chemistry

Oswald Croll

Oswald Croll is a chemistry topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Oswald Croll rather than just read about it. In short: 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.

Key takeaways

Oswald Croll belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Oswald Croll to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Oswald Croll from memory before moving on to harder problems.

Reference excerpt

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. In 1608, Croll's opus magnum Basilica Chymica (Chemical Basilica) was first published, self-described as "containing a philosophick description, confirmed by the experience of [Croll's] own labours, and application of the choicest chymical remedies drawn from the light of Nature and of Grace". It is a hefty summary of his researches, methods of preparation, and studies into chemical medicine or iatrochemistry. In 1609 his treatise De signatura rerum (Treatise of signatures) was published. 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. It also discussed matters such as compound remedies, chemical organization and acted as an introduction to chemistry in later years. 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. Croll died suddenly in 1609. His reputation and influence grew after his death, and was noted by Robert Burton in his Anatomy of Melancholy. In 1618, Croll was deemed one of alchemy's heroes in Johann Daniel Mylius’ Basilica Philosophica (1618 - Opus Medico-Chymicum, third book). An emblematic seal dedicated to him appears in this work alongside the motto:

Oswald Croll of Wetter, Disciple of the Philosophers: This knowledge is nothing but the secrets of wise teachers and Philosophers.

Alchemical studies Croll believed that chemistry and alchemy were two halves of a tightly related field, in the same way that organic and inorganic chemistry are related. 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.

La royalle Chymie de Crollius . Lyon : Drobet, 1624 Digital edition by the University and State Library Düsseldorf Oswaldi Crollii Basilica chymica : pluribus selectis et secretissimis propria manuali Experentia approbatis Descriptionibus, et Usu Remdiorum chymicorum selectissimorum. Genevae : Chouet, 1643 Digital edition / 1658 Digital edition by the University and State Library Düsseldorf

References

Illustrations

Worked examples

Example 1 — a first encounter with Oswald Croll

Start with the simplest possible case. Write down what Oswald Croll claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Oswald Croll before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Oswald Croll ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Oswald Croll

In research: Oswald Croll appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Oswald Croll in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Oswald Croll is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1609 deaths, 16th-century German male writers, 16th-century German medical doctors, so understanding it makes those chapters shorter.
In everyday life: Look for Oswald Croll outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Oswald Croll in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Oswald Croll means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Oswald Croll out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Oswald Croll in simple terms?

Why does Oswald Croll matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Oswald Croll?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Oswald Croll.