The Hermetic Touchstone

Images from 'Hermetischer Probier Stein..' 1647, 

by Oswald Croll (Kroll or Crollius)

"..without this Chymical Phylosophy all Physick is but liveless [..] '..and this internal signature, force or occult virtue..' [..] which as Natures Gift insisted, and infused by the most high God, into the Plant or Anima, from the Signature and mutual Analogick Sympathy and harmonious concordance of Plants, with the Members of the Human Body, is by prudent Physitian only inquired into: and thence by the industrious help of Vulcan, or Anatomick Knife, is drawn out and applied to its proper use, not drousily passed over in noxious Silence, as is by Vulgar Herbarists too frequently done."
Oswald Crollius, 1609* 'De Signatura Rerum'

Touchstone: "Black, silica-containing stone used in assaying to determine the purity of gold and silver."*

The title page is an elaborate symbolic engraving (by Jan Sadeler), with portraits of Hermes Trismegistus, Morienus, Lull, Geber, Roger Bacon and Paracelsus (the so-called Alchemy dream team). 

'Hermetischer Probier Stein..' 1649 by Oswald Kroll is online in full at Herzog bibliothek Wolfenbüttel.

The full title of 'Hermetischer Probier Stein' translates approx. to:
'The Hermetic Touchstone in which every last one of the processes and chemical medicines found in Oswald Crollius’s work entitled 'Royal Alchimist Treasure' is not only examined and put to the test, but also complemented and enhanced, in the Latin language, with various other beautiful and useful medicines tried by the author's own hand and his daily experience'.

The title page image, up top, first appeared in Kroll's most famous book (1608/9) 'Basilica Chymica' (.. "it became the standard scientific work of iatrochemistry"*..) so the present work is most likely a later slimline version edited by Johann Hartmann.

"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]

• Oswald Crollius biographies: The Galileo Project & Wikipedia.
• See: 'The Chemical Philosophy: Paraclesian Science and Medicine in the Sixteenth and Seventeenth Centuries' by Allen G Debus 2002 [snips]
• See: 'From Alchemy to Chemistry in Picture and Story' by Arthur Greenburg, 2007 [scribd]
• Adam Mclean's Alchemy Website.
• On BibliOdyssey previously: alchemy.
• Thanks NiNa!

This knowledge is nothing but the secrets of wise teachers and Philosophers