Published online by Cambridge University Press: 12 April 2016
Despite only a few percentages of the interstellar mass are contained in solid dust grains knowledge of its distribution is of importance per se, for dereddening purposes and because it probably correlates with the interstellar gas. General information on the bulk of the interstellar mass is thus obtainable from continuum absorption studies. Compared to diffuse emission data interstellar reddenings have the additional advantage by including an upper distance to the material observed.