12 Glass of the Alchemists. I N T R ODUCTIO N HAT IS GLASS? This seemingly simple question has no easy answer—not even in the present day, when scientists believe they have some understanding of the chemical and physical properties of glasses. 1. Neri 1612, foreword: “molto si assomi­ The question must have been much more perplexing to people of earlier ages. glie ad ogni sorte di minerale, & mezzo W minerale, quantunque sia un composto, et Glass did not easily comply with scholarly attempts to classify materials. In 1612, the Florentine dall’Arte fatto.” priest and alchemist Antonio Neri noted the close resemblance of glass to rocks and minerals, but 2. Pharmacopoea Spagyricae, chap. 20, he emphasized that glass is “a compound, and made by art.” 1 The German alchemist Johann Rudolf after Glauber 1689, p. 167. 3. Gnilius 1711, p. 5: “mihi probabilius Glauber described the relationship between glass and metal in this way: “For all Sand or Flint, of videtur. Vitrum positum esse inter me­ which Glass is made, is the Matrix or Mother of all Metals.”2 As late as 1711, Johannes Gnilius, a talla & lapides, quippe de utrisque aliquid mutuo petit: v[idelicet] gr.[?] de metallis, Strasbourg scholar, seconded Vannoccio Biringuccio’s opinion that glass should be positioned be­ quod sit liquabile: de Lapidibus, quod non tween metals and stones because it displayed properties of both, being liquefiable like metals and sit ductile malleo, sed fragile &c.” 3 4. Boyle 1673, pp. 70–71. brittle like stones. Perhaps because the debate was leading nowhere, the Irish nobleman and sci­ 5. Lemery 1716, pp. 576–577: “Vitrum, entist Robert Boyle considered certain characteristics of glass in 1673 and concluded that it allowed en François, Verre, est une matiere rendue 4 transparente par la violence du feu, qui “ponderable parts of Flame . to pass through the pores.” Nicolas Lemery may have had this com­ après en avoir chassé les parties grossieres, ment in mind when he wrote in 1698 that “glass . is a material that is made transparent by the sulfureuses & mollasses, y a formé des pores droits en sorte que la lumiere puisse force of fire. After having chased away the coarse, sulfuric, and weak particles, [the fire] has formed passer & repasser facilement au travers.” straight pores of a sort that the light can easily pass back and forth through [the glass].” 5 Knowledge. 6. Glass does appear in nature, and it LASS must have been attractive to alchemists for one reason in particular: unlike silver, was sometimes used for crafts. The use 6 of obsidian in Mesoamerica, for example, wood, and clay, it was made, not found. Man’s own creation was mixed from some simple is well known. Less well known is the Graw materials and then fashioned in the fire into something entirely new—a substance that showed production of buttons from Proterobas (lamprophyre) in the Fichtelgebirge re­ none of the characteristics of its source ingredients and that could not be turned back into them. gion in Germany. However, natural glasses For millenniums, the only way this experience had been understood was as an alchemical process, a were of no concern to vessel glassmakers in Renaissance and Baroque Europe. transformation not unlike the presumed transmutation of base metals into precious metals. While such transmutations were often attempted and never accomplished (although practitioners fre­ quently pretended otherwise), the successful results of glassmaking could be witnessed every day. Like any other manufacturing process, the production of glass requires trained and skilled workers (Fig. 1). Glassblowing demands considerable control and virtuosity, at least in part because hot glass can be worked only for a short time. More than many other crafts, however, glassmaking relies on knowledge. The slightest change in the composition of the raw materials or even a minor variation in furnace conditions can result in unwanted effects: the glass might suddenly change its color, accumulate various kinds of faults, or even crizzle (deteriorate) soon after it is made. Some glassmakers were content to draw upon the experience of the past, and they did well not to change any of their procedures. This was the case, for example, with the German glasshouses that produced green Waldglas (forest glass) of uniform quality for many centuries (Fig. 2). Yet if progress was de­ sired, knowledge became the key ingredient. And the best source of expertise was to be found among the alchemists. Introduction 13 Fig. 1. Purification of ashes and the making of glass, illustration from Laboratory, or, School of Arts, 1738, pl. before p. 75. The upper half of the illustration shows equipment used to dissolve, boil, and calcine potash, “out of which may be made the finest Glass you can wish or desire.” The lower half presents glassmaking instruments, the two parts for a double-walled glass with enclosed gold-leaf decoration ( Zwischengoldglas), and a kiln to fire the enamels on glass panes. 14 Glass of the Alchemists. Fig. 2. “Unbreakable” Waldglas beaker. Germany, dated 1656. H. 13 cm. The Corning Museum of Glass (79.3.617, gift of The Ruth Bryan Strauss Memorial Foundation). The beaker bears the diamond-point engraved and gilded inscription “Trinch mich auss vnnd würff mich Nider / heb mich auff vnnd vill mich wider 1656” (Empty me and throw me down; pick me up and fill me again, 1656). Fig. 3. Three cristallo goblets. Venice, about 1600. H. (tallest) 17.8 cm. The Corning Museum of Glass (61.3.135, 60.3.17, 70.3.8). nature. This goal was shared by artists, and it gave rise to innumer­ able points of contact. Smith notes that alchemy, which was con­ cerned with both practical and scientific considerations, bridged the divide between the scholar and the artisan. Newman (pp. 35– 47) states that alchemists regarded themselves as “searchers into nature’s secrets.” They were “chymists,” the true precursors of mod­ ern chemists, and it was in the context of “chymistry” that the term “research” was first employed. Newman reports on the scien­ tific reasoning of alchemists in the 17 th century—including such concepts as the corpuscular theory and the organic growth of met­ als in the earth—and their attempts to prove their beliefs in the laboratory. The term “alchemist” is about as precise a professional char­ Recently discovered sketches in the notebook of a 16th­cen­ acterization as “healer” would be for an otorhinolaryngologist. tury alchemist perfectly illustrate the ideas of alchemy and their Alchemy was a form of worldview that involved amateurs as well usefulness to humankind (pp. 48–61). The fact that this alchemist, as professionals. The field of study for the alchemists encom­ Antonio Neri, was also the author of L’Arte Vetraria, the single passed the entire world in all its facets, natural and scientific as most influential glassmaking manual of all time, makes these well as spiritual. Some researchers were specialists, such as the drawings even more intriguing. We are very grateful to Paul Engle, iatrochemists, who employed alchemical principles to create med­ their discoverer, for allowing us to include selected drawings from icines. Those who devoted their attention to what today might this manuscript in the present volume. be called the “material sciences” were particularly successful. The number of alchemists who followed Neri’s example and The breadth of the inquiry into the subject was matched by gained substantial expertise in glassmaking was probably small. the body of literature that it produced. Modern accounts have But those few practitioners possessed the necessary skills for suc­ often added to the confusion about alchemy, leaving readers with cess. They had a laboratory at their disposal, which permitted the impression that impenetrability was one of its chief features. them to conduct experiments on a small and thus affordable scale. Some much­needed clarification is provided in the introductory They were experienced in the treatment of raw materials, and they chapters of this catalog by Pamela H. Smith and William R. proceeded to study the effects on glass of a wide range of elements. Newman, two of the best­known experts in the field. Their chap­ They formed networks by which they communicated their find­ ters amount to a translation of alchemical reasoning into modern­ ings to other experts, and they were able to access publications day terms. Smith (pp. 23–33) provides an overview of the extent on the subjects that interested them. None of these benefits was of alchemy and focuses on one of its chief aims, the imitation of easily available to general glassmakers. Introduction 15 Innovation. T IS one thing to claim that improvements in glass were brought about by some interactions between alchemists and glassmakers, but quite another to present proof. Because of a dearth of Isurviving documents, we know very little about the circumstances surrounding the invention of new types of glass. One of the most important such inventions is Venetian cristallo, which is credited to 7. Zecchin 1987, pp. 237–241. Angelo Barovier on the glassmaking island of Murano in 1453.7 Not much has been recorded about this event. We do not know, for example, how the development of cristallo is related to the emer­ gence of colorless glass in the 13th and 14th centuries, and the meager sources do not tell us if, and 8. Cf. Kerssenbrock­Krosigk forth­ to what extent, alchemy informed Barovier’s achievements.8 We do not even have vessels that can coming. be unmistakably attributed to his time or workshop, but we do know that cristallo was at the center of Venice’s success in glassmaking for the next couple of centuries. It is most typically identified with paper­thin wineglasses of the late 16th and early 17th centuries (Fig.