9. The Romans began to gild the interior of their houses immediately after the destruction of Carthage. The wainscots of the Capitol were first ornamented in this manner; and afterwards it became fashionable to gild the walls and ceilings of private dwellings, as well as articles of furniture. 10. _Gold wire._--The ductility of gold is more conspicuous in wire than in leaves. The wire thus denominated, is in reality silver wire covered with gold. It is formed by covering a silver rod with thick leaves of gold, and then drawing it successively through conical holes of different sizes, made in plates of steel. The wire may be reduced, in this manner, to a degree of extreme fineness, the gold being drawn out with the silver, and constituting for it a perfect coating. 11. Wire thus formed is often used in the manufacture of _gold thread_. Before it is applied in this way, it is flattened between rollers of polished steel, and then wound on yellow silk by machinery. The coating of gold on the silver wire employed in this way, does not exceed the millionth part of an inch in thickness. THE JEWELLER. 1. The jeweller makes rings, lockets, bracelets, brooches, ear-rings, necklaces, watch-chains, and trinkets of like nature. The materials of the best quality of these ornaments are gold, pearls, and precious stones, although those of an inferior kind are often used. 2. There are several stones to which is applied the epithet _precious_, of which the following are the principal: the diamond, the ruby, the sapphire, the topaz, the chrysolite, the beryl, the emerald, the hyacinth, the amethyst, the garnet, the tourmalin, and the opal. To these may be added rock crystal, the fine flints of pebbles, the cat's-eye, the oculis mundi or hydrophanes, the chalcedony, the moon-stone, the onyx, the carnelian, the sardonyx, agates, and the Labrador-stone. These stones, together with different kinds of pearl, are also called gems or jewels. 3. The precious stones are valuable, as articles of merchandise, in proportion to their scarcity, weight, transparency, lustre, and hardness. In most of these particulars, the diamond is superior to any other; but those of the same size are not always of equal value, for all are not of the same color or brilliancy. The very best are said to be _diamonds of the first water_. The diamond was called adamant by the ancients, although this term was not confined exclusively to this stone. 4. The weight and consequent value of the most precious stones are estimated in _carats_, one of which is equal to four grains troy weight, and the value of each carat is increased in proportion to the size of the stone. In England, the cost of a cut diamond of the first water is thus estimated: 1 carat is = _l._8 2 do. is 2 × 2 × 8 = 32 3 do. is 3 × 3 × 8 = 72 4 do. is 4 × 4 × 8 = 128