ROMANCE OF ELECTRIC LIGHTING.

Otago Witness, Issue 3015, 27 December 1911, Page 85

ROMANCE OF ELECTRIC LIGHTING.

One October night, in the year 1781, a German scientist, working in his laboratory bv the light from tallow candles, discovered a metal which he found impossible to melt in his crude charcoal furnace. He called the new metal tungsten, from the Swedish “tung” (heavy) and “sten” (stone), because the heavy ores had come from Sweden. Little did the old man know that his find would one day completely revolutionise electric lighting. Twenty-five years ago the first successful incandescent electric lamp was produced, after the world’s scientists had worked for nearly 50 years to perfect the device, '■'ire filaments for these first lamps were made of carbonised strips of bamboo heated white hot in a vacuum globe by electricity. Subsequently carbonised cotton cellulose was used for the filaments, and it seemed as though the lamp had surely reached perfection. The filaments were made of carbon because no other material could he found which would withstand the intense heat. Every well-known metal was tried, but melted before reaching the required temperatures. Then the Inventors began to experiment with the more uncommon and again a German scientist took up the study of tung-

stem At first the great trouble was to secure pure tungsten. This difficulty was overcome with the aid of an electric furnace; but the product, in the form of a grey metallic powder, proved so refractory that it could not be melted into ingots or drawn out into wire. An experimental filament was mad© by mixing the fine powder with a paste and squirting the mixture through a die, much the same as a spider spins its web. This thread was in turn heated in an electric furnace till the powder was fused into the form of a fine wire. With the melting point of tungsten so much higher than any other known metal it was possible to heat the filament to greater incandescence, producing more and better light, with less waste of current in useless heat. T ] ie " the electrical inventors awoke to the fact that the very substance they were seeking, that which Edison had scoured the world to find, lay under their hand all the time, and tungsten, useless and practically unknown for over a century, came into its own, and began the wonderful task of revolutionising incandescent electric lighting. The advent of the new tungsten lamp, or metallic filament lamp as it is popularly known, was startling to the users of electricity for lighting purposes, for they at once saw that the metallic filament lamp would easily give the same light as the common incandescent limp for one-third the cost. A home that was lighted by electricity for 8s a month could be lighted with the new lamps for 2s 6d. Not only that, but the light from the new tungsten lamps proved to be pure white, very nearly akin to actual sunshine, soft, pleasing, and beneficial to the eyes, and not of a yellow cast like the common incandescent lamps. When the metallic filament lamp made its appearance it was thought the apex of achievement, in incandescent electrical illumination had been reached. Yet the present year has witnessed a still further advance in the manufacture of electric lamps. In the early autumn it was announced that a British firm of electrical engineers had succeeded in rendering tungsten into a ductile form and drawing it into a wire one-thousandth part of a inch in thickness, and were making filaments of electric lamps . out of it. Thus has the last, and perhaps the only, defect of tungsten for electric lamp filaments been remoyed.