81. Some modern chemists consider the whole earth as metallic; and all the different earths to be nothing more than various oxides, or rusts of metals, produced by the continued action of the air and water on them; and capable, by suitable means, of being re-converted into metals!

82. Platina is the heaviest of all metals, being 23 times heavier than water; but it is a modern discovery. The colour is light grey, and it cannot be melted in ordinary fires.

83. Gold is 19 times heavier than water; and the most brilliant of all the metals. It is so malleable, that an ounce of it will gild a silver wire, 1300 miles in length; and it may be beaten into leaves; 300,000 of which are only the thickness of an inch.

84. Silver is 11 times heavier than water; and next to gold in beauty; such is its ductility, that may be drawn out in wire finer than a hair.

it

85. Mercury, or Quicksilver, is 14 times heavier than water; and is remarkable for being liquid like water; and for not becoming solid, except in cold greater than that which renders water solid.

86. Copper is 9 times heavier than water; and is found in great abundance in the mines in Sweden. It unites well with other metals; and forms a variety of useful compounds.

87. Iron is 8 times heavier than water; and is the most useful; and the most abundant, of all the metals. It mixes with the animal, vegetable, and mineral kingdoms. It is melted with more difficulty than gold, silver, or copper; and it use». fully strikes fire with flint.

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

88. Tin is a metal, 7 times heavier than water. It is very maileable; 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.

90. Nickel is 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 colour, and used in various compounds.

92. The other metallic substances are Antimony, Bismuth, Cobalt, Arsenic, Manganese, Palladium, Rhodium, Potassum, &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 a compound of zinc and copper. Bell-metal is brass with a little silver. Pewter is a mixture of tin, lead, and brass. Bronze is a mixture of copper and tin.

94. Coals are minerals dug out of the ground in immense mines; and they are the best fuel yet discovered by man. The British islands are celebrated for their coal mines; many countries being obliged to depend on wood: which is often scarce and dear.

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.

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.

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 his convenience.

Obs. Hence, the origin of money; and as it was found inconvenient to weigh metal in every transaction, (as Abraham did when he bought the burying-place of Saral;) stamps were put on pieces of metal, to indicate that they might be safely received for a settled weight or value. Hence, there are pieces of stamped gold of known value; as guineas, half guineas, eagles, half eagles, &c.: pieces of stamped silver, as crowns, dollars, half dollars, &c. pieces of stamped copper; as cents and half cents;-all of universal worth.

V. Of Building.

98. Man, like other animals, would seek places in which he might shelter himself, from the inclemency of the weather. Beasts of prey retire to thickets and caves; beavers build mud houses; and rabits 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 the savage tribes in Siberia and the most northern parts of America, their habitations are constructed in the rudest manner, principally with earth intermixed with leaves, twigs, and the stems of weeds, &c. and the bottoms of their huts are frequently partly under the ground or the snow, and are thus more effectually clothed during the long continuance of their winter season. In warmer regions, the American Indians build wigwams of stakes, leaves, turf, and straw, in the shape of a soldier's tent.

In Africa, the materials of the kraals are the same as the wigwams; but the shape is circular, with a hole at the top to let out the smoke; and the entrance is so low, in order to keep out beasts of prey, that the inhabitants crawl in and out.

100. A number of these habitations in one place; or a collection of wigwams or kraals, forms a Siberian, American, or African 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.

Obs.-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 insterstices 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, bouses would soon be raised to two stories, and increased in size and convenience.

102. Burning clay into bricks, was a further invention of great importance; because, it afforded a universal material for building, as durable as stone, without carriage, and often with less labour than was required to dig and fashion the

stone.

The best bricks are made of clay, and are nine inches long, four and a half broad, and two inches and a half thick.

Obs. Hence, in laying bricks two in breadth, with the interstices for mortar, are equal to one in length, and the requisite crosses and ties may then be made without inequalities in the wall.

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