Filaments, Electric Lamp

Baron Auer von Welsbach, 1858-1929. Austrian chemist and chemical technologist. Discoverer of praseodymium and neodymium. Inventor of the Welsbach gas mantle, the osmium filament electric lamp, and the automatic gas lighter. 

This material has been known for many years, being used originally in the making of electric lamp filaments. In principle vulcanised fibre is produced by the action of zinc chloride on absorbent paper. The zinc chloride causes the cellulosic fibres to swell and be covered with a gelatinous layer. Separate layers of paper may be plied together and the zinc chloride subsequently removed to leave a regenerated cellulose laminate. 

Incandescent lamps consist of glass bulbs that enclose an electrically heated filament that emits light. For over 50 years prior to Thomas Edison s success, scientists had experimented with developing electric lamps. With financiers such as J. P. Morgan and the Vanderbilts, Edison founded the Edison Electric Light Company in 1878 with the prime mission to generate cheap electric power to provide an illumination source. For the filament of his electric lamp, Edison reportedly experimented on 6000 different types of materials, eventually narrowing his focus on fine platinum wire and a mix of 10% iridium with platinum. Unfortunately,... 

Unalloyed tungsten has several major applications. An important use is in the electric lamp filaments for light bulbs. Also, it is used as electrodes in arcwelding, in heating elements for high-temperature furnaces, in electron and television tubes, in glass-to- metal seals, and in solar energy devices. 

Niobium and tantalum suddenly received considerable attention about the year 1905 as possible materials for the filaments of incandescent electric lamps in place of the carbon filament then in use The metals were then prepared in the pure state for the first time by Dr Werner von Bolton,6 and their properties were examined. Niobium was found to be unsuitable for the purpose in view, but tantalum proved to be satisfactory. Tantalum lamps were manufactured in large quantities between the years 1905 and 1911, when the metal was displaced by the electrically more efficient tungsten. 

FILAMENT. The resistive element (I) in a common electric lamp and (2) in a thermionic tube through which current is passed to provide the temperature required for thermionic emission. The surface of the filament may supply the emission, or the filament may be employed as a heater for an indirectly heated cathode. 

Uses.—Osmium has been used in the manufacture of filaments for certain electric lamps on account of its high infusibility, for, next to tungsten, it is the most refractory of metals. 

The metal is used in toughening steel and for supporting tungsten filaments in electric lamps and other devices. It burns in oxygen at red heat ... 

In 1905 niobium and tantalum received commercial attention, as possible material for electric lamps filaments to replace the fragile carbon then in use. Niobium was soon found to be useless, but tantalum with a melting point of 2850° C proved valuable, and was extensively used during 1905 to 1911. In 1910 the National... 

---