held that all matter is made of four elements earth air fire and water
Matter (philosophy) Empedocles held that there are four elements, from which things are derived, Earth, Water, Fire and Air. Some added a fifth element, the Aether, from which the heavens were derived. Socrates accepted (or at least did not reject) that list, as seen from Plato's Timaeus, which identified the five elements with the Platonic solids. Earth was associated with the cube, air with the octahedron, water with the icosahedron, fire with the tetrahedron, and the heavens with the dodecahedron.
Alkaline earth metal The alkaline earth metals are named after their oxides, the alkaline earths, whose old-fashioned names were beryllia, magnesia, lime, strontia, and baryta. These oxides are basic (alkaline) when combined with water. "Earth" is an old term applied by early chemists to nonmetallic substances that are insoluble in water and resistant to heating—properties shared by these oxides. The realization that these earths were not elements but compounds is attributed to the chemist Antoine Lavoisier. In his Traité Élémentaire de Chimie (Elements of Chemistry) of 1789 he called them salt-forming earth elements. Later, he suggested that the alkaline earths might be metal oxides, but admitted that this was mere conjecture. In 1808, acting on Lavoisier's idea, Humphry Davy became the first to obtain samples of the metals by electrolysis of their molten earths,[24] thus supporting Lavoisier's hypothesis and causing the group to be named the alkaline earth metals.