Monochromatic intensity measurements are taken in a water-cooled furnace, 20 cm in diameter, burning methanol and a methanol/coal slurry. The primary interest is to determine the contribution of particulate radiation to the total intensity. Temperature, carbon dioxide, carbon monoxide, water, methanol, and particulate concentration levels are quantitatively measured throughout the furnace chamber. A computer code is discussed which integrates the equation of transfer over a nonhomogeneous path containing combustion gases and particulates. This allows comparison of the measured intensity with a theoretical prediction based upon known concentration and temperature profiles. The intensity and emittance measurements from the methanol furnace are compared with measurements in other experimental furnaces burning oil and gas.