540 POPULAR SCIENCE MONTHLY.
sented more than another the fundamental state to which all of them bore relation. In short, gold, silver, copper, and lead were really, in the eyes of the alchemists, mixtures or compounds, the properties of which could be modified at will by adding or subtracting certain of the components.
The idea of this fundamental unity of matter was derived from a more remote principle. It was subject to the existence of the four elements — earth, water, air, and fire — from the association of which, according to Plato and Aristotle, all the substances in ISTature were constituted. We know now that these ancient elements were not real substances, but symbols of the fundamental states of matter, such as solidity, liquidity, the gaseous and all static conditions; the fourth element, fire, represented a dynamic state of bodies. These symbols had, on the other hand, a really substantial value for the alchemists, a character defined by the approximate identification of their supposed elements with certain products, in which the properties corresponding with one of the elements seemed to reside in a more eminent degree. Modern science has become more precise. At the same time the substantial elements of the ancients have come to be regarded by it as symbols of qualities and phenomena. Still, the Grecian philosophers conceived, behind the elements which were supposed to add their peculiar properties to bodies, an essential unity, residing in a higher degree in indeterminate primary matter; modi- fied by multiple forms and accidents, it concurred in forming all things. The elements, they said, are opposite by their quality and not by their substance. This more general notion did not cease to prevail in the Cartesian conceptions and in those of our own times too.
Such metaphysical views were, however, too vague to furnish the goldsmiths and alchemists a clear explanation of the facts which their daily practice offered them. In this a special state of mind is manifested. Chemistry, indeed, has always had a singular apti- tude for creating a sort of materialistic metaphysics, in which the names of beings and of first principles are employed with a restric- tive and in a certain way a tangible significance. The Grecian chemists said that the metals were like man: they had a body and a soul. The soul was, however, to most of the ancient philosoj^hers, nothing else than a more subtle matter. The alchemists were thus led to imagine a primary matter, appertaining to the metals alone, which constituted their common essence. It seemed to be indicated by that general condition of fusion which all metals take under the action of fire, in which they are ready to go into alloys and receive coloration and the impression of new properties. The ancient Egyp- tians regarded lead as this primary matter, and gave it the name of Osiris. About the time of the Peloponnesian war a new substance