In 1669 Sylvius founded the first academic chemical laboratory .[citation needed] For this reason, the building in which much of the Leiden University chemistry and natural science faculties are housed has the name Sylvius Laboratory. His most famous students were Jan Swammerdam, Reinier de Graaf, Niels Stensen and Burchard de Volder.
He founded the Iatrochemical School of Medicine, according to which all life and disease processes are based on chemical actions. That school of thought attempted to understand medicine in terms of universal rules of physics and chemistry. Sylvius also introduced the concept of chemical affinity as a way to understand the way the human body uses salts and contributed greatly to the understanding of digestion and of bodily fluids. The most important work he published was Praxeos medicae idea nova (New Idea in Medical Practice, 1671).