Question

In early eighteenth-century Europe, the secret to manufacturing hard-paste porcelain—a material previously imported exclusively from China—was uncovered in Saxony through the collaborative efforts of the mathematician Ehrenfried Walther von Tschirnhaus and the alchemist Johann Friedrich Böttger. Prior to their breakthroughs in 1708, European artisans had produced only soft-paste porcelain, a fragile substitute composed of ground glass and white clay that warped under high firing temperatures. Tschirnhaus hypothesized that true porcelain required fusing a refractory clay with a fluxing mineral capable of melting at lower temperatures to form a natural glass matrix. Crucially, Böttger identified cold-fired kaolin from domestic Saxon deposits near Aue as the indispensable refractory component, while alabaster served as the initial fluxing agent. While popular historical accounts often attribute the invention solely to Böttger due to his imprisonment by Augustus II and subsequent oversight of the Meissen manufactory established in 1710, archival records indicate that Tschirnhaus’s systematic thermal experiments using large burning lenses laid the requisite thermodynamic foundation. Furthermore, Tschirnhaus had insisted on replacing traditional bone ash additives with alabaster, which stabilized the structural integrity of the ceramic paste during vitrification. Following Tschirnhaus’s sudden death in late 1708, Böttger refined the kiln atmosphere controls, introducing a reducing environment that eliminated yellowish iron impurities from the finished porcelain. Consequently, while Böttger finalized the commercial production protocol, the technological breakthrough relied fundamentally on Tschirnhaus’s empirical thermal methodology and material selection.

According to the passage, which of the following was a specific contribution made by Ehrenfried Walther von Tschirnhaus to the development of hard-paste porcelain?