Principle (chemistry)
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Principle, in chemistry, refers to a historical concept of the constituents of a substance, specifically those that produce a certain quality or effect in the substance, such as a ''bitter principle'', which is any one of the numerous compounds having a bitter taste. The idea of chemical principles developed out of the
classical elements The classical elements typically refer to earth, water, air, fire, and (later) aether which were proposed to explain the nature and complexity of all matter in terms of simpler substances. Ancient cultures in Greece, Angola, Tibet, India, ...
.
Paracelsus Paracelsus (; ; 1493 – 24 September 1541), born Theophrastus von Hohenheim (full name Philippus Aureolus Theophrastus Bombastus von Hohenheim), was a Swiss physician, alchemist, lay theologian, and philosopher of the German Renaissance. H ...
identified the '' tria prima'' as principles in his approach to medicine. In his book ''
The Sceptical Chymist ''The Sceptical Chymist: or Chymico-Physical Doubts & Paradoxes'' is the title of a book by Robert Boyle, published in London in 1661. In the form of a dialogue, the ''Sceptical Chymist'' presented Boyle's hypothesis that matter consisted of cor ...
'' of 1661,
Robert Boyle Robert Boyle (; 25 January 1627 – 31 December 1691) was an Anglo-Irish natural philosopher, chemist, physicist, Alchemy, alchemist and inventor. Boyle is largely regarded today as the first modern chemist, and therefore one of the foun ...
criticized the traditional understanding of the composition of materials and initiated the modern understanding of
chemical element A chemical element is a chemical substance whose atoms all have the same number of protons. The number of protons is called the atomic number of that element. For example, oxygen has an atomic number of 8: each oxygen atom has 8 protons in its ...
s. Nevertheless, the concept of chemical principles continued to be used.
Georg Ernst Stahl Georg Ernst Stahl (22 October 1659Stahl's date of birth is often given erroneously as 1660. The correct date is recorded in the parish register of St. John's church, Ansbach. See – 24 May 1734) was a German chemist, physician and philosopher. ...
published ''Philosophical Principles of Universal Chemistry'' in 1730 as an early effort to distinguish between
mixture In chemistry, a mixture is a material made up of two or more different chemical substances which can be separated by physical method. It is an impure substance made up of 2 or more elements or compounds mechanically mixed together in any proporti ...
s and compounds. He writes, "the ''simple'' are ''Principles'', or the first material causes of ''Mixts'';..."
Georg Ernst Stahl Georg Ernst Stahl (22 October 1659Stahl's date of birth is often given erroneously as 1660. The correct date is recorded in the parish register of St. John's church, Ansbach. See – 24 May 1734) was a German chemist, physician and philosopher. ...
(1730
Philosophical Principles of Universal Chemistry
Peter Shaw translator, from
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To define a Principle, he wrote :A Principle is defined, ''à priori'', that in a mix’d matter, which ''first existed''; and ''a posteriori'', that into which it is at ''last resolved''. (...) ''chemical Principles'' are called ''Salt, Sulfur'' and ''Mercury'' (...) or ''Salt'', ''Oil'', and ''Spirit''. Stahl recounts theories of chemical principles according to Helmont and
J. J. Becher Johann Joachim Becher (; 6 May 1635 – October 1682) was a German people, German physician, Alchemy, alchemist, precursor of chemistry, scholar, polymath and adventurer, best known for his ''terra pinguis'' theory which became the phlogiston theo ...
. He says Helmont took ''Water'' to be the "first and only material Principle of all things." According to Becher, ''Water'' and ''Earth'' are principles, where Earth is distinguished into three kinds. Stahl also ascribes to Earth the "principle of ''rest'' and ''aggregation''." Historians have described how early analysts used Principles to classify substances: :The classification of substances varies from one author to the next, but it generally relied on tests to which materials could be submitted or procedures that could be applied to them. "Test" must be understood here in a double sense, experimental and moral: gold was considered noble because it resisted fire, humidity, and being buried underground. Camphor, like sulfur, arsenic, mercury, and ammonia, belonged to the "spirits" because it was volatile. Glass belonged among the metals because, like them, it could be melted. And since the seven known metals – gold, silver, iron, copper, tin, lead, and mercury – were characterized by their capacity to be melted, what made a metal a metal was defined by reference to the only metal that was liquid at room temperature, mercury or quicksilver. But "common" mercury differed from the mercuric principle, which was cold and wet. Like all other metals, it involved another "principle", which was hot and dry, sulfur.Bernadette Bensaude-Vincent & Isabelle Stengers (1996) ''A History of Chemistry'', Deborah van Dam translator,
Harvard University Press Harvard University Press (HUP) is an academic publishing house established on January 13, 1913, as a division of Harvard University. It is a member of the Association of University Presses. Its director since 2017 is George Andreou. The pres ...
,
Guillaume-François Rouelle "attributed two functions to principles: that of forming mixts and that of being an agent or instrument of chemical principles." :Thus the four principles, earth, air, fire, and water, were principles both of the chemist's operations and of the mixts they operated upon. As instruments they were, unlike specific chemical reagents, "natural and general," always at work in every chemical operation. As constituent elements, they did not contradict the chemistry of displacement but transcended it: the chemist could never isolate or characterize an element as he characterized a body; an element was not isolable, for it could not be separated from a mixt without re-creating a new mixt in the process.


See also

* Sulfur-mercury theory of metals


References

{{Reflist History of chemistry Alchemical substances