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Ireland. The gold coin current in Great Britain is composed of twenty-two parts of gold, and two of copper.

3. Silver, in a pure state, is ten times heavier than water; is soft, opake, and flexible; white, shining, and very malleable. Silver is more abundant than gold, being dispersed through most countries; it occurs in a pure state, as also combined with copper, lead, and other metals. English coin contains fifteen parts of silver to one of copper: the purposes to which this metal is applicable are too well known to require repetition.

4. Mercury or Quicksilver. Mercury is thirteen times heavier than water; it generally occurs in a pure state, and also combined with silver, which it resembles in colour; but the peculiarity which distinguishes it from other metals, is the fluidity it preserves at the common temperature of the atmosphere. This is less abundant than the last: the uses to which it is applicable in medicine, the arts, and experimental philosophy, are numerous; and it is highly valuable in the separation of gold and silver from their ores, which process is termed amalgamation.

5. Lead is of a blueish grey colour; it is upwards of eleven times heavier than water; is soft, malleable, ductile, but inelastic. Next to iron, lead is the most extensively dispersed, and is one of the most abundant of metals; it has never been found pure, but mostly combined with iron, manganese, antimony, silver, or their ores. The lead used for common purposes is obtained from an ore called Galena, or sulphuret of lead, which is composed of lead, sul

phur, oxyde of iron, and silver, and sometimes it contains lime and silex. Among the various uses to which it is applied, is the glazing earthenware; the oxyde of lead is used in making glass; and, combined with one-fifth part of antimony, it forms the types used in printing.

6. Copper. When pure, copper is about eight times heavier than water; its colour is a yellowish red; it is exceedingly sonorous, is harder than silver; and in respect to fusibility is between gold and iron. Copper in point of usefulness yields only to iron; it is widely dispersed, being found pure, and also combined with various mineral substances; it is used, as already observed, for alloying gold and silver. Copper alloyed with zinc, forms brass, pinch-beck, and tinsel; with a small proportion of tin it forms bellmetal; two-thirds of copper and one of tin are used in forming the speculums in reflecting telescopes: copper filings, or plates oxydized by acetous acid, forms into green crystals, which are used in painting, under the name of verdegrease or verdigris.

7. Tin. This metal has never been found pure, being generally combined with copper, sulphur, iron, &c.; it is about seven times heavier than water. Tin is the lightest of the ductile metals; it is harder and more tenacious than lead, and is very fusible. Tin is used as an alloy with various other metals; it is formed into exceedingly thin plates or leaves, under the name of tin-foil, and this, combined with mercury, is used for silvering the backs of mirrors and looking glasses. Tin is also used for the purpose of lining copper vessels for domestic purposes; this is

done by heating the vessels, having previously scraped the inside with an iron instrument, and then rubbing the internal surface with sal ammoniac: when the vessel is quite hot, a small quantity of pitch or resin is thrown in and suffered to spread entirely over the internal surface, which completely prevents the copper from oxydizing, as tin will not combine with oxyde of copper. When these preparatory measures are taken, a piece of pure tin is applied all over the inside of the hot copper vessel, which instantly assumes a bright silvery whiteness, and prevents any unpleasant effects in using tinned copper vessels for culinary purposes. Most of the saucepans, &c. used for kitchen purposes, under the name of tin ware, are formed of thin plates of iron, coated with tin; these are first scoured, and then thrown into a solution of sulphuric acid, which destroys all the rust or' oxyde, and renders the surface perfectly clear; the plates are then dipped into melted tin, the surface of which is covered with oil or fat to keep it from the action of the air; by these means the iron coming in contact with the pure melted tin, it comes out completely coated, the tin frequently penetrating the substance of the iron.

8. Iron. This is one of the most abundant of metals, being found in almost every rock and soil; it is about seven times heavier than water, of a blueish or reddish grey colour, is hard, ductile, and malleable, and in tenacity is next to gold. Iron is found combined with numerous minerals, and forms a principal part of those substances known under the name of meteoric stones; it is magnetic, and so

easily is this property imparted to iron, that a bar placed in a vertical position for a considerable time acquires polarity, which may also be communicated to it by suddenly striking it at the point against any hard substance; for instance, if a common poker be struck forcibly on a hearth, the point of contact becomes polar. The uses of iron are numerous, and are so well known as not to require repetition: without it man could scarcely subsist in a civilized state, as it forms the principal part of his agricultural, domestic, and mechanical implements.

9. Zinc is about seven times heavier than water; it is of a colour between silver and lead; is hard, but not so ductile as some of the preceding metals. Zinc is less abundant than most of the foregoing metals; it has not been met with pure, being either mineralized with sulphur, or combined with oxyde of iron, silex, &c. It enters into many alloys; preparations of it also are used for medicine, and in the arts.

10. Palladium. When pure it is eleven times heavier than water; it resembles platina in colour, is very malleable, and equal in hardness to bar iron. This metal is generally obtained in small quantities, alloying native platina. Native palladium is infusible.

11. Nickel. The specific gravity of nickel is about nine; its colour is yellowish white, it is ductile, malleable, and possesses the magnetic property, though in a less degree than iron. Nickel has been found combined with iron and other substances, and enters into the composition of all the meteoric stones

which have fallen from the atmosphere, in this and various other countries; its uses are principally confined to alloys.

BRITTLE METALS.

12. Arsenic. Specific gravity nearly eight; colour blueish or greenish white; becoming, on exposure to the air, dark, almost black; its substance is exceedingly brittle; it occurs nearly pure, and also combined with gold, silver, iron, lead, &c. Arsenic is one of the most active of mineral poisons; it is of frequent occurrence; is used in glazing porcelain, and the manufacture of glass: when combined with sulphur in certain proportions, it is either the realgar or orpiment used by painters. Its presence may be detected by submitting it to the action of heat, or striking it with a hammer, when it gives out a garliclike smell; it is also remarkable that the same appearance is produced on silver and steel by the application of arsenic, as by the application of onion or garlic.

13. Antimony. This metal is of a dull whitish colour, of a brittle and compact substance, and is about six times heavier than water. Antimony is a metal frequently used in various arts; as we before remarked, it forms one-fifth of the composition of printing types; it is used in medicine, and for alloys with other metals: it occurs combined with arsenic, silver, iron, sulphur, &c.

14. Bismuth. Pure bismuth is of a white colour, tinged with red; its substance is brittle, and it is nearly eleven times heavier than water. This is not

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