SCIENCE NOTES

Otago Witness, Issue 2179, 28 November 1895, Page 54

SCIENCE NOTES

• . • In Paris M. Moi^san baa recently succeeded in preparing fairly large masses of pure molybdenum. The metal thus obtained has a specific gravity of 0, and is only fused with difficulty. The pure metal is quite as soft and a3 malleable as wrought iron, and can be easily forged at a red heat. It can be preserved without oxidation under water for several days. The most remarkable propany of the metal is, however, the fact that it can be cemented like wrought iron, forming a " steel," if the term may be used, which can be tempered similarly to ordinary steel. Moreover, cast molybdenum containing several per cent, of carbon can be Boftened by placing it in a mass of oxide of the metal, just as in the ordinary process of making malleable castings. Having a very great affinity for oxygen, M Moissan suggests that it may be usefully added to the iron in a converter, replacing manganese or aluminium. As the oxide of the matal is volatile, it does not remain in the converter. • . • Professor Wiley says that " one of the grandest discoveries of modern science " is the agency of the microbes In enabling plants to absorb from the air the nitrogen which is the chief factor of their growth, The theory was first suggested by Pasteur, and it Ib thought to be fully nonfirmed by the resesrehea of independent investigators. If it does not deceive expectation it will completely revolutionise agriculture. To increese the growth of plants it will only be necessary to feed their roots with water containing the proper microbes. • . • Messrs Cross, Bevan, and Beadle, who are well known as experimental chemists, discovered some months ago a new class of substances which are derived from cellulose which seem destined to have various industrial applications of a most important kind. Sfco new material can be procured ;

U) At a solution which it is believed will form a substitute for glue, which can be used for oloth sizing, paper sizing, and as a vehiolo for pigment printing. (2) As a dense solid mass having much the appearanoe of ebonite, which can be turned, worked in any direotion, will bear a high polish, and can be used for a variety of articles including insulators. (3) In the form of films or sheets, including a transparent variety which can be used for photographic purposes in lieu of glass. (4) As films or sheets attaohed to cloth, for bookbinding, upholstery, and a variety of purposes. And (5) In a porous state for the manufacture of artificial sponges and other articles. The solution will also lend itself to admixture with various foreign substances, which much increases its usefulness. Full particulars of this valuable new addition to the resources of the manufacturer will be found in the August number of the Journal of the Franklin Institute, Philadelphia.

• . • The old belief that projeotiles sometimes kill men in battle without hitting them must be abandoned in view of recent scientific experiments. It was formerly supposed that the air, compressed and driven before the projectile, and technically called " the wind of the shot," was capable of striking a fatal blow, and even army surgeons have assented to this theory. Bat experiments sliow that the air driven by a projacUla does not possess sufficient energy to produce any destructive effect. Another theory which recent investigations have overturned is that the explosive effect sometimes exhibited by bullets is due to compressed air driven into tho wound. Experiment shows that the appearance of explosion arises from the nature of the substance penetrated by the bullet. If this substance is plastic or watery, the impulse of the projectile is distributed laterally in all directions among its particles, and they are driven asunder. By firing bullets into dough made thoroughly wet, every indication of an explosion has been produced, although the same bullets, fired with identical velocity into a solid substance, such ss a pieca of bone, made only round, clean-cut holes.

' . • The belief that the formation of cloud is often accompanied by electrical effects ie confirmed by Professor Schuster, who deEcribea an experience In Switzerland. As he was descending from Dent Blanche after : sunset, .fee found himself in a wide valley at , a height of about 12,000 ft. A current of air I was apparently blowing up the valley, and ! I below him he observed the formation of a ' cloud at a height a little below the enow line. As night came on, and the descent over the glacier and down the valley was continued, a series of electric discharges were Been between the cloud, which was lying in a deep-cat valley, the sides of the mountain, and the bine eky overhead. The moist air was evidently flowing through the cloud, depositing its moisture in the form of drops, and leaving the cloud in an electrified state. Wherever water rubs against air positive electricity is generated. Bvery wave that breaks icto fpray under the action of a strong wind leaves the water negatively electrified, the air carrying away the positive charge. Professor Schuzter suggests that it would be of great interest to possess observations on atmospheric electricity on board ship while waves are breaking in the neighbourhood. So far we have to guide ns only the observations of Ezner, who found on the Oeylon coast that the spray from breaking waves showed by the electrometer that it was positively electrified. . * The lighting value of acetylene is about four and one-half times that of good coal gas when consumed In the new Welsbach burner. The temperature of tho acetylene name ia less than that of the common gas flame, and the heating effects are mach less. Acetylene can be liquefied by a comparatively moderate preesure. It can be kept in the liquid form and easily converted into gas by reducing the pressure, and is then ready for combustion. On account of tho great saving of space it is probably in this liquid form that it will find most convenient application in many cases of isolated lighting, such as buoys, lighthouses, and perhaps in private dwellings. In this foim it will be specially convenient for ns9 in enriching common ooal ga°, and this will very probably be one of its most immediate applications. Acetylene light is pure white, and it therefore shows more truly the natural colourß of objects. It is now, thought that calcium carbide will be eventually produced at a cost not exceading £1 per ton. If this expectation be realised, acetylene will certainly prove the ideal illuminating gas, if not the ideal illuminant. • . • Green is popularly supposed to be the colour' which best protects the eye, but a German professor denies that it has any beneficial effect whatever, and declares that green newspapers, green glasses, and green umbrellas are all a mistake. His theory is at all events, plausible. It is that each different colour tires a different Bet of. nerves and vision,' and' therefore looking at one particulav colour saves one set of nerves at the expense of another. The besS method, he points our, is to dim all tha rays of light by smoked or grey glasses, which rest all the optic nerves. • . • A curious operation may be seen ia progress at .the works of Messrs Cornell, of New Ydrk, who have erected on the banks of the Hudson river a complete plant for heating and dipping' in the salt water of the ' river steel plates which are intended for bur- ■ glar-proof safes. By this salt-water treat-

meat the plates are rendered harder and bettor in other respects than if they were cooled ia fitah rotter. The building of burglar-proof safes is now curled to a degree of sofoutifio perfection whioh v?fll hardly be oredited. The plates employed are of a compound charaoter, being mado ot alternate layers of hard and soft nootal which are welded together. By snoh a cord> bination the plates will yield neither to drill nor sledge-hammer, and the burglar's efforts to break through them are futile. One safe now being built has an outer cage, made or railroad Iron interlaced, the lasterstices being filled in with Portland osmsnfc. * . ' Dr A. M. Bleile explains the cause of death in eleotric sheck as follows :— Death is due to the fact that the current prodoceo a contraction of the arteries through an influence on the nervous system, and this constriction of the arteries throws in fuoh a mechanical impediment to the flow of blood as the heart is unable to overcome. When Buoh a drug as nitroglycerine or nitrite of amyl Is given to counteract this effect, much larger doses of electricity than the ordinary can be borne. Artificial respiration may be of use in case 3of simple stunning, bat when large quantities of current pass no rational means of resuscitation have as yet been suggested.