Is that stone genuine?
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- Martinón-Torres, M. Metascience (2012) 21: 489. doi:10.1007/s11016-011-9577-6
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Archaeologists are well aware that the main motivation behind the early production and use of glass was to imitate precious and semi-precious stones. As such, glassmaking, documented regularly since the second millennium BC onwards, represents one of the earliest and most unequivocal expressions of the old alchemical precept of ‘art imitating nature’. It is therefore surprising that glass has received such little scholarly attention by historians of alchemy and chemistry—generally more concerned with metal transmutation—and Beretta’s book is a welcome contribution to redress this historical neglect. In essence, the monograph presents a history of glassmaking from its origins in Bronze Age Mesopotamia and Egypt until the early modern period, placing particular emphasis on how practical experience with natural and artificial stones informed evolving theories of matter. The author thus makes a valuable attempt at linking technological and intellectual history—another approach that, with a few notable exceptions, is missing in much scholarship on early alchemy and chemistry.
Following an introduction to the invention and early use of glass and other artificial vitreous materials in the first chapter, the core of the book (Chapters 2–4) concentrates on the developments in glassmaking technology and the diversity of theories to explain stones and glass during Classical Antiquity. Herein lies the main strength of this work, as it presents an important compilation of sources that illustrate the interest that glass arose among natural philosophers, craftspeople and consumers alike, as well as the important role glass played in a plethora of theories of matter. Particularly enthralling is Beretta’s argument about the revolution brought about by the discovery of glassblowing in the first century BC (Chapter 3), not only in widening the range of practical applications for this versatile material (including developments in optics and instrumentation with a direct bearing in alchemical pursuits, detailed in Chapter 4), but also in prompting further research and discussion about its nature and properties. This was, in Beretta’s view, a major step towards turning hyalos, the material of craftspeople, into vitrum, the material of scientists (p. 75). Lengthy and relevant quotes from Pliny, Theophrastus and others evidence that, while the author should be commended for beginning to pave the way, there is a wealth of source material to be tapped into for the historical relationships between glassmaking and natural philosophy to be duly reconstructed. In Chapter 5, the diachronic tour gains speed to cover glassmaking and related theorisation from the Byzantine to the early modern period, drawing on excerpts of relevant sources such as Albert the Great and Antonio Neri as well as delving into extant examples of glass use such as the Mausoleum of Galla Placidia in Ravenna and others. This brings the reader to the Epilogue, where the author contemplates selected highlights of the more recent history of glassmaking and succeeds in providing a captivating end to the book with suggestive links between remote and recent pasts that will no doubt appeal to the lay reader.
In terms of its chronological coverage, even though several strands are followed through up until the end of the eighteenth century, The Alchemy of Glass certainly thins down from late Roman times onwards. In addressing selected areas of medieval and later glass history, however, Beretta leaves us pondering about the motivations behind his choices. In particular, it would perhaps have been pertinent to cover early modern experiments dissolving glass and precipitating silica carried out by alchemists such as Jan Baptist van Helmont, as they are arguably key in debates on the reversibility of transmutation and the development of corpuscular theory, and are thus very relevant for the topic in hand. Readers interested in early modern glass may resort instead to the excellent volume on Glass of the Alchemists directed by D. von Kerssenbrock-Krosigk to accompany the 2008 exhibition in the Corning Museum of Glass, which suitably dovetails chronologically with Beretta’s book.
There are, however, much more important omissions in this otherwise engaging volume. The first one is quite crucial to the justification of the book and its very title—namely, discussion of the extent to which one can speak of ‘alchemy’ when addressing early pyrotechnologies that predate the use of this term. Beretta admits to being “well aware of its anachronism” (p. 87), but this does not stop him from simply using the term freely and without addressing its important implications. If alchemy is understood—in the old-fashioned, restrictive way—as related to the philosopher’s stone and metal transmutation only, then the topic of this book would fall outside its scope. If alchemists are only those who recognised themselves as such, then most of the authors quoted become irrelevant. If, at the opposite end of the spectrum, alchemy includes anything to do with chemical experimentation with matter, then cooking, dye making and many other activities should deserve an even more important recognition than glassmaking. Lacking any other guidance, this reviewer is left to assume that alchemy is understood as the pursuit of imitating nature by art—a generally acceptable stance, and one that comfortably accommodates glassmaking history. However, if we accept this as the defining characteristic of alchemy, then long-lived discussion of the ‘authenticity’ or ‘actuality’ of imitations and transmutations, and the relative value of natural versus artificial materials, become very relevant topics that, bar some excerpts from Pliny and a few others, are only superficially touched upon in spite of the book’s subtitle.
The second inexplicable omission is a general introduction to glass as a material and its basic manufacturing ingredients. The generally accessible language and style of the book will no doubt make it an enjoyable read for lay people interested in either alchemy or glass. However, non-specialists are left to their own devices to understand, to start with, what glass is and how it was made. A brief explanation of glass as a non-crystalline material formed through a necessary combination of a network former (silica), a network modifier (a flux) and a stabiliser (typically lime), and how different historical glassmakers have achieved these three key components by variously mixing sand, crushed pebbles, mineral natron, shell, plant and wood ash, among other additives and colourants, would give the reader a basic starting point to more fruitfully follow the rest of the book, as well as an insight into the ingenuity of early glassmakers and the diversity of glassmaking recipes that clearly derived from different learning traditions and experimentation with natural elements.
The last omission is admittedly the one closest to the heart of this reviewer: archaeology. At the outset, Beretta promises to use archaeology “above all” as a source of information (p. xi). However, there is little archaeological research as such and, with some exceptions, material remains are generally just brought up to illustrate the points previously made on the basis of historical sources. An example of the priority given to documentary over material information is his claim that “Mesopotamian glass makers did not develop theories” (p. 5). The basis for this statement is no other than the lack of written texts attesting to it but, as any archaeologist would say, absence of evidence does not mean evidence of absence. More importantly, Beretta largely ignores the wealth of data obtained by archaeological scientists who analyse material remains to reveal insights about the raw materials, origins and manufacturing techniques of ancient glasses (often more unequivocal here than in obscure or biased historical sources). A word search for ‘glass’ in Archaeometry or the Journal of Archaeological Science, among other journals and edited volumes, would have opened Beretta’s eyes to a wealth of relevant information. To name but two relevant examples, the book overlooks recent work on the earliest archaeological remains related to glassmaking (by Th. Rehren, A. Shortland and others) as well as research on Roman glass that directly compares analytical data to Pliny’s texts (by I. Freestone, C. Jackson, A. Silvestry and others). Archaeological science also offers plenty of data on natural and artificial colourants and related techniques employed to obtain the variety of visual effects commented on by Beretta. Having said this, it should be emphasised that the blame for this oversight is not in this author alone, but rather in a compartmentalisation of academia that makes it increasingly difficult for us to look outside our own fish bowl. Just as Beretta will benefit from a more detailed consideration of archaeological science, no doubt archaeologists should resort to The Alchemy of Glass for much inspiration about the philosophical importance of the materials they study.
Overall, the combined impetus provided by this book and the Corning Museum volume should further promote a focus on glass within a much needed broader diversification of topics and approaches in the history of alchemy and chemistry. As anyone trying to break new ground in an interdisciplinary field, Beretta may become a relatively easy target for criticism from specialists—as perhaps epitomised in this review. However, he deserves much credit for bringing such an important topic out of historical neglect and for advancing some interesting theories and sources. Deservedly, this volume will find its way to institutional and private educated libraries alike, and it should become a valuable reference point for both science historians and archaeologists.