Platinum

—A somewhat rare, silvery white metal, specific gravity 21.5, nearly the heaviest known, while it melts at about 3650° Fahr. Platinum is very ductile, is not di olved by any acid, and is very difficult to oxidize. Its coefficient of expansion is practically the same as that of gla , ‘ fice it is used for the little connecting wires through the top of an incandescent lamp, leading the current from the contact pieces to the filament.