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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
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.
H. But we have none of those in England, I suppose. 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
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 N. 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.
1. How many metals are now known? 2. Tell me the number and names of the malleable metals.
3. Who will sum up to me the character of a metal as given in the lesson ?
4. What is mineralogy and metallurgy? 5. Why are gold and silver called perfect metals?
Evenings at Home.
6. How far may the gold of a guinea be drawn on a wire?
7. Where is gold most plentifully found?
10. How heavy is it?
VII.-MIGRATION OF THE COD-FISH AND THE HERRING.
THE next kind of fishes that migrate for the purpose of spawning, which I shall notice, is one, which though it falls far behind the sturgeons in size, exceeds them infinitely in numbers and dispersion, and in the vast supply of food with which it furnishes the human race; it will readily be seen that I am speaking of the Cod-fish. This valuable animal belongs to the class of fishes with a bony skeleton, and the tribe of Jugulars, (Lat. jugulum, the collar bone,) or those whose ventral (Lat. venter, the belly,) fins are nearer the mouth than the pectoral, (Lat. pectus, the breast). It frequents shallows and sandbanks, between the fortieth and sixtieth degrees of North Latitude, both in the Atlantic and Pacific Oceans, where it is taken in infinite numbers, The fishery for it employs both European and American seamen and vessels in abundance. The most celebrated is that on the great bank of Newfoundland, where thousands of men are employed in catching, salting, and barreling these fish, and whence they are dispersed principally into the Catholic countries, where they form a considerable portion of the food of the people, especially during Lent and other fasts.
The cod-fish makes for the coast at spawning time, going northward, this takes place towards the end of winter or the beginning of spring. Leeuwenhoek1 counted more than nine millions of eggs in a cod-fish of the middle size; allowing for a large consumption by other fishes which devour them, still enough are left, that when hatched produce a superabundant supply. They are deposited in the inequalities of the bottom amongst the stones.
The herring, to which I now allude, belongs to the tribe called abdominal fishes, or those whose ventral fins are behind the pectoral, and may be said to inhabit the arctic seas of Europe, Asia, and America, from whence they annually migrate, at different times, in search of food and to deposit their
1 Leeuwenhoek, a celebrated Dutch natural philosopher, born at Delft in Holland, 1632, died 1723. He devoted all his attention to microscopic researches.
spawn. Their shoals consist of millions of myriads, and are many leagues in width, many fathoms in thickness, and so dense that the fishes touch each other; they are preceded, at the interval of some days, by insulated males. The largest and strongest are said to lead the shoals, which seem to move in a certain order, and to divide into bands as they proceed, visiting the shores of various islands and countries, and enriching their inhabitants. Their presence and progress are usually indicated by various sea-birds, sharks, and other enemies. One of the cartilaginous fishes, the sea-ape, is said to accompany them constantly, and is thence called the king of the herrings. They throw off also a kind of oily or slimy substance, which extends over their columns, and is easily seen in calm weather. This substance in gloomy still nights, exhibits a phosphoric light, as if a cloth, a little luminous, was spread over the sea.
Some conjecture may be formed of the infinite numbers of these invaluable fishes that are taken by European nations from what Lacepede1 relates-that in Norway twenty millions have been taken at a single fishing, that there are few years that they do not capture four hundred millions, and that at Gottenburgh and its vicinity seven hundred millions are annually taken; "but what are these millions," he remarks, "to the incredible numbers that go to the share of the English, Dutch, and other European nations?"
Migrations of these fishes are stated to take place at three different times. The first when the ice begins to melt, which continues to the end of June; then succeeds that of the summer, followed by the autumnal one, which lasts till the middle of September. They seek places for spawning, where stones and marine plants abound, against which they rub themselves alternately on each side, all the while moving their fins with great rapidity. According to Lacepede, William Deukelzoon, a fisherman of Biervliet, in Dutch Flanders, was the first person who salted herrings, this was before the end of the fourteenth century; others attribute this invention to William Benckels or Benkelings of Bierulin. To show his sense of the importance of this invention the Emperor Charles V.2 is stated to have visited his tomb, and
1 Lacepede, a French philosopher, born 1756, died 1825.
2 Charles V. Emperor of Germany, King of Spain and of the two Sicilies, born 1500, died 1588.