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Obs.-The loadstone, which possesses the singular and unaccountable property of always pointing to the north, is an ore of irou..

Red and yellow ochres are impure oxides of iron; generally where redness is found in the soil, the presence of iron may be suspected.

88. Tin is an English or Cornish metal, 7 times heavier than water. It is very malleable; and is highly useful as a coating to iron and copper; requiring only, to have iron dipt into it, and copper to be rubbed with it, to become perfectly coated.

89. Lead is 11 times heavier than water; easily melted, and highly useful for various purposes

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90. Nickel is a Chinese metal of a light grey; 9 times heavier than water, and melted with difficulty.

91. Zinc is 7 times heavier than water, of a bluish white white colour, and used in various compounds. daily joilt

92. The other metallic substances are Antimony, Bismuth, Cobalt, Arsenic, Manganese, Palladium, Rhodium, Potassium, &c., to the number of thirty; although the ancients knew of only seven metals.

93. Iron is formed into steel, by being heated with charcoal. Brass is composed of zinc and copper. Bell-metal is a mixture of tin and cop per. Pewter is a mixture of tin and lead. Bronze is a mixture of copper and tin.

94. Coals are minerals dug out of the ground in immense mines; particularly at Newcastle, Whitehaven, and Wednesbury; and they are

the best fuel yet discovered by man. The Bri tish islands are celebrated for their coal-mines; many countries being obliged to depend on wood; which is often scarce and dear.

Obs. Coals are, in all probability, the remains of submerged forests, brought to their present state by some unknown process of subterraneau chemistry,

95. Half the civilized, employments of man, 'consist in working the metals and minerals. In England, the large towns of Birmingham and Sheffield are wholly engaged in the useful and ornamental manufactures of various metals.

Obs. All that boys effect with lead and a tobaccopipe, men effect in regard to all the metals, by similar or slightly-varied means.

96. Civilization depends so much on the discovery of the useful metals, that little progress can be made from a savage state, without the useful trade of a blacksmith.

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He makes all the implements of gardening and agriculture; all domestic utensils; knives to cut with; and spears and swords to defend the soil and its produce, against invaders.

97. To avoid the inconvenience of exchanging or bartering, men, in early ages, fixed on metals; as on gold, silver, copper, or iron, for a medium of value: so, that, if one man, had too much corn and wanted wine, he was not obliged to give corn for the wine, but he might sell his corn for so much metal, and buy the wine with the metal, at bis convenience.

Qbs,Hence, the origin of money; and as it was found inconvenient to weigh metal in every transaction, (as Abraham did when he bought the nurying-place of Sarah;) stumpa were put on pieces of moial," as kings'

heads, to indicate that they might be safely received for a settled weight or value. Hence, in England, we have, or had, pieces of stamped gold of known value; as guinens, hall guineas, sovereigns, half sovereigns, &c, : pièces of stamped silver, as crowns, shillings, &c, i and pieces of stamped copper; as pennies and half-pennies all of universal worth. But of late years, a pernicious attempt has been made, to pass stamped paper for money; ariginally, mere promises to find money, but latterly, as money itself! Gold coin in particular has, consequently, almost disappeared; and become very dear in relation to the paper-money.

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N. B. From 76 to $1 was numbered 92 to 97 in the former edition,

V. Of Building,

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98. Man, like other animals, would seek places in which he might shelter himself from the inelemency of the weather. Beasts of prey retire to thickets and caves; beavers build mud-houses, and rabbits make burrows under ground. Man, in his most savage state, imitates their practices; and then improves on them, by the aid of his

reason.

99. Among savage tribes we find, at this day, that the Siberians and Northern Americans reside under ground; having their filthy habitafions entirely closed during the winter-months. In warmer regions, the Americans build wigwams of stakes and leaves, and turf, in the shape of a soldier's tent.

In Africa, the materials of the kraals or houses are the same as the wigwams; but the shape is circular, with a hole at the top to let out the smoke; and, in order to keep out beasts of prey,

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the entrance is so low, that the inhabitants crawl in and out.

100. A number of these subterranean habitations in one place; or a collection of wigwams or kraals, forms a Siberian, American, or Afri > can tribe. In many islands of the South Seas, the natives, when first discovered, had learnt to elevate the roofs on poles, and to fill in the sides of their houses with boughs or rushes, mud or sods.

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Ob-The cottages of many of the poor, are still built In this manner in England; and few need travel a mile from their own residence to see the original style of architecture.

101. Those nations which first raised the roofs "of their houses on poles, were discoverers in this art. Those which first used stone, however rude, and mud or clay to fill up the interstices between the stones, and cement them together, made considerable improvements.

After the discovery of iron and metals, when the axe, the hammer, the saw, and the plane, became the tools of builders, it may be supposed, that houses would soon be raised to two stories, and increased in size and convenience, mant

102. To make artificial and equally-shaped stones, by burning clay into bricks, was a further invention of great importance; becmise, it afforded for building an universal material, as durable as stone, without the expense of earriage, and often with less labour than 'was required to dig and fashion the stone.

The best London bricks are made of clay,

and, and ashes; and are nine inches long, four and a half broad, and two inches and a half thick.

s-Hence, in laying bricks, two in breadth, with the interstices for mortar, are equal to one in length, and she requisite crosses and ties may then be made without nequalities in the wall,

79b1031: The first cement for walls, was either Thuid or clay; but, in due time, experiment led to the preference of a mixture of lime, sand, and water; to which, for plastering, the hair of oxen is now added. Trees presented the next building material, for beams, and boards in floors.

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Obs.-Lime is a stone deprived of its carbonic acid or fixed air by fire: by mixing it with sand or ashes, containing fixed air, you restore the lime to stone again in a short time. Hence the composition of mortar,

With bricks and mortar, therefore, well laid by a bricklayer; with wood well put together with nails, by a carpenter; the dwellings of the whole civilized world are now made.

Obs.-Cast-iron for many purposes, to which timber was usually applied, bas lately been used to great advantage.

9104. Simple as is the contrivance of chimnies to carry off smoke, they are yet a recent invention; and, in building, were unknown till within the last five hundred years; down to that period, the smoke escaped through a hole in the roof of the house.

A middle contrivance, between a hole in the Foof, and a close fire-place, was the open chimney against the wall; which we yet see in many old farm-houses; and the family sit under the hole that carries off the smoke.

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