Chemistry as a tool for historical research: Identifying paths of historical mercury pollution in the Hispanic New World

This article is the first of a series that explore the potential of chemistry as an efficient tool for historical research. Basic chemical principles such as the stoichiometry of chemical reactions provide the historian with a powerful tool to judge the reliability of archival records and interpret better the historiography of events that relate directly to processes of production based on chemical reactions. Chemical mass balances have determined both revenue streams and environmental consequences in the past. A very appropriate case study to apply this approach is the first industrial scale chemical process to have caused a global economic impact. The application of mercury amalgamation to extract silver from the ores of the Hispanic New World during the Early Modern Era was a complete break in technique and scale from all previous methods used to extract silver around the world. Until the middle of the sixteenth century all refining methods applied in Europe to refine silver ores were lead-based: smelting of argentiferous lead or liquation of silver-bearing copper ores (1). In the Hispanic New World initial smelting with lead would be overshadowed by the industrial scale amalgamation of silver ores. During 250 years over 120,000 metric tons (t) of mercury would be lost to the environment through a combination of physical and chemical pathways. This article will use the chemistry of the reactions that occur during the amalgamation of silver ores to identify and quantify the different mercury loss vectors that resulted from the amalgamation process as practiced in the Hispanic New World.