Mountains that are liable to volcanic action, before an eruption takes place, are generally the most fertile, and the most attractive of all eminences. Illustrations of this remark are found upon a magnificent scale in Mexico; and, among the rest, that of Jorullo, in the extensive intendency of Valladolid, lying on the west coast of America, between the intendencies of Mexico and Guadalaxara, (pronounced Quadalahàra.) Mechoacan, a part of it, is an expanse of table-land which enjoys a fine and temperate climate, and is intersected with hills and charming valleys, presenting an appearance unusual in the torrid zone, of extensive and well-watered meadows. On the twenty-ninth of September, 1759, from the centre of a thousand burning cones was thrown up the volcano of Jorullo; a mountain of scoriæ and ashes, seventeen hundred feet high, in an extensive plain, and covered with most luxuriant vegetation. When plains, hills, and valleys, are thus spoken of, the reader should remember, that all of them are reared upon the lofty chain of the Andes, for volcanic eruptions only, so far as we know, take place in mountainous regions.
But some of the most remarkable examples are to be met with in the Spice Islands, or Moluccas. The pointed and conical mountains, which characterize this group of islands, exhibit great fertility. Nothing can surpass the richness of vegetation with which their sides are covered, nor the balmy healthfulness of the breezes that encircle round them, to temper the heats of the sultry zone. But the nature of these mountains is closely connected with volcanic action; so that, in fearful apprehension, we might look at each one of these beautiful peaks, as if it were destined one day to be torn from its station and thrown into the sea.
“I will stretch out mine hand upon thee, and roll thee down from the rocks, and will make thee a burnt mountain,” was one of the Divine denunciations against Babylon, Jer. li. 25. Judgment has not thus fallen on Ternate, one of the most lovely of the cluster just adverted to; but the top of the highest rock has been torn off, and hurled from a height of five or six thousand feet, into the sea. A huge gap was left behind, which seemed to a traveller when standing on the edge, like a deep valley, or ravine, betwixt two mountains. As the portion rent away in this tremendous struggle was split into fragments of various sizes, there is, besides, a vast pile at the water’s edge, a road, or causeway, strewed with half-vitrified pieces of rock and cinders, from the margin of the rift to the declivity of the mountain; so that the island, so lovely under other aspects, presents on this side a fearful scene of desolation. What a striking comment on the words, “I will make thee a burnt mountain;”—I will tear off thy summit, shiver it into ten thousand pieces, and therewith overwhelm and destroy the natural verdure of thy sides, which once looked so goodly and so fair! Some time in March, 1839, another eruption took place at Ternate; so that, long before these ejected matters could yield to the decomposing action of the atmosphere, and afford a soil for vegetable growth, another layer, of equally forlorn and broken kind, was scattered over them.
In connexion with these astounding phenomena, it may be remarked that an apparatus has recently been contrived called the fire-annihilator, the origin of which is not a little curious. It is said that the inventor observed that the smoke hovering over a burning mountain diminished its fury, and that, on analysing it and combining similar elements, he discovered the means of extinguishing fires, and thus of arresting at the outset what might otherwise prove a tremendous calamity.
Many processes of art, like the operations of nature, are dependent on heat. By this agent, the most obdurate masses soften like wax, and yield to the forms which are demanded by our wants and our tastes; and compounds, knit together by stubborn affinities, are resolved by it into their original elements. The baron Von Tchivanhausen constructed a burning mirror in 1687, five feet three inches in breadth, and reflecting the solar rays with extraordinary power. When exposed to its force, wood took fire, and continued to burn, notwithstanding a most violent wind; and water, contained in an earthen vessel, quickly boiled, so that eggs were cooked, and the liquid soon after evaporated. Copper and silver were fused in a few minutes, and slate was transformed into a kind of black glass, which, when held by a pair of pincers, could be drawn out into filaments. This mirror afterwards came into the possession of the king of France, and was kept in the Jardins du Roi. Other mirrors have been formed of different substances. At the Polytechnic Institution, some years ago, there were two metallic discs placed at the extreme ends of the great hall, and when a vessel of burning coals was held in the focus of one, and a piece of meat in the focus of the other, the latter was cooked with marvellous rapidity by a simple and apparently an unimportant instrument.
The blow-pipe has immense power. Two volumes of hydrogen, and one of oxygen gas, when pure, form a mixture which produces in this instrument intense heat, and most substances may be fused by the flame. In the experiments of Dr. E. Clarke, lime, strontion, and alumine, yielded to its powers. The alkalis were fused and volatilized almost the instant they came into contact with the flame: and rock crystal became a transparent glass full of bubbles. Opal changed into a pearly white enamel, and flint into one that was frothy. Blue sapphire was melted; and Peruvian enamel changed into a transparent and colourless glass. Lapis lazuli fused into transparent glass, with a slight tinge of green. Iceland spar, next in difficulty, as to fusion, to its native magnesia, melted at last into a limpid glass, giving out an amethyst-coloured flame. Diamond first became opaque, and was then gradually volatilized. Gold, mixed with borax as a flux, was fused; platina wire melted the instant it was brought into contact with the flame, and ran down in drops; brass wire burned with a green flame; and iron wire with brilliant sparks.
At a recent meeting of the British Association, Dr. Faraday exhibited some diamonds, which he had received from M. Dumas, which had, by the action of intense heat, been converted into coke. In one case, the heat of the flame of oxide of carbon and oxygen had been used; in another, the oxyhydrogen flame; and, in the third, the galvanic arc of flame from a Bunsen battery of one hundred pairs. In the last case, the diamond was perfectly converted into a piece of coke; and, in the others, the fusion and carbonaceous formation were evident. Specimens in which the character of graphite was taken by the diamond were also shown. The electrical characters of these diamonds were stated also to have been changed, the diamond being an insulator, while coke is a conductor.
A rope, nearly three miles long, was recently lying on the verge of the borough of Gateshead, which was shortly before a stone in the bowels of the earth. Smelted, the stone yielded iron. The iron was converted into wire. The wire was brought to the wire-rope manufactory of Messrs. R. S. Newall and Co., at the Teams, near Gateshead, and there twisted into a line 4,660 yards long. It was supposed to be the stoutest rope of the kind that was ever made. It weighs twenty tons, five hundredweights, and cost the purchasers upwards of £1,134. It was intended for the incline on the Edinburgh and Glasgow Railway, near the latter city. A rope of hemp of equal strength would weigh thirty-three tons and-a-half, and cost about three hundred pounds more. It would also entail greater expense while in operation, (owing to its greater weight,) and would sooner wear out.
“The process,” says the Pharmaceutical Journal, “for purifying and agglomerating caoutchouc, preparatory to its being cut into sheets, and also for effecting the latter operation, are due to the ingenuity of M. Sievier. The general principle is this:—Pieces of caoutchouc, mixed, as they are in their native state, with various impurities, are put into a strong metallic drum, through which passes an axle, studded with chisel-shaped teeth. The interior of the drum is supplied with similar ones, but stationary. Therefore, when the axle is made to revolve, the caoutchouc becomes subjected to a most powerful rending and kneading motion, in the course of which sufficient heat is evolved, notwithstanding a current of cold water continually passes through the drum, to agglutinate the material into a compact mass. This mass is now subjected to the pressure of a powerful screw apparatus, and made to assume the form of a cuboid, from which sheets of caoutchouc may be eventually cut by the rapid vibratory action of a knife, kept moistened with water. As solvents for caoutchouc, equal parts of coal naptha and turpentine are commonly used; and, of late, the bisulphuret of carbon has been much employed.”
Mr. J. Wishaw has lately shown the advantages arising from the application of currents of heated air to the following purposes: seasoning timber, generally; preserving timber, purifying feathers, blankets, clothing, etc.; drying coffee, roasting coffee, japanning leather for table-covers, and other purposes; drying silks, drying yarn, drying distillers’ tuns, drying papier-máché, and drying vulcanized india-rubber. The process has also been successfully tested for drying loaf-sugar, drying printing-paper, or setting the ink, to enable books to be bound more quickly than usual; drying starch, and converting it into dextine, or British gum; and preserving meat. It has been also stated, that sixty suits of clothes, which had belonged to persons who had died of the plague in Syria, had been subject to the process of purification, at a temperature of about 240°, and afterwards worn by sixty persons; not one of whom ever gave the slightest symptom of being affected by the malady. In describing these processes, the writer referred to the mode adopted by the North American Indians for preserving the meat of the buffalo—that of drying it in the sun; and stated that heated currents had been applied successfully. The discovery seems highly important for shipping; as, instead of sailors consuming salted provisions from one month’s end to another, they might thus have an occasional supply of fresh meat. Meat treated in this way occupies much less space, too, and is much lighter in weight. It is believed that the juices of the meat contain about seven-eighths of watery moisture: this, the current of heated air removes, leaving the albumen and all the flavour and nutrition behind.