Emissivity of Small Particles in Flames

IT is a striking fact that solid (or massive) carbon behaves as a black body, whereas small carbon particles which are responsible for the luminosity of hydrocarbon flames have an absorption coefficient which is strongly dependent on wave-length. This difference is important in the measurement of the colour temperature of luminous flames. It has been shown theoretically by Mie 1 that the, absorption coefficient is strongly dependent on wave-length when particles are smaller than a wave-length, an effect which is analogous though not identical with the dependency of scattered light on wave-length.