Speculum metal metal mixtures usually contain two parts copper to one part tin along with a small amount of arsenic, although there are other mixtures containing silver, lead, or zinc. The knowledge of making very hard white high luster metal out of bronze-type high-tin alloys may date back more than 2000 years in China although it could also be an invention of western civilizations. Such metals were used in sculpture and to make more effective mirrors than the more common yellow easily tarnishing bronze mirrors. In that era mirrors of speculum metal, or any precious metal, were rare and only owned by
Tube Alloys national leader to approve a nuclear weapons programme on 30 August 1941. The Chiefs of Staff Committee supported the decision. A directorate of Tube Alloys was established as part of Appleton's Department of Scientific and Industrial Research, and Wallace Akers, the research director of Imperial Chemical Industries (ICI), was chosen as its head. Anderson and Akers came up with the name Tube Alloys. It was deliberately chosen to be meaningless, "with a specious air of probability about it". An advisory committee known as the Tube Alloys Consultative Council was created to oversee its work, chaired by Anderson, with its other