Exploring the ancient chemistry of mercury

Abstract

This paper explores the chemistry of mercury as described in ancient alchemical literature. Alchemy's focus on the knowledge and manipulation of natural substances is not so different from modern chemistry's purposes. The great divide between the two is marked by the way of conceptualizing and recording their practices. Our interdisciplinary research group, composed of chemists and historians of science, has set off to explore the cold and hot extraction of mercury from cinnabar. The ancient written records have been perused in order to devise laboratory experiments that could shed light on the material reality behind the alchemical narratives and interpret textual details in a unique perspective. In this way, it became possible to translate the technical lore of ancient alchemy into the modern language of chemistry. Thanks to the replication of alchemical practices, chemistry can regain its centuries-long history that has fallen into oblivion.

Keywords: alchemy; cinnabar; extraction; mercury; replication.

Fig. 1.

Left, ceramic mortar in which HgS and copper powder were ground—droplets of mercury are visible at the bottom. Right, comparison between the XRPD pattern (blue solid line) of the residual powder obtained from the reaction of synthetic mercury sulfide and copper powder in the presence of acetic acid (reaction mixture ground with a ball mill for 4 h at 25 Hz; the high background in the pattern is due to the presence of the amorphous phase of metallic mercury in the final powder) and the XRPD pattern of synthetic mercury sulfide (red solid line). The asterisks in the red XRPD diffractogram indicate the peaks assigned to cinnabar. Phase identification was performed using the PDF 2 Release 2004 database.

Fig. 2.

Top, reaction vessel with iron plate and cinnabar powder before the reaction (A and B) and after 10 min of heating using a Bunsen burner (C)—the mercury condensed on the lid (D). Bottom, comparison between the XRPD of the cinnabar ore (sample C4, red solid line) and the residual powder obtained from the reaction of the cinnabar ore (sample C4) and iron plate (blue solid line); the reaction mixture was heated with a Bunsen burner. The asterisks in the red XRPD diffractogram indicate the peaks assigned to cinnabar.

Fig. 3.

Top, residual powders obtained after 48 h of heating at 300 °C—a mixture of cinnabar ores and sodium carbonate (Left) and the cinnabar ore (Right). Bottom, comparison between the XRPD of the cinnabar ore (sample C1, red solid line) and the residual powder obtained from the reaction of the cinnabar ore (sample C1) with sodium carbonate (blue solid line); the reaction mixture was then heated with a mantle (at 300 °C) for 48 h. The asterisks in the red XRPD diffractogram represent the peaks assigned to the cinnabar.