Зображення сторінки
[graphic][merged small]

METALS. el-e-ments [L. elementa, first principles), simple substances, the constituent principles of anything. au-ri-fe-rous (L. aurum, gold; fero, to bear], gold producing. pho-to-gra-pher (Gh. phos, light; grapho, to write or draw], one who produces pictures by the agency of light. Of upwards of sixty elements, or simple bodies, to which the chemist has reduced all material things, more than twothirds are metals, the principal of which are platinum, gold, silver, mercury, copper, lead, tin, and iron.

Platinum is a very valuable metal, being nearly, if not quite, as dear as gold. It is of a soft, grey colour, and possesses the remarkable property of resisting the action of acids. If sulphuric acid, or oil of vitriol, were placed in an iron spoon, the acid would act upon it at once, and in a few days render it useless. But if the same acid were placed in a platinum cup, it might stand for years without the cup being affected by it. On this account the stills used in the manufacture of sulphuric acid are made of platinum, and they sometimes cost above two thousand pounds. The strongest fire also does not affect it. It remains unharmed in a fire that would melt iron as easily as the parlour fire would melt

lead ; it is therefore much used for crucibles and other vessels exposed to intense heat. Platinum is found in South America, and in some parts of the Ural Mountains. The Russians coin it into money, and find it no easy matter to do so. Platinum is valuable to the optician and the watchmaker, as well as to the chemist.

Gold is the most precious of metals. It has been known to man for ages, and has always been keenly sought after. As it is the most beautiful, as well as the most precious of metals, it is used for many purposes, for coins, plate, jewellery, gilding picture frames and lace for uniforms, and an almost endless variety of ornamental work. The ancients, who were well aware of its manifold advantages, called it the king of metals. Gold is found in many parts of the world. The fields last discovered are in British Columbia, California, Australia, and New Zealand. During the last twenty years numbers of persons have flocked to these places in search of it; and thus the desire to obtain it has caused these far off lands to be colonised by the energetic and ambitious of the inhabitants of the over-peopled countries of the old world. India, Siberia, Western Africa, Brazil, and Peru also produce it; indeed, these were almost our only sources of supply before the new fields were discovered. Gold is found in various conditions, but in the largest quantities in the sands of certain rocks, termed auriferous or gold-bearing rocks, which are composed mainly of quartz. The quartz in which it is found is crushed in mills made for the purpose, the gold-dust being afterwards separated by washing. This metal is so extremely ductile, that a single grain can be drawn into a wire five hundred feet long. Its malleability is equally wonderful, sheets being made of it nearly a thousand times thinner than paper. This property causes it to be largely used for covering the surface of various articles, by a process called gilding, the most familiar example of which is the gilt edging upon the leaves of our Bibles and other books, and the bright lettering and designs upon the covers. By the process of electrotyping, goods made of an inferior metal can be covered by it, a very little gold sufficing to give them a really golden appearance. On account of its softness gold requires to be

mixed with silver or copper, for general use. Our gold coin consists of twenty-two parts of gold and two of mixture, or alloy. This is called twenty-two carat gold. Wedding rings are made of at least eighteen parts gold and six alloy, or eighteen carat gold. Watch-guards, chains, earrings, brooches, finger rings, and other articles, are of fourteen to sixteen carat gold.

Silver ranks next to gold in beauty and value. Few things are more pleasing in a house than a silver tea-service of chaste design, if carefully kept. The magnificent displays of the silversmith of articles in this metal, from the little thimble to the finest works of art, are familiar to all. Silver is found in Saxony, America, and other places, and to a small extent in this country, along with an ore of lead called galena. The silver mines of Mexico and Peru have been famous for centuries.

Our silver coin is always alloyed with copper, to impart hardness to it. When nitric acid is poured upon it, nitrate of silver is formed, known in trade as lunar caustic, and to boys as an excellent thing for taking warts off the hands. The compounds of silver are most useful to the photographer,

Mercury, which is a fluid metal at ordinary temperatures, is as white and pretty as silver. It may be seen in our barometers. Combined with sulphur it forms cinnabar, in which state it is largely found in California. Mercury is also obtained at Almeida, in Spain, and in different parts of Austria. Its compounds are largely used in medicine and the arts. Vermilion, a well-known pigment, is one. Mercury in combination with tin forms the substance which is spread over the backs of looking-glasses to impart to them their reflective power,

Copper, with its reddish colour, is well known. It is used for coins, kettles, saucepans, and various other culinary



utensils. The distiller finds it the best material of which to construct his stills. Shipbuilders sheathe ships in it, and in all the arts and sciences it is used more or less. It is highly malleable, flexible, and ductile. It can be easily melted, and, at the same time, is the most sonorous of all metals. The compounds of copper are numerous and inportant. Combined with zinc, in one proportion, it forms brass; and in another the bronze, so useful for statues, and formerly so largely employed by the ancients. With a little tin it makes gun-metal, with more it forms bellmetal. With nickel and zinc it becomes the well-know? German silver. Copper is found in Britain and many other places.

The qualities of lead are well-known. It is used for covering houses, making pipes and tanks, lining cisterns, and many other purposes. It forms the deadly bullet, lately rendered more destructive than ever by the invention of the rifled gun. The most useful purpose to which it is applied, is the manufacture of type for printing; and for this purpose it is alloyed with antimony. In such a capacity this dull, heavy metal performs no unimportant part in furthering human progress and happiness; there being no power mightier than the press, unless it be its master, the pen, which Lord Lytton truly says “is mightier than the sword.”.

Tin is largely employed in covering sheet iron, thus forming the tin-plate of the whitesmith, or tinsmith. Tin is found in Cornwall, where it has been worked for ages. The Phænicians are said to have visited our shores to purchase it. From the tin mines of Cornwall the Prince of Wales, as Duke of Cornwall, derives a considerable income. No fewer than five thousand tons of the ore are ann

nnually raised to the surface; and to accomplish this some of the largest engines in the world are employed.

Iron is the most useful, and in this sense, the most valuable and important of metals. In a civilized country few things can be done without it, and by men in a state of barbarism it is employed, though in a smaller degree. Iron furnishes us with mighty ships, the flying locomotive, the rails of the iron way, and a thousand other objects of utility, down to the smallest nail. In the form of steel, it


supplies us with the sword, bayonet, and cutlery of all kinds, from the razor to the needle. The Creator has bountifully made this useful article one of the most abundant materials in nature. It may be said to pervade everything; it is found in the bands of the coal measures, and most mineral and vegetable substances, while it also forms an important constituent of the blood of both animals and man.

A very remarkable variety of iron is the loadstone, which imparts that property to the needle of the compass by which the sailor finds his way across the trackless ocean, and the miner traces his course for miles many fathoms beneath the surface of the earth. The prettiest kind of iron ore is the red oxide, which crystallizes into a very fine form called specular iron. Some fine speciinens of this ore are obtained from the island of Elba, to which Napoleon was banished. The blood-red ore is called hæmatite. A small quantity put into the smelting furnace together with the other ores, such as black band or clay band, is said to cause the metal to run better in the making of pig-iron.

Some fine iron is found in America, Norway, and numerous other places. Britain yields about four millions of tons every year. Gratefully may we thank our heavenly Father for having bestowed upon us so much of this valuable treasure, and for giving us the skill and enterprise to turn it to so good an account.

Of the other metals the most used are antimony, which in addition to the purpose mentioned above is largely employed in medicine, especially for emetics. Aluminum, a light coloured metal, is manufactured into ornaments for the person. It is only of late that it has been obtained in sufficient quantity to turn it to account. Arsenic, in its compounds, is a virulent poison. Cobalt gives us our secret inks. Manganese is useful in preparing oxygen gas. Nickel is an important element in German silver, there are mines of it at Inverary, in Argyleshire. Potassium and sodium are very light, and possess the remarkable property of taking fire when placed in water; for this reason they require to be kept in naphtha. Zinc is largely used in combination with copper. It is useful to the alater and plumber, and the electrician could not well do

0 be the

« НазадПродовжити »