Ursula Klein

Klein's interdisciplinary work draws upon history, philosophy of science, epistemology and semiotics. She is interested in the manipulation of sign systems on paper and their relationships with experimental and classificatory performance in the laboratory sciences.[9][10]^:ix Klein introduced the concept of the paper tool through an examination of Berzelian formulas and their impact on inorganic and organic chemistry.[11] Berzelian formulas were particularly important because they connected a world of signs with the world of laboratory experimentation.[12] They enabled scientists to describe complex materials and reactions in organic chemistry in organized ways, similar to the ways in which chemists had identified and classified inorganic substances.[13][11]

Berzelian formulas offered a graphically suggestible representation of compositional structure that could be manipulated to investigate chemical reactions.[14] In this way, formulas became a "material resource" for the creation and manipulation of chemical models.[12] These interpretive models of organic reactions were not based on a particular theory but could be applied to a variety of theories. They gave scientists a new tool for the examination of their ideas. Theories could be supported by the manipulation of Berzelian formulas as well as by experiments.[14] In this way, paper tools acted as causal mechanisms and became the precursors of new theories.[15][16][17] The idea of paper tools has been adopted since by others and applied to constructs such as periodic tables,[18][19] Feynman diagrams[12] and the molecular architecture of Linus Pauling, among others.[20] Klein examines paper tools, models and experiments in terms of their impact on scientific reasoning and practice in early-nineteenth-century organic chemistry in her book Experiments, models, paper tools (2003).[10] She is credited with identifying the "invisible turning point" of a "quiet revolution" which shifted chemistry's foundation from natural history, medicine and pharmacy to carbon chemistry.[3]

Much of Klein's work has focused on the ontology of materials, the notion of substance, and the development of the observational and experimental sciences. She is particularly interested in forms of knowledge, including bodily skills, technical competence, explicit knowledge, connoisseurship, and analytic and theoretical knowledge; and in methods of measurement, data collection, and classification.[21][22][23]

In Materials in Eighteenth-Century Sciences (2007)[24] Klein and Lefèvre discuss ways in which eighteenth century chemistry was grounded in a world of materials such as balsams, fats, salts, alloys, plant materials and blood, and practiced in a wide variety of settings including “apothecary's shops, foundries, assaying laboratories, arsenals, dye manufactories, distilleries, [and] coffee shops.”[25] They then focus on a transitional period in eighteenth-century European chemistry, around 1830. At this time, methods of classification of substances changed, from focusing on experiential classification such as chemical composition, provenance, and properties of the substance, to more fundamental levels such as chemical structure and application. The book was praised for its breadth and "well-written exposition of an important change in materials science".[26]

Materials and expertise in early modern Europe (2010)[27] presents a nuanced understanding of the relationships between academic science and industrial technology in the late eighteenth century, examining the work of both artisans and scholars.[28]

Throughout her career, Klein has promoted the notion that theories and practices of science and technology overlap, creating what she and others such as Bruno Latour and Bernadette Bensaude-Vincent called "technoscience". Though she has explored meaning and materials of technosciene in reference to numerous European settings, her most influential work relates to experimentalists, industrialists and savants in Germany. She has explored the topic in Humboldts Preußen. Wissenschaft und Technik im Aufbruch (2015), discusses Alexander von Humboldt and his contemporaries in the context of the early development of Prussian science and technology. Other figures discussed include Andreas Sigismund Marggraf, Franz Karl Achard, Martin Heinrich Klaproth and Carl Abraham Gerhard.[3] and, more recently, in Technoscience in History: Prussia, 1750–1850 (2020).[29]