Joseph Priestley and the fate of eudiometry: debates on method, progress, and the politics of science

The eighteenth century has been seen as an age of unbounded faith in scientific progress. The enthusiasm for new discoveries, however, was often mingled with doubts; moreover, different stances on issues of theory or method could become charged with ideological meanings, merging with ideas about politics, the social order, or popular education. The diffusion of printed materials contributed to divulge and amplify these debates among a wider public, who increasingly perceived scientific topics as matters of personal and national relevance. One such case was eudiometry, a method developed by Joseph Priestley to measure the “virtue” (that is, the purity) of air. Envisaged as a tool to test and eventually control the environment, it reflected a progressive idea of science as a political force, emancipating people from ignorance and providing means to better living conditions. This view was mirrored in Priestley’s style, which aimed at presenting natural philosophy as a truly open domain; thus, he encouraged participation by presenting himself not as a talented experimenter, but rather as a simple observer of natural phenomena; he emphasised that his results could be easily (and cheaply) reproduced, and even supported other scientists’ attempts to enhance his own method. Yet, the hope to measure air was eventually abandoned when it became clear that no consensus could be reached about the procedure to be used; this outcome, though, did not only stem from strictly scientific factors, but was influenced by other concerns. Starting from an analysis of Priestley’s Experiments and Observations on Different Kinds of Air, my paper investigates emerging tensions between conflicting ideas of progress, society, and the politics of science.