The next on-line seminar of the Society for the History of Alchemy and Chemistry will be given by Dr Sarah Hijmans (Université Paris Cité) who will present:
Not quite simple: The classification of “undecompounded bodies” in nineteenth-century chemical textbooks
This will be live on Thursday, 23 January 2025, beginning at 5.00pm GMT (6.00pm CET, 12 noon ET, 9.00am PT). The format will be a talk of 20-30 minutes, followed by a moderated discussion of half an hour.
As with recent seminars the Zoom link can be freely accessed by anyone, member of SHAC or not, by booking through the following Ticket Source link:
The seminar will be also accessible live on YouTube at
Most previous on-line seminars can be found on the SHAC YouTube Channel: https://www.youtube.com/SocietyforHistoryofAlchemyandChemistry
Not quite simple: The classification of “undecompounded bodies” in nineteenth-century chemical textbooks
Sarah Hijmans
Near the end of the eighteenth century, Antoine-Laurent de Lavoisier famously argued that any substance which could not be decomposed should be seen as a chemical element. Often called the “negative-empirical” criterion for elementary nature, this characterization of chemical elements remained dominant in chemical textbooks until the end of the nineteenth century. While there has been much discussion in the literature on the origins of the negative-empirical criterion, few have questioned whether this term adequately captures nineteenth-century views of chemical elements. In this talk, I will argue that the actual identification and characterization of chemical elements during the first half of the nineteenth was neither strictly based on the negative criterion of failed decomposition, nor a simple empirical fact. I will illustrate this by focusing on a group of “undecompounded bodies” and their classification in the textbooks of Jöns Jacob Berzelius (1779-1848), Louis Jacques Thenard (1777-1857) and Thomas Thomson (1773-1852). This will show a distinction that only few chemists explicitly reflected upon: on the one hand, not all undecompounded bodies were seen as simple, and on the other, not all simple bodies could be isolated in the form of undecompounded bodies.
Best regards
Rob Johnstone
Hon Treasurer, SHAC