FRENCH SCIENTIFIC GOSSIP.

New Zealand Times, Volume XXX, Issue 4402, 29 April 1875, Page 3

FRENCH SCIENTIFIC GOSSIP.

(from a correspondent.) Paris, January 23. The snow has been unusually continuous in Paris as elsewhere this season, and which has had for consequence to diminish the intensity of the cold. Each flake of snow actually brings heat with it ; thus the watery vapor in the air, on encountering a cold current, is converted into a liquid, and thence into crystals of ice, that is, snow. The sun at the equator heats the water, which evaporates and ascends into the air. Now, to convert a quart of water into vapor requires about seven ounces of coal, so that clouds saturated with vapor convey to the atmosphere the heat produced, as if resulting from thousands of tons of coal. But when this vapor condenses, it parts with the heat stored up and distributed in the atmosphere ; still more heat is liberated when the condensed vapor passes from a liquid into snow. Thaw setting in, cold is produced, because the snow, to become liquid, absorbs heat from surrounding objects,. retakes the heat given, and the low temperature resulting occasions bronchitis. The absence of thermometers —;only invented by Galileo in 1597, and Fahrenheit in 1726 prevented the ancients recording noted inclement seasons. The Romans believed the Crimea (Tauris) to be the coldest part of the earth, till they became acquainted with Germany and Gaul. In Siberia, cold has been registered by Severow at 75 deg. below Fahr. zero, and mercury there remains frozen for several months in the year—can be hammered like lead ; iron also becomes as brittle as glass; wood cannot be out or split; fire loses even part of its warmth; and the inhabitants had in 1819 to wear masks when going into the open air, to prevent the loss of their noses and ears. Mercury has never been known to freeze at St. Petersburg—an event that has occurred, however, twice at Vienna. Winter may be said to possess its flowers as spring, for the snow-flake is a sparkling diamond flower, having a centre from which radiate six needle-shaped petals, these needles have branches in turn, taking the most varied and marvellous forms, as fine as gauze and as delicate as lace. If a number of snowballs firmly pressed be thrown into a pot of boiling water, they will approach each other—become as it were soldered. This phenomenon of re-freezing was discovered by Faraday in 1850, and it explains the rigidity of the snow bridges encountered in the Alps, in marching across which the particles composing it become welded together. Pressing snow in a mould, for example, ■will make it as clear as crystal ; thus statuettes can be obtained ; cups made of compressed snow, plates, and glasses, will hold together serviceably for an evening in a warm room, the layer of water on the exterior of them protecting the rest against the heat; hence, to prevent a plant from being frozen, some persons envelop it in a wet cloth. The ice palace erected in 1710 at St. Petersburg, with blocks of ice from the Neva, and which remained undissolved for a few years, is a proof of the resistance of ice to thaw; the walls sparkled, the ceilings reflected all the colors of the rainbow ; the brilliant crowd was nearly stifled in these drawing-rooms; the windows were composed of compressed snow, ■ and proved as good as glass ; and though the “walls” were covered with humidity, not one of them gave way. M. Tissandier believes snow is an .excellent sweeper of atmospheric impurities. He has collected snowflakes in Paris on glass, before they touched the ground, and found them to contain debris of charcoal, fragments of stuff, particles of feoula, sand, &c.; in the country, the flakes gathered contained 50 per cent, less of impurities. A quart of snow thus collected in the capital, contained about 2 grains of grey, pidverUlent matter, of which 70 per cent was inorganic, the remainder organic, and not only lime, alumina, and salt were detected in this inorganic residue, but notably iron. M. Tissandier is inclined to not only attribute the iron to the wear and tear of vehicle in the streets, but from the dust of .those aerolites which burst and break in our atmosphere. Nordenskioldhas found in northern snowfields such dust, containing cobalt, nickel, iron, &c., and Erhenberg has discovered the same elsewhere. By the formation of their crystals, M. Tissandier has detected the salts of ammonia and soda in'snow, and holds with Boussingault, that the presence of these and other foreign matters may explain how snow fertilises the soil. M. Pouchet has found on the summits Of the ancient monuments of Egypt, substances that could have only been carried there by currents of air ; and Davinu, in 1832, collected in the Atlantic ocean, dust which had fallen from the air, and that consisted of fresh water animalcuhe.

M. Cornu has conducted 604 experiments to test the velocity of light, and hence the distance of the earth from the sun. He reflected light from the Paris Observatory to the tower of Mouthling, a distance of fourteen and a-half miles, calculating by a revolving disk, which measures the “luminous echo” to the thousandth part of a second. M. Le Vender asserts M. Cornu has satisfactorily settled the question of the rate at which light travels ; if so, the expeditions to observe the transit of Venus can only corroborate a fact already known—not a small result in any case. M. Flammarion has observed a variation in the brilliancy of two of Jupiter’s satellites during their transit over his disk, and which he attributes to immense atmospheres enveloping them, and the presence more or less of clouds, making the atmosphere of one satellite to be clearer than another, producing thereby a difference in brilliancy. Prom time immemorial, the black spots on the surface of the moon led to the belief that that planet contained inequalities like the earth, and gave rise to several superstitions, such as the presence of the body of Judas Iscariot, confined in the moon as a punishment for his treason. The Indians believed that they recognised a hare, and Asiatic tribes held that the spots were but the reflection of the seas and continents of our globe, &o. The perfection of telescopes has revealed that the moon contains immense plains, having the appearance of dark spots, and which are roughly palled “ seas.” Some of those seas are surrounded by a rampart of mountains, and during full moon luminous jets have been observed to issue from some of the craters, reflecting light some hundreds of miles around. These “ seas,” from presenting a dark green, sometimes grey, and occasionally pale red colors, are concluded by many to represent vegetation, but such cannot exist, as the moon has no atmosphere. The mountains are rarely isolated in plains, but are connected in groups, all of which astronomers have now named and mapped. The Apennino Range is 450 miles long, hills piled upon hills, mountains upon mountains, until all terminates in vertical peaks 20,000 ft. high, and the absence of an atmosphere renders the spectacle more savage, as there is no medium to tone down the light. The crater of “ Archimides” is over fifty miles in diameter. M. Tholozan, physician to the Shah of Persia, draws the attention of the Academy of Science to the spontaneity in the outbreaks of plagues among the nomadic Arabs in and about Persia. The doctor cannot explain the causes, which are very contradictory ; and in reference to our knowledge of plagues generally, we are not a whit more advanced to-day than in the time of Hippocrates and Thucydides. He insists on studying the aspects of pests under the heads of epidemic and con-

tagious. Dr. Demarquay continues his experiments as to the presence of animalcules in sores. He placed the pus taken from various ulcers in phials, and after forty-eight hours, examined the liquids with the microscope, and found them to be swarming with infusoria. He next tried if antiseptics would kill them, but carbolic acid, alcohol, resin, balsams, and such substances as are ordinarily employed in dressing sores had no effect, except in quantities that would have destroyed the healthy flesh. Glyceride; however, rendered the animalcules motionless. The doctor concludes that invigorating air and the patients’ own strength, are the chief remedies to be trusted to. In the discussion which has taken place at the Academy as to the propagation of the virus of carbuncle by insects, it was held, that while flies could absorb the poisonous liquid matter from decomposing substances, they could not, without a penetrating proboscis, inject such virus into the flesh ; but in the case of lighting on an abrasion of the skin, the case might be different. M. Max-Paulet concludes that railway sleepers impregnated with sulphate of copper, intended to preserve the wood, rather promote its decay. The' process does not, as is generally supposed, succeed in causing the copper to so unite with the tissue of the wood and nitrogenous matters as to render them insoluble and repugnant to insects. The altered tissue he shows, from sleepers that had lain many years under ballast, to be perfectly soluble in water, and that in proportion as carbonic acid, derived from the lime in the ballast and the carbonate of ammonia in rain water, penetrates the wood, it drives out the copper, and a solution of iron takes its place, chemically decomposing the timber, and reducing its density to less than one-half of its uninjected condition.

M. Bert continues his interesting experiments on the influences of barometric pressure on the phenomena of life ; whether we ascend too high in mountain regions, or penetrate too deeply into the earth, we alike become ill, from the difference in the pressure of the air disturbing the quantity of oxygen dissolved in the blood, by increasing or diminishing it; however, the extremes of pressure can be guarded against by regulating the supply of oxygen accordingly. M. Ponchet has minutely studied the influence of the nerves in producing change of color in animals, reptiles, and fish. For example, Stark showed that fish, when placed in a vase enveloped with light or dark-colored stuff, assume these colors respectively. The color of a frog’s skin varies in proportion as the animal lives in or out of water, or has had its nerves out, the irritation producing contraction of the coloring cells proportionately. Young turbots, if placed in a vase with a sandy or a rocky bottom, take the corresponding tones in the course of half-an-hour. Other fish change color when irritated, or even at the view of some external object. By cutting the optic nerve of the turbot—by removing its eyes, in a word—the fish lost the function of changing color. M. Van Beneden, of the University of Louvain, denies that parasites form a distinct class. All classes of animals possess them. However, there are parasites which live on other animals without relinquishing their vagabond life, as leeches, vampires, &c. The leech makes a triangular wound, saws, as it were, the skin, and sucks the blood till it becomes drunk. In Senegal there is a leech which absorbs its own weight of blood. All leeches are riot aquatic. In Ceylon, Japan, and Chili there are some that are independent of water, and others, as in the Philippine Isles, that attack man and boast. There are parasites that live even upon the electric ray. It appears gnats are as parasitical as leeches, and it is the female insect that alone is sanguinary, the male living on the juice of flowers, sucking blood only when pushed thereto by want. In the central regions of Africa the tsetsa is so venemous that its bites kill an ox, a horse, or a dog, after a few hours; yet they have no effect upon man. In Mexico, however, there are actual homicidal flies. All birds have more or less of vermin. Fleas are more ferocious than gnats, as the males, like the females, live on blood; but they are very intelligent. Welckener formerly saw, in Paris, an exhibition of fleas, where they sat on their hind legs, holding morsels of stick like pikes between their fore legs, and others were yoked to a Queen Mab carriage. As late as the last century fleas were believed to engender the measles, gout, and jaundice. In South America there is a flea called “ chique,” which pierces clothes and shoes to lodge its eggs in the akin. Some of these infinitely little animals act as sanitary, police, as, they live upon the dead animal matter that accumulates along the sides and at the mouths of rivers. The ichneumon deposits her eggs in the caterpillar, and instead of a butterfly quitting the larva it is a swarm of winged flies. Thus the too rapid devolpment of caterpillars is checked. Some parasite attack also the eggs of insects in which to deposit their own., and so have them hatched. Thus the beautiful dragon-fly deposits her eggs upon a leaf of the water-lily—-a sort of floating island—but another insect is in ambush, and pierces the eggs in order to place therein its own. ,It would seem, as Schiller remarked, that the edifice of the world is sustained by two springs—famine- and love. ■ After some ten years of perseverance, oyster culture in the basin of Archaohon, large enough to supply the universe with bivalves, has succeeded. The basin, some- fifteen miles from Bordeaux, is favorably situated. A single oyster produces every year sufficient; spawn to develop four millions of oysters. M. Grugny arranges tiles, coated with an adhesive substance, so that when the spawn is deposited he : can detach it without injury when it is about the size o£ a four sous silver coin; he then transfers it to wooden tanks, lined outside with tin, protected on top by a perforated sheet of iron net fastening. After the oyster has grown, secured from external attack it is placed in grand trenches or beds, that will, at the lowest tides, ever remain covered with a sheet of water, so as to prevent the oysters from the severities of winter and the heats of summer. M. Ligor, in his interesting work on iron and its historical and modem applications, repeats the tradition, that iron was first revealed metallurgically by the accidental burning down of forests. In China and Egypt iron was known two thousand years before our era. Babylon had iron idols, and though that metal was then as valuable as the precious ones now, it was not the less used in Nineveh for bits for bridles. Iron was known in the time of Moses, and under David the Jews made their farming implements of that metal. It was only under the Romans that the utility of iron became general ; then doors moved on hinges instead ot pivots, and looks superseded bolts and bars. The Egyptians were acquainted with padlocks.