi, in Tuscany. In this church, there are several excellent pictures, and some statues by Michael Angelo. We went to see the cathedral, a magnificent structure, the steeple of which is faced with black and white marble; it is one of the finest and most sumptuous churches in the world. […] 
The same day we went to see the duke's palace. This prince spends a good deal of his time in making imitations of oriental precious stones and chrystal: he has a great taste for alchemy and the mechanical arts, especially architecture, of which he has a more than ordinary knowledge. Next day, M. de Montaigne ascended, the first of us, to the top of the cathedral, where there is a ball of gilt brass, which, from below, seems about the size of your head, though when you get up to it you find it capable of holding forty persons. […]  
Messrs. d'Estissac and Montaigne went to dine with the grand duke, for such is his title here. His wife occupied the post of honour; the duke sat on her right, next to him sat the duchess's sister-in-law, and next to her husband, the duchess's brother. The duchess is a handsome woman, according to the Italian notion of beauty, with a countenance at once agreeable and dignified, and a bosom of the most ample proportions. M. de Montaigne had not been with her long, before he thoroughly understood how she had managed to wheedle the duke into entire subjection to her will, and he had no doubt she would be able to retain him at her feet for a long time to come. The duke is a dark stout man, about my height, with large limbs, and a countenance full of kindliness: he always takes his cap off when he meets any one, which, to my mind, is a very agreeable feature in his character. He looks like a healthy man of forty. On the other side of the table were the cardinal, and a young man of about eighteen, the duke's two brothers. When the duke or his wife want to drink, they have presented to them a glass of wine and a decanter of water, in a sort of bason; they take the wine, and pour as much of it as they do not want into the bason, filling the glass up with water; and when they have drunk it, they replace the glass in the bason, which a page holds for them. The duke took a good deal of water; the duchess hardly any. The fault of the Germans is to make use of glasses out of all proportion too large; here they are in the extreme the other way, for the glasses are absurdly small. I do not understand why this city should be called, par excellence, the Beautiful: it is handsome, no doubt, but not more so than Bologna, and very little more so than Ferrara; while Venice, beyond all comparison, superior to it, in this respect. No doubt the view of the city and its suburbs, from the top of the cathedral, has an imposing effect, owing to the immense space which the suburbs occupy, covering, as they do, the sides and summit of all the neighbouring hills for two or three leagues round; and the houses being so close to each other that they look almost like streets. The city is paved with Hat stones, but in no sort of method or order. […] 
[T]he style of living at the boarding-houses is miserable, though they charge for gentlemen more than twelve crowns a month. There is nothing to amuse you here, or to exercise either body or mind; there is neither fencing, nor riding, nor literature. Pewter is very scarce all about here; you are seldom served in any tiling but coloured earthenware, and that generally dirty. Thursday morning, 24th November, we left this place, and proceeded through a country which did not appear to us very fertile, though it was cultivated on all sides, and thickly inhabited. The road was rough and stony, and, though we went on without stopping, it was not till very late that we got to Sienna, thirty-two miles, four posts.
 Montaigne 1842: Michel de Montaigne, The Complete Works of Michael de Montaigne: Comprising the Essays ... ed., William Hazlitt (London: Templeman, 1842). pp. 564-566.

Friday, July 12, 2019

Hooke's Tears

Glass drops or tears coated in glue,
after detonation, (cross section is left)
from Robert Hooke's
Micrographia 1664, between p. 10, 11.
In 1661, an Italian reprint of Antonio Neri’s book of glassmaking recipes appeared. One year later, an English translation was published in London by physician Christopher Merrett. As an appendix, Merrett included an account of “glass drops” or tears as demonstrated to the Royal Society. These were molten gathers of glass that were allowed to drip into a bucket of cold water and cool. They formed a round, bulbous front end and a tail that trailed off to a thin filament. What made them so fascinating was that the bulbous end can easily endure strong blows with a hammer, but when the thin filament tail is snapped off, the whole piece explodes into a hail of tiny fragments “and in the dark, sparks [flash] at every break of their surface.” [1]

These glass drops became a novelty at royal courts throughout Europe, given a glass furnace they were easy to make, easy to demonstrate, and never failed to amaze observers who had not seen them before. They sparked animated discussion in the many scientific societies that had sprung up; what forces of nature were involved that a piece of glass could resist a hammer yet explode into dust at the loss of its slender tail? 

In the late seventeenth century a Roman publisher by the name of Tinassi [2] regularly issued compilation of noteworthy letters. In his journal’s edition for the year 1672, he published two letters by Geminiano Montanari, a mathematics professor at the university in Bologna, both on the subject of glass drops. In the introduction, he suggests that these curiosities were
Believed to be introduced in Sweden, Holland, then in England, France and Italy; In Paris in the year 1656, many experiments were made at the Academia which met at the home of Mr. Montmor. [3] Many have written of this, among others Monconys [4] in his "Journey to England,” [5] Thomas Hobbes in his Problematica Physica, [6][…] and Christopher Merrett, which in the Latin translation of L’Arte Vetraria of Antonio Neri, [7] is inserted the experiences of the Royal [Society] of England, [and] Mr. Robert Hooke [8] in his Micrographia. [9]
At a time when the concepts of atoms and molecules were still being debated, the glass drops became a nucleus around which a new science developed of mechanical tension and compression. A simple drip of glass caused sharp minds to puzzle and to take a closer look. 

In  Micrographia, Robert Hooke wrote about how he “ground away neer two thirds of the ball, yet would it not fly to pieces, but now and then some small rings of it would snap and fly off, not without a brisk noise and quick motion, leaving the Surface of the drop whence it flew very prettily branched or creased, which was easily discoverable by the Microscope. This drop, after I had thus ground it, without at all impairing the remnant that was not ground away, I caused to fly immediately all into sand upon the nipping off of the very tip of its slender end.”

Hooke continues to describe coating drops in fish glue (isinglass) which was tough enough to hold the piece together when the tail was snapped. “The drop gave a crack like the rest, and gave my hand a pretty brisk impulse: but yet the skin and leather was so strong as to keep the parts from flying out of their former posture and, the skin being transparent, I found that the drop retained exactly its former figure and polish, but was grown perfectly opacious and all over flaw’d, all those flaws lying in the manner of rings, from bottom or blunt end, to the very top or small point.” (See illustration above.)

He discovers that heating the glass drop and then allowing it to cool slowly neutralizes the explosive effect. Finally, he puts it all together: rapid cooling of the surface causes the interior to be compressed like a spring. Snipping the tail, where the skin is thinnest releases all the pent-up energy at once and the piece explodes.

[1] Tinassi 1672, p. 95.
[2] Niccolò Angelo Tinassi, active 1654-1690.
[3] Henri-Louis Habert de Montmor (c. 1600–1679), founded the Montmor Academy, which met at his house in Paris from 1657 until its dissolution in 1664.
[4] Balthasar de Monconys (1611–1665). 
[5] Monconys 1677,  for glass drops see pp. 32, 42 (fig. 4).
[6] 1662. Problematica Physica (translated in English in 1682 as Seven Philosophical Problems)
[7] This reference is not to Merrett’s 1662 translation of Neri (1612), but to the 1668 or 1669 edition by Frisius in Amsterdam which includes Merret’s annotations.
[8] Robert Hooke (1635–1703). 
[9] Hooke 1664, pp. 33–44.
*This post first appeared here 2 January 2015

Wednesday, July 10, 2019

Neri's Travels

“Roma,” Antonio Neri,
from Tesoro del Mondo (Neri 1598–1600).
The length and breadth of Antonio Neri's travels are far greater in thumbnail biographies and off hand remarks than can be substantiated by actual documentation. While stories of the glassmaker's travels through Europe abound, the truth of the matter is that only a small number of his movements have been verified through contemporary materials. But even if a minority of the wanderings attributed to Neri are true, then he certainly was a man of the world. Writing nearly two centuries after his death, historian Giovanni Targioni-Tozzetti claimed the priest left Italy to elude "thugs" in Florence who hounded him for the secret of transmutation. Tozzetti says he fled to England first and then visited Spain, Holland and France. [1] No evidence has yet turned up to support any of this. 

Other accounts say he "traveled all over Europe" and that he deceitfully posed as a "common assistant" in order to learn scientific secrets that he could not gain access to by other means. [2] One story I have heard making the rounds among glass workers is that Neri was chased to the "gates of Prague" by assassins. This is most likely confusion with a similar story about Venetian glassmakers leaving Murano without state permission to ply their craft elsewhere.

There are four cities in which Neri is confirmed to have been present: Florence, the city of his birth; Pisa where he worked at the glass furnace run by Niccolò Sisti; Antwerp, where he spent about seven years visiting his friend Emmanuel Ximenes and in Mechelen, at the Hospital of Malines, where he wrote about pioneering medical treatments in a letter to a friend back in Florence.[3] 

In addition, there are other locations that are strongly hinted at in various writings. In his Treasure of the World manuscript, Neri has an allegorical depiction in the form of a simplistic map showing “The Ways to Rome.” It depicts the walled enclave of the Vatican (see illustration) with various paths representing different chemical routes to transmutation. If nothing else, this leaves the door open to a personal familiarity with the eternal city. In his glass book, L’Arte Vetraria, Neri mentions a number of specific locations in northern Italy, but perhaps none as authoritatively as Venice. He comments about the materials and techniques specific to the glassmakers on Murano. There is little doubt that Neri was exposed to Venetian glass workers in Florence, Pisa and Antwerp, so they provide a perfectly plausible source for his knowledge of their distinctive techniques. This would be a sufficient explanation, except that there is also a letter written by his friend Emmanuel Ximenes, detailing a route for Neri's visit to Antwerp; a route that runs through Venice. Below is the passage from a letter, dated 5 December 1602. The glassmaker would be delayed by illness, but the following year he did make the journey. While it seems a good bet that he followed Ximenes' instructions that is another detail in need of confirmation.
Anyway, the lack of peace in these countries prevents me from recommending them for you to come or not, but if you make up your mind to come, God willing, you will have the same fortunes as we have. Besides, after your arrival, is not a marriage indissoluble, having no other bond than mutual affection? If you decide to come I would recommend that you should go with the courier from Florence to Venice, arriving in Venice in time that you would be able to accompany the merchants who come to the fair held in Frankfurt at mid Lent; you will stay there the length of the fair for fifteen days, which will not displease you for having seen it. After that, you would go in the company of other merchants to Cologne and then with them or others, by land or sea to Holland, ending up at this city. This sea, however, is nothing more than rivers. I recently went by land to Basel and from there by water ending here. But for Your Lordship,  who does not speak the German and Flemish languages, I would consider better the way that I say, with merchants from Venice to Frankfurt and then with others by water to arrive here. To this end, if you decide to come, upon giving me notice I will immediately send letters of recommendation to Venice to find a person who will help you to find company that must end up in Frankfurt and another for a friend in Frankfurt to get you started and perhaps it would be the same one with whom Guillelmo Reineri, servant of my brother Mr. Niccolò, came from here. Guillelmo usually goes to every fair by water up to Frankfurt, then back when it ends. He is close to me, a friend and very practical in his travels. This Renieri may give a report of the Frankfurt fair and also details of the voyage, as he made the outward journey for the fair last September. I shall send him a letter by means of my brother to give him the money on my account that would be necessary. But you should decide and advise me immediately, in order to go to Venice in time to find a group. I will wait for your decision, asking God to inspire the best . . .  [4]

[1] “E fatto con prestezza fagotto, la mattina all'aprir della porta uscì el di Firenze e se n'andò in Inghilterra. Girò la Spagna, Olanda, Francia e Germania…” [He packed in haste and in the morning opened his door, left Florence, and went to England. He toured Spain, Holland, France and Germany…] Targioni-Tozzetti 189, p. 149.
[2] See Rodwell 1870.
[3] Neri 1608.
[4] Ximenes 1601–11, 5 December 1602.
* This post first appeared here on 19 Dec. 2014.

Monday, July 8, 2019

Golden Yellow Glass

Yellow Neon Chandelier, 1995
Dale Chihuly.
(Columbus, Indiana Visitors Center). 
"Very few people know how to make colors like golden yellow and solid red well. These are difficult and troublesome in the art of glassmaking, since in making them you must stick precisely to the doses, the timing, the details and the materials as prescribed. The smallest error will cause everything to be ruined, and the colors to be irreparably spoiled. Therefore, you must be on guard not to make mistakes. [1]
So says Antonio Neri in his groundbreaking 1612 book of glass recipes, L’Arte Vetraria. Elsewhere he warns in several places not to add “tartar” to any glass destined for yellow pigmentation. Tartar was a common additive to boost the ‘sparkle’ of a glass because it contained a high level of potassium carbonates. These converted to potassium oxide in the melt, which has a higher refractive index than the usual glass flux, sodium oxide. However, his actual glass recipes tend to contradict this advice. 

Neri says of his “fern glass,” which is entirely potassium based:
…This frit can be given a wonderful golden yellow color provided there is no tartar salt within, as described in the caution, because then golden yellow will not emerge. This crystal is given to a golden yellow that is far more beautiful and pleasant than can be achieved in cristallo made with Levantine polverino salt and with this crystal unlike the other, every kind of job can be done. [2]
“Polverino” was a sodium based plant product used in many of Neri’s glass recipes, which he says was derived from the Kali plant grown in the Levant. The plot thickens when, for yellow, he recommends substituting ‘rocchetta’ another soda based Kali derivative. 

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

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

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

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

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

Friday, July 5, 2019

Lead Crystal

Roemer type drinking glass c. 1677,
George Ravenscroft.
The entire fourth part of Antonio Neri's 1612 book L'Arte Vetraria is devoted to the preparation of lead glass, a forerunner of what is now commonly known as lead crystal. This section is unique in the book in that it contains the only instance of the author giving direct advice to glass artists themselves:
"To work lead glass into various drinking glasses or other vessels, or even to draw cane for beadmaking, it is necessary to raise the punty [out of the melt], and to make a gather of glass by turning. Take it out, let it cool somewhat and then work it on a well-cleaned marble [marver]. The marble should be somewhat cool, and well bathed with water before use."
He goes on to describe what might be termed a kind of dance with the glass. As with a human partner, gentle patience is required in learning the boundaries of what can and cannot be done. Ultimately, an artist must come to understand the material's behavior and personality in order to result in a great partnership. For the artist who makes unrealistic demands, glass can be a heartbreaker.  
"This sort of glass, lead glass, is so runny that were it not cooled, and taken up by turning [the punty] to wind a gather, it would be impossible to work. It is so runny that it would not even hold onto the punty, because it is as loose as soup. This arises out of [the fact that] the lead calx causes it to become very fluid."
"Namely, gather the glass little by little, allow it to cool, and work it over marble frequently bathed in water. Furthermore, make sure to keep the pot of glass rather calm, and in a place in the furnace where it will not see too much heat, otherwise it will not be possible to work this glass at all."
The formulation of lead crystal as we know it is a relatively recent development. This is a composition of crushed silica (sand or quartz), potash (potassium carbonates) and lead oxide substituting for calcium to stabilize the composition. It is also true that lead has been added to glass since its invention a few thousand years ago. It is not clear that this addition was always intentional, but a Babylonian tablet of 1700 BCE gives a recipe for pottery glaze that explicitly contains lead. At some point, a discovery showed that small amounts of lead and pigment smeared on glass and fired made stained glass paintings possible. The earliest known examples of colored stained glass windows date to 800-820 (San Vicenzo Abbey excavation in Volturno, Italy.)  In medieval Europe, leading up to Antonio Neri's time, lead glass was used in mosaic tesserae and in artificial gems.

Finally, it is worth noting that Neri's childhood church in Florence, Cestello (now called Santa Maria Maddalena dei Pazzi), was then run by Cistercian monks. It was the Cistercian luminary St. Bernard of Clairvaux who, in the twelfth century, built the first church with large windows, urging, "The soul shall seek the light by following the light."

This post first appeared here 15 November 2013.

Wednesday, July 3, 2019

Benjamin Franklin and Glass

Note: This is a shorter version of a piece appearing in the Spring/Summer 2016 issue of the NAGC Bulletin. Many thanks for their permission to share it here. A copy of the complete article is available through interlibrary loan from the numerous public and art museum libraries which subscribe to this journal(including the Rakow Library at The Corning Museum of Glass). The Bulletin can also be obtained directly from its publisher, the National American Glass Club.

Benjamin Franklin and His Gathering of Glassmakers

Portrait of Benjamin Franklin, lampworked glass murrina, 
2016, by Stephen BoehmeRivertonUtah
Benjamin Franklin (1706-1790) became famous in his own lifetime as a printer, author, inventor, statesman, diplomat and scientific investigator. The man gracing the hundred-dollar bill has been celebrated for his work in a formidable range of fields, so perhaps we should not be surprised to learn of one that has largely escaped notice. In fact, there is an extraordinary further chapter to be told. Franklin fostered a lifelong fascination with glass and spent considerable energy in efforts to attract talent from Europe to work in America.

Glass and glassmaking garnered not only Franklin’s own enthusiasm, but also that of his family and friends. He worked closely with artisans on two continents and applied his considerable knowledge of glass to areas ranging from music to optics to electrical experimentation. On his European diplomatic missions, he tirelessly encouraged foreign glass workers to set up shop in the colonies. In the decades before America gained independence, he recognized and promoted the vital importance of glassmaking. Unbeknownst to many, Benjamin Franklin played a sustained and influential role in the formation of the American glassmaking industry. 

His connections to the field were wide ranging; his older, favorite brother, John Franklin, became co-founder of a glass factory in Braintree Massachusetts from the late 1740s to early 1750s. [1] In Philadelphia, Benjamin befriended Thomas Godfrey (1704–1749), a glazier, optician, glass and instrument maker who rented space from Franklin to work on new inventions. Lambert Emerson was another glass related acquaintance and fellow Freemason; an émigré from Dublin who advertised in Franklin’s newspaper The Pennsylvania Gazette as a “looking glass maker at the Sign of the looking Glass in Front Street, Philadelphia.” [2] Franklin’s neighbor, Caspar Wistar, was a German glassmaker from Cologne. He owned the nearby glassworks at Alloway Creek in Salem County, New Jersey, just twenty miles south of Philadelphia. Besides making windows and bottles, Wistar manufactured special “philosophical” glassware for Franklin, used in his electrical investigations. 

But Franklin had much more than a passing familiarity with glassmaking. In 1746, he advised Connecticut businessman Thomas Darling on the particulars of running a glass foundry, referring to Wistar’s New Jersey operation. In his correspondence, Franklin consistently referred to his neighbor’s ‘Wistarburgh Glass Manufactory’ as “our glasshouse,” strongly implying a business relationship with Wistar. He is credited with several of his own glass inventions. Two popular items that particularly employed glass were bifocal spectacles and his musical armonica. 

Over his lifetime, Franklin traveled to Europe four times between 1725-75. In London, Paris and on side excursions throughout Europe, he was in frequent contact with glassmakers and he spent considerable effort encouraging them to immigrate to America. 
He understood the strong potential of a glass industry as an economic driver and as a window to groundbreaking scientific discoveries. Critically, he also understood the value of inviting foreign workers to participate in the American dream. In London, he frequented the Royal Society (of scientific investigators) and was correspondent and houseguest of such luminaries as Joseph Priestly, David Hume and Erasmus Darwin. Glass was a hot topic of discussion in these circles due to the recent development of electrostatic generators and Leyden jars, which all had critical components made of glass. 

Franklin continued his efforts to woo glassmakers to America, but plainly, it was not always easy. In a correspondence of 1771, we see a rare pessimism rear its head. In Philadelphia, Joseph Leacock, a cousin of his wife, partnered with a local tanner to start a glass factory on what is now Richmond Street. They wrote to Franklin in London hoping to find workers, but his reply was not encouraging, “It is always a Difficulty here to meet with good Workmen and sober that are willing to go abroad. I heartily wish you Success in your laudable Undertaking to supply your Country with so useful a Manufacture…” [3] He had already seen a deal fall apart a couple of months earlier. Dutch glassworker Jacob Schaub borrowed money from Franklin to book passage across the Atlantic bound for the Stiegel Glassworks in Lancaster, Pennsylvania. Unfortunately, Schaub then failed to appear for work. [4]

After nearly four decades championing an American glass industry, word seems to have gotten around. Although his responses are not available, glassmakers wrote to Franklin from around Europe. In 1778, he received a letter from French master glassmaker Müller de la Piolotte, who explained his family’s long history in the art, starting with his ancestors in the Black Forest of Germany. The 43-year-old bachelor had worked in Champagny, Burgundy and in the Alsace-Lorrain regions of France. 

By 1783, the war was over; Britain conceded and signed an armistice with the United States. Franklin received official permission to entertain applications from those willing to immigrate to the former colonies to work; the floodgates opened and finally he received the interest among glassmakers that he had sought all along. Among the letters from many diverse tradesmen around Europe, in July he received one from Bremen, Germany. The family of Herman Heyman thanked Franklin for letters of introduction. They asked for the ambassador’s consideration of “a Plan which we lately received from one of our principal Glass Manufacturers in upper Germany, who intend to establish a Glass Manufactory in Nord [sic] America.” [5]

In October, he received a letter from a Paris glassmaker who worked for the famed Brossard family of Normandy. This man, Sutter, had heard rumors that Franklin was looking for master glassmakers to work in Philadelphia. He offered his services and suggested that he could convince several other glass workers to accompany him. [6]

In January of 1784, Franklin again heard from the Heyman family, in Germany, who wrote,
… to inform you that three other Gentlemen with me Considered most Earnestly … to Erect a Glass-Manufactory in some part of the United states, and we Chused Maryland to be the properest Country for it. … One of my three Friends Mr. John Fried Amelong who had the Mánage of a Glass Manufactory here in Germany will go himself in the spring by the first Vessell [sic] over to Baltimore and take the Direction of the intended Establishing Glas[s] Manufactory, he Carries besides him 80 more Families all Experiented to our Purpose in the Vessell for Baltimore [sic]. [7]

In February of 1784, Caquery de Mezancy wrote to Franklin, on behalf of five other French glassworkers. He had come from a well-known glassmaking family and a month earlier, he discussed with Franklin his desire to establish a glassworks in America. Franklin assured him that once there, they would have no trouble finding a partner who would furnish all necessary funds; he also indicated that they would receive free passage on an American ship. [8]

In 1785, Franklin himself boarded one of those ships and returned to America for good. Even into his eighties, as a senior statesman-scientist he was engaged and still thinking about glass. In 1787 his good friend, astronomer and mathematician David Rittenhouse wrote him this note, perhaps about a sample of copper ruby or gold ruby glass, in which the color develops upon reheating, a so-called 'striking glass':
I broke a little bit off the colourless end of the Glass Tube and placed it in the focus of the Burning Glass leaving it there several minutes, but no change was produced in its Colour. After examining it I exposed it again to the collected rays of the Sun without observing the least change in its colour, but touching it with the end of a small splinter of Cedar wood the wood took fire and the Glass immediately became a fire red. [9]
Franklin and Rittenhouse enjoyed a regular Wednesday appointment, when they met with others and talked about their interests. Thomas Jefferson once commented that he would happily trade a week in Paris for a single evening shooting the breeze with Franklin and Rittenhouse at one of their gatherings. [10]

Franklin’s America was driven by the promise of fresh talent flooding in from abroad. In the realm of glassmaking, he spent a lifetime courting workers from foreign lands to settle here and become his trusted friends and neighbors. Perhaps we should end with a light-hearted but poignant piece of advice written in his Poor Richard’s Almanac, in August of 1736 when he was just thirty-years-old, “Don't throw stones at your neighbors, if your own windows are glass.” [11]

 [1] The glass factory in Braintree Massachusetts was founded by Joseph Crell, John Franklin and Peter Etter in the late 1740s. In 1752, others assumed management. See Carla J.Mulford, Benjamin Franklin and the Ends of Empire, Oxford: Oxford Univ. Press, 2015, p. 156. Thanks to Gail Bardhan of the Rakow Research Library of the Corning Museum of Glass for her assistance on this point and many others throughout the article.
[2] The Knight of Glin, James Peill, John Rogers, Paul Mellon Centre for Studies in British Art., et al (2007), Irish Furniture, New Haven: Yale Univ. Press, p. 37. For the Freemason reference, see The Pennsylvania Gazette, June 25, 1741. Franklin was the chapter’s grand master by 1734.
[3] Letter to Joseph Leacock and Robert Towers from BF, London dated 22 Aug 1772. See The Papers of Benjamin Franklin (1959–) New Haven: Yale Univ. Press, v. 19, p. 282. Also, see 
[4] Henry William Stiegel (1729-83) owned three glasshouses, in Lancaster County Pa. See letter from Richard Bache to Franklin, dated 16 May 1772 (Bache was Franklin’s son-in-law).
[5] Letter from sons of Herman Heyman, Bremen to BF, Passay, dated 31 July 1783. Op. cit. Papers of BF, v. 40, p. 143.
[6] Letter from Mr. Sutter to BF, Passay, dated 29 October 1783. Op. cit., Papers of BF, v. 41, p. 548.
[7] Letter from Herman Heyman Jr., Bremen to BF, Passay, dated 19 January 1784. Op. cit., Papers of BF, v. 41, p. 489–90.
[8] Op. Cit., Papers of BF, v. 41, p. 552.
[9] Note to Dr. Franklin, from David Rittenhouse, Monday noon [c. 1787]. Op. cit. Papers of BF, (forthcoming).
[10] Kevin Keim, Peter Keim, (2007). A Grand Old Flag, a History of the United States through Its Flags. New York, New York: Dorling Kindersley Ltd. p. 43.

[11] BF (1736), Poor Richard’s Almanack, Philadelphia, August 1736, (v. 2, p. 141), see