(Chemical symbol Pt). Metallic element atomic number 78, atomic weight 195.08, mp 1772C, specific gravity 21.45. First discovered in South America by Ulloa in 1735 but used by the Indians of Ecuador and Columbia who sintered the metal with gold. Finds are known particularly from La Tolita dating to the early centuries BC. It can be present in the native state, usually alloyed with some iron. The metal is malleable and ductile. It is used in early scientific instruments since its coefficient of expansion is very similar to soda-lime glass.