« НазадПродовжити »
amethyst was by the ancients worn as a charm. They imagined that if they wore a piece of it, they could drink as much wine as they chose without becoming intoxicated.
Chalcedony, which is generally of a cream-colour, is another variety of quartz. When it is of a red or yellowish colour, it is called carnelian. In all its different forms, chalcedony is a general favourite.
The seal engraver regards it with particular fondness, as it engraves well, and imparts much credit to his work. The whole quartz family, indeed, are very much prized. There are few individuals, of any standing, who do not possess one or other of them, either in the form of a seal, or ring, or at the end of the key of the watch-guard, on all of winich are generally displayed the devices of the engraver. Jasper and agate claim relationship to quartz. The prettiest of the whole class, however, is the opal, a gem highly valued, and deservedly so. Who has not examined the changing colours in a cat's eye, as she lies basking in the sun ? An opal is similar, and on account of this quality it commands a high price. The last of the family is the well-known flint, of proverbial hardness, so extensively used in the manufacture of crystal and glass.
Felspar is naturally of a white colour. In this state it is used by the dentist in making artificial teeth. Its occasional redness is due to the presence of oxide of iron, or common rust. Felspar, when decomposed, is of great service to the potter, being no less than the famous kaolin, or porcelain clay. It is largely found in China and Japan, where it has been employed for ages in the manufacture of utensils for the table, known as "china.” In Devonshire and Cornwall there are also large quantities, and it has been turned to so good account by English enterprise, that our home-made china now rivals that of the Orientals. For this excellence, thanks are due to the famous Wedgwood, and the artist Flaxman. The magnificent blue stone called lapis-lazuli is a variety of felspar. From it are formed some of the finest ornaments, and when ground, it is the valuable ultramarine of the painter, once worth its weight in gold. It is found in China, Siberia, Thibet, and other parts of Asia. Ultramarine can now be formed artificially, which renders it less expensive than when made from lapislazuli.
Mica, the next mineral, is scaly, lustrous, and smooth. It splits into thin plates, which being semi-transparent are, when thin enough, used for glass in Russia. Mica is of service to the surgeon in the dissecting-rcom. It is found in large quantities in Siberia.
In connection with granite, we must not omit to mention serpentine, as it is often found side by side with it. It is of a reddish green appearance, spotted like the skin of certain serpents : hence its name. Steatite, or soapstone, from the soapy feeling it imparts to the touch, belongs to the serpentine family. This is the stone of which is formed the famous meerschaum of the smoker.
Many other minerals could be mentioned, but enough has been said to show how much information even a bit of granite may lead to, and the numerous and important family of minerals of which it is the progenitor.
EXERCISE.-26. COMPOSITION. 1. Describe the uses of the science of mineralogy, and show how it differs from metallurgy.
2. Name the component parts of a piece of granite.
5. Make a list of the various minerals named in this lesson, placing opposite each a brief description of its use.
PART II. A PIECE OF COAL. in-struc-tion [L. in, together ; struo, to build, or fill up), teaching, information, conveying knowledge. il-lus-tra-tion [L. illustro, to light up, from in, into; lux, light], explanation, the act of rendering clear, a picture or diagram. The best of all instruction begins with illustration. We have just seen how much can be done by this method ; let us choose another stone and see how far it will lead us. Here is a piece of coal. It has been jocularly called the black diamond. Common as it is, it is of the same composition as the prince of all gems, the white diamond. This stone has been highly prized for ages, because it refracts
light most powerfully, and is unequalled for its dazzling appearance in the sun's rays or even in artificial light. Great. numbers are found at the foot of the Neilla Mulla Hills, near the banks of the Krisna and Penar rivers, about 100 miles from Golconda, in India. The diamond is also found in Brazil, and in the rivers flowing from the Ural mountains. So valuable is it that one carat of four grains costs no less than twenty shillings, and not unfrequently more. As it increases in size and purity of colour-or water, as the dealers call it-the price increases enormously. A diamond of five carats is worth at least £200. The magnificent Koh-i-noor, or mountain of light, the largest diamond in the world, is valued at an enormous sum. It would have been worth much more, had not unskilful cutting shorn it of its first dimensions.
The small diamonds are used by the glacier for cutting glass ; and the seal-engraver puts them into a strong iron mortar, pounds them to dust, and places the fine particles on his tools, for the purpose of increasing their cutting power.
The shales in the coal introduce us to alumina, the baso of the important alum used in dyeing. The beautiful blue sapphire found in India and Germany belongs to this family.
From a variety of coal, known as parrot coal, we obtain our gas and the oil called paraffin. To this, also, are we indebted for the beautiful mauve and magenta colours, now so common, though but recently discovered. Very fine ornaments have been formed of parrot coal, besides lookingglass frames, pillars for work tables, and other articles.
The best variety of coal for ornamental purposes is jet. It is rather brittle, however, and for this reason a compound of gutta percha, called vulcanite, is coming into favour as a
substitute for jet in making watch-guards, bracelets, and ! other things usually made of that material.
Somewhat closely allied to the diamond and sapphire, are the ruby, of a deep red colour, like rich port wine : the topaz, of a pure, clear yellow : the emerald, of a fine green : and the pretty zircon.
Anthracite is a brownish variety of coal found in Wales and other parts of Britain, and also in the Hartz mountains
The lead, or rather so called lead, of pencils, is not lead at all, but a variety of coal mixed with iron. It is found in Bavaria, but the finest is got in Cumberland. under the names of plumbago, wad, or graphite.
In coal there is often a quantity of sulphur, which causes an offensive smell in a close room. In the form of sulphuret of iron, it may be seen upon a newly split piece of coal in pretty sparkling crystals. In this form sulphur exists in quantities too small to be of any use. In Poland, however, it is obtained in large quantities; but the principal locality for it is the island of Sicily, where it is found in an exceedingly pure state.
The limestones which lie next the coal measures introduce us to a large and important family of minerals. There is the limestone which is used for building purposes, and the fine stone called lithographic limestone, used by the lithographer. The prettiest of the family is fluor-spar, which is not unlike the amethyst in colour but very soft. It is found in Derbyshire, where there is a famous cave called the Spar Cave, in which are some beautiful specimens.
Gypsum or alabaster is another form of limestone. In company with gypsum is found rock-salt, an extensive article of consumption. A variety, called trona, is found in Barbary. A sister mineral, found in a lake in Thibet, is borax, or tinkal, which is much used in manufactures.
From magnesian limestone we have the important medicine, magnesia. Talc-spar and bitter or brown spar are crystallized forms of magnesian limestone.
With regard to spar, a sort of baryta called heavy spar is much used for the adulteration of white lead. When heated or lighted this mineral will remain luminous in the dark for some time. It is found in the island of Arran and other places.
EXERCISE.-27. PARSING, ETC. 1. What do the following adjectives in the first paragraph qualify :best, much, common, famous, some, valuable, less, more, least
2. Parse (with reasons) the following sentences :- It has been jocularly called the black diamond. One of five carats is worth at least £200, 3. Give examples from the lesson of adverbs modifying adjectives and 4. How many simple sentences are there in the lesson ? 6. What are the conjunctions in the last twenty-four lines ?
ALEXANDER POPE. sub-li-mer [L. sublimis, higb], loftier, more clevated. syl-van [L, silva, a wood), rustic, woodland. frauds (L. fraus, deceit], impostures, tricks. pas-ture [L. pasco, to feed], herbage for cattle.
YE nymphs of Solyma, (1) begin the song :
* ALEXANDER POPE was born in London, May 21, 1688, and died at his villa on the banks of the Thames, near Twickenham, May 30, 1744. His“ Essay on Criticism” is one of the finest poems in the English language, but his genius appears to the greatest advantage in a poem called the “Rape of the Lock," and the force of his satire in the Dunciad.” His translations of Homer's “Iliad” and “ Odyssey" still maintain their popularity. It has been said that he was undoubtedly more the poet of artificial life and manners than the poet of nature. lIe was a nice observer and an accurate describer of the phenomena of the mind, and of the varying shades and gradations of vice and virtue, wisdom and folly.
(1) Jerusalem, the Holy City, the centre and seat of the Jewish religion. (2) Pindus, a range of mountains in Northern Greece, separating Thessaly and Epirus. (3) The nine Muses, so called from Boeotia or Aonia, in which was Helicon, a mountain which was supposed to be their seat. (6) See Isaiah, ch. vi. 6.