On the Incombustible Sulfur

Περὶ τοῦ θείου ἀκαύστου

On the Incombustible Sulfur is a brief pseudepigraphical treatise attributed to the anonymous figure known as Alchemist I, whose works are preserved in Byzantine compilations of Greek alchemical writings. The text is a single procedural passage focused on the concept of a divine, incombustible sulfur, a purified and philosophical form of the substance considered fundamental in Greco-Egyptian alchemical theory. The work provides instructions for processing this material, involving grinding with specific reagents, boiling, and testing until it achieves a state impervious to fire. This quality of incombustibility signifies a perfected, stable principle, central to alchemical ideas of transmutation. The treatise survives within the corpus of Greek alchemical texts found in medieval Byzantine manuscripts, notably the tenth- or eleventh-century Marcianus graecus 299 and the thirteenth-century Parisinus graecus 2327. While minor and fragmentary, its thematic concern with a perfected sulfur principle contributes to the broader alchemical theory of primal components, a concept that remained central in the later development of Islamic and Latin alchemical thought.