In 1616, while still a medical student, Mylius published Duncan Burnet's Iatrochymicus. The Opus medico-chymicum, Mylius' own alchemical work, was published two years later. He is known for the collection Thesaurus gratiarum (1622) of pieces for the lute. In the same year his Philosophia Reformata was published. Mylius was the personal physician of Moritz of Hessen and his patrons included Maurice and Frederick Henry of Nassau.