SCIENCE AND INVENTION.

New Zealand Mail, Issue 1425, 22 June 1899, Page 16

SCIENCE AND INVENTION.

THE NEW ELECTRIC LIGHT. According to Messrs Swinburne and Ayrton, the celebrated English chemists, Professor Walter Nernst's incandescent light is one of the greatest discoveries of the age. That Professor Nernst had discovered a new light has been known for some time, although the general details of the invention, or more properly speaking, disco very, were not made public until quite recently. That the incandescent electric lamp now in general use was by no means an ideal one has been fully appreciated by scientists for some time, but in lieu of something better it has been almost universally adopted, and has come to be recognised as a standar dof illumination. The principal objection urged against the incandescent lamp in its present form is that it requires a considerable amount of current to raise the carbon filament to the point of incandescence, In other words, the proportion of the luminous radiation to the total radiation is very small. The experiments which Professor Nernst has been carrying on ior some time were apparently with a view to overcoming these defects, and how well he has succeeded may be gathered from the fact that his new incandescent light is said to require but approximately one-third the amount of energy of an ordinary incandescent lamp. The light recently discovered by the Gottingen professor differs materially from the ordinary form of lamp in that no vacuum and no fragile filament are required. In the place of the filament a rod composed of magnesia or other rare earth ie made use of, which Professor Nernst discovered could be kept in an intensely luminous condition by a very weak current under certain circumstances. The essential point of the invention is that the rod must first be heated above 6000 degrees Fahr. before it becomes a good electrical conductor. Other inventors have from time to time endeavoured to adapt metallic oxides, such as alumina, magnesia, lime, etc., to incandescent lamps, but have invariably failed, owing principally to these substances being such poor conductors of electricity at ordinary temperatures. Of late Professor Nernst has been developing and perfecting his invention, and apparently the principal difficulty yet to be overcome before the invention can be placed upon the market is the procuring of suitable appliances for heating the rod of magnesia to the necessary temperature. With the tenacity of purpose and unquestionable ability possessed by Professor Nernst this last obstacle to the perfecting of an invaluable discovery will undoubtedly be overcome in the near future.

LIQUID AIR. It is certainly surprising (says the “ Century Magazine ” for April) to see the liquid air poured upon ice fiy off hissing like water from hot iron; but when one reflects that the ice is 344 degrees hotter than the liquid, it does not seem so strange; or to see one’s breath, blown into the open can of the liquid, sent back instantly, its moisture congealed into a miniature snowstorm. A jet of steam is frozen as quickly, for steam in the open air is only 144 degrees hotter than the breath, while from the temperature of steam to that of liquid air is a terrible drop of 524- degrees! In this freezing effect probably is found the greatest obstacle to the use of liquid air as a motive power. The moisture of the air is deposited rapidly as ice upon the machine, especially around the orifice from which the jet of extremely cold air emerges. This soon closes the orifice completely and stops the machine. Another surprise is given when the experimenter puts his hand directly into the liquid for a moment. But the sensation is only as of a soft cushion of air about the hand. Such it really is. The heat of the hand forms a layer of vapour or air about the hand, and the liquid air does not come in contact with the flesh. Should the liquid actually touch the flesh a severe injury like a burn results, which some times is months in healing. In a few seconds an egg is frozen so that it requires a hard blow' of a hammer to break it. Probably its germ of life is extinct. Seeds of grain and vegetables have been tested in liquid air. These were all natives of the temperate zone, the seeds of which will pass the winter in frozen earth without loss of vitality, such as barley and oats for grains, and pease, cucumber, and squash for vegetables. They are kept for one hundred and ten hours at 312 degrees below zero, and then slowly thawed for 50 hours. After this treatment they are still alive. On being planted, they germinated and grew 7 . The liquid air boils in a disli (i.e., goes off in vapour) till it has cooled the dish to its own temperature. Its boiling point is 312 degrees below' zero. After this the vapour of air which covers the liquid so retards evaporation that it may be kept eight or ten hours in a can packed only in felt. It lias in this way been carried two hundred and fifty miles from tlie place of manufacture. The cooling effect upon the air of the room is very marked. The writer gave two lectures in one afternoon w'ith liquid air. Said a lady of the second audience, as she entered the lecture-rooom, rr How cold your room is!” Tlie temperature had been lowered ten degrees or twelve degrees by the evaporation of the air used in the first lecture. 411 other liquids are frozen when put into liquid air. Mercury becomes like iron, so that it will drive a nail, hold up a weight, or serve any other purpose as a metal, so long as it is kept frozen. Absolute alcohol soon becomes solid. A tube of liquid air dropped into a glass of water rapidly converts the water into ice.—(Mr Charles E. Tripler, of New York, is now manufacturing liquid air by the gallon.)