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It forms two oxides, the black and the

grey. Nickel alloys with most of the metals, and it is found alloyed with iron in those masses that fall from the atmosphere, called meteoric stones. The origin of those lapideous masses that appear in so extraordinary a manner is entirely unknown: büt the numerous well-authenticated accounts we have had of the fact put it now beyond dispute. They are first seen as large meteors, at a great height in the air, which suddenly burst with an explosion, and the fragments are seen to fall to the earth. It is very remarkable that their composition is always the same, although they have fallen åt many different times, and in different places. They always contain native iron alloyed with nickel, in grains imbedded in a stony matter. The substance of these meteoric stones is not like any bodies which are found in the earth. In 1795, one weighing $6lbs. fell in Yorkshire.

MANGANESE.

This metal is never found native. Indeed its attraction for oxygen is so powerful; that it is with difficulty preserved in the metallic state. When pure, it is of a greyish colour, much like cast iron, and not malleable. It soon tárnishes, and at last becomes black. This change takes place more rapidly, if the metal be leated, or put into water.

There appear to be two oxides of this metal; the protošide, which is of a greenish colour; and the pèròxide, which is steel black, and has a considerable lustre: the latter is found in abundance, particularly near Exeter, and is much used in bleaching, and also for procuring oxygen gas, as it parts with it simply by the application of heat. It

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contains one-third of its weight of oxygen. This oxide is sometimes very beautifully crystallized. Manganese is also employed by glass-makers to destroy the greenish tint of glass, and for making violet-coloured glass.

Almost all the salts of manganese are soluble in

water.

COBALT.

Cobalt is never found but in a state of combination. It is met with united to sulphur, arsenic, and other metallic substances.

The ores of cobalt had been long used for giving à blue colour to glass, before its metallic nature was known.

The metal itself is not applied to any use. When pure, it is a reddish grey colour; rather soft and brittle. Like iron, it is attracted by the magnet. It is not oxidized by the air nor by water. It is converted into a deep blue by exposure to heat and flame.

There are two oxides of cobalt. The protoxide may be formed by precipitating by potass, a solution of cobalt in nitric acid. It is of a blue colour when first precipitated, but becomes black by absorbing oxygen. To recover the blue colour, it must be heated red hot, by which the oxygen is expelled. This oxide dissolves in aci

e dissolves in acids. The muriate of cobalt is green, and forms a sympathetic ink. Letters written with it are invisible, until they are warmed, and then they appear of a fine green; when cold they disappear again.

The peroxide of cobalt is procured by drying in the air, with heat, the protoxide just precipitated; by this the protoxide absorbs oxygen, and becomes the peroxide. It is black.

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Ores of cobalt are very valuable. Zaffre is a substance produced by roasting the ores of cobalt, by which the volatile matters (generally arsenic and sulphur,) are driven off; the remainder is then fused with sand or pounded flints. A blue glass is thus formed, which, when ground and washed, constitutes the pigment called smalt.

MOLYBDENA.

Molybdena is found in nature combined with sulphur; forming the sulphuret of molybdena, which resembles plumbago in some of its properties. This mineral is of a bluish colour, more brilliant than plumbago, and makes on paper a trace of a grey tint. The metal has only been procured in small grains, which do not differ much in their properties from the sulphuret. It combines with oxygen, so as to form an acid called the molybdic acid. The molybdate of lead is a beautiful yellow mineral.

The protoxide of molybdena is a tasteless pow. der of a brown colour. Molybdena alloys with the

. other metals,

TUNGSTEN.

A mineral called tungsten, or ponderous stone, affords a peculiar metal. This metal is capable of being acidified, and when in this state it is joined to lime, it forms the tungstate of lime.

The metal when pure is much like steel, and is one of the hardest of the metals; a file can scarcely make any impression on it; it is also the heaviest,

The pro

except gold and platinum. It is not used for

any purpose.

When heated in an open vessel it is oxidized, and there are two oxides of tungsten. toxide is of a brown colour, and when heated it burns, and is converted into the peroxide, which is yellow, and has some of the properties of an acid, being capable of combining with salifiable bases.

The mineral called wolfram is composed of tungstic acid, manganese, iron, and tin.

OSMIUM.

This metal was discovered by Mr. Tennant, in the ore of platina. The metal is of a dark

grey colour, and is oxidized when heated. Its oxide is volatile, and has a peculiar smell. It is little known, and has not been fused.

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IRIDIUM.

This metal was also discovered by Mr. Tennant, in the ore of platina. It is of a whitish colour. It is fusible, and malleable. It unites with

oxygen, and alloys with the metals. Its combinations are little known.

RHODIUM,

Dr. Wollaston discovered this metal in the ore of platina. It is very infusible, and forms malleable alloys with the malleable metals. It unites to oxygen like all the other metals, but is

very

little known,

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PALLADIUM,

CADMIUM, TELLURIUM.

PALLADIUM.

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This metal was discovered by Dr. Wollaston, who found it in the ore of plațina. Its colour is of a duller white than platina; it is malleable and ductile, and for fusion it requires ą stronger heat than for gold. It is rather harder than iron.

It unites with sulphur, and is acted on by the acids, but most readily by the nitro-muriatic.

It forms alloys with other metals, that with gold has been usefully employed in astronomical instruments, as it is hard, and does not tarnish.

CADMIUM.

This metal was discovered by M. Stromeyer, in 1817, in ores of zinc, particularly in brown fibrous blende. It resembles tin, but is rather more fusible. It does not tarnish in the air.

It readily disolves in acids, but its salts are little known. It is a rare metal, and not applied to any use,

TELLURIUM.

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This metal was discovered by Muller in 1782. It is of a bluish white colour, of considerable brilliancy. It is extremely brittle ; -melts in a heat a volatimeater than that required for lead. It is so volatile that it may be distilled like mercury:

Its oxide has acid properties. It is formed by burning the metal; a white smoke is disengaged, which is the oxide. It may be also obtained by

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