Popular Science Monthly/Volume 2/January 1873/Miscellany
Experiments on Sound.—Prof. Mayer, of the Hoboken Technological Institute, N. J., has made some rare and remarkable researches on sound, of which he lately gave an account before the Lyceum of Natural History, New York. The following is a summary of the views he presented: That sound reaches the ear by a series of waves or undulations, is a generally-accepted fact. But, although so accepted, it may well be doubted whether many persons, even among those of considerable general culture, are possessed of a clear view of the nature of these waves. To obtain this, it is necessary to bear in mind that the waves of sound which take place within a gaseous medium are in no wise similar to those waves which undulate on the surface of water or other liquids. The latter form around their point of origin in concentric circles; the former are generated around that point in concentric spheres; all deviations from these forms being in both cases due to mere special disturbing influences. This conception having been fixed in the mind, it is readily seen that sound-waves consist of alternate swellings (involving a rarefaction) and contractions (involving a condensation) of the air, propagated from the point of origin, and that the thickness (length) of each wave is measured by the distance between the curved surfaces corresponding to the periods of maximum swelling (rarefaction) and contraction (condensation). Within the wave-limits, the progress of sound-motion is by no means uniform; and, could we accurately trace the steps in variation, we could readily delineate the march of sound within the wave.
This result may be obtained approximately by attaching a small piece of copper-foil to one of the prongs of a tuning-fork, and quickly drawing this (while vibrating) across a plate of smoked glass. A very beautiful representation of this march of sound may also be obtained by operating with an organ-pipe, having a hole at the middle (nodal-point), which is covered by a thin elastic membrane, offering no impediment to the transmission of the undulations. Directly over this membrane a little box or capsule is placed, through which a current of illuminating gas is conducted to a jet burning in front of a revolving mirror. The sound-waves being communicated to the gas, give rise to a series of flame-pulsations. When the mirror revolves, the quiet flame is reflected as a continuous, the pulsating flame as a serrated, band of light.
If, at this point of the experiment, the aid of one of Helmholz's resonance-spheres be called in—the resonance-waves being conducted by a pipe through a box and membrane (like those already described), to a second gas-jet placed exactly under the first—the image in the mirror will be duplicated. The resonance-spheres (resonators) here mentioned are thin, hollow, brass globes, with two openings opposite to each other; one being furnished with a neck for attaching a pipe, the other serving as a mouth for receiving sound-impulses. They act by sympathy, as it were, taking up and resounding with a special note, and that only, the special character of the note depending upon the relative capacity of the sphere, and the size of the mouth.
As the waves of sound, propagated through a uniform medium, travel with uniform velocity, it follows that, when the pulsations transmitted to the first jet from the organ-pipe, and the pulsations transmitted to the second jet from the resonance-sphere, pass through equal lengths of air, they will be reflected from the revolving-mirror as coincident serrations. When, however, the pulsations from the organ-pipe are transmitted through a depth of air equal to one wave-thickness or length, and the pulsations from the resonance-sphere are transmitted through a depth, either less or more (and not an exact multiple) than the wave-thickness or length, the two serrated bands of light, reflected from the revolving-mirror, will not be coincident. If, starting with equal distances of the organ-pipe and resonance-sphere from the jets, that of the latter be gradually increased, the serrations of the two images will be at first coincident, then non-coincident; then, when a distance of two wave-thicknesses is reached, again coincident, then again non-coincident; each coincident corresponding to a distance equal to a simple multiple of the wave-length of the note. And if, on the other hand, the resonance-sphere be moved in such a manner that the coincidence of the serrations is not disturbed, it is evident that the motion must be in lines traced upon the curved surface of a body of air—exactly similar in size and form to one, two, three, etc., pulsations sent forth by the organ-pipe. Prof. Mayer was the first to trace the surface of sound-waves by this beautiful and ingenious method. It is highly probable that, by this arrangement, some hitherto unapproachable acoustic problems may meet with a solution.
The velocity of sound is not influenced by variations in the density of a uniform gaseous medium, provided the temperature of this medium remain stationary. But, when the temperature changes, the velocity is at once affected. Hence, a gradual rise in the temperature of the air, passing from the resonance-sphere to the gas-jet, will be productive of a successive alternation of coincidences and non-coincidences of serrated images, analogous to the alternations produced by increase of distance. This remarkable fact Prof. Mayer proposes to employ in measuring temperatures, and particularly the high temperatures of furnaces. This is to be accomplished by interposing a coil of porcelain or other fire-proof pipe between the resonance-sphere and the jet, and introducing it slowly into the furnace. By this method, Prof. Mayer expects to be able to measure temperatures with an accuracy equal to about twenty-five degrees of the Centigrade thermometer, or even less.
A New Species of Rhinoceros.—A writer in Nature is disposed to see, in the hairy-eared, two-horned rhinoceros at present in the menagerie of the London Zoological Society, a new species, which he proposes to call R. casiotis, the hairy-eared rhinoceros. When this animal arrived in England, it was taken to be the Sumatran rhinoceros, though naturalists were surprised that a Sumatran rhinoceros should be taken so far north as was this specimen—Chittagong, the northern extremity of the Bay of Bengal. There is a fringe of long hairs on the posterior rim of the otherwise naked ears, and the tail is long, and tufted at the extremity. The head is very broad, and the skin comparatively smooth.
Nothing new under the Sun.—Humboldt, in his "Cosmos," states that the Chinese had magnetic carriages with which to guide themselves across the great plains of Tartary, one thousand years before our era, on the principle of the compass. The prototype of the steam-engine has been traced to the eolipyle of Hero of Alexandria. The Romans used movable types to mark their pottery, and indorse their books. Mr. Layard found in Nineveh a magnifying lens of rock-crystal, which Sir D. Brewster considers a true optical lens, and the origin of the microscope. The principle of the stereoscope, invented by Prof. Wheatstone, was known to Euclid, described by Galen fifteen hundred years ago, and more fully in 1599 a. d., in the works of Baptista Porta. The Thames Tunnel, thought such a novelty, was anticipated by that under the Euphrates at Babylon; and the ancient Egyptians had a Suez Canal. Such examples might be indefinitely multiplied, but we turn to photography. M. Jobard, in his "Nouvelles Inventions aux Expositions Universelles," 1857, says a translation from German was discovered in Russia, three hundred years old, which contains a clear explanation of photography. The old alchemists understood the properties of chloride of silver in relation to light, and its photographic action is explained by Fabricius in "De Rebus Metallicis," 1566. The daguerreotype process was anticipated by De la Roche in his "Giphantie," 1760, though it was only the statement of a dreamer.
The Sun as a Borer of Mountains.—1. The universe is filled with rays of heat and light, which vibrate among the heavenly bodies perpetually without loss or gain, and which, on alighting upon a heavenly body, pass first into common sensible heat, to be reflected afterward as cold, invisible rays.
2. Of the inexhaustible supply of these rays, our sun receives at every instant of time as much as he radiates back again.
3. A portion of his rays fall upon our earth, where they are converted into sensible heat.
4. By means of this sensible heat, water is converted into aqueous vapor; the sensible heat being at the same time changed into so-called latent heat, or chemical motion.
5. Aqueous vapor having less specific gravity than air, it ascends and represents a lifted weight. In this process, heat is converted into motion—the ascent of the weight.
6. The expansion of the air (during which heat is converted into mass-motion) causes the aqueous vapor to be spread over the surface of the earth.
7. By the condensation of the aqueous vapor, chemical motion escapes as common heat, and the resulting water is deposited on the mountain-heights in the form of snow; thus, again, representing a lifted weight.
8. The warm winds from the Mediterranean melt the snow and glacier-ice; sensible heat is thus converted again into insensible chemical motion.
9. The downward current of the Alpine streams generates motion in virtue of their mass, and of the space passed over during their descent.
10. This mass-motion, when temporarily checked by any resisting object, is converted back into heat.
11. Man arrests a portion of this motion by means of a large water-wheel, and, by the aid of a crank and a connecting-rod, transmits the motion to the piston-rod of an air-compressor.
12. In compressing air, we accumulate motion as a force or tension; and the compressed air yields this force again without loss (exception made of the loss occasioned by the friction of the piston, which reappears as heat).
13. Compressed air—a storehouse of motion—is made to pass into a contrivance similar to the steam-chest of a steam-engine, where a sliding-valve forces the air to enter alternately above and below the piston to which it thus imparts common mass-motion. The process is the same as the one operating in the steam-engine, with the difference that the motor agent is compressed air in place of steam, and that the motion is ultimately obtained, not from the combustion of fuel, but from the descent of water.
14. The mass-motion of the water, now transferred to a drilling-machine, is modified by means of mechanical contrivances in a manner such that powerful blows are dealt in rapid succession upon the cutting-tool which drills the hole; mass-motion is thus converted back into heat.
15. The drill-hole is filled with a mixture of substances containing chemical motion, which, at any time, may be given out as heat and mechanical motion. By the ignition of the mixture, new combinations of substances occur, which, owing to the new distribution of chemical motion, take up a much greater space, and thereby split the rocks.
16. Mont Cenis Tunnel (as will be the future one of St. Gothard) was bored by the sun's heat.—Mohr, translated by Hotze.
Cinchona in Bengal.—In 1862 Dr. T. Anderson began the cultivation of cinchona (the tree that yields the Peruvian bark) in Sikkin, Bengal. The venture has proved profitable; and at the present time he has under cultivation cinchona-trees of three species, to the number of 1,707,115, yielding about 300 pounds of bark per acre. Besides these, he has 480,000 young plants in nursery.
Bulb-Culture in Holland.—Although one-fifth of the entire land in the Netherlands is worthless for cultivation, and another fifth is meadow-land, yet 47,500 acres of the remainder are devoted to tobacco, 35,000 to hemp, and 500 acres to raising tulips, hyacinths, and other flowering bulbs. Holland has ever excelled in this sort of horticulture.
Antiseptic Properties of Borax.—A paper by M. Jacquez on the preservative action of borax and the sub-borate of ammonia, on animal matter, read before the French Academy of Sciences, gives an account of some important experiments made by the author during a period of five years, with a view to ascertain the antiseptic properties of the substances named. In June, 1853, he dissolved 25 grammes (about 387 grains) of gelatine in 100 grammes (a little over 3 ozs. of water) with 4.50 grammes—nearly 70 grains—of borax. The mixture remained in an open flask all through the summer, without any sign of mould or putrefaction. In August of the same year, pieces of meat dropped into a solution of borax and water (5 parts of the former to 100 of the latter) were there preserved unchanged for a month—being then taken out of the solution and exposed to the air, they dried slowly, and did not undergo decomposition. The next series of experiments was with a mixture of borax, sub-borate of ammonia, and tepid water, in the proportion of 5 or 6 parts of borax, and 10 or 12 of sub-borate of ammonia, to 100 of rain or pure river water. By injecting this mixture into the bodies of rabbits killed two days previously, the water kept them without sign of decomposition for several months. M. Jacquez is of opinion that this process is of high importance for the dissecting-room, as it does not alter either the coloring or the firmness of the tissues, and at the same time imports no poisonous element into the subject. Furthermore, the edge of cutting-instruments is not at all affected by the presence of the antiseptic. Probably, if 6 per cent, or even 8 per cent, of borax were used with the liquid at about 40° C. at the moment of injection, the cadaver itself having been previously kept for some hours in some warm medium, the borate of ammonia might be omitted. Then an adult cadaver might be prepared at the trifling expense of two francs. For purposes of embalming, the writer recommends a concentrated solution of both salts, injected two or three times into the blood-vessels at intervals of a few days. Pulverized borax would also be of service in preserving the skins of stuffed animals and birds; and the solution might be used instead of alcohol in cases where the latter is now employed to preserve specimens.
Disintegration of Tin.—Two cases of the disintegration of tin are given in the American Artisan, the phenomenon being in the one case traceable to the action of intense cold and long-continued vibration, while in the other the cause of the disintegration is unknown. A certain quantity of tin in ingots was shipped from Rotterdam to Moscow by rail during extremely cold weather. On reaching its destination it was found to have been reduced to a powder, with coarse crystalline grains. When fused, instead of forming a solid mass, it gave only oxide of tin, a gray powder. The second case was that of two pigs of "Banca tin," purchased by the United States Ordnance Bureau. They had lain in store for several years; and, when at length they were taken from their resting-place, one was found almost entirely reduced to a gray powder, while the process of disintegration in the other was as yet confined to the edges. Dr. I. Walz, who communicates to the Artisan this piece of information, tried in vain to learn the previous history of these two pigs of tin. It is his belief that the instances here recorded are the only ones known of tin assuming a granular condition.
A Squirrel-Pest.—In some parts of Arkansas the squirrels were so numerous the past season that they destroyed entire fields of corn. As many as 125 have been killed by one person in a day.
Welding Copper.—According to the Journal of the Franklin Institute, Mr. Rust has succeeded in perfecting a method by which he accomplishes a perfect welding of copper. He mixes together 358 parts of phosphate of soda and 124 parts of boracic acid. This powder is applied when the metal is at a low red heat; it is then brought to a cherry-red, and at once hammered with a wooden hammer.
Effect of Atmospheric Pressure.—Mr. Paul Best, in a very interesting memoir, shows that the destruction of life by diminished barometric pressure is chiefly to be attributed to deficiency of oxygen. An animal that will die with the pressure reduced to 18 centimetres (7 inches) of mercury, will endure a reduction to 6 centimetres (2.4 inches) if an additional supply of oxygen be furnished. And the converse is also true, that the danger of too great pressure is from the increased amount of oxygen in a given volume of air inhaled.
Relations of Local Diseases to the Nature of the Soil.—Dr. Moffat read before the British Association a paper on the above subject, in which he shows that the nature of the soil exercises considerable influence on the character of endemic disease. His district lies on the carboniferous and red, or Cheshire, sandstone formation. Anæmia is the prevailing condition of the inhabitants of the carboniferous land, who are both miners and farmers, while it is almost unknown on the red sandstone. Consumption is also more prevalent in the first-named district. Since anæmia is a want of iron in the blood, Dr. Moffat examined the constitution of wheat grown on the Cheshire sandstone, and found it produced much more ash, and hence a larger proportion of mineral constituents, including oxide of iron, than that grown on the carboniferous soil. He estimates that a pound of wheat from the first furnishes five grains more of oxide of iron to the consumer than a pound of wheat from the second soil, which accounts for the comparative poverty of the blood of the miners in iron and phosphoric acid. An examination of the blood of the animals kept in the two districts confirmed the above observations.
Sensitive Streams.—Prof. Edwin J. Houston, while spending a summer's vacation in Pike County, Pa., had the good fortune to discover the sensitiveness of water to sound-waves. Among the many beautiful water-falls of that section he found one scantily supplied with water, which dripped in small streams from the ends of the moss covering the rocks of the precipice; the air being still and the stream free from ventral segments. And it was found that, on sounding a shrill falsetto note, the streams would instantly respond, and change the grouping of the drops and the position of the ventral segments. A heavy rain, however, flooded the stream, and prevented further investigation.
Vegetable Caprice.—It would almost seem that too much can be asserted as to the uniformity of habitat, or natural location, of a given species of plant. The Bunch-flower (Melanthium Virginicum) has been set down as invariably occupying moist meadows and damp borders. A correspondent of the Torrey Botanical Club reports seeing, "when crossing the Alleghanies by carriage-road to the Peaks of Otter, and frequent, high and dry, on the rocks, tall and stout Melanthium Virginicum" and adds: "I was unprepared for that, as with us it grows along the margins of marshes, as at Bergen, N.J."
The Tails of Comets.—Prof. Zöllner, in his book "On the Nature of Comets," accounts for some of the phenomena by showing that water, mercury, and many other substances, even in the solid state, always give off vapor; hence, a mass of matter in space will ultimately surround itself with its own vapor, and present the appearance of a comet. It is quite probable that some of the masses moving in space may be fluid, in which case, on approaching the sun, the development of vapor would be very rapid, as is well exemplified by some of the smaller comets. And, as regards the swift growth of the tail, Prof. Zöllner demonstrates that if the free electricity of the sun be not greater in amount than that observed at the surface of the earth, it would be sufficient to communicate an impulse which, as exemplified by the comet of 1680, would produce a train or tail 60,000,000 miles long in two days. Having proved this mathematically, he does not think it necessary to seek further for a theory of repulsive force by which to account for the tails of comets.—Chambers's Journal.
Phosphoric Acid.—The occurrence of phosphorus in combination with the ores of iron has long been an annoyance to iron-manufacturers, and many rich ores are worthless from the presence of phosphorus, which makes the iron brittle and useless. Julius Jacobi proposes a method of freeing iron-ores from phosphorus, and at the same time saving the phosphoric products for agricultural purposes. His process consists in roasting the ore and crushing it, and, after placing it in a proper receiver, submitting it to the action of water charged with sulphurous acid under pressure. The ore is then washed with water to remove all the soluble products, and the phosphoric acid precipitated from the water with fresh-burnt lime is obtained as a neutral phosphate of lime. If effectual, and not too expensive, the proposed method is very important, as rendering many ores available which are now regarded as worthless, and at the same time supplying a demand in agriculture which has heretofore been but imperfectly met.
The Osage Orange.—The Madura aurantica, a familiar shrub from its general use as a hedge-plant, it is now proposed to utilize for other purposes. A decoction of the wood is said to yield a beautiful and very permanent yellow dye. This decoction, carefully evaporated, forms a bright-yellow extract, called aurantine, which may be used in imparting its color to fabrics. In addition to this coloring-matter, the wood of the Osage orange is rich in tannin. Experiments made in Texas represent that hides are tanned quicker with the wood of this tree than with oak-bark. The seeds yield a bland, limpid oil, resembling olive-oil, and which may, in general use, be substituted for it.
Test for Silk Goods.—In the present methods of silk manufacture the amount of adulteration to which the fabric is subjected is enormous. Although linen is often used, the favorite adulterator is jute, which is cheaper, is heavy, and so easily takes the dye, and in other ways is made to simulate the silk, that it is the more difficult of detection by an unpracticed eye. If a sample of the "goods suspected to contain other kinds of fibre be treated with hydrochloric acid of 1.13 specific gravity, the silk will be dissolved, while other kinds of fibres, such as jute and linen, will remain undissolved."
Opium-poppy in France.—The cultivation of the opium-poppy in France is steadily increasing. It now occupies 50,000 acres, of the value of 4,500,000 francs, yielding opium to the value of 2,000,000 francs a year. Different samples of opium, raised in various parts of Europe, are said to have yielded from 8 to 13 per cent. of morphine.