"Chemistry of Common Life," that "the energy is greater, and the body is actually stronger in a bright than in a cloudy day." There is science as well as poetry in the following address 10. 11. 12. 13. 14. 15. 16. 17. 18. TO THE SUNBEAM. Thou art no lingerer in monarch's hall; I looked on the mountains-a vapor lay, I looked on the peasant's lowly cot- Thou tak'st through the dim church aisles thy way, And thou turn'st not from the humblest grave, Sunbeam of summer! oh, what is like thee? One thing is like thee, to mortals given The FAITH, touching all things with hues of heaven.-MRS. HEMANS. 19. In striking contrast with the cheering and enlivening influences of the glorious sun is the scene presented by the dissolution and gloom described in Byron's Dream of Darkness, in which "the bright sun was extinguished." 20. "The world was void, A lump of death-a chaos of hard clay. The rivers, lakes, and ocean, all stood still, And nothing stirred within their silent depths; Ships, sailorless, lay rotting on the sea, And their masts fell down piecemeal; as they dropped, The waves were dead; the tides were in their grave; The moon, their mistress, had expired before; The winds were withered in the stagnant air, And the clouds perished; Darkness had no need Of aid from them-she was the universe." LESSON V.—CHEMICAL AGENTS CONTINUED. ELECTRICITY. 1. WHEN certain substances, such as glass, amber, and sealing-wax, are rubbed with dry silk or cloth, they acquire a power of first attracting bits of paper and other light substances, and afterward of repelling them. The same power manifests itself, only in a different way, in the thunder-cloud when it shakes the earth with its explosions; it resides, though often silent, unfelt, and unseen, in every particle of air, in every drop of water, and in the solid earth; directing the needle to the pole, it guides the mariner in his course; and modern science has trained it to transmit intelligence, literally, with "lightning speed." 2. In the great laboratory of nature this power is doubtless the chief agent by which chemical changes are wrought; and in "earth's hidden chambers" it is believed to be constantly in operation, separating compounds, and from their elements forming new combinations. Modern science has learned to imitate, though on a feeble scale, some of its wonders; and although it has not discovered the long-sought "philosopher's stone," which was supposed to be able to transmute the baser metals into gold, it has, nevertheless, in the development which it has given to the useful arts, done a better service to mankind than the older alchemists ever dreamed of. 3. The question, "What is electricity ?" is more easily asked than answered; but we see its effects all around us, and can tell what it does. A flash of lightning is an electrical phenomenon; and on a small scale we imitate it when, in a dry, cold atmosphere, and in the dark, we produce sparks of light by briskly rubbing a strip of paper with India-rubber, glass with a dry cloth, or, in the perhaps more familiar experiment, by rubbing the hair on a cat's back. By the aid of a powerful electrical machine we may collect a sufficient quantity of this "electric fluid" to kill a man by its explosion. 4. By the aid of this same "fluid" we may also decompose water, resolving it into its two elements, oxygen and hydrogen; and again, if these two constituents be collected and mixed in a suitable glass vessel, and a spark of electricity be passed through them, they will combine with explosive force, and form the original quantity of water. 5. Yet most frequently electrical phenomena are silent op erations, caused by means that can be detected only by careA tree or dwelling may be shivered when "From cloud to cloud the rending lightnings rage;" ful scrutiny. but the great work of electricity is performed in "The stilly hour, when storms are gone, Sleeping in bright tranquillity." It is chiefly in the form of what is called galvanism that the quiet but mighty operations of this power are carried on, as may be illustrated by the following experiment. 6. If we place a piece of zinc in dilute sulphuric acid, and extend a metallic wire from the dissolving zinc to a similar piece of copper, also immersed in the dilute acid, we form what is called a simple galvanic battery, and a faint electric spark may be seen whenever the contact of the wire with the copper is broken or closed. A current of what is called galvanic electricity, silent and unseen, may thus be created and be made to pass through the liquid; and by it gold, silver, and copper, dissolved in suitable acids, may be taken from the solution and deposited in a pure state, in a thin film or coating, on the surface of other metals-a process which is called by different names, as galvanizing, electro-plating, and electrotyping. 7. Such electrical currents are known to be in constant action beneath the surface of the earth, and even far down among the rocky strata; and it is probably by this quiet electric power, in connection with heat, that the mineral wealth of the earth-its gold, its silver, its iron, its crystals, its precious stones, and all the infinite variety of inorganic combinations of elementary substances-has been formed. 8. Thus electricity is found, in conjunction with heat or light, and sometimes with both, to be an all-pervading agent, assuming various forms and modes of action; but whether it is a material substance or not we can not tell. Like heat and light, it is called an imponderable agent, because, however much of it may be collected, it has no appreciable weight, and, like them, it is known only by its effects. 9. "That power which, like a potent spirit, guides The sea-side wanderers over distant tides, Inspiring confidence where'er they roam, By indicating still the pathway home; Through nature, quicken'd by the solar beam, Directs the cavern'd crystal in its birth, And frames the mightiest mountains of the earth, LESSON VI.-THE ELECTRIC TELEGRAPH. 1. THE greatest of modern inventions, next to the application of steam to the propulsion of machinery, is the application of galvanic electricity to the transmission of thought by means of the electric telegraph. An extensive series of the simple galvanic batteries before described may be made to produce effects so powerful, that metals which can not be fused at any furnace heat are readily melted by it; and by causing the electric current to pass repeatedly around a bar of iron or steel, the most powerful magnets are formed. 2. When the bar is of soft iron, it loses its magnetism as soon as the electric current is stopped; and by an ingenious contrivance, an instrument has been made by which the power of the soft iron magnet can be created and destroyed instantaneously any number of times in succession. Advantage is taken of this to work a needle which prints marks upon paper at the will of the operator. These marks, which are formed into an alphabet, the operator uses to spell out the words which he wishes to write. As the electric current may be made to pass through a wire thousands of miles in extent, an operator at one extremity of the wire can direct the motions of the needle at the other, and thus thought may be transmitted with lightning speed wherever the "wonderworking wire" can be extended. The transmission of thought in this way is indeed swifter than light, for the electric fluid flashes over the wire at the amazing rate of more than two hundred and eighty thousand miles in a second of time! & Borne o'er mountains, lakes, and seas, Boston speaks at twelve o'clock, Intellect has conquered time! Sing who will of Orphean lyre, Marvel! triumph of our day, Flash till power shall learn the right, Sing who will of Orphean lyre, Ours the wonder-working wire!-Anonymous. 1. AMONG all the wonders of the material world, there are none greater than those which are exhibited in the likings, or affinities, which the different elementary particles or atoms show for each other. Each readily forms an intimate union with some, while it repels others as if disdaining any relationship; and, moreover, where two kinds of matter show an affinity or congeniality, they will unite in certain definite proportions, and in no other. 2. Let us begin with that all-abundant element oxygen, and exhibit some of its affinities for other elements, which are so strong that it is never found by itself, unless under compulsion. It is the only element which is capable of uniting with all others, with perhaps a single exception. In forming water, just eight parts of oxygen by weight unite with one part of hydrogen, and in no other proportions will they form water. Yet eight additional parts of oxygen, that is, sixteen parts, will unite with one of hydrogen, but the compound is a bitter, disagreeable liquid. 3. Oxygen will unite with nitrogen in the proportion of eight parts of oxygen to fourteen of nitrogen, and with carbon in the proportion of eight parts of oxygen to six of carbon. We have thus given the most simple combining proportions of these four elementary substances, that of hydrogen being taken as the standard; and it is found that, with whatever elements they combine, they never vary from these proportions, or multiples of these. Thus the combining proportions of oxygen are always 8, 16, 24, 32, 40, or some higher multiple of 8; and the combining proportions of carbon are 6, 12, 18, 24, 30, or some higher multiple of 6. A similar prin |