The Salt of the Earth: Natural Philosophy, Medicine, and Chymistry in England, 1650–1750 (review)

In recent years Anna Marie Roos has published a number of articles comprising case studies of early modern authors who wrote about the nature and function of saline substances. Now, she has produced a volume comprising a series of chapters in which such case studies are used to illuminate broader themes in the evolution of ideas about salts in the period, starting with Paracelsian and Helmontian ideas and continuing with “the rise of acids” and “from saline acids to acidifying oxygen,” in which Newton and his followers play a prominent part. There is also a chapter on patent medicines and chemical satire, mainly referencing the early eighteenth century. Each chapter goes some way toward giving a general account of the topic in hand, often with a patchwork of quotations from primary and secondary sources, but each is mainly devoted to an exposition of the ideas of particular thinkers; the author is never happier than when she is telling us about some obscure but intriguing theorist. There are thus lengthy accounts of books ranging from Thomas Tymme’s translation of Joseph Duchesne in his Practice of Chymicall and Hermeticall Physick (1605) to Bryan Robinson’s Treatise of the Animal Oeconomy (1734) and John Campbell’s translation of J. H. Cohausen’s Hermippus Revivus (1744). There is a particular focus on authors of the late seventeenth century, and Roos brings out well the sheer fertility of ideas in English natural philosophical circles in that period in the course of her lengthy accounts of Thomas Philipot’s chemical theory of the tides, the ideas put forward by William Simpson in his Zymologica Physica (1675), and Martin Lister’s and Nehemiah Grew’s contrasting views on the origin and function of salts. In the case of Lister, she even appends a fully annotated translation of his treatise on healing springs.

Overall, Roos makes some valuable points, not least in reinforcing the recent conclusions of William R. Newman, Lawrence M. Principe, and Antonio Clericuzio by illustrating the overriding significance of Joan Baptista van Helmont in late-seventeenth-century theories on such topics. On the other hand, for all its fascinating detail, the book is weaker in weaving its parts together into a broader whole, since we do not end up with as comprehensive a picture of changing understanding of salts in the period as we might have done. Even some of the connections that are made are not pursued as fully as they might have been. For instance, although Roos intriguingly points out the similarity between Newton’s and the obscure William Simpson’s views on the role of fermentation in the atmosphere, the issue of whether this similarity is purely coincidental or whether Newton might have had access to Simpson’s ideas is not satisfactorily resolved. More surprising is the rather cursory treatment of Robert Boyle, who was central to many of the debates dealt with here, two treatises by whom on key themes in the book—Reflections Upon the Hypothesis of Alcali and Acidum (1675) and Short Memoirs for the Natural Experimental History of Mineral Waters (1685)—are not even referred to. Though Boyle is the subject of repeated allusions, often through secondary sources, no systematic exploration of his ideas on such topics is attempted. The role of thinkers like Descartes is also surprisingly little addressed. Hence, though the book contains a feast of valuable information, it is less successful than it might have been in giving a comprehensive view of the developments to which it is devoted.