Читать книгу The Story-book of Science - Fabre Jean-Henri - Страница 15

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“COPPER and tin are called metals,” continued Uncle Paul. “They are heavy, shining substances, which bear the blows of the hammer without breaking. They flatten, but do not break. There are still other substances which possess the considerable weight of copper and tin, as well as their brilliancy and resistance to blows. All these substances are called metals.”

“Then lead, which is so heavy, is a metal too?” asked Emile.

“Iron also, silver and gold?” queried his brother.

“Yes, these substances and still others are metals. All have a peculiar brilliancy called metallic luster, but the color varies. Copper is red; gold, yellow; silver, iron, lead, tin, white, with a very slightly different shade one from another.”

“The candlesticks Mother Ambroisine is drying in the sun,” said Emile, “are a magnificent yellow and so shiny they dazzle. Are they gold?”

“No, my dear child; your uncle does not possess such riches. They are brass. To vary the colors and other properties of the metals, instead of always using them separately, they often mix two or three together, or even more. They melt them together, and the whole constitutes a sort of new metal, different from those which enter into its composition. Thus, in melting together copper and a kind of white metal called zinc, the same as the garden watering-pots are made of, they obtain brass, which has not the red of copper, nor the white of zinc, but the yellow of gold. The material of the candlesticks is, then, made of copper and zinc together; in a word, it is brass, and not gold, in spite of its luster and yellow color. Gold is yellow and glitters; but all that is yellow and glitters is not gold. At the last village fair they sold magnificent rings whose brilliancy deceived you. In gold, they would have cost a fine sum. The merchant sold them for a sou. They were brass.”

“How can they tell gold from brass, since the color and luster are almost the same?” asked Jules.

“By the weight, chiefly. Gold is much heavier than brass; it is indeed the heaviest metal in frequent use. After it comes lead, then silver, copper, iron, tin, and finally zinc, the lightest of all.”

“You told us that to melt copper,” put in Emile, “they needed a fire so intense, that the heat of a red-hot stove would be nothing in comparison. All metals do not resist like that, for I remember very well in what a sorry way the first leaden soldiers you gave me came to their end. Last winter, I had lined them up on the luke-warm stove. Just when I was not watching, the troop tottered, sank down, and ran in little streams of melted lead. I had only time to save half a dozen grenadiers, and their feet were missing.”

“And when Mother Ambroisine thoughtlessly put the lamp on the stove,” added Jules, “oh! it was soon done for: a finger’s breadth of tin had disappeared.”

“Tin and lead melt very easily,” explained Uncle Paul. “The heat of our hearth is enough to make them run. Zinc also melts without much trouble; but silver, then copper, then gold, and finally iron, need fires of an intensity unknown in our houses. Iron, above all, has excessive resistance, very valuable to us.

“Shovels, tongs, grates, stoves, are iron. These various objects, always in contact with the fire, do not melt, however; do not even soften. To soften iron, so as to shape it easily on the anvil by blows from the hammer, the smith needs all the heat of his forge. In vain would he blow and put on coal; he would never succeed in melting it. Iron, however, can be melted, but you must use the most intense heat that human skill can produce.”