The French physicist Jean Baptiste Perrin is widely credited with providing the conclusive argument for atomism. The most well-known part of Perrin’s argument is his description of thirteen different procedures for determining Avogadro’s number (N)–the number of atoms, ions, and molecules contained in a gram-atom, gram-ion, and gram-mole of a substance, respectively. Because of its success in ending the atomism debates Perrin’s argument has been the focus of much philosophical interest. The various philosophers, however, have reached different conclusions, not only (...) about the argument’s general rationale but also the role that the multiple determination of N played in it. This paper emphasizes the historical development of Perrin’s experimental work in order to understand the role that the multiple determination of molecular magnitudes played in his argument for molecular reality. It claims that Perrin used the multiple determination strategy to put forward an exceptionally strong no-coincidence argument to argue for both the correctness of the values for the molecular magnitudes determined and the validity of the auxiliary assumptions upon which the different determinations were based. The historicist approach also allows the identification of the elements responsible for the epistemic strength of Perrin’s no-coincidence argument. (shrink)

The French chemists of the nineteenth century insisted that the ‘rupture lavoisienne’ had marked the advent of a new world. In their view, Lavoisier not only overthrew the theory of phlogiston, he also established the science of chemistry. In the conceptual gap between notions of ‘revolution’ and ‘foundation’ an origin-myth was created. The cult of Lavoisier that developed can be interpreted as a projection of political interests and national pride. By coincidence, the Traité élémentaire appeared in 1789, Year One in (...) the calendar of modern chemistry and the year of the French Revolution. Because of this conjunction, Lavoisier easily became a symbol of France's revolutionary spirit. But veneration brought the danger of excessive conservatism with regard to chemical theory.Les chimistes français du 19ième siècle soulignent que la ‘rupture lavoisienne’ a été l'avènement d'un nouveau monde. A leurs yeux, Lavoisier n'a pas seulement renversé la théorie du phlogistique, il a aussi fondé la science chimique. Par ce glissement de la notion de ‘révolution’ à celle de ‘fondation's créé un véritable mythe fondateur. Le culte de Lavoisier qui se développe alors recouvre des intérêts politiques et des enjeux nationalistes. Coïncidence: Le Traité Elémentaire est publié en 1789, l'année même de la Révolution française et l'an 1 de la chimie moderne. A la faveur de cette conjonction, Lavoisier a pu devenir le symbole de l'esprit révolutionnaire français. Mais à trop vénérer la révolution, les chimistes français ont pris le risque de s'illustrer par un conservatisme excessif en matière de théorie. (shrink)