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may be obtained pure by burning these substances. It is white, moderately hard, acrid, and corrosive; changes vegetable blues green, and approaches in its properties to the fixed alkalies. Water being applied to it, combines with it and becomes solid, heat being evolved. This is called slacking, the combination being a hydrate of lime. Water will dissolve rather less than 0,002 of its weight of lime. Davy discovered the metal of lime; it is only four or five times heavier than water, solid and white like silver; it burns with brilliance, leaving its oxide lime behind. The metal is named CALCIUM,-7. MAGNESIA is a soft white powder; it is also a metallic oxide. Its metal, which is white, and sinks rapidly in water, has been named MAGNIUM.-8. BARYTES is yielded by a mineral known by the name of ponderous spar, is porous, and of a greyish white. It is more caustic than lime, and is a violent poison. It may be slacked like lime, thus becoming a hydrate of barytes. Its base is now known to be a white solid metal, four or five times heavier than water, and is named BARIUM.-9. STRONTIAN, which is obtained from its carbonate or sulphate, is porous, of a whitish grey colour: it is acrid, and has alkaline properties. Its metal, named STRONTIUM, nearly resembles barium.

We shall now proceed to the metals which were known before the discoveries of Davy: these are twenty-seven in number.-1. GOLD, of a yellow colour, high lustre, and the most ductile and malleable of all known bodies. Sp. gr. 19,376. When

melted, it is of a bluish green colour.-2. PLATINUM is white, but not so bright as silver. It is as hard as iron, and very ductile and malleable. It is the heaviest of all bodies, sp. gr. being, at least, 23. Neither gold nor platinum will unite with sulphur.3. SILVER, is of a fine white, and capable of a very high polish, and is next to gold in malleability and ductility. Sp. gr. about 10,510.-4. MERCURY, or quicksilver, is white, and has a considerable degree of lustre. It is fluid except when cooled down to 39° below zero, when it becomes solid, and is then malleable. It boils at 656°, its vapour being invisible. It amalgamates and combines with most metals.

-5. PALLADIUM is a white metal, resembling platinum. Sp. gr., when hammered, 11,871. It is malleable, breaks with a crystalline texture, and, when strongly heated, its surface becomes of a blue colour. It was discovered by Dr. Wollaston, and obtained by him from crude platina.-6. RHODIUM is white; its sp. gr. exceeds 11. No known degree of heat will melt it alone. Its oxide is of a yellow colour, and mixed with salt, of a deep red. It also was obtained by Dr. Wollaston. Platinum and palladium, when combined with gold, destroy its colour, but rhodium does not.-7. IRIDIUM was discovered by Mr. Smithson Tennant, in crude platina. It is white, and much resembles platinum. It strongly resists the action of acids; its solution in muriatic acid becomes first blue, then green, and lastly a deep red. --8. OSMIUM was also discovered by Mr. Tennant. It is of a dark grey or blue colour, and possesses a

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metallic lustre. It is unaltered by heat in close vessels, but is soon dissipated in the open air. It is easily oxidized by heat, in the open air; its oxide having an oily appearance and a peculiar smell.-9. COPPER is of a fine red colour, but soon tarnishes. When melted it is of a bluish green colour. Sp. gr. about 8,9. It is very malleable and ductile. Our silver coin consists of 123 of silver alloyed with 1 of copper; the alloy being harder than silver alone. -10. IRON is of a bluish white colour, and is one of the hardest of the metals. Its sp. gr. is from 7,6 to 7,8. It is malleable and ductile. It is attracted by the loadstone, and is itself the constituent substance of the loadstone. Its combination with sulphur exists native, and is the magnetic pyrites.. Cast or pig iron is its name, when first extracted from the ore: when it is either white, which is hard and brittle; grey, which is softer and less brittle; or black, which is the softest and most fusible. By long melting and repeated forging it is rendered soft, or wrought iron; and if kept red hot for some time, in a bed of charcoal, it is converted into steel.-11. NICKEL is obtained from a German ore, called kupfer nickel, or false nickel: it resembles copper, though none can be got from it. It is white like silver: sp. gr. 8,820. It is softer than iron, malleable both cold and hot: and, like steel, may be converted into a magnet, by which it is powerfully attracted. This metal is constantly found in the meteoric stones which fall from the sky.-12. TIN, which is of a bluish white; sp. gr., when ham

mered, 7,299. Not so hard as silver. It is very malleable, but not equally ductile or tenacious: it crackles in being beat, and melts at 442°, cooling in rhomboidal crystals. From different alloys with copper are formed bell metal, mirrors for telescopes, bronze and gun metal.-13. LEAD is also of a bluish white, but very soon tarnishes; it is very soft. Sp. gr. 11,407. It is very malleable; but its ductility and tenacity are not great. It renders gold brittle as glass, and renders silver and platinum also brittle.14. ZINC is of a bright white, rather harder than silver; sp. gr. when hammered 7,1908. It soon tarnishes, and when heated red hot, it burns and is converted into a white oxide, which flies off in white flakes, the oxide or flowers of zinc. Zinc combines with copper, and forms brass. This combination is with the oxide; but when the metal itself is employed, the result is pinchbeck, or prince's metal. -15. BISMUTH. It is of a reddish white, and harder than silver. Sp. gr. 9,822. It has but little malleability, and is not so ductile as to allow of being drawn into a wire. It renders most of the metals brittle; but eight parts being mixed with five of lead and three of tin, fusible metal, as it is called, is produced, which melts at 212°.-16. ANTIMONY is of a greyish white, and brilliant. It is hard as silver, and very brittle. Sp. gr. 6,712. Heated in an open ves sel, it flies off in a white oxide, flowers of antimony, in the form of smoke. The alloy of tin and antimony forms pewter; and of lead and antimony, me

tal for printers' types.-17. TELLURIUM. It is brilliant, of a bluish white, and very brittle. It melts at a degree of heat a little above that for melting lead. It has been discovered by Davy, that it will combine with hydrogen and form a gás, soluble in water, and having the characters of a weak acid.-18. ARSENIC is of a bluish white; brilliant, but soon tarnishes. It is remarkably soft and brittle. It sublimes without melting at 356°, smoking and emitting an odour like garlic. Sp. gr. 8,31. White arsenic, as it is called, is the ordinary white oxide. It is white, compact, and of a glassy appearance. Exposed to heat, it emits a smoke, and its peculiar smell is like that of garlick. It is one of the most virulent poisons. It is formed of 75,2 of arsenic, and 24,8 of oxygen. The peroxide, which is also white, but sourer and more soluble than the preceding, is known as arsenic acid. It is composed of 65,4 of arsenic, and 34,6 of oxygen. -19. COBALT is not very brilliant; it is a greyish coour, shaded with red. It is brittle, and reducible to powder. It is about the hardness of silver, and is susceptible of magnetic influence. Sp. gr. 7,7. It forms three oxides. The protoxide is of a blue colour, the deutoxide is of an olive colour, and the peroxide is black.-20. MANGANESE is of a greyish colour, appearing like cast iron. It is brittle, and so hard as only just to bear the file. Sp. gr. 8,013. It combines rapidly with oxygen, forming three oxides; the protoxide, which is green; the deutoxide, or brown oxide; and the peroxide or black oxide, which is found

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