<p><i>On Alums and Salts</i>, sometimes attributed to the Persian polymath al-Razi, is one of the most influential treatises in the European alchemical tradition. This Arabic alchemical work, produced in twelfth-century al-Andalus, gained wide fame in its Latin translations, and is also represented by a unique and fascinating Hebrew manuscript that includes practical commentary added by its anonymous Jewish compiler. Gabriele Ferrario¿s new edition presents both the Arabic and the Hebrew texts, each with a full translation into English. Together, the two editions of <i>On Alums and Salts</i> tell the story of the active acquisition of chemical knowledge, of lexical creativity and ingenuity, and of scientific engagement that crossed chronological, linguistic, cultural, and religious boundaries.</p>