The practices of Galenic pharmacy that dominated the Western pharmaceutical tradition throughout the medieval and early modern periods generally eschewed methods of alchemical processing and the use of high heat. A unique 10th-century Arabic pharmaceutical treatise, the Kitab al Tasrif by al-Zahrāwī/Abulcasis, however, discussed thermo-chemical techniques of distillation, calcination, and sublimation at length and would go on to have a major impact on Galenic pharmacy. It included recipes, for example, for two highly important distilled substances – rosewater and Philosophers' Oil (...) – that were copied and revised in Latin texts from the later Middle Ages and early modern Spanish formularies. By the end of the 16th century, these recipes had formed the basis for two new categories of distilled medicines – distilled waters and distilled oils – in Galenic pharmacy. Their inclusion in the Galenic formulary indicates that apothecaries in the Latin West were familiar with and indeed practicing thermo-chemical operations during the medieval and early modern periods. (shrink)