> as lemmas

8. History of Science. One of the elemental principles of which all substances were formerly believed to be composed, and which was thought to be present in all metals. Also †mercury of metals, †mercury of the philosophers.Over the 8th–10th centuries a sulphur–mercury theory of metals developed (perhaps deriving from the Aristotelian Meteorologica, Book 3), in which these two substances were thought of as ‘philosophical’ principles rather than as the familiar physical substances. The concept was carried to the West, and in the mid 13th cent. Albertus Magnus wrote of a new sulphur–mercury theory of the metals to be found in translations of the work of Avicenna (980–1037).Paracelsus (1493–1541) expanded this view to include all substances, when he added salt as a third principle. The triad of salt, sulphur, and mercury was employed by chemists in the 16th–17th centuries in opposition to the traditional Aristotelian elements (earth, air, fire, and water), although many used both systems in their explanations, taking the former set in a spiritual sense and the latter in a material one.During the course of the 17th cent. it became increasingly common to combine the three Paracelsian principles and the four Aristotelian elements into a system comprising five components, such as that of Joseph Duchesne who accepted the three Paracelsian principles plus water and earth in his Grand Miroir du Monde (1587). Robert Boyle rejected the Aristotelian elements and cast doubt on the existence of the Paracelsian principles in his Sceptical Chymist (1661). The subsequent development of the phlogiston theory, and of other concepts based on experiment, led to the idea of mercury as a fundamental component of all metals being finally abandoned.