Chemistry, history Aristotle

The two contributions in the next section of the volume take up two important contributions to chemistry s relationship to the history and philosophy of science. First is Paul Needham s careful discussion of Aristotle s views about chemical reaction and chemical substance (Chapter 3). This is followed by Jaap van Brakel s eye-opening discussion of Kant s long neglected Opus Postumum, a work that only recently has come to wide attention. Its neglect allowed Kant s earlier dismissive views of chemistry to dominate philosophical considerations of chemistry. Here is a central source of chemistry s philosophical invisibility. 

The Greek world had been dramatically changed by Aristotle s pupil, Alexander the Great (356-323 BC). Prior to Alexander, Greece had been composed of a number of small city states. Alexander not only united these city states but also conquered much of the known world. His empire included Egypt and Mesopotamia, and stretched eastwards towards India. He founded cities which acted as centres of Greek culture in the lands he had conquered. The most important of these cities in the history of chemistry was Alexandria, which was founded at the mouth of the Nile in Egypt in 332 BC. 

The Jabirian theory of the formation of metals was clearly based on the views of Aristotle but included a significant new idea. Aristotle had considered metals to be formed by the combination of moist and dry exhalations, and in the Jabirian works these exhalations are identified with the vapours of mercury and sulphur. The cause of the different metals was the different quality of the sulphur from which they were formed. We must beware of identifying the sulphur of the Islamic alchemists with the pure material that we know by that name. The term sulphur probably embraced a whole range of sulphurs of varying purity and colour, and when used as a component of metals probably referred to a volatile combustible material to which no known substance corresponded exactly. Likewise mercury as we know it may only have been considered an approximation to the other volatile liquid component of metals. The sulphur-mercury theory is extremely important in the history of chemistry. The notion that metals contained a combustible principle persisted, and in European chemistry provided the inspiration for the phlogiston theory. 

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. 

Aristotle is sometimes regarded as a bad influence on chemistry because of his criticism of atomism and his role as a prime source in the development of alchemy. The mystical ideas with which alchemy infused the study of matter have been taken to reflect on him, as in the picture Robert Siegfried paints of Aristotle in his history of modern chemistry ... 

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