| Best brass | Copper 70%, | Zinc 30%. | |
| Admiralty brass | Copper 70%, | Zinc 29%, | Tin 1%. |
| Ordinary brass | Copper 67%, | Zinc 30%, | Lead 3%. |
Gun-metal is a mixture of copper, tin, and zinc. The standard Admiralty mixture is copper 88, tin 10, zinc 2. It possesses a tensile strength of 14 tons per sq. inch.
Bronzes.—The bronzes are alloys of copper, with zinc or tin mainly. They can be cast easily, and when heated to a dull red the metal can be forged, stamped, rolled, pressed, or extruded. They are largely free from corrosion.
Phosphor Bronze.—This is a specially strong bronze. A typical composition is copper 89.5, tin 10, phosphorus 0.5. The tensile strength is higher than that of pure copper or brass (about 15 tons per sq. inch), and it has about one-half the electrical conductivity of pure copper. It is used for small castings, and it can be drawn into wire, which is used in alternating-current electric-railway construction for the overhead conductor.
Delta metals are bronzes of specially high tensile strength (30-50 tons per sq. inch).
Manganese bronzes are bronzes of high tensile strength and ductility, and are largely used for marine propellers. Manganese bronze is not affected by sea-water. It usually contains copper, zinc, and manganese, with a little aluminium and tin.
A recently-discovered copper alloy is known as monel metal. It is a naturally-occurring alloy of copper, nickel, iron, and manganese (copper 27-29 per cent, nickel 68-70 per cent, iron and manganese 4-5 per cent), and possesses, roughly, the qualities of a mild steel and copper. It has a high tensile strength, which it retains over a wide range of temperature change. It is ductile, is not affected by immersion in sea-water, and can be machined. It is used for pump-valves, pump-pistons, turbine blading, &c.
In the British silver coinage silver is alloyed with 7.5 per cent copper, which renders it harder and more durable. British gold coinage contains 8.3 per cent of copper.—Bibliography: Law, Alloys; Osmond and Stead, Microscopic Analysis of Metals; Mellor, Crystallization of Iron and Steel; Desch, Metallography.
All Saints' Day, a festival of the Christian Church, instituted in 835, and celebrated on 1st Nov. in honour of the saints in general.
All Souls' College, a college of Oxford University, founded in 1437 by Henry Chichele, Archbishop of Canterbury. Attached to it are the Chichele Professorship of International Law and the Chichele Professorship of Modern History.