Oswald Croll

Oswald Croll or Crollius (c. 1563 – December 1609) was an alchemist, and professor of medicine at the University of Marburg in Hesse, Germany.

Some of his work pushed for the understanding and recognition of chemical compounds and medicinal value of herbs and other processes first put forth by Paracelsus.

The second book covered alchemy's and chemistry's relation to other fields of science, especially botany, suggesting the use of the doctrine of signatures to determine the medical property of plants.

[5] In 1618, Croll was deemed one of alchemy's heroes in Johann Daniel Mylius’ Basilica Philosophica (1618 - Opus Medico-Chymicum, third book).

He used the framework of Parcelsus' works to organize his beliefs about the geometrically important relationships between various forms of matter and alchemical reactions, from rectangles to megagons.