Within a homogeneous media such as a solution, there is no scatter.  For this case, the function is linear with both the concentration of the absorbing species and the path-length.  Additionally, the contributions of individual absorbing species are additive.  For samples which scatter light, absorbance is defined as "the negative logarithm of one minus absorptance (absorption fraction: ) as measured on a uniform sample".  For decadic absorbance, this may be symbolized as:     .   Even though this absorbance function is useful with scattering samples, the function does not have the same desirable characteristics as it does for non-scattering samples. There is, however, a property called absorbing power which may be estimated for these samples. The absorbing power of a single unit thickness of material making up a scattering sample is the same as the absorbance of the same thickness of the materiel in the absence of scatter.