Laboratory work in early geoscience: changing the story
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- Norris, J. Metascience (2012) 21: 575. doi:10.1007/s11016-011-9621-6
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The general inaccessibility of the Earth’s mineral-forming processes has long confounded our desire to know about the generation of rocks and minerals. And when modern experimental petrology can still seem like a struggle, we might marvel at the considerable disadvantages faced by workers attempting to understand the formation of rocks and minerals two and three hundred years ago. Naturally, the questions of today differ greatly from those of the past. Indeed, the questions of the past were to a large extent foundational issues, and the struggle was thus a double one: ‘Mineralists’ had to answer the questions about the compositions and generation of rocks and minerals while at the same time developing techniques for doing so. The reviewed book tells this story by charting the history of deliberate experimentation in understanding earth processes. The author, Sally Newcomb, begins her analysis around the mid-eighteenth century, though mention is made of earlier times throughout the text. During the roughly hundred-year scope of this study, ideas concerning rocks and minerals, and the roles of heat, water, and pressure in geological processes, underwent rapid yet dramatic changes.
The monograph is a detailed account that avoids panegyrics and mostly leaves aside historiographical issues. The Preface states that the discussion will consider the work of the past authors in the context of their own times, as opposed to what is believed today. Related to this is the author’s stated understanding that what constituted an experiment, and what was regarded as convincing proof supporting an hypothesis or theory, was in these earlier times different from today. Such adjustments will be necessary for readers as well, in evaluating this earlier stage of things.
However, the first chapter, entitled ‘Origins of Geology’, is disappointingly superficial, particularly concerning the treatment of alchemy. Newcomb almost apologizes for beginning a discussion of early geology with alchemy and then reaches a vaguely stated conclusion that it did not contribute significantly to the beginnings of geological thought. As the pre- and early-modern mineral-based chemical science with a long and rich tradition of interrelated experiment and theory, alchemy would seem to hold considerable relevance to the discussion. Even if we restrict ourselves to the sixteenth century onward, as the author does throughout her book, it can be seen that alchemy shared much with the interrelated spheres of mining, mineralogy, and assaying. This common ground principally concerned the practice of working with metallic and mineral substances, and a complex body of theoretical views on the generation and composition of metals and metallic minerals (to say nothing about rocks, salts, mineral waters, and vapours). Unfortunately, the author does not take the opportunity to discuss any of this in relation to alchemy or mining. However, while it is conceded that alchemy at least involved technical processes that were of assistance in gaining practical knowledge of materials and that it raised questions concerning the ultimate constituents of matter, such a generalized evaluation overlooks the intertwining of theory and practice, and the range of ‘geological’ ideas, that alchemy involved.
The author’s treatment of Robert Boyle’s experimental work on the generation and composition of crystals occasions another surprisingly slight evaluation. Boyle’s crystallization experiments would seem to offer a perfect early case for the author’s purposes. Yet, Boyle is criticized for considering mineral generation in terms of mineral exhalations and juices (common theories at that time), while the experiments themselves are not even mentioned. Despite her assertion to evaluate ideas of the past in context, one gets the feeling that the author has neglected this stage of geological thought simply for not being modern enough. Unfortunately, then, not much emerges about the origins of geology in this chapter. Of course, a book by a single author cannot cover everything, especially a book like World in a Crucible, which handles a large amount of information. This criticism of an otherwise excellent book could have been avoided if the author had simply left out the initial chapter, stating that the literature and ideas of those times are outside her focus (which is de facto the case).
Where the author is particularly strong is in her description and explanation of the experimental apparatus and procedures of the eighteenth and nineteenth centuries, and their advances concurrent with further developments in theory. This is all quite complex, as it involves not only the geological theories that were tried and adjusted as a result of experimental trials but also the theory behind the construction and use of technical equipment. The second chapter discusses the organization of rocks and minerals by external characteristics in the work of late-eighteenth-century authors, and the progressive efforts to classify them according to their composition. This effectively sets the stage for the ensuing discussions concerning how the compositions of rocks and minerals were analysed by the dry and wet methods and how heat, pressure, and solution were used to study the possible processes of rock origins.
Indeed, Chapters 2 to 8 show the author in her element, providing instructive descriptions of the tools and apparatus while holding to the interplay between laboratory work, field observations, and theoretical views. Chapters 3 to 5 treat heat and fire analysis, while Chapters 6 and 7 detail the chemistry of ‘humid’ analysis. In each case, the discussions are well referenced and instructive. Though many of the sections on processes, reagents, and geological samples are regrettably, though necessarily, brief, they are yet detailed enough to serve the author’s purpose. The entries about salts, mineral acids, and the analysis of mineral waters and volcanic gases are especially noteworthy and likely to encourage further interest among readers. In this group of chapters, the author demonstrates well the interconnected problems of understanding one’s equipment, recognizing fresh samples for analysis, identifying the resulting materials, and seeking a programme of standard procedures with which to conduct such analyses. It also allows modern geologists and chemists to reflect on how much they can (thankfully) take for granted.
The remainder of the book (Chapters 9 to 12) puts the preceding material to use in a thorough discussion of rock and mineral formation. Throughout these chapters, the author explains the changing details of the discussions concerning granite, limestone, and basalts. Her sections on the generation of granite include British, French, and German authors of the late eighteenth and early nineteenth centuries, whose work involved consideration of crystal form, the use of microscopes, and the determination of fusion points and of mineral solubilities. The question as to whether granite crystallized from a state of fusion or aqueous solution is handled in an especially instructive manner that goes far beyond the tired consideration of the Hutton/Werner controversy and the popular literature on Hutton himself. Deciding the matter by experimental means was problematic, as the attempts to dissolve or fuse granite samples were fraught with difficulties, the descriptions of which make most interesting reading. Geologists of today who study granites, and who may be unaware of the enormous difficulties faced by their colleagues of 200 years ago, will learn much from this chapter.
Some readers may be surprised to find the section on experimenting with granite followed by a similar one on determining the origin of limestone. The crystallinity of many limestones raised questions of heat and pressure, suggesting an igneous origin to some, while solution experiments remained difficult to conduct and interpret. In fact, the case of limestone origins shows how questions about degrees of heat, fusion, pressure, and the role of water in all these factors gradually led to an appreciation of the variety of rock-forming processes.
The issues surrounding basalts and volcanoes are likewise given a rich account. A surprisingly full description of Buffon’s experiments with his cooling spheres of various sizes and compositions leads in Chapter 10 to a consideration of the behaviour and effects of heat within the Earth. This chapter contains much of interest, including the attempts to understand the various textures of basalts, and the difficult circumstances under which the compositions of these rocks were analysed. The author’s account of the range of experiments deployed here is highly informative. Attempts to understand such rocks in terms of fusion involved not only the basalts themselves but also the ‘country rocks’ among which they occur, the fusion of which might perhaps have resulted in the former. The study of volcanic rocks had the apparent advantage of accessibility in actively volcanic regions though Newcomb points out that the even here complications in interpretation were numerous. She delves into the field trips and laboratory trials to reveal all that it took to try to understand these rocks.
The book tackles a huge subject, in which questions concerning mineral composition and crystal formation were every bit as important as those of the generation of mountains and continents. The emphasis on technical descriptions does not entail any neglect of the theoretical issues involved, as the two strands are skilfully interwoven in the author’s narrative. For example, the detailed account of Sir James Hall’s ideas and work in Chapter 5 is especially valuable, as it explains his struggles, both mental and physical, with his equipment and with his understanding of the ‘degrees of heat’ (temperatures) he was achieving. The author remains grounded in the geological processes Hall was attempting to imitate, even those involving lateral pressures. Hall’s results, and their mixed reception by his contemporaries, are given a mature, thought-provoking summary in which his ideas and methods are compared to those of his contemporaries who chiefly emphasized field observations and sometimes indulged in speculation.
The purpose of the present book is to illustrate the eighteenth- and nineteenth-century rise of experimental methods in studying the Earth and demonstrate how the gradually increasing range of laboratory procedures—with the concomitant elaboration of theory—steered geology toward its modern state. Leaving aside from the rather uninformative first chapter, the author achieves this goal admirably, bringing much interesting material to light. Such a study is most welcome in geohistorical studies as few of the well-known modern works address the subject of laboratory experimentation at all, and the few that do so are not so richly detailed for the period treated by The World in a Crucible. All of this contributes toward a book that will certainly be of lasting value. Indeed, its subject and the manner in which the story is told would seem to make it equally useful and interesting to both historians of geoscience and its modern practitioners.