An integrating sphere was used to determine the black carbon (BC) content of aerosol filter samples dissolved in chloroform (method originally described by Heintzenberg <1982>). The specific absorption coefficient Ba (equal to absorption per mass) of the samples was also measured using the sphere as an integrating detector for transmitted light. Comparing the Ba of ambient samples taken in Vienna, Austria, to the BC concentrations measured on the dissolved filters, a value of approximately 6 m2/g was found to be a reasonable value for the Ba of the black carbon found at the site. The size dependence of Ba of a nebulized suspension of soot was measured using a rotating impactor, and a reasonable agreement between measured and calculated values was found. ¿ American Geophysical Union 1996