“Oswald Croll (~1560-1609) was a professor of medicine and alchemy at the University of Marburg in Hesse, Germany. A strong proponent of alchemy and of using chemistry in medicine, he attempted to influence thinkers of his day towards viewing chemistry and alchemy as two separate fields. He published one volume in 1609, the year of his death, containing two books 'Basilica Chymica’ and 'De Signatura Rerum’ plus a long preface in which he expounds the ideas of Paracelsus to whom he was devoted.
'Basilica Chymica’ is a comprehensive summary of his researches, methods of preparation, and studies into chemical medicine or iatrochemistry. He pushes for the understanding and recognition of chemical compounds and the medicinal value of herbs and other processes first advanced by Paracelsus. It also discussed matters such as compound remedies, chemical organisation and acted as an introduction to chemistry in later years. The 'Tractatus Novus de Signaturis’ covered the relation of alchemy and chemistry to other fields of science, especially botany, suggesting the use of the doctrine of signatures to determine the medical property of plants.” [source]