NATURAL

One of the numerous o::ides of iron; po e ed, however, of properties peculiar to itself, if we except the metals nickel and cobalt, which po e it also in a very slight degree. The magnet consists chiefly of two oxides, together with a small portion of quartz and alumine. Its colour varies in different specimens, according to minute differences in the ratios of the two oxides, and the nature of the foreign substances with which they are found united; but it is usually of a dark-grey hue, and has a dull metallic lustre. It is found in considerable ma es in the iron mines of Sweden and Norway j in the Isle of Elba; in different parts of Arabia, China, Siam,and the"Philippine Islands. Small magnets are also occasionally, though rarely, met with among the iron ores of this country. The properties are, — 1. It attracts iron in all its states except the oxides. 2. If formed into a bar, and suspended freely by a hair, or on a pivot pa ing through its centre, it will turn itself round, and, after a few pendulous vibrations, settle into some one position; which it will retain if left undisturbed, or if disturbed will, after a few similar vibrations, return to it again as before. 3. By rubbing on a bar of steel it will give the bar the same properties; and a bar of soft iron will, wiiile contiguous to it, even when not touched by it, obtain the same properties, which, however, tiie iron docs not, like the steel, retain upon removal. Cy4 [s. 707]