A New Method for Determining the Temperature of a Luminous Flame.

(Hermann Senftleben and Elisabeth Benedict. Eine Methode zur Temperaturbestimmung leuchtender Flammen. Phys. Ztsch. 19 p. 180, 1918).

The method developed by the authors consists of the following. Into a luminous flame (a Bunsen burner, a Hefner candle, etc.) a thin platinum wire is introduced, through which a current is passed. The deposition of incandescent particles of carbon, which cause the luminosity of the flame, on the wire will obviously continue until the temperature of the latter is below the temperature of the flame. By selecting the strength of the current heating the wire, one can find such a temperature at which the deposition of soot just ceases; at this moment the temperatures of the flame and of the wire are equal. On the basis of the laws of radiation and the known reflecting power of platinum, the temperature of the wire was determined with a Holborn-Lummer pyrometer. Into the results obtained it is necessary to introduce a correction for the radiation of the layer of luminous gas lying between the wire and the pyrometer, and also for its absorption. The magnitude of this correction, found pyrometrically, is very small (not more than 1%). The temperature of a Hefner candle found in this way, 1690°, agrees excellently with the figures found by other methods. The results of measurement, within comparatively wide limits, do not depend on the thickness of the wire introduced into the flame.

S. Vavilov.