REVOLUTION IN ELECTRIC LIGHTING.

West Coast Times, 12 June 1912, Page 1

REVOLUTION IN ELECTRIC LIGHTING.

TUNGSTEN ORE,

Within tho last three years electric lighting has been revolutionised by tho introduction of tungsten in place of tho old style carbon filaments which had been previously used in incandescent lamps. This change of tungsten meant that for tho same candle power, only onc-third as much current wms consumed, as the carbon filament lamp which made electricity to compete and practically drive out any other system of illumination. Until recently the tungsten filaments were made by preste ing fine metallic tungsten through diamond dies, this being known as the pressed filament. The filament wms verj brittle, and the least vibration would cause it to break and thus destroy tho use of tho lamp. It was supposed that one of tho inherent characteristics of tungsten was brittleness as with the most defined methods of analysis brittleness was always present. After exhaustive research work a method has at last boon found by which it is possible to draw tungsten into wire as fine as one-thousandth of an inch in diameter, and to change its character from brittleness into a now form ol tungsten heretofore unknown to science. The wire is ductile and its tensile strength is far superior even to piano steel wire, that of drawn wire tungsten of ono and a half thousandth inches diameter being approximately 500,0001b5. per square inch. The new discovery has opened up fields of scheelitc, as new uses for this metal will increase very rapidly now. In connection with tho electric lamp industry the new drawn wire lamps are finding a field in the places where the pressed filament will not stand tho vibration, Tho British-Thompson-Houston Company of Rugby, England, are ono of the largest lamp manufacturer in tho world, and they are now using tho now filaments in their tungsten lamps. Those lamps are being sold under the trade name of Mazda. Those new lamps can now bo obtained from Messrs!, Drown B’ros., electrical engineers, Christchurch. No doubt it will surprise many of our readers to learn that a largo proportion of tungsten (seheelite) used in tho manufacture of the filament referred to is exported from the Mairae district, Contra! Otago. Not only is tungsten used for oloctrio lighting purposes, but it also played an important part in tho manufacture of tungsten steel tools used in nearly' every fac tory in the world; motor cars, flying machines, gas mantles, armament, and in every article whore toughened steel is required. Tho vast mineral resources of the Mairae district are only just becoming known. There is a belt of seheelite twenty-five miles in extent, that recently has been taken up to Canterbury gentlemen, who have proved the -stability of the tungsten oro reefs in the district, and find them highly payable propositions. The'oro has been exported to tho Krupp Company, Germany, where tho price of seheelite lias been steadily rising in price during tho last three yeors until it has reached £l2O per ton pure scheelite. Tins is accounted for by the fact that tiio world’is supply being limited, the largest deposits known in the world have been found at Mairae about fifteen miles from Palmerston South, where seheelite and goldmining is really in -its infancy. As showing tho extraordinary value of these reefs, pure seheelite is being obtained from the Golden Bar Company, Limited’s mine, ami exported direct to Germany without the necessity of being crushed or separated in the ordinary process. An inspection of the wonderful filaments at Messrs Brown Bros., establishment, Christchurch, indicated that tho lamps aro a remarkable improvement upon those hitherto utilised.