In 1856, Michael Faraday (1791–1867) conducted nearly a year's worth of research on the optical properties of gold, in the course of which he discovered the first metallic colloids. Following our own discovery of hundreds of the specimens prepared by Faraday for this research, the present paper describes the cognitive role of these “epistemic artifacts” in the dynamics of Faraday's research practices. Analysis of the specimens, Faraday's Diary records, and replications of selected procedures (partly to replace missing kinds of specimens and partly to understand the “tacit knowledge” implicated in Faraday's research) are outlined, and a reconstruction of the events surrounding the initial discovery of metallic colloids is presented.

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Author notes

Ryan Tweney is a Professor of Psychology at Bowling Green State University, Ohio, where he has been part of the BGSU faculty since 1970. Effective in May, 2005, he assumed the status of Emeritus Professor, and is currently dividing his time between Bowling Green and his home in Beatty, Nevada. Currently, he is continuing his work on Michael Faraday and a recent series of studies on the cognitive underpinnings of religious belief and its relationship to scientific thinking.