Crollius

Oswald Croll or Crollius (c. 1563 – December 1609) was an alchemist, and professor of medicine at the University of Marburg in Hesse, Germany. A strong proponent of alchemy and using chemistry in medicine, he was heavily involved in writing books and influencing thinkers of his day towards viewing chemistry and alchemy as two separate fields.

Croll received his doctorate in medicine in 1582 at Marburg, then continued studies at Heidelberg, Strasburg, and Geneva. After working as a tutor, he arrived in Prague in 1597. He remained there for two years, and again from 1602 until his death. There, through Rudolf II, he came into contact with other alchemical writers such as Edward Kelley.