Three-principle theory

The next step away from the traditions of antiquity involved the addition of a third principle to Jabir s sulphur and mercury salt. Whereas the first two were components of metals, salt was considered an essential ingredient of living bodies. In this way alchemical theory became more than a theory of metallurgy and embraced all the material world. The three-principle theory is generally attributed to the Swiss alchemist Paracelsus (1493-1541), although it is probably older. Paracelsus asserted that sulphur, salt, and mercury form everything that lies in the four elements . 

In Chap. 3, Jo Hedesan addresses Boyle s Sceptical Chymist as a case study for theory choice in the 17th cenmry. The original discussion focuses on three competing theories concerning the chemical components of matter the four-element theory of Aristotle, the three-principle theory of Paracelsus and the atomistic theory. Hedesan argues, that in effect the book is an attack on Paracelsianism by Boyle. This is evident from the fact that the other two theories fall out of the discussion quite early in the text. In the history of Chemistry, this seminal text is often taken as a successful attack on Paracelsianism. 

Clearly, the real blow to the tria prima could only have come from the alchemical coimnunily itself. In the 1640s, the strongest challenge to the three principle theory came fiom the Flemish physician and alchemist Jan Baptist Van Helmont (1579-1644). 

The characteristic features of a cord—mbber composite have produced the netting theory (67—70), the cord—iaextensible theory (71—80), the classical lamination theory, and the three-dimensional theory (67,81—83). From stmctural considerations, the fundamental element of cord—mbber composite is unidirectionaHy reinforced cord—mbber lamina as shown in Figure 5. From the principles of micromechanics and orthotropic elasticity laws, engineering constants of tire T cord composites in terms of constitutive material properties have been expressed (72—79,84). The most commonly used Halpin-Tsai equations (75,76) for cord—mbber single-ply lamina L, are expressed in equation 5 ... 

Chemistry is an experimental science, and to rationalize our observations we gradually develop and invoke a number of rules and principles. Theories may have to change as scientific data increase, and as old principles cease to explain the facts. All of the foregoing description of atomic and molecular orbitals is a hypothesis for atomic and molecular structure supported by experimental data. So far, the description meets most of our needs and provides a good rationalization of chemical behaviour. However, it falls short in certain ways, and we have to invoke a further modification to explain the facts. Here are three observations based upon sound experimental evidence, which are not accommodated by the above description of bonding ... 

The Sceptical Chymist, which is written in the form of a dialogue between five people (two of whom mysteriously disappear in the part following the second title page and reappear near the end of the book), is a discussion of the chemical philosophies that prevailed in Boyle s day, the Aristotelian theory of the four elements and Paracelsus s theory of three principles. Boyle discusses them in exhaustive detail in order to foster skepticism concerning them. 

A considerable part of the book is an attack on the Paracelsian theory of three principles. Boyle argues, for example, that none of the principles can be used to explain how a prism breaks up white light into different colors. Furthermore, authors who argued in favor of the three principles generally described them in such obscure ways that it was doubtful that they understood these supposed principles themselves. 

Adopted with some important changes by Plato and Aristotle, the doctrine of the four elements became the generally accepted theory of matter until the rival doctrine of the three principles, the tra prima of Paracelsus, appeared, in the sixteenth century. 

In the De Generatio Rerum Naturalimn lie relates his three principles to the theory of body, spirit and soul ... 

The works of these practical chemists of the sixteenth century manifest a more serious appreciation of the dignity and importance of chemistry in its relation to the practical arts, and had a great stimulating influence on all chemical workers. It will be noticed however that with the exception of Paracelsus these men were not greatly interested in the problems of chemical philosophy. To the extent that they refer to chemical theory they accept the conventional Aristotelian or Arabian concepts. Paracelsus by the- impression made by his three principles indeed did much to shatter the blind faith in the ancient theories and to pave the way for later constructive speculation. In so far as chemical theory is concerned the sixteenth century marks... 

The importance of the wide acceptance of the three principles lay not in any permanent value this theory possessed, but in that this acceptance was a distinct break with ancient authorities and appealed to experience for its justification, and opened the way for further development on the basis of wider future experience. 

Alkahest. He also blamed the Galenists for resisting the progress of medicine by their obstinate conservatism. Robert Boyle manifestly considered Sennert one of the chief exponents of the theory of the three principles and cites him in the Sceptical Chymist. 

As a student of medicine he was strongly influenced by the works of Paracelsus, not only by his progressive ideas, but also by his transcendental and mystical philosophy. Van Helmont resembled Paracelsus, however, too much in his disregard of traditional authority to be a blind follower of Paracelsus. While he accepted some of the latter s most characteristic ideas, as the Archaeus presiding over functions of digestion, etc., he rejected some of his more prominent theories as, for example, the three principles of matter. 

Van Helmont s chemical experiments and his chemical theories exerted a powerful influence on the chemists of his century. No chemist is cited more frequently nor with higher respect. Yet, his theory of the two elements, air and water, did not, with many, replace the four Aristotelian elements, nor the three principles, though the latter had by this time been frequently elaborated into five, sulphur, mercury, salt (the active principles), and phlegm (water) and earth (the passive principles). The suggestion of the rational and desirable term gas which he used, was ignored by his early successors. Boyle, Boerhaave, and Priestley used instead the terms artificial air, factitious air, ... 

It is difficult to see in the characteristics and properties of the three earths of Becher any substantial improvement on the tria prima of Paracelsus and his successors, other than the avoidance of the use of the three names which were in common use in two different meanings. For the three principles of that name, as chemists of that school took great pains constantly to explain, were not the same as the common substances so named. Nevertheless, the new name terra pinguis or fatty earth for the older sulphur, as the substance which departs in combustion, certainly gave the stimulus which incited Stahl and his followers to develop the influential phlogistic hypothesis and Becher thus played a not unimportant part in the history of chemical theory. 

In the Alchemical Theory, says Albert Poisson, the four Elements, not any more than the three Principles, represent particular substances they are simply states of matter, simple modalities. Water is synonymous with the liquid state, Earth with the solid Air with the gaseous and Fire with that of a very subtle gaseous state, such as a gas expanded by the action of heat.. . Moreover, Elements represent, by extension, physical qualities such as heat, (Fire) dryness and solidity, (Earth) moisture and fluidity, (Water) cold and subtility, (Air) Zosimus gives to their ensemble the name of Tetrasomy. 

Medieval alchemists had generally adhered to a dyad theory, in which Sulfur and Mercury were the principles of all metals and change was produced by the interaction of these two principles. Substances rich in Sulfur were more combustible, while those rich in Mercury were less so. Paracelsus took this dyad theory and added a third principle of Salt to it. His three principles—the tria prima, or three first things—were able to explain the alchemical transformations of all bodies. This material trinity matched the Holy Trinity in heaven as well as the three principles of which we are made vital spirit, soul, and body. Important in this scheme are correspondences between the great world, the... 

Most of modern physics and chemistry is bast d on three fundamental ideas first, matter is made of atoms and molecules, very small and very numerous second, it is impossible in principle to observe details of atomic and molecular motions below a certain scale of smallness and third, heat is mechanical motion of the atoms and molecules, on such a small scale that it cannot be completely observed. The first and third of these ideas are products of the last century, but the second, the uncertainty principle, the most characteristic result of the quantum theory, has arisen since 1000. By combining these three principles, we have the theoretical foundation for studying the branches of physics dealing with matter and chemical problems. 

None of these principles appeared alone, however, as a simple substance. The fact that chemists could not make complete extractions and produce these principles in pure state rendered Beguin s theory somewhat uncertain. His three principles remained as yet ideal substances. 

In terms of the theory of elements, Paracelsus s contribution was not his work, although he did write about how the three principles made up most of terrestrial matter, but his role in the redirection of alchemy. He de-emphasized the concept of transmutation (although it is likely he believed it possible) and focused on practical aspects of the study of matter, particularly iatrochemistry. He also encouraged the investigation of materials through experiments. While this should not be confused with modern experimentalism, since Paracelsus included spiritualism and occult theory in his system of investigation, it was far more systematic than most alchemy tended to be. He also based his work on a conception of pure compounds, and that concept, in turn, led to work on purification and qualitative control of chemical research and production. 

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