“…The content of material extractable into organic solvents (Table 6) is in the range that is reported (Black and High, 1979;Huisingh et al, 1979;Dietzmann et al, 1980;Gibbs et al, 1980;Gabele et al, 1981) for diesels, as are also optical properties (Pierson and McKee, 1978;, cf. Vuk et al, 1976Scherrer and Kittelson, 1981) and the specific surface areas of particles before and after organic solvent extraction (Frey andCorn, 1967, cf.…”