Brass melting point of brass (, depending on composition) and its flow characteristics make it a relatively easy material to cast. By varying the proportions of copper and zinc, the properties of the brass can be changed, allowing hard and soft brasses. The density of brass is . Today, almost 90% of all brass alloys are recycled. Because brass is not ferromagnetic, it can be separated from ferrous scrap by passing the scrap near a powerful magnet. Brass scrap is collected and transported to the foundry where it is melted and recast into billets. Billets are heated and extruded into the
Tube Alloys to produce a chain reaction in a bomb with the power of thousands of tons of TNT. This led to the formation of the MAUD Committee, which called for an all-out effort to develop nuclear weapons. Wallace Akers, who oversaw the project, chose the deliberately misleading name "Tube Alloys". His Tube Alloys Directorate was part of the Department of Scientific and Industrial Research. The Tube Alloys programme in Britain and Canada was the first nuclear weapons project. Due to the high costs, and the fact that Britain was fighting a war within bombing range of its enemies, Tube Alloys was