===
| | | | |
| | | | APPROXIMATE |
| SYMBOL | ATOMIC | DENSITY | MELTING | OXIDES
| | WEIGHT | | POINT |
________|________|________|_________|_____________|________________
| | | | |
Iron | Fe | 55.9 | 7.93 | 1800 deg. | FeO, Fe_{2}O_{3}
Cobalt | Co | 59.0 | 8.55 | 1800 deg. | CoO, Co_{2}O_{3}
Nickel | Ni | 58.7 | 8.9 | 1600 deg. | NiO, Ni_{2}O_{3}
===================================================================

~The family.~ The elements iron, cobalt, and nickel form a group in the
eighth column of the periodic table. The atomic weights of the three are
very close together, and there is not the same gradual gradation in the
properties of the three elements that is noticed in the families in
which the atomic weights differ considerably in magnitude. The elements
are very similar in properties, the similarity being so great in the
case of nickel and cobalt that it is difficult to separate them by
chemical analysis.

The elements occur in nature chiefly as oxides and sulphides, though
they have been found in very small quantities in the native state,
usually in meteorites. Their sulphides, carbonates, and phosphates are
insoluble in water, the other common salts being soluble. Their salts
are usually highly colored, those of iron being yellow or light green as
a rule, those of nickel darker green, while cobalt salts are usually
rose colored. The metals are obtained by reducing the oxides with
carbon.

IRON

~Occurrence.~ The element iron has long been known, since its ores are
very abundant and it is not difficult to prepare the metal from them in
fairly pure condition. It occurs in nature in many forms of
combination,--in large deposits as oxides, sulphides, and carbonates,
and in smaller quantities in a great variety of minerals. Indeed, very
few rocks or soils are free from small amounts of iron, and it is
assimilated by plants and animals playing an important part in life
processes.

~Metallurgy.~ It will be convenient to treat of the metallurgy of iron
under two heads,--Materials Used and Process.

~Materials used.~ Four distinct materials are used in the metallurgy of
iron:

1. _Iron ore._ The ores most frequently used in the metallurgy
of iron are the following:

Hematite