There are altogether in Nature between 50 and 60 different metals, but on account of the unfitness of many through difficulty of extraction from their ores, rarity, or rapid oxidation when exposed to the atmosphere, the numbers that can be used for general manufacturing purposes are only about a dozen.

The qualities possessed by metals which enable them to be used for so many purposes are: -

Metallic Lustre, or the property of reflecting rays of light.

Tenacity, or the strength with which the particles of which a metal is formed resist being pulled asunder.

Malleability. The property which many metals have of being hammered or rolled out into a large surface or thin sheet without fracture.

Ductility is the property which enables a metal to be drawn into a thin wire.

Specific Gravity, or relative weights of metals all compared to the weight of an equal volume of water.

Conducting Power for Heat. The property which metals possess in varying degree of transmitting heat along or through them.

Conducting Power for Electricity. The particular quality which metals have of becoming the medium for the passage of electricity.

Fusibility. The property which metals possess of becoming liquid when heated to a sufficiently high temperature.

Expansion and Contraction is the property which a metal has of increasing its length or volume when heated, or decreasing the same when cooled.

Specific Heat, or the relative quantities of heat absorbed by metals all compared to the heat absorbed by an equal weight of water when raised through the same temperature.

In the following table the metals are arranged in the order of their respective qualities, the first in the list being the best: -