  The problem besetting those seeking experimental support for atomic theories is most evident in chemistry. Although many eighteenth-century chemists espoused versions of Newtonian chemistry their chemical practice owed nothing to it (Thackray, 1970). As philosophers they payed lip-service to atomism but as experimental chemists they worked independently of it. As early as 1718 Ettienne Geoffroy spelt out how the blossoming experimental science of chemical combination, involving extensive use of mineral acids to form an array of salts, could be understood in terms of what substances combined with what and could be recovered from what and to what degree. His table of the degrees of ‘rapport’ of chemical substances for each other summarised experimental data acquired by manipulating substances in the laboratory and became an efficient device for ordering chemical experience and for guiding the search for novel reactions. Klein (1995) has highlighted this aspect of Geoffroy's work and how his 1718 paper in effect shows how a large section of the experimental chemistry of the time could be construed as a practical tradition divorced from a speculative metaphysics, atomistic or otherwise. Eighteenth-century tables of affinity, modelled on Geoffroy's version, became increasingly detailed as the century proceeded. Many of the chemists who employed them interpreted the affinities featuring in them as representing attractions between chemical atoms, but such an assumption added nothing that could not be fully represented in terms of combinations of chemical substances in the laboratory.