The Clangor Buccinae ("Blast of the Trumpet") is a medieval Latin alchemical treatise of uncertain authorship, first printed in the collection Alchimia (De Alchimia Opuscula Complura Veterum Philosophorum, Frankfurt, 1550) and subsequently reprinted in Volume I of the Artis Auriferae (Basel, 1572), beginning at page 480. The title evokes the apocalyptic trumpet blast announcing a revelation, and the text presents itself as a proclamation of alchemical truth in bold, declarative language. Its author is unknown, though the treatise circulated widely in the sixteenth and seventeenth centuries as part of the standard alchemical reading list.

The Clangor Buccinae belongs to the genre of alchemical "manifestos" that announce the secrets of the Art with urgency and rhetorical force. Its core teachings concern the purification of the philosophical matter through repeated washing and the interplay of wet and dry principles. The text emphasizes that the alchemical ore is "dropsical" and must be cleansed through graduated applications of heat and moisture, a process it describes through medical analogies of curing the body of excess fluids. The trumpet metaphor signals that these truths, long hidden in obscure allegorical language, are now being proclaimed openly for those with ears to hear.

Maier borrows directly from the Clangor Buccinae for the motto of Emblem XIII in the Atalanta Fugiens. De Jong identifies this borrowing explicitly: the motto reads "The philosophical ore is dropsical, and wants to be washed seven times in the river, just as Naaman the leper in the Jordan" (De Jong, Netherlands Yearbook article, p. 162). The biblical story of Naaman, commanded by the prophet Elisha to bathe seven times in the Jordan to cure his leprosy, becomes an allegory for the repeated purification of the alchemical substance. The plate for Emblem XIII would have depicted this theme of washing and purification, connecting the Old Testament narrative to the laboratory process of dissolving and reconstituting metallic matter.

The Clangor Buccinae also informs Emblems XI, XIV, and XV through its teachings on the relationship between fire and water in the alchemical work. Maier's discourse in these emblems develops the paradox central to the Clangor Buccinae: that the philosophical fire is equivalent to water, and that washing by fire and burning by water amount to the same operation. De Jong traces this paradox through the Turba tradition and the Aurora Consurgens, showing how the Clangor Buccinae served as a transmission point for ideas that originated in Arabic alchemy and reached Maier through the Latin anthological tradition.

De Jong's source-critical method reveals the Clangor Buccinae as one of several intermediate texts through which Maier accessed the Turba tradition. Rather than reading the Turba Philosophorum in isolation, Maier encountered its ideas refracted through later compilations and commentaries, of which the Clangor Buccinae was among the most important. This layering of sources within sources is characteristic of alchemical textual transmission, and De Jong's identification of specific borrowings allows us to reconstruct the reading path by which a motto in the Atalanta Fugiens connects back through the Clangor Buccinae to Arabic cosmological alchemy.

The trumpet of the title is itself a clue to the playful dimension of alchemical writing. Maier's Atalanta Fugiens, with its three-voice fugues accompanying each emblem, is a book designed to be heard as well as seen and read. The Clangor Buccinae, which announces its teachings as a trumpet blast, participates in the same tradition of synesthetic alchemical pedagogy that Maier brought to its fullest expression. The reader who encounters the motto of Emblem XIII is hearing, across the centuries, the echo of that medieval trumpet.