Platinum

Platinum, chemical element, symbol Pt; for physical constants see Periodic Table. Platinum was discovered by Julius Scaliger in 1557. It is a metallic element occurring native, and as the mineral sperrylite, an important source of the element. Platinum is a silver-white, malleable, ductile metal. The element does not oxidize in air at any temperature, but reacts with halogens, cyanides, sulfur, and caustic alkalis. The metal absorbs large volumes of hydrogen at ordinary temperatures. It is used in resistance wires for constructing high-temperature electric furnaces. In the finely divided state the metal is used as a catalyst. Platinum and its compounds are used in plating, jewelry, wire, corrosion-resistant apparatus, magnetic alloys, electrical contacts, and dentistry.