Nickel, a silver-white, metallic, chemical element. Nickel is the third most magnetic element, exceeded in this quality only by iron and cobalt. Nickel is almost always found in combination with other elements, chiefly in the mineral ores pentlandite and garnierite.

Nickel is hard and moderately strong. It is long-wearing, resists oxidation, and is not easily corroded by acids or alkalis. Nickel's most important use is in alloys; it makes them hard and very resistant to corrosion. Several thousand different nickel alloys have been developed.

A large percentage of the nickel produced is used in making various types of steel, particularly stainless steel. Nickel is also an important ingredient in many powerful magnets. It is used to plate other metals to prevent them from corroding. Cupronickel, an alloy of 75 per cent copper and 25 per cent nickel, is used to make United States five-cent coins (nickels); the same alloy is also used for the outer layers of all other United States coins except the penny. Nickel silver, formerly called German silver, is an alloy of copper, nickel, and zinc. It is used for screws and rivets, and as a base to be plated with other metals. Inexpensive jewelry is sometimes made of plated nickel silver.

Nickel also forms many useful chemical compounds. Nickel oxide is used in paints for porcelain and in the manufacture of some types of glass. Nickelic oxide is used in storage batteries. Several nickel compounds, including nickel acetate and nickel-ammonium chloride, are used as mordants, substances that fix dyes to cloth.

Canada is the world's largest producer of nickel. Most of it comes from the Sudbury district of Ontario.

In one refining method nickel ore that contains nickel sulfide, copper sulfide, and other compounds is crushed and then separated into copper, nickel, and iron concentrates by the flotation process. The nickel concentrate is roasted to remove part of the sulfur and then smelted to remove other impurities. The result of the smelting is Bessemer matte, a material that contains nickel plus small amounts of copper and sulfur.

The Bessemer matte is poured into molds and allowed to cool slowly so that large crystals of nickel sulfide form. The cooled matte is then crushed. The nickel sulfide crystals are separated from the rest of the material and roasted to remove more of the sulfur. The resulting material is melted and then cast into blocks, which are used as anodes in electrolytic cells. Electric current causes the anodes to dissolve and the nickel to be deposited as a coating on the cathodes. The nickel produced by electrolysis is about 99.9 per cent pure.

Nickel was first isolated in 1751 by Baron Cronstedt, a Swedish chemist. The name nickel comes from Kupfernickel, an old German name for the metal.

Symbol: Ni. Atomic number: 28. Atomic weight: 58.69. Specific gravity: 8.9. Melting point: 2,647 F. (1,453 C.). Boiling point: 4,950 F. (2,732 C.). Nickel has five stable isotopes: Ni-58, 60, 61, 62, and 64. It belongs to Group VIII of the Periodic Table and may have a valence of +2 or 3, 0 and +1.