  This paper presents new investigations on coherent scattering in the forward
direction (orders of magnitude; conservation of energy; dependence of scattered
light on geometry and wavelength), and on how scattered light contamination in
the spectrum of reddened stars is possibly related to as yet unexplained
observations (the diminution of the 2200 A bump when the obscuring material is
close to the star, the difference between Hipparcos and photometric distances).
This paper then goes on to discuss the fit of the extinction curve, a possible
role of extinction by the gas in the far-UV, and the reasons of the inadequacy
of the Fitzpatrick and Massa [ApJSS, 72 (1990) 163] fit.
