Historical epistemology, according to the historian of science Hans-Jörg Rheinberger, is a space through which "to take experimental laboratory work into the realm of philosophy". This key concept, together with the crucial events and challenges of his career, were discussed in a public conversation which took place on the occasion of Rheinberger's retirement. By making sense of natural phenomena in the laboratory, the act of experimenting shapes the object; it is this shaping which became the core of Rheinberger's own research across biology and philosophy into history. For his intellectual agenda, a history of the life sciences so constructed became "epistemologically demanding".

This article is an account of a screening programme in search of new antibiotics established by CEPA (Compañia Española de Penicilinas y Antibióticos) and Merck in Madrid in 1954. An exploration of the genealogy for such a programme, its narratives and practices, shows that the main inspiration for this programme was the factory system of production, on the one hand, and Selman Waksman's research agenda on microorganisms of the soil, on the other. In this article, the relationship between industrial production of antibiotics and the research program aimed at identifying new candidate drugs is examined. I suggest that this screening program in search of new antibiotics was organised like industrial manufacturing. The research objects and tools came, both materially and conceptually, from industrial production: a line of artisanship put together in order to obtain a product with the collaboration of every member of the production line. Following the style developed by Selman Waksman in Rutgers, the screening program evaluated samples manually, and the microbiological skills were enhanced with every test. The Madrid team's practice of applying instructions for use led to circulation of knowledge and practices, including research material and microbiological methods.

This paper is a history of iodine. To trace the trajectory of this element, goiter is used as a guideline for the articulation of a historical account, as a representation of thyroid disorders and of the spaces of knowledge and practices related to iodine. iodine's journey from goiter treatment and prophylaxis in the late interwar period took on a new course after WWII by including the element's radioactive isotopes. I intend to show how the introduction of radioiodine contributed to stabilize the epistemic role of iodine, in both its non-radioactive and radioactive form, in thyroid gland studies and in the treatment of its disorders.