A Temperature Scale for Tungsten

Temperature variation of the resistance of tungsten from 273°K to 3655°K.—In the range from 273°K to 1500°K measurements were made of the resistance of coils of pure, well-aged, tungsten filaments (diam. 2.61 mils) placed in the center of a constant temperature compartment of an alundum resistance furnace through which a stream of pure dry hydrogen was continuously passed. Temperatures were measured by a carefully standardized chromelalumel thermocouple. In the range 1200°K to 3655°K tungsten filaments (V shape, length 40-50 cm, diam. 2.61, 5.00 and 9.85 mils) were mounted in lamp bulbs and their resistances measured. Temperatures were determined by pyrometering against a standard lamp. The specific resistance of tungsten was found to vary from 5.00×${10}^{-6\mathrm{}}$ ohm cm at 273°K to 117.1×${10}^{-6\mathrm{}}$ at 3655°K.

Temperature variation of the rate of radiation from tungsten filaments.—Lamps of the above type were also used to determine the variation with temperature of the energy radiated per ${\mathrm{cm}}^2$ of the tungsten filaments. Temperatures from 300°K to 1500°K were measured by the resistance method, from 1500°K to 3655°K by the optical pyrometer. The rate of radiation varied from.000016 watts/${\mathrm{cm}}^2$ at 300°K to 399.4 at 3655°K.