Spheres of Influence: Illustration,Notation, and John Dalton's Conceptual Toolbox, 1803–1835

In the early years of the nineteenth century, the English chemist John Dalton (1766–1844) developed his atomic theory, a set of theoretical commitments describing the nature of atoms and the rules guiding their interactions and combinations. In this paper, I examine a set of conceptual and illustrative tools used by Dalton in developing his theory as well as in presenting it to the public in printed form as well as in his many public lectures. These tools—the concept of ‘atmosphere’, the pile of shot analogy, and Dalton's system of chemical notation—served not just to guide Dalton's own thinking and to make his theories clear to his various audiences, but also to bind these theories together into a coherent system, presented in its definitive form in the three volumes of A New System of Chemical Philosophy (1808, 1810, and 1827). Despite these links, Dalton's contemporaries tended to pick and choose which of his theories to accept; his system of notation failed to be adopted in part because it embodied the whole of his system indivisibly.