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on bonus coproperty to always pointing ro the nne ch.
possesses the singular ard" js as vre' of irou.
Red and yellow ochres are impure oxides of iron : generally where redness is fuaod in the svil, te presence of iron may be suspected.
88. Tin is an English or. Cornish metal, ģ 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 pur
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 colour, and used in various compounds.
digishy joita 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 metals.
93. Iron is formed into steel, by being heated with charcoal. 1 Brass is composed of zinc and copper. Bell-metal is a mixture of tin and corper. Pewter is a mixture of tip 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 tisli islands are celebrated for their coul-mines; many countries being obliged to depend on wood, which is often source and dear. Obx, ou
... Ooals' are, to all probability, the remains of wubmerged forests, brought to their prevent state by soine unknown process of subterraneitti chemistry.
96. 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 tobacco. pipe, 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 oun 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 irou, for a mediumn of value: so, ilmt, it one man, bad too much corn and wanted wine, he was not obliged to give corn for the wine, but le miglit sell his corn for so much metal, ami buy the wine with the melal, at his contenience.
Qbolçoçe, the origin of nowey, and as it was found fuconvenient to weigli metal in every transaction, (as Abraham did whru he buoght the nurying-place in Barab.) sampe won put on pieces of metal, a kings'
heads, to indicnte that they might be safely neceived for a seuiled weight or value. Hence, in Englund, we love, or bad, pieces of stamped gold of known value : as guia Nens, hai gaineas, sovereigns, balfsovereigns, &c,: pieces of stamped silver, as crowns, shillings, &r í und pieces of stamped coppers as pennies and half-pennies manill universal worth. But of late a cars, a pernicious altempt has been made, to pass slumped paper for money i ariginally, mere promises to find money, but lutterly, as modry itself! Ciold coin in particular hins, consequently, Hlmont disappeared, and become very dear i relation to the paper-money.
NB, From 70 10 $1 was, gambered 92 to 97 in the former edition,
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 rabbits nake burrows under ground. Man, in liis inost savage state, imitates their practices; and then improves ou them, by the aid of his reason.
99. Among savage tribos we find, at this day, that the Siberians and Northern Americans reside ander ground; having their filthy habitations 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 naterials of the kraals or honses are the same as the wigwauns; but the shape is circular, with a hole at the top to let out the stroke: and, in order to keep out boasts of prey,
the entrance to low, that the inhabitants crawl in and out,
100, A number of these subterranean habitations in one place; or a collection of wigwams ox kualm, fontos a Siberian, American, al ANTA oan tribe. In many inlands of the South Sear, the natives, when first discovered, had learnt to elevate the foot on polen, and to fill in the wides of their houses with boughs or rushes, mud or sods.
Oh..---The entinges of many of the poor, are siin hulle in this manner in ingland and few need travel a mile from their own residence to see the original lyle of 4f chitecture,
101. Thune nations which first raised the roof of their houses on poles, were discoverers in this art. Those whicle rat used stone, however rude, and mud or clay to fill up the interntioca bietween the stones, and cement them together, made considerable improvements,
After the discovery of iron and metals, wbea 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 eonvenieniee, niin
102, "To make artificial and equally shaped stones, by burning clay into bricks, was a turther invention of great importance : because, It afforded for building an inivernal material, us durable as stone, without the expense of car riage, and otten' with less labour than 'was re. quired to dig and tushion the stone.
The best London bricks are made of clay.
tanil, and ashes, and are nine inches long, four and a half broad, and two inches and a half thick. 1
"Ils. Hence, in laying bricks, two in breadth, with the interstices for mortar, are equal to une in length, and the reqaisite crosses and ties may then be made without Cinegualities in the wall,
» 203. The first cement for walls, was either Thud 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. Frees presented the next building material, for beams, and boards in floors.
05s.-Lime is a stone deprived of its carbonic acid or hxed 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 ad. vaqtage. - 104. 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 soof, 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.