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G. A stone !—Yes I could not mistake a piece of lead or iron for a stone.
T. How would you distinguish it?
But glass and crystal are very bright, too.
H. But one may see through glass, and not through a piece of metal.
T. Right. Metals are brilliant, but opaque, or nor transparent. The thinnest plate of metal that can be made, will keep out the light as effectually as a stone wall.
Ĝ. Metals are very heavy, too.
T. In general they are ; but there are some metals which are lighter than water; these light metals, however, are difficult to be procured, and are more curious than useful. Well, what else ?
G. Why, they will bear beating with a hammer, which a stone would not, without flying in pieces.
T. Yes; that property of extending or spreading under the hammer is called malleability ; and another, like it, is that of bearing to be drawn out into a wire, which is called ductility. Metals have both these, and much of their use depends upon them.
G. Metals will melt, too.
T. Yes; all métals will melt, though some require greater heat than others. The property of melting is called fusibility. Do you know anything more about them?
G. No; except that they come out of the ground, I believe.
T. That is properly added, for it is the circumstance which makes them rank among minerals. To sum up their character, then, a metal is a brilliant, opaque, heavy, malleable, ductile, and fusible mineral,
G. I think I can hardly remember all that.
T. The names may slip your memory, but you cannot see metals at all used without being sensible of the things.
G. But what are ores? I remember seeing a heap of iron ore which men were breaking with hammers, and it looked only like stones.
T. The ore of a metal is the state in which it is generally met with in the earth, when it is so mixed and combined
with stony and other matters, as not to show its proper qualities as a metal.
H. How do people know it then?
T. By experience. It was probably accident that in the early ages discovered that certain minerals by the force of fire might be made to yield a metal. The experiment was repeated on other minerals ; so that in length of time all the different metals were found out, and all the different forms in which they lie concealed in the ground. The knowledge of this is called Mineralogy, and a very important science it is.
G. Yes, I suppose so; for metals are very valuable things Our next neighbour, Mr. Sterling, I have heard, gets a grea deal of money every year from his mines in Wales.
T. He does. The mineral riches of some countries are much superior to that of their products above ground, and the revenues of many kings are in great part derived from their mines.
H. I suppose they must be gold and silver mines.
T. Those, to be sure, are the most valuable, if the metals are found in tolerable abundance. But do you know why they are so ?
H. Because money is made of gold and silver.
T. That is a principal reason, no doubt. But these metals have intrinsic properties that make them highly valuable, else probably they would not have been chosen in so many countries to make money of. In the first place, gold and silver are both perfect metals, which are indestructible in the fire. Other metals, if kept a considerable time in the fire, change by degrees into a powdery or scaly matter, called a calx, or oxide. You have melted lead I dare say.
G. Yes, often.
T. Have you not, then, perceived å drossy film collect upon its surface after it had been kept melted a while.
T. That is an oxide; and in time the whole lead would change to such a substance. You may see, too, when you have heated the poker red-hot, some scales separate from it, which are brittle and drossy.
1 Mineralogy, that branch of natural history which makes us acquainted with the relations and properties of minerals. Metalurgy, is the art of separating metals from their ores, comprising the processes of assaying, refining, and smelting.
H. Yes—the kitchen poker is almost burnt away by being put into the fire.
T. Well, most metals undergo these changes, except gold and silver ; but these, if kept ever so long in the hottest fire, sustain no loss or change. They are therefore called perfect metals. Gold has several other remarkable properties. It is a very heavy metal.
H. What, is it heavier than lead ?
T. Yes—above half as heavy again. It is between nineteen and twenty times heavier than an equal bulk of water. Gold, too, is the most ductile of all metals. You have seen leaf-gold?
G. Yes; I bought a book of it once.
T. Leaf-gold is made by beating a plate of gold placed between pieces of skin, with heavy hammers, till it is spread out to the utmost degree of thinness. And so great is its capacity for being extended, that a single grain of the metal, which would be scarce bigger than a large pin's head, is beat out to a surface of fifty square inches.
G. That is wonderful indeed! but I know leaf-gold must be very thin, for it will almost float upon the air.
T. By drawing gold out on a wire, it may be still farther extended.
H. Prodigious! What a vast way a guinea might be drawn out, then!
T. Yes; the gold of a guinea, may thus be made to reach above nine miles and a half. This property in gold of being capable of extension to so extraordinary a degree, is owing to its great tenacity or cohesion of particles, which is such, that you can scarcely break a piece of gold-wire by twisting it; and a wire of gold will sustain a greater weight than one of any other metal, equally thick.
H. Then it would make very good wire for hanging bells.
T. It would ; but such bell-hanging would come rather too dear. Another valuable quality of gold is its fine colour. It will keep its colour fresh for a great many years in a pure and clear air.
H, I remember the vane of the church steeple was new gilt two years ago, and it looks as well as at first.
T. This property of not rusting would render gold very useful for a variety of purposes, if it were more common.
G. But is not gold soft? I have seen pieces of gold bent double.
T. Yes; it is next in softness to lead, and therefore when it is made into coin, or used for any common purposes, it is mixed with a small proportion of some other metal, in order to harden it. This compound metal is called an alloy. Our gold coin has one-twelfth part of alloy, which is a mixture of silver and copper:
G. How beautiful new gold coin is !
T. Yes—scarce any metal takes a stamp or impression better; and it is capable of a very fine polish.
G. What countries yield the most gold?
T. South America, the East Indies, and the coast of Africa. Europe affords but little ; yet a moderate quantity is got every year from Hungary. Great quantities are now obtained in California in America, and more especially in Australia.
H. But what a fine thing it would be to find a gold mine on one's estate !
T. Perhaps not so fine as you imagine, for many a one does not pay the cost of working. A coal pit would probably be a better thing.
G. For my part, I will be content with a silver mine.
T. We have no silver mines properly so called, but silver is procured in some of our lead mines. There are, however, pretty rich silver mines in various parts of Europe ; but the richest of all are in Peru, in South America.
G. Are not the famous mines of Potosi there? T. They are. Shall I now tell you some of the properties of silver ?
G. Yes; if you please.
T. It is one of the perfect metals. It is also as little liable to rust as gold, though indeed it readily gets tarnished.
G. Bright silver, I think, is almost as beautiful as gold.
T. It is the most beautiful of the white metals, and is capable of a very fine polish; and this, together with its rarity, makes it used for a great variety of ornamental purposes. Then it is nearly as ductile and malleable as gold.
G. Does silver melt easily ?
T. Silver and gold both melt more difficultly than lead; not till they are above a common red-heat. As to the weight of silver, it is nearly one-half less than that of gold, being only eleven times the weight of water.
H. Is quicksilver a kind of silver ?
T. It takes its name from silver, being very like it in colour ; but in reality it is a very different thing, and one of the most singular of the metal kind.
G. It is not malleable, I am sure.
T. Not when it is quick or fluid, as it always is in our climate. But a very great degree of cold makes it solid, and then it is malleable, like other metals.
G. What a weight quicksilver is ! I remember taking up a bottle full of it, and I had like to have dropt it again, it was so much heavier than I expected.
T. Yes, it is one of the heaviest of the metals—about fifteen times heavier than water.
H. Is mercury of much use.
T. Yes—for a variety of purposes in the arts, which I cannot now very well explain to you. But you will perhaps be surprised to hear that one of the finest red paints is made from quicksilver.
G. A red paint !—which is that ?
T. Vermilion or cinnabar, which is a particular combination of sulphur with quicksilver.
H. Is quicksilver found in this country?
T. No. The greatest quantity comes from Spain, Istria, (a peninsula in Ñ. of Adriatic Sea,) and South America. It is a considerable object of commerce, and bears a high value, though much inferior to silver. Well—so much for metals at present.
We will talk of the rest on some future opportunity
Evenings at Home. 1. How many metals are now known ? 6. How far may the gold of a guinea be 2. Tell me the number and names of drawn on a wire ?
7. Where is gold most plentifully found? 3. Who will sum up to me the character of a metal as given in the lesson ?
9. What is the other name for quick4. What is mineralogy and metallurgy? silver ? 5. Why are gold and silver called per. 10. How heavy is it?
the malleable metals,
8. Where are silver mines found?
11. Where is it found?
VII.-MIGRATION OF THE COD-FISH AND THE HERRING.
.......annus. De-pos’it, V........ poněre.
Dense, adj........ ... densus.