Open main menu

Popular Science Monthly/Volume 9/September 1876/Miscellany

< Popular Science Monthly‎ | Volume 9‎ | September 1876


The Cruise of the "Challenger."Nature, for June 1st, gives an exceedingly interesting account of the voyage round the world recently completed by the Challenger. This voyage was undertaken chiefly for scientific purposes, the principal object being to "determine as far as possible the physical and biological conditions of the great ocean-basins of the Atlantic, the Southern Sea, and Pacific."

Important discoveries made during recent expeditions on the European border of the Atlantic and in the Mediterranean, by Dr. Carpenter, Mr. Gwyn Jeffries, and Prof. Wyville Thomson, stimulated a desire for further investigation, and this great voyage under direction of Prof. Thompson, as chief of the civilian staff, was inaugurated and carried through to a successful issue.

The ship left England on December 21, 1872, and returned to Spithead on May 24, 1876, having been absent a little less than three and a half years, and making a voyage of nearly 69,000 miles.

During this voyage 362 observing-stations were established, at each of which the depth and bottom temperature of the ocean were ascertained, and samples of the water, mud, and animals of the bottom, brought up for examination.

The direction and rate of currents were carefully studied, and "serial soundings" were made with special instruments to determine the temperatures at different depths. Upward of 50,000 meteorological observations were made during the first twelve mouths of the cruise.

The regular work of the expedition began at Teneriffe, from which point a line of soundings was carried across the Atlantic to the small island of Sombrero, a distance of 2,700 miles.

At 1,100 miles from Teneriffe, and 1,600 miles from Sombrero, bottom was found at 3,150 fathoms, which consisted of "perfectly smooth red clay, with scarcely a trace of organic matter," but at depths of only 2,200 fathoms the bottom was one mass of calcareous shells of foraminifera.

The red clay was found to be almost pure clay and a red oxide of iron with some manganese. This material is supposed by Prof. Thomson to be the residue or ash from decomposition of the shells. Experiments were made by Mr. Buchanan, of the staff of scientists, confirming this conclusion. He subjected globigerina ooze to the action of a weak acid, and found that after the carbonate of lime was removed there remained about one per cent, of a reddish mud, consisting of silica and alumina, and a red oxide of iron.

The globigerina shells were abundant at depths not exceeding 2,200 fathoms, but at greater depths a gray ooze occurred, the shells being in a state of decomposition; in deeper parts this disappeared, leaving the residuum of red clay.

This clay was found to be widely distributed in both the Atlantic and Pacific Oceans, and in many places contained concretions of the peroxide of manganese.

The specific gravity of ocean-water was carefully tested by Mr. Buchanan, and very unexpected results were obtained. The notion that the specific gravity increases with increase of depth seems unfounded, as it was ascertained to be greatest near the surface, diminishing to a depth of about 500 fathoms. From this downward it is nearly uniform.

Dredgings at great depths usually brought to the surface living organisms. At 3,150 fathoms (upward of three and a half miles) on the Atlantic cruise, only foraminifera were found, but other organisms were abundant at similar depths elsewhere.

By the serial temperatures taken in several places, it is evident that conditions exist which may greatly modify the distribution of the deep-sea fauna. Near Raine Island, not far from the entrance to Torres Straits, there was found at 2,650 fathoms, with bottom of red clay, a temperature of 35 Fahr. But it was also found that the same temperature occurred at a depth of only 1,300 fathoms. Here, then, the waters through 1,350 fathoms of depth, were of a uniform temperature. Over a wide area similar results were obtained, and the conclusion is, that this area, known as the Melanesian Sea, is so surrounded by a reef, rising to within 1,300 fathoms of the surface, that free communication of its waters with the outside ocean is prevented.

Animal life was found to be scarce in this sea, but sufficient to show that it is "possible in the still bottom water, although such conditions in the Mediterranean do not seem to favor life."

The deepest water was found on the line from Admiralty Islands to Japan, one sounding giving the enormous depth of 4,575 fathoms, or five and a half miles. This is said to be the deepest trustworthy sounding yet made, excepting two by the Tuscarora off the east coast of Japan, where a depth 600 feet greater was found.

One of the results of this expedition has been to extend a knowledge of the fauna of the deep oceans, and the forthcoming work of Prof. Thomson will be brilliant with illustrations of new and beautiful forms.

The great voyage is divided into four sections. The first is from Sheerness, England, to the Cape of Good Hope, but by the very roundabout course of St. Thomas, Bermuda, Halifax, and St. Vincent. The second section is from the Cape of Good Hope to Hong-Kong by the way of Australia and the Polynesian Islands. The third section is from Hong-Kong to Valparaiso, touching at Japan, the Sandwich Islands, Tahiti, and Juan Fernandez. The fourth section is from Valparaiso to Sheerness, arriving on the 26th of May last.


Recently-Discovered Fossils.—In an appendix to the American Journal of Science for June, Prof. O. C. Marsh gives notices of a new sub-order of Pterosaurians, Pteranodontia, and of three new species of Odontornithes. The distinctive feature of the sub-order Pteranodontia is the absence of teeth (hence the name). The new genus Pteranodon is readily distinguished from any pterodactyls hitherto described by the cranial characters, which are well shown in a nearly perfect skull and portions of others in the Yale Museum. The cranium is very large, and the facial portion greatly elongated. There is a high sagittal crest which projects backward some distance beyond the occipital condyle. The maxillary bones are closely coössified with the premaxillary, and the whole forms a long, slender beak. There are no teeth or sockets for teeth in any part of the upper jaws, and the premaxillary shows some indications of having been incased in a horny covering. The lower jaws also are long and pointed in front, and entirely edentulous. In several other respects the jaws in this genus are more like those of birds than of any known reptiles.

From the same localities, and from the same geological horizon, the Upper Cretaceous of Western Kansas, which have yielded the specimens constituting the suborder of edentulous Pterosaurians, come the remains of the Odontornithes, or birds with teeth, and the two doubtless lived together in the same region. The remains of one of these birds with teeth indicate a bird fully six feet in length from the apex of the bill to the end of the toes. The femur and the tibia resemble those of some modern diving-birds, but the toes are shorter and stouter.


The Prehistoric Pig.—In an essay on "The Prehistoric Pig of Britain," Prof. Rolleston arrives at the following conclusions: 1. The domesticated pig of pre-Roman times he refers to the wild variety of Sus scrofa. 2. The Indian wild-hog (S. cristatus) differs mainly by the retention of structural conformations which are only temporarily respresented in the European wild species. 3. Taking the changes which domestication produces into account, S. Indicus he conceives to be a modified S. cristatus, and not derived from S. leucomystax, or other species. 4. The skull of a wild-sow from the alluvium at Oxford possesses such a combination of characters as to cause the author to hesitate in accepting the Torfschwein (S. scrofa), variety palustris of Rütimeyer, as a distinct species. 5. Simplicity of third molars in a large skull of the Bornean pig (S. barbatus) has no value. 6. The S. verrucosus, in its tear and cheek bones, differs from the S. barbatus, and these peculiarities obtained in the old Irish "greyhound pig" figured by Richardson.


Appropriation of Silica by Plants.—Prof. P. B. Wilson, of Washington University, Baltimore, having, in a chemical examination of the ash of grasses, discovered that the silica contained in such ash differs essentially from silica reduced from natural silicates—that, in fact, it had been assimilated by the plant in the free state—determined to apply infusorial earth to land sown in wheat, and afterward with the microscope to search for the siliceous shields of diatomaceæ in the straw. Of course, if these were to be found occurring in the plant with the same forms which they have in the infusorial earth, it is plain that they must have been taken up by the plant and distributed through its system unaltered. The event fully justified this conclusion. The straw having been treated with nitric acid, the siliceous residuum was placed on the field of the microscope, and was seen to consist wholly of the siliceous shields of diatomaceæ the same as found in the infusorial earth, excepting that the larger disks in their perfect form were absent—evidently because these disks were not sufficiently minute to enter the root-capillaries. The result of these investigations shows the necessity of finely-divided silica in the soil; also, that simple or compound silicates are useless as fertilizing agents.


Forestry.—The first of a series of papers on "European and American Forestry," now appearing in the Penn Monthly, contains a brief history of "Deforestation," or devastation of forests, in the Old World. The subject is one that nearly concerns the inhabitants of the United States, where the process of deforestation advances with unparalleled rapidity. Among the many instances quoted by the author of the evils consequent on the denudation of woodlands is that of Sicily, once the granary of Rome, now almost a waste from the effects of forest devastation. The island has scarcely a stream that lasts through the summer, and few perennial springs. The soil has suffered deplorably for want of sufficient irrigation. Greece, in common with Asia Minor, has been shorn of its original forests, and its characteristic feature is represented in steppes and unproductive barren wastes. Of Spain it may be said that at one time one-fifth of its surface was forest; now the proportion is only nine per cent. Indifferent portions of the country noble forests still exist; but, on the whole, the destruction of the useful woods has been indiscriminate and improvident, and Spain, like all other countries, has suffered under the abuse of that universal law according to which soil and climate depend on the extent of forest-land.


Air-Bags for raising Ships.—Prof St. Claire, of Edinburgh University, in 1785 proposed the use of air-bags for the purpose of raising sunken ships. In 1864 airbags were first practically applied for raising a steamer sunk in the lake of Boden; in this case the bags, owing to some defect, gave way. The Alexandrovsky system, perfected some ten years ago, has already rendered good service to the Government and commerce of Russia on several occasions. The bags adopted in the Russian Navy, as we learn from Engineering, are, when inflated, of cylindrical form, measuring twelve feet in diameter and twenty feet in length. They are composed of three layers of the thickest canvas saturated with India-rubber. Their lifting power averages sixty tons. In order to lift a vessel, several chains are drawn by divers under her bottom, and air-bags attached to the ends of each of them as near the ship's bottom as possible: the bags, being inflated by means of air-pumps, cause the ship to rise. Before pumping air into the bags, all the chains are connected in a transverse direction, so as to form one system, thus preventing the pairs of bags from sliding off from beneath the hull of the ship. As the vessel rises the surrounding water-pressure decreases, and the excess of air passes out through safety-valves.


Night-Habits of Fish.—Mr. W. Saville Kent had in the Manchester Aquarium a number of young herrings, which were so tame as readily to take their prepared food from the hand of a keeper. But a large number of the fishes were found dead each morning, a fact which seemed inexplicable, considering their quiet behavior during the day. A night inspection, however, revealed the cause of this rapid destruction. It was found that the nocturnal movements of the herring, at least in confinement, are altogether different from their movements in daylight. In the latter case, these movements are quiet and uniform, the fish swimming around their tank in one shoal and one continuous stream. At night, on the contrary, the shoal is entirely broken up, each fish taking an independent path, and darting from one side of the tank to the other with surprising agility. It was during these active nocturnal movements that the fish struck against the rockwork of the tank and came to an untimely end; this mortality, however, was soon arrested by placing a dim light over their tank, which illuminated the outline of the rockwork just sufficiently to enable them to recognize and avoid it. With this dim light the fish still retained their active habits, and it was noticeable that during these night-hours they were more than ordinarily alert for food, dashing vigorously at any entomostracan or other minute organism that passed through the water. This circumstance would seem to explain why "drift-net" fishing for herrings can be carried on successfully only at night, that being the time when the fish rise to the surface of the water to feed on the innumerable organisms that there abound.


Prof. Mayer on Sound.—Prof. Mayer, of the Stevens Institute of Technology, read at the late meeting of the Academy of Sciences a paper on the "Sensations produced by Concurrent and Rapidly-succeeding Sounds," a synopsis of which appears in the Tribune. The author showed how certain sounds extinguish the sensation of other sounds. The rule appears to be that, while low sounds cannot extinguish high ones, high sounds may obliterate low ones. He had been led to this course of observation by noticing that the click of a noisy clock was, at certain intervals, silenced if a watch was held to the ear. These intervals of silence, he ascertained, occurred when the sharp tick of the watch and the low click of the clock were simultaneous. Then by various and elaborate devices he satisfied himself, not only of the general fact, but as to what balancing of intensities was requisite. Prof. Mayer proceeded to demonstrate the application of the rule to musical sounds. This he made plain to the Academy by means of apparatus producing a certain low note from a wind-instrument simultaneously with the same note several octaves higher and of greater intensity. The high note killed, so to speak, the low one. But, on the other hand, a low note of great intensity was powerless to extinguish a faint high note: the high note utterly refused to be drowned by any volume of the lower sound.


Ancient Condition of Great Salt Lake.—According to Prof. G. K. Gilbert, of Wheeler's Expedition, the Great Salt Lake of Utah anciently had an outlet northward, the overflow being carried to the ocean by the Columbia River. But the Great Salt Lake was then a great inland sea, as is evidenced by the existence of an ancient beach 970 feet higher than the Great Salt Lake of to-day, and 700 feet higher than Sevier Lake. The subsequent changes of level are described as follows by Prof. Gilbert in the American Journal of Science: "From the upper beach the water slowly subsided by desiccation, recording its lingerings in a series of fainter shore-lines. When it had fallen to the level of the divide between the Sevier and Salt Lake Basins, it was separated into two unequal portions. In one of these the evaporation exceeded the inflow from rivers, and the subsidence continued; in the other the inflow exceeded the evaporation, and the surplus was discharged over the divide into the former portion, just as the surplus of Utah Lake is now discharged into Great Salt Lake. In the course of time, as the climate became drier, this overflow ceased, but not until it had carved a channel of some magnitude. This channel is crossed by the old overland stage-route, and is known as the Old River-Bed." It is the opinion of Prof. Gilbert that the humid climate which was marked by this inundation of Utah was preceded by one as arid as the present, and that the humidity was a phenomenon of the Glacial epoch. A fuller statement and discussion of the facts will appear in the forthcoming geological volume of the "Reports of Wheeler's Surveys."


Spontaneous Hypnotism.—A case of spontaneous hypnotism is described by Dr. Bouchut in Les Mondes. A little girl of ten had been apprenticed five months to the business of making waistcoats. One day, after a month of steady but not excessive work, and while sewing a button-hole, she became unconscious and slept for one hour. On awaking, she resumed her work, but with the same result. This hypnotism did not occur with any other kind of sewing. The case having now come under the notice of M. Bouchut, he gave the girl a buttonhole to sew. She had hardly sewn three stitches when she sank from her chair on the ground, and fell fast asleep. M. Bouchut raised her up, and noted catalepsy of the arms and legs, dilatation of the pupil, slowness of pulse, and complete insensibility. She slept for three hours. Next day he made a similar experiment, when the girl slept only one hour. While no other kind of sewing could affect the girl in this way, M. Bouchut found that he could produce hypnotism by causing her to look intently on a silver pencil held at the distance of ten centimetres from the root of her nose. The case evidently was one of Braid's hypnotism, only occurring spontaneously, and not brought on by way of experiment.


Periodic Movements of the Foliage of Plants.—The Abies Nordmanniana, a coniferous tree now widely diffused on account of the elegant coloration of its leaves, appears to bear uniformly whitish foliage, when observed in the morning or toward evening, but when observed in the middle of the day the green tint seems general. The reason of this difference is found in the fact that the position of the leaves on the branch is different in the daytime from what it is at night; in the former case the leaves are spread out upon the branch and present their upper surface, producing the greenish aspect of the foliage; during the latter period, on the contrary, it is the lower or whitish surface that is presented to the observer. Thus there is a diurnal and a nocturnal position. As the day declines, the leaves, which at noon were horizontal, are seen gradually to erect themselves upon the branch, often becoming nearly perpendicular to it, and this movement of erection is accompanied by a movement of torsion in the basal part of the leaf, often traversing an arc of 90°.


Treatment of Lunatics by Colored Light.—Medical journals give an account of experiments recently made by Dr. Ponza, director of the lunatic asylum at Alessandria, Piedmont, to determine the influence of the solar rays on brain-diseases. Dr. Ponza, having communicated his views to Father Secchi, was encouraged to study the subject. In his letter to Dr. Ponza, the Roman astronomer expressed the opinion that the violet rays are of special importance. "Violet," he writes, "has something melancholy and depressive about it; perhaps violet light may calm the nervous excitement of maniacs." He then advises Dr. Ponza to perform his experiments in rooms with stained-glass windows, and with the walls painted of the same color as the glass panes. One patient, who had been affected with morbid taciturnity, became gay and affable after spending three hours in a red chamber; another, a maniac who refused all food, asked for breakfast after having staid twenty-four hours in the same red chamber. In a blue chamber a highly-excited madman became calm in one hour. A patient was made to pass the night in a violet chamber; on the following day he felt himself cured, and has been very well ever since.


Unhealthy Trades.—Among the lectures delivered by Dr. Richardson before the London Society of Arts, on "Unhealthy Trades," is one devoted to the "Industrial Diseases of Workers in Earthenware." He shows from the official statistics that potters are among the three sections of the population of England who represent the lowest vitality. The males of fifteen years and upward die at the rate of 38 per cent, above the males of all ages; and the commencement of this increased mortality is at the period when the men are approaching their prime of life, namely, at thirty-five years, and it extends onward to the end of life. Thus where in the general population 100 males of thirty-five years die, a proportion equal to 154 potters dies. For the four subsequent increments, namely, forty-five, fifty-five, sixty-five, and seventy-five years, for 100 deaths in the general male population, the deaths among male potters are proportionately 182, 181, 192, 141. The wages of the potters are good, and the labor not physically severe on healthy, fully-developed persons. The special diseases incident to this kind of employment are bronchitis with "potter's asthma," pulmonary consumption, and lead paralysis. Subsidiary to these are rheumatic affections and affections of the stomach. The special causes of disease are: variations of heat and cold, and constant inhalation of dust; these causes produce chronic bronchitis and asthma. The paralytic diseases are induced by lead; of these diseases the victims are the dippers and the women who assist them. "Could we," remarks Dr. Richardson, in conclusion, "relieve the earthenware manufacturers from the two grand causes of disease to which they are exposed, dust and lead, though some generations would be required in order to restore them, as a community, to perfect vitality, there is no reason why their death-rate should not, at once, be reduced to at least half its present excess, and the steady progress of their vital regeneration be immediately commenced."


Effects of Cold on Milk.—The effect of cold upon milk has been made a subject of experiment by M. Eugène Tisserand, who finds that if cow's milk is immediately, or soon after being drawn, placed in vessels at various temperatures between freezing-point and 90° Fahr., and the initial temperature maintained for twenty-four or thirty-six hours, the nearer the temperature of the milk is to freezing-point the more rapid is the collection of cream, the more considerable is the quantity of cream, the amount of butter is greater, and the skimmed milk, the butter, and the cheese, are of better quality. These facts, he believes, may be explained by Pasteur's observations on ferments. It is probable that the refrigeration arrests the development of living organisms and hinders the changes due to their growth. The facts stated indicate room for great improvement in the methods of storage and preservation of milk. To keep milk at its original quality, extreme cleanliness and a low temperature are absolutely necessary. In the north of Europe the value of cold is already recognized, and in warmer climates the need of its assistance is greater.


Coal-Gas as a Fuel.—The use of coal-gas in the place of gross fuel for the purposes of heating and cooking is rapidly coming into public favor in England. In this country the high price of gas is doubtless the principal reason why this most convenient form of fuel has not been more widely adopted, in the place of coal. The advantages of gas are manifold, and are clearly set forth in a paper read by Mr. John Wallace at a meeting of the London Society for the Promotion of Scientific Industry. First, we can absolutely control the amount of gas consumed and the degree of heat produced. In cooking, this control of the degree of heat is of the utmost importance: too quick or too slow a fire must result in bad cooking. Now, the heat of a coal-fire is very irregular, and is liable to be affected by so many circumstances that constant attention is required to keep it in the proper condition for delicate operations. Then, in point of cleanliness and facility of application, gas-stoves are far superior to coal-stoves. "The increasing cost of household labor," adds Mr. Wallace, "renders it highly probable that the same measure of success awaits the domestic application of gas as has already established the sewing-machine among our household gods. It is to be hoped that among the numberless schemes of gas-manufacture which have recently been made public we may soon be provided with a gas which shall be sufficiently cheap and plentiful to be used not only for lighting and heating in private dwellings, but also for trade and manufacturing purposes in workshop and warehouse."


Toxic Action of Putrid Blood.—The influence of various conditions upon the toxic property of blood has been investigated by V. Feltz, whose results, as communicated to the Paris Academy of Sciences, are briefly stated in the Lancet. He first determined the effects on a healthy dog. The injection of from one to three cubic centimetres caused all the symptoms of intense blood-poisoning in from three to eight days. Exposure to the air for periods of 24 to 96 hours made no difference in the toxic properties of the blood; exposure to compressed air for 24 to 144 hours was also without effect. Exposure to oxygen had different results, according to the time of exposure. Contact with oxygen for from 6 to 72 hours had no effect. Animals injected with blood which had been exposed to oxygen for 96 to 216 hours recovered after five or six days' illness. The result was the same with blood through which a continuous stream of oxygen was passed. A very similar effect was produced by exposure of the blood to a vacuum for many hours. A second series of experiments was to determine the influence of time on poisonous material. When the putrefied blood was kept so long that no living bodies could be discovered in it by microscopical examination, the same toxic effects were produced by its injection, but were less intense. Putrefied blood was then dried by slow exposure to the air, powdered, mixed with distilled water, and injected. The effects were not, as in the other cases, immediately manifest. After four to six days of incubation, the animals became ill; some died, others recovered. M. Feltz concludes that, as exposure to a vacuum and desiccation did not remove the toxic agent, it cannot be a gas; that activity on the part of the minute moving particles within it is not necessary for its septic effect; and that the development of bacteria, etc., in the blood of the animals injected, points to the germs of those bacteria as being the probable efficient means of the production of the poisonous effects.


Ostrich-Farming.—Ostrich-farming has within the past few years attained a remarkable development in South Africa. We present to our readers a few notes upon this new industry, taken from an address by Mr. P. L. Simmonds before the London Society of Arts. The climate in all parts of the Cape Colony is said to be alike favorable to the growth and production of the ostrich, and there are but few districts of the colony where this industry is not carried on. Mr. A. Douglas, of Hilton, appears to have been the first systematic breeder of ostriches in the Cape Colony. About eight years ago he bought a pair of birds, and subsequently added four more, making in all two cocks and four hens. By means of an incubator he succeeded in raising from these six birds 130 young ostriches in one season. The ostrich-farm of Mr. Kinnear, of West Beaufort, consists of eight acres of land, inclosed with fences. In this inclosure, which is sown with lucern, thirty ostriches are kept. There are two methods of obtaining the feathers, plucking them, and cutting them a little above the roots, which are removed two months afterward. Mr. Kinnear prefers the latter mode. The first plucking takes place when the bird is about eight months old, but the feathers are then not of much value. The operation is renewed every eight months. Three pluckings of birds in full plumage realized to Mr. Kinnear £240, or £120 per annum, that is, £8 per bird.

In the wild state, five female ostriches are often attached to one male, and they all lay their eggs in one nest, and sit on them in turn. Mr. Kinnear, however, only assigns one female to each male. They are coupled in July (the second month of winter), and commence laying in August, and continue laying for about six weeks, after which they sit till October. A month or six weeks later, they recommence to lay for about five weeks, provided the young brood are removed. In forming the nest—a large hole scraped in the sand—the male bird is most assiduous, and when all is ready the laying of the eggs commences. From fifteen to twenty eggs are laid and carefully arranged in the nest. The male bird usually sits by night, the female morning and evening; in the wild state the birds frequently leave the nest untended during the heat of the day.

Ostriches are, comparatively, inexpensive to keep, as during three-fourths of the year they require only a little artificial food, the grass produced on the farm being nearly sufficient for their maintenance; during the remaining fourth, they only need some supplemental supplies of green food, with a little Indian-corn. Each ostrich eats about twenty pounds of lucern a day.


Culture of the Cochineal Cactus.—The culture of the cochineal cactus was introduced into the Canary Islands in 1840. This plant, as indicated by its name, is the favorite food of the cochineal insect, whose body furnishes the well-known dyestuff cochineal. The culture developed rapidly, still for some years the supply of cochineal fell short of the demand. In 1848 prices varied from eleven to twelve francs per pound Spanish, the cost of production not exceeding 25 per cent, of this sum. A "cochineal mania" was the result, and all other crops had to give way before cochineal. Prices began to fall under the influence of this excessive production, and from 1860 to 1870 the cochineal sold for five to six francs, and there has been a steady decline ever since. In 1870 the price was four francs, in 1871 3.50 francs, in 1872 three francs, in 1873 2.50 francs. There is now a very general disposition to abandon this culture, and since 1872 the amount produced has been growing less from year to year. This decline is also, in a great measure, due to the introduction of new dyestuffs of mineral origin.


Detection of Arsenic in Organic Matter.—Dr. Armand Gautier proposes a new method for separating arsenic from animal matters, and for detecting its presence. By combining the sulphuric-acid and the nitric-acid processes he has obtained very satisfactory results, as regards both the rapidity of the operation and the exactness of the determinations. He first treats the matter supposed to contain arsenic with nitric acid, then with sulphuric acid, and finally with nitric acid again. By the first operation the organic substances are disaggregated; by the second they are destroyed very rapidly, and by the third, with the addition of more nitric acid, the last traces of organic matter are eliminated, while the formation of sulphide of arsenic is prevented. Having made a number of quantitative experiments, M. Gautier never met with a discrepancy amounting to so much as one-tenth of a milligramme between the amount of arsenic introduced and that found.


Timidity of Birds.—Dr. J. G. Cooper, in the Naturalist, comments on the "sociable and confiding disposition" of the birds of the Western United States, compared with the same species eastward. This difference, he remarks, has been noticed by several writers, but the reasons have so far been scarcely mentioned. According to the author, the chief reason is that in the West bird-collectors and idle boys are less numerous, while sportsmen find larger game so plenty that they do not waste ammunition on small birds. Besides this, the prevalence of prairies over most of the Western region makes any garden full of trees and shrubs a rare nursery for the woodland species, where they find more protection from hawks and weasels than in their native groves, while they may also levy a small contribution on the fruits in return for the insects they destroy, and their lively songs. In California, the poison intended for ground-squirrels has also destroyed millions of birds about the fields, and left them unhurt in gardens.


Fattening Oysters.—Salt oysters, on being transferred to fresh water, are "fattened" in the course of two or three days; if allowed to remain longer they become lean again, and are flavorless. Prof. Persifor Frazer, of the Academy of Natural Sciences of Philadelphia, holds that this change cannot be due to an increase of flesh, and attributes it rather to a simple distention of the tissues, owing to the admission into them of a greater quantity of fluid. During the oyster's period of growth on the sea-coast, its tissues are constantly saturated with the ocean-brine; on removing the animal to merely brackish or to fresh water, the conditions are at once favorable for osmose to be commenced. The fresher and less dense liquid without permeates inward more rapidly than the more saline and denser liquids within escape, and the effect is to swell the tissue, as a cow's bladder half filled with air and immersed in a vessel of hydrogen is swollen, or still more nearly like the swelling of a bladder half filled with copper sulphate when immersed in water. "It is worth while to inquire," adds Prof. Frazer, "whether means could not be devised to effect this fattening while yet not depriving the oyster of the salty flavor which is its chief charm to many consumers. Perhaps an immersion in concentrated brine for several days and its subsequent removal to ocean-water would suffice."


"Shooting-Stars."—We make a few selections from an interesting paper on "Shooting-Stars," by Prof. C. A. Young, published in the Boston Journal of Chemistry. These shooting-stars, he says, are very small, for the most part weighing certainly not more than a few grains, and possibly only some thousandths of a grain mere particles or cloudlets of dust, which are traveling in space under the same laws as those which govern the motions of the planets and comets, and with a velocity as great. Their least velocity is more than thirty times that of a cannon-ball. When they encounter our atmosphere, this velocity is destroyed by the resistance, and, according to well-known laws, their energy of motion is converted into heat of intensity sufficient to render them incandescent, and even to dissipate any solid portions in vapor. Their numbers are very great. About forty per hour is a fair average for one station, or nearly one thousand each day. If the calculation is carried out for the whole earth, allowing that at each station all are observed which come within a circle two hundred miles in diameter, the total number reaching the earth daily is found to be about five million; indeed, Prof. Newton, who is perhaps the highest authority on this subject, sets the number still higher, at seven and a half million. A curious fact is, that the hourly numbers increase from sunset to sunrise by some fifty per cent. The reason is simply that in the evening we are, so to speak, behind the earth as it rushes through space, and see only those which overtake us; in the morning, on the other hand, we are in front, and see all we meet, as well as those we overtake.

The most remarkable discovery of recent times in respect to these bodies remains to be mentioned. It is found that in four well-marked cases the orbits of important meteoric swarms coincide exactly with the orbits of well-known comets; that the swarm of meteors follows in the wake of the comet and is somehow connected with it. The discovery dates from 1866, when Schiapparelli first proved the connection between the Leonids (November meteors) and Temple's comet. Since then the same thing has been shown of the Perseids, Lyrids, and Bielids.


Cause of the Aurora.—According to Groneman's hypothesis, an account of which is given in the Academy, there are streams of minute iron particles circulating around the sun like the well-known meteor-streams, and these, when they come near the earth, are attracted by its poles, and form filaments stretching out into space, in the same way as iron-filings, sprinkled on paper, arrange themselves in lines under the influence of a magnet underneath, each particle attracting the next by virtue of its induced magnetism. Groneman refers the phenomenon of the aurora to the ignition of this cosmical iron-dust in its passage through air, the distinction between this and an ordinary meteor-shower being that, on account of the filamentous arrangement of the particles in the direction of the dipping needle, streamers are formed, which by an effect of perspective appear to radiate from a point in that direction, and therefore nearly overhead. It is necessary to suppose that this meteor-stream is traveling nearly in the same direction as the earth, and Groneman enters into elaborate calculations to show that the velocity of the particles would not be too great to permit the magnetic attraction to form filaments of 200 miles in length.


Dr. Roberts on Spontaneous Generation.—Dr. William Roberts, of Owens College, Manchester, whose experiments were quoted by Dr. Bastian, in a recent communication, as favoring the doctrine of the spontaneous generation of bacteria, contradicts this interpretation of the results of his investigations. "On the contrary," writes Dr. Roberts, "the weight of my experiments is entirely against him" (Bastian), "and in favor of Pasteur's conclusions. It appears to me," he adds, "that the attitude of Dr. Bastian on the question of the origin of bacteria arises from what I may call the inverted significance which he attaches to the two contrasted results—barrenness or fertility—which follow after boiling an organic infusion. Throughout the controversy Dr. Bastian speaks of the barren tubes and flasks as 'failures,' or 'negative results;' and he evidently regards the fertile tubes and flasks as 'successful' experiments, having the force and authority of 'positive' results. The true view is just the reverse of this: it is the barren flask that has the character of a positive result. For what does the experimenter set himself to do in these experiments? He seeks to destroy, by boiling, all preëxisting bacteria in these infusions, and to leave unimpaired their powers of promoting the growth of bacteria. And it is found, in fact, that this latter quality is perfectly preserved in boiled infusions; for they breed bacteria with the utmost luxuriance when they are reinfected from an extraneous source. . . . When I take up one of the flasks or bulbs which have remained barren in my chamber for three or four years, though supplied with air (filtered through cotton-wool) and suitable heat, my wonder never ceases. Each one is a new experiment, every day repeated, and multiplied indefinitely; day after day I ask myself, 'Why does it not germinate?' I compare it to a field in spring not yet sown, but ready for the reception of the. seed: for if I withdraw the plug of cotton-wool and admit the dust of the air, or introduce a drop of water, all is changed; in a few hours the stillness of years gives place to life and activity. I repeat, it is the fertile flask, and not the barren flask, that wears the complexion of a failure and of a negative result."