How widely its uses vary: To save, to ruin, to curse, to bless; Now stamped with the image of the good Queen Bess, 3. The most interesting chemical property of gold is its want of affinity for oxygen; hence gold will not rust, nor suffer corrosion by contact with any of the common acids; and when gold used for coin or for gilding tarnishes, it is because it is alloyed with copper or other metal. But, although gold is the heaviest and most dense of all substances except platinum, like ice it has been liquefied in the laboratory of the chemist, and even converted into gold steam; yet its properties as gold have never been changed by human art. 4. Notwithstanding the great value of gold, it is not so useful for many purposes as iron. Glaucus made a good bargain when he exchanged his golden armor with Diomedes for one of brass, although Homer has told us that Yet in point of lightness, and in power of resisting the weapons of the enemy, the brass armor was better than the one of gold. 5. Pure silver, like gold, is sometimes found in veins in granite and other primary rocks, where it was doubtless deposited, ages gone by, by chemical agencies. Pure silver is not acted upon by common acids; but nitric acid dissolves it, forming nitrate of silver, or lunar caustic, which has the property of turning black on exposure to solar light. This is the chief ingredient in indelible ink, and it is also used in the preparations of the photographer. 6. Silver can be drawn into a wire much finer than the human hair; and it is this wire, gilded, that is manufactured into what is called gold or silver lace. We certainly do not know of a more appropriate use to which this lace has been put than is stated in the following account of the Silver Bird's-nest; and we think no one will be apt to forget the ductile property of silver, after associating it with so beautiful an illustration. 7. 8. "A stranded soldier's epaulet The waters cast ashore, A little winged rover met, The silver bright so pleased her sight, On that lone, idle vest, She knew not why she should deny Herself a silver nest. The shining wire she peck'd and twirl'd; 9. 10. Where on a flowery twig 'twas curl'd, Her house to make, she would not take, And when the little artisan, With here and there a plume to spare Of these, inlaid with skill, she made But do you think the tender brood Were prouder when they understood Do you suppose they ever rose, Of higher powers possess'd, Because they knew they peep'd and grew Within a SILVER nest?"-H. F. GOULD. 11. And now last, though not least, we have to consider some of the properties, chemical and otherwise, of that very common metallic substance, iron. We hazard nothing in asserting that it is by far the most useful of the metals. The smelting of the ore, and the fashioning of the metal by hammer and fire, must have been understood at a very early day in the world's history; for we read in the fourth chapter of Genesis that "Tubal Cain was an instructor of every artificer in brass and iron." And truly a 'man of note," as well as a man of might," he must have been, as a modern poet has sung: 12. "Old Tubal Cain was a man of might, In the days when earth was young; By the fierce red light of his furnace bright, And he lifted high his brawny hand On the iron glowing clear, Till the sparks rushed out in scarlet showers, As he fashioned the sword and spear. And he sang, 'Hurrah for my handiwork! Hurrah for the hand that shall wield them well, 13. In combination with oxygen and sulphur, iron is so widely diffused that few minerals can be found that do not contain traces of it. Combined with oxygen, it is the coloring matter of our most beautiful marbles, as well as of clays and soils; and were it not for the wide dissemination of oxides of iron, the earthy matter of the globe would be as white as chalk. The artist derives some of his richest tints from iron. Ye rivaled the tints of the blushing dawn Till the humblest work of art has shown 14. Iron is found in the blood, where it performs important offices, conveying the oxygen of the air we breathe from the lungs to our very fingers' ends, and bearing back from the capillaries the waste carbon that requires to be thrown out of the system. It is also much used in medicine; and the tonic properties of those mineral springs called chalybeate are due to the presence of iron. I come where the suffering patient lies On his couch, all wan and weak, And the lustre returns to his sunken eyes, And the bloom to his pallid cheek. -CUTTER. 15. Iron is the only metal that combines with carbon, forming steel when the proportion of carbon is small, and black-lead or plumbago when the proportion is very large. Cast-iron contains earthy impurities and some carbon, which must be burned out to render the iron malleable. Some of the manifold uses and applications of iron or steel are enumerated in the following lines: "Iron vessels cross the ocean, Iron engines give them motion; Iron bolts, and rods, and bands; Iron cannon, iron balls; Iron axes, knives, and chains, Iron augers, saws, and planes; Iron globules in our blood, Iron particles in food; Iron lightning-rods on spires, Iron telegraphic wires; Iron hammers, nails, and screws- Iron every thing we use." LESSON XI.—ACIDS, ALKALIES, AND SALTS. 1. In common language, an acid is any sour substance, but in chemistry the term is more extended. An alkali, a term originally applied to the ashes of plants, is a substance which has a peculiar acrid taste, like potash or soda. The acids and alkalies have a remarkable affinity for each other, uniting with the greatest facility, losing thereby their distinctive qualities, and by their union forming a large class of compounds which are known in chemistry as salts. This latter T term, therefore, though in ordinary language limited to common salt, is applied in chemistry to all combinations of acids with alkalies. 2. That common article, soap, is formed by the union of an alkali with the fatty acid of some oily substance; and hence soap itself may be considered one of the chemical salts. The alkali most frequently used is the common ley of wood ashes, which is essentially the same as pearlash or potash dissolved in water. It is well known that oil and water have no disposition to unite; but the alkali has a strong affinity for both, and in uniting with them brings about a mutual combination differing from either of the ingredients. The principles displayed in this process are well illustrated in the following 3. EASY LESSON IN CHEMISTRY. "Some water and oil One day had a broil, As down in a glass they were dropping, And would not unite, But continued to fight, Without any prospect of stopping. Some pearlash o'erheard— He jumped in the midst of the clashing; And united with speed, And soap was created for washing." 4. The commonness of an article is apt to induce us to overlook its importance; a truth which is perhaps nowhere more fully exemplified than in the case before us. Liebig says, "The quantity of soap consumed by a nation would be no inaccurate measure whereby to estimate its wealth and civilization." According to Pliny, the invention of soap must be ascribed to the Gauls, by whom, he says, it was composed of tallow and ashes, and was probably at first an accidental combination. Homer had long before described the washing of the royal robes in the "limpid streams;" but we have reason to suspect, from the known absence of soap on that occasion, that the picture of their "snowy lustre" is overdrawn. They seek the cisterns where Phoacian dames POPE'S Odyssey, b. vi. LESSON XII.-THE CHEMISTRY OF A CANDLE. (Adapted from Dickens's Household Words.) THE Wilkinsons were having a small party-it consisted of themselves and Uncle Bagges-at which the younger members of the family, home for the holidays, had been just admitted after dinner. Uncle Bagges was a gentleman from whom his affectionate relatives cherished expectations of a testamentary nature. Hence the greatest attention was paid by them to the wishes of Mr. Bagges, as well as to every observation which he might be pleased to make. "Eh! what? you sir," said Mr. Bagges, facetiously addressing himself to his eldest nephew, Harry-"eh! what? I am glad to hear, sir, that you are doing well at school. Now-eh? now, are you clever enough to tell me where was Moses when he put the candle out ?" 66 "That depends, uncle," answered the young gentleman, on whether he had lighted the candle to see with at night, or by daylight to seal a letter.' "Eh? Very good, now! 'Pon my word, very good," exclaimed Uncle Bagges. "You must be lord chancellor, sirlord chancellor, one of these days." 66 And now, uncle," asked Harry, who was a favorite with the old gentleman, "can you tell me what you do when you put a candle out ?" 66 Clap an extinguisher on it, you young rogue, to be sure." "Oh, but I mean, you cut off its supply of oxygen," said Master Harry. "Cut off its ox's-eh? what?" "He means something he heard at the Royal Institution," observed Mrs. Wilkinson. "He reads a great deal about chemistry, and he attended Professor Faraday's lectures there on the chemical history of a candle, and has been full of it ever since." "Now, you sir," said Uncle Bagges, "come you here to me, and tell me what you have to say about this chemical, eh? -or comical; which?-this-comical chemical history of a candle." "Harry, don't be troublesome to your uncle," said Mr. Wilkinson. "Troublesome? Oh, not at all. I like to hear him. Let him teach his old uncle the comicality and chemicality of a farthing rush-light.” |