Discovered in the fifteenth century, although its discoverer is not known. Bismuth is a brittle metal which is silvery in color with a pink tinge. It is stable in air and water. It has poor thermal and electrical properties and finds applications in the manufacture of fusible alloys, a range of materials with low melting points which are suitable for various applications including solders and thermal fuses. Pure bismuth shows a high absorbtion of gamma rays which makes it useful as a filter or window for these particles, whilst at the same time permitting the passage of neutrons. Foil - Thin sheets of pure metal and metal alloys. Due to their fragile nature, some foils are coated on one side with an acrylic or polyester support. Where foils are supported they are indicated in the detailed item description.