Period 6 element form, as an X-ray radiocontrast agent for imaging the human gastrointestinal tract. Soluble barium compounds are poisonous due to release of the soluble barium ion, and have been used as rodenticides. New uses for barium continue to be sought. It is a component of some "high temperature" YBCOsuperconductors, and electroceramics. The lanthanide or lanthanoid (IUPAC nomenclature) series comprises the fifteen metallic chemical elements with atomic numbers 57 through 71, from lanthanum through lutetium. These fifteen elements, along with the chemically similar elements scandium and yttrium, are often collectively known as the rare earth elements. The informal chemical symbol Ln is
Silver steel Silver steel Silver steel is common tool steel that is supplied as a centerless ground round bar (with tolerances similar to that of drill bit). The name comes from the highly polished appearance of the rods; there is no silver in the alloy. Amongst other applications, it has been widely used to make such things as punches, engravers, screwdrivers. Sheffield silver steel is used in France as a blade steel for straight razors. In Finland, German silver steel was and still is widely used for Puukko knives. The composition is defined by UK specification BS-1407, and is given below. In