Metals
There are three states in which metals occur in nature. First, some of them, as gold, silver, platinum, and mercury, are frequently found uncombined. These are said to occur in their native state. Second, many are obtained alloyed with each other, as gold and silver with mercury; but invariably they are found in combination with the metalloids, for which they have a strong attraction; these constitute the third state, and are known as metallic ores. The metals are conductors of electricity and heat, but differ in this respect. Some metals are so volatile that they may be distilled from their compounds. Mercury boils at 662 deg.; lead is volatilized to some extent, and in a slight degree copper also, in the smelting-furnaces; and gold will dissipate in vapor in the focus of a powerful burning-glass. With regard to their fusibility metals show a marked difference. Mercury remains fluid at 39 deg.; sodium and potassium fuse below the boiling-point of water; silver and gold melt at a red heat, iron at a white heat; and platinum only yields to the action of the oxyhydrogen blowpipe. There are great differences with respect to specific gravity of metals. While platinum is twenty-two times heavier than water, lithium is only about half as heavy as that liquid. The lightest metals have the strongest affinity for oxygen. Some of the metals are neither malleable nor ductile, yet others again have those properties to a remarkable extent. Gold may be hammered to the 200,000th of an inch in thickness, and wire has been drawn from platinum to the 30,000th of an inch in diameter. The metals exhibit wide differences in hardness. Steel may be tempered to scratch glass, while potassium is as soft as wax. To pulverize gold or copper great force is required; yet others again, notably antimony and bismuth, may be reduced to powder in a mortar.
The following table gives the relative properties of various metals, their names being arranged in a descending series:
Power to conduct Electricity. Brittleness. Malleability. Tenacity. Ductility. Power to conduct Heat.
Silver Antimony Gold Iron Gold Silver Copper Arsenic Silver Copper Silver Copper Gold Bismuth Copper Platinum Platinum Gold Zinc Cerium Tin Silver Iron Tin Iron Chromium Cadmium Gold Copper Iron Tin Cobalt Platinum Zinc Zinc Lead Lead Columbium Lead Tin Tin Bismuth Antimony Manganese Zinc Lead Lead Bismuth Titanium Iron Nickel Tungsten Nickel Cadmium