Glass and Alchemy: approaches to glass in the 17th and 18th century’s laboratories.
Alchemy has not been properly placed nor in the art history nor in the science history: Until the 1960s it was totally ignored by science history  and in history of art I can say it still being somehow ignored. I see in alchemy an approach to both art and science in a way that can be pertinent to the subject of this academic program: under the filter of glass, new highlights on alchemy and early science can be uncovered in a rich and interesting manner that brings them together.
During the 16th and 17th centuries, the patronage of nobles to a variety of investigations and intellectual activities was common and the motivations for the support of alchemy works were diverse. Some were interested in the mystical side of it, some on the materialist side and even in the promise of gold manufacturing or the production of innovative luxury items (which lead to the development of gold ruby glass, hard-paste porcelain, and other innovations). It’s important to remember that, in alchemy, both the philosophical and the practical approaches were coexistent: the relationship between matter and spirit and the will of the adept of deciphering and imitate the mysteries of nature are what made alchemy special. It created for itself an own language and imaginary that results nowadays seductive and mysterious. That coded knowledge in images could even be compared with a kind of symbolist mixed with surrealist movement long before the XXth century avant-gardes. The fact is that is even more interesting than that, because there is no modern movement, besides the Bauhaus, that includes other area of knowledge as the alchemy do with “science”, even if we can’t consider it as science at that stage, the way the alchemist relate to the world and to materials to explore their nature and their mysteries making use of a laboratory and observation is very close to ours today. Many sources affirm the alchemy as the “mother” of modern chemistry and for sure it had a huge impact in the pharmaceutics industry as well as in cosmetics, spirits beverages, metallurgy, and material science for industrial applications. Some alchemists can be called chemical philosophers. Those were able to saw those industrial applications as a “natural outgrowth of theory”. 
Alchemy was a subject of interest of many, beside them, Antonio Neri, priest and researcher of the time and well known by his glassmaking manual L’arte vetraria. His manuscripts and drawings describe not only the glass instruments used in the laboratory but also the alchemical processes done in that time by teams of people. In the court of Don Antonio de Medici the alchemists were welcome and encouraged to work on the nature of materials. Thanks to the curiosity of this patronage, achievements like the finest glassware made outside Venice were achieved, as well as a close imitation of Chinese porcelain and a bunch of innovations in metallurgy. 
In the time Neri became a priest, over a decade before writing L’arte vetraria, he wrote a manuscript devoted to “all of alchemy” in which we can appreciate the illustrations of the laboratory glassware of the time. Distillation had an important role in the alchemical procedures. Cucurbits and alembics, as well as retorts, were common glassware in those labs. Other kinds of vessels, made in ceramic, were used in the other alchemical processes of sublimation, calcination, and melting.
Vessels used in the laboratory, from Neri’s manuscripts.
The preferred glass alembics of the alchemist were made of German green glass, which was known as very resistant even to temperatures as high as 600°C. This instrument was used to separate mixtures to individual substances, a key procedure in the laboratory. For that, they used to heat the mixture and vaporize the ingredient with the lowest boiling point that rises and condenses on the cool surface to become liquid, or in the case of sublimation, solid again. There is a need for a source of heat, a flask known as matrass and a cucurbit, neck, and head. There is a vessel that is a combination of those last three and prevents any leakage: the retort. It is a distillation apparatus better sealed than an alembic but its way most difficult to clean and fill.
Most of Neri’s listed items were used in the most basic technique of alchemists, the distillation as pointed before. From powerful acids to alcoholic spirits and other reagents, alchemists could reach a diversity of products by this means.
With what Neri’s call a “serpentine”, a condenser coil, the distillation process could be sped up significantly. In the cucurbit, the steam is built up and routed through its snout to a coiled tube submerged in cold water. This operation speeds up the condensation process and sends more liquid to the receiver vessel. Neri uses this method to create acids to dissolve metals and therefore create the material he needs to color his glasses. Today this same technique is still applied in industry to produce perfumes, medicines, industrial-chemicals and alcohol spirits. However, in the production of alcoholic beverages, the distillation is made in copper containers. Neri was often experimenting with metal reactions and glass provided a very good solution as a container for those experiments. Even though, he discusses that in the long run, precautions must be taken to avoid cracks or breakings when heating and cooling suddenly.
Retort from the Corning Museum of Glass’s collection
Alembic from the Corning Museum of Glass’s collection
Some 17th and 18th Century alchemical equipment. 1 aludel, for condensing vapors; 2 “Moor’s Head” still; 3 clay vessel; 4 alembic, for distilling; 5 retort; 6 bronze mortar; 7crucible.
When we need to talk about the 17th century in glass innovations thanks to alchemy, the name of German Johann Rudolf Glauber comes to light. He was the most important promoter of glass experimentation during that century, even not being glass his main area of research. In his laboratory, in Amsterdam, he received commissions and used to work in several projects. He colored glass, using metals and achieving green with copper, blue with cobalt, yellow with iron, purple with manganese and red using colloidal gold. This production of gold ruby glass was definitively linked to alchemy. It is in the belief that the metals will reveal their soul or true color towards glass and then extracted to possess the spirit of the metal and affect real alchemical transmutations that this kind of innovations were made. Is the idea of finding a “philosopher stone” that glass enters to play a role in alchemy and is in this approach that new batches and colors came to the glass industry of the time. His discoveries in glass were summarized and published and he can be established as an important primary voice in the glassmaking history.
After Glauber, his assistant Johann Daniel Crafft continued to develop experiments and, even being known in Venice, he rediscovers the white glass made with bone. The knowledge Glauber achieved was passed as the scientific discoveries were passed in those early stages: by oral tradition or by coded documents that treasured the technological secrets achieved. It was the personal interaction within the circles of people committed to the same interests that moved the information in the Baroque era.
During this time the glass production in Central Europe was prolific, especially in Bohemia. A leading role in the glassmaking developments was made by Johann Joachim Becher, that was not only interested in alchemy but also in mathematics, geology, economy, medicine, linguistics, education and politics. He was a partner of Crafft and even not being glass the main interest of his career, he understood it as a strategic part of the economy and conducted several experiments in glass technology. “Glass, Becher believed, was the result of amalgamation by fire of mineral substances (sand and quarz), vegetable substance (potash), and animal substance (bone ash). Glass produced from plant ash acquired a vegetable green, while white glass had the whitness of bone. In a morbidly poetic flight of fancy, Becher expressed his wish that friends would “use his bones, exhausted by weariness and labor, to make a translucent substance, eternal and resistant to decay, having not a vegetable green but a milk-colored image of a sparkling narcissus.” Might it not be better, he inquired, to use his remains in this way rather than letting them rot in a cemetery?”
Milk glass flask
Probably Saxony (Germany), Dresden, about 1710-1720
10.8 x 6.1 cm
Corning Museum of Glass collection
Bold figures in science history as Isaac Newton, Robert Boyle, and Robert Hook were also interested in alchemy and there is evidence of them interested in lead glass, known as “vitrum saturni” in the allegory of lead as a Saturn-related metal. In Newton’s laboratory notebook (1669-1693) we can find notes about the composition of that glass as well as Boyle’s (1664). This basin, attributed to George Ravenscroft in England is an example of a lead glass of the time:
There is also correspondence between the glassmaking fluxes used to reduce the melting temperature (tartar, saltpeter, barilla, and borax), pure alkali, and the fluxes used by the alchemists in the separation of the pure and impure during their search of the transmutation of metals. The collaboration and stretch relationship between men of science and glassmakers were fructiferous: better furnaces, color glass and excellent colorless glass resembling rock crystal. Even being the alchemy so rich in imaginary, the style of the glass production was not dictated by the people that worked in the glassmaking or collaborated with it as the alchemist did, but by the market, by the people that used to sell them.
It was believed since the ancient Greek times that a red stone was the key to the transmutation of metals. Second Dedo Von Kerssenbrock-krosigk, the Persian philosopher and physicist Rhaze (about 865-between 923 and 935) had the first known written formula for gold ruby glass and the belief it could be the philosopher’s stone itself. 800 years later, Johann Kunckel (1637?-1703), an alchemist, pharmacist, and glassmaker would bring it to light again. 
It is worth highlighting that not only Kunckel not only experimented with doing gold ruby glass but also translated Antonio Neri’s Ars Vitraria adding his personal improvements and comments on recipes after trying them. From this book, there is an actual formula using gold which demonstrates that in Italy its properties were already known in the early 17th century.
Thanks to Kunckel’s glass interest, Chemistry had a huge advance in the 18th century. He invented the blow-pipe for scientific purposes, an apparatus to blow air into a flame. “Many possibilities are concealed in this art; in a chemist’s workshop, for example, it might prove very useful. One use would be to melt a metal lime in order to see what metal it contains. This can be done most conveniently by placing the lime to be analyzed into a hollow of a small piece of charcoal and blowing the flame onto it for a very short time.” During the 18th and 19th centuries, by means of the blow-pipe, the cobalt, nickel, tungstene, tantalum, manganese and in part tellurium and cadmium, were discovered.
Illustration of Blowpipe equipment
Another alchemist that experimented with gold and glass and in addition developed the hard-paste porcelain in Europe was Friedrich Botter (1682-1719) in Saxony. His knowledge and competence were so valuable that he was maintained under custody in the Konigstein castle, as a very well treated prisoner provided with all the means for his research.
In the early 18th century the fascination for the gold ruby glass began to decline and rises again in the 19th century. Today, this kind of glass has been modified and other colorants as selenium and rare-earth elements have replaced the gold.
Glass and alchemy were linked in many ways: from innovations and improvements in the glass industry in colors, compositions, to collaborations between glassmakers and earlier scientists to the production of laboratory glassware and better furnaces, the relationship between one and the other has been fructiferous. Nowadays we can recognize this historic period as something vital in the development both of science and glass.
Brandenburg (Germany), Postdam, about 1725-1735
Corning Museum of Glass collection.
 Kerssenbrock-Krosigk D. (2008). Glass of the Alchemists. Corning, N.Y.: Corning Museum of Glass. p. 33
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 Kerssenbrock-Krosigk D. (2008). Glass of the Alchemists. Corning, N.Y.: Corning Museum of Glass. p. 123
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