Matthew D. Eddy's first book is based upon his doctoral dissertation that analyzed the work of John Walker, professor of natural history at the University of Edinburgh from 1779 to 1803. Eddy argues that chemistry underlay Walker's research and classification schemes in mineralogy, explicitly connecting eighteenth-century geology to chemistry taught in medical settings. Moving away from a Whiggish interpretation of Enlightenment chemistry culminating in Lavoisier's work on oxygen, Eddy cogently demonstrates how “chymical” concepts, particularly their “commitment to descriptive vocabularies, mnemonic tables, measurements, and ordering methods” served as a conceptual focal point for natural philosophy in Enlightenment Scotland (5). By concentrating upon natural history and mineralogy, Eddy also reconfigures the canon of texts associated with the Scottish Enlightenment by shifting our gaze away from philosophers David Hume, Thomas Reid, James Ferguson, and Adam Smith.

After a brief biography and analysis of Walker's early chemical education in chapters 1 and 2, Eddy demonstrates that Walker's recognition of the importance of the salt principle in natural philosophy connected him to the larger culture of pharmacological and industrial experimentation in Edinburgh's medical school. William Cullen was Walker's most important patron, and his “Doctrine of Salts” was particularly influential upon Walker's experimental history of Hartfell Spa. Chapter 3 elucidates Hall's methods of collecting of specimens and his travels, as well as the influence of earlier natural philosophers such as Robert Boyle and John Woodward on his classification of minerals. Chapters 4 and 5 successfully argue that Hall's mineralogical classification schemes were based on chemistry, which in turn influenced his conception of geology. In a welcome departure from an analysis of the usual Wernerian-Huttonian debates about the formation of the earth, Eddy shows that Swedish and German chemists, such as Tobern Bergman, considered the chemical composition of strata, something that Hall also found important. Rejecting the theoretical work of René Descartes and Comte de Buffon, Hall preferred an empiricist framework based on his observation of mineral samples to create his own system of geological strata.

One major strength of this book is Eddy's use of manuscript evidence in the form of letters, notebooks, and student lecture notes to demonstrate that Walker and his contemporaries did not reject the matter theory of Lavoisier out of “chemical ignorance” (194). To the contrary, their sensitivity and concerns about the proper use of chemical nomenclature made them skeptical of Lavoisier's attempts to “initiate a new language of chemistry” (94). It is a pleasure to see how Eddy uses manuscript sources to reconstruct Hall's network of patrons and colleagues, and even the contents of his library, recreating a microcosmic portion of the macrocosmic Enlightenment culture of knowledge. Appendix VII, which comprises the University of Edinburgh's Natural History Course Attendance Lists, is particularly valuable to demonstrate the influence of Edinburgh's pedagogical models on later thinkers. Although outside the scope of this book, a visual “Web,” whether written or in hyperlinks, would be an interesting media application of this knowledge network.

That said, Hall's methods to create his network via travel, patronage, and correspondence networks were tried-and-true procedures a century earlier; the Republic of Letters was a humanist institution. The reciprocal relationships between “improvement-minded” landowners and naturalists that occurred in Enlightenment Scotland also occurred previously in seventeenth-century England. In fact, as a scholar whose work analyzes natural philosophy and chemistry in England approximately a century before John Walker was active, I was immediately struck at the extent to which Walker built upon the work of earlier natural historians and physicians. Walker's and his contemporaries’ work on saline principles, for instance, was foreshadowed by a number of thinkers in the early Royal Society, such as Daniel Coxe and William Simpson, whom Eddy mentions, as well as other figures who are not referenced, such as Martin Lister and Robert Plot. Plot and Lister, for instance, formulated chemical models of fossilization based on salt crystallization. Walker's interest in the saps and fluids circulating in plants was also a topic discussed by Lister, John Ray, Nehemiah Grew, and Malphigi a century earlier, and Walker's analogies between gallstones and mineral samples taken out of the earth were also subjects of papers published in the Philosophical Transactions of the Royal Society in the seventeenth century. Like Walker, many of these natural philosophers and doctors are not canonical names in the history of chemistry, and like Walker, these marginalized thinkers deserve consideration in the literature.

Overall, Eddy has done a magnificent job in further clarifying the puzzling and fascinating development of the history of chemistry from its alchemical beginnings. His portrayal of the rich interdisciplinarity of early modern natural history, chemistry, and natural philosophy is an important addition to the field, and his use of Hall as a focus is a clever means of reconstructing a portion of the scientific enterprise in Enlightenment Scotland.