Magnetism

That IMG:content-1208.jpg:[graphic][merged small] property of certain substances, notably of iron, nickel, and cobalt, in virtue of which they attract iron. Magnets may be natural, as in the case of the magnetic ore or lodestone; or artificial, as a piece of hard steel which has been magnetized. If a piece of soft iron be surrounded by a coil of insulated wire, and an electric current be pa ed through the wire, the iron becomes a magnet, and the whole is called an electro-magnet. The strength of a magnet is found to be greatest near the ends or poles. When freely suspended, a magnet sets itself nearly n. and s. All bodies belong to one of two cla es, according as they set themselves axially or equatorially when suspended in a magnetic field of force; when axially, they are paramagnetic, ferromagnetic, or simply magnetic; e.g. , iron, nickel, cobalt; when equatorially, they are diamagnetic; e.g. , bismuth, antimony, zinc.