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
Argentium sterling silver Argentium sterling silver Argentium silver 935 is a modern sterling silver alloy, containing 93.5% silver. The traditional sterling alloy (92.5% silver + 7.5% copper) is modified by removing some of the copper and adding the metalloid germanium. Argentium silver 960 is a higher-purity jewellery alloy also containing germanium. It meets the standard for Britannia silver (95.84% silver) hallmarking. Argentium silver is the result of research by Peter Johns at the Art and Design Research Institute (ADRI), School of Art & Design, Middlesex University. The project began in 1990 with research on the effects of germanium additions to silver alloys. Germanium