  For directions of sufficcient reddening (E(B-V) >~ 0.25), there is a simple
relation between the slope of the extinction curve in the far-UV and E(B-V).
Regardless of direction, the far-UV extinction curve is proportional to
1/lambda^n exp(-2e(B-V)/lambda) (lambda in micron, n = 4), in accordance with
the idea that reddened stars spectra are contaminated by scattered light
(Zagury, 2001b).
  This relation is not compatible with the standard theory of extinction which
states that far-UV and visible extinctions are due to different classes of
grains. In the standard theory model the two (far-UV and visible) extinctions
vary thus independently according to the proportion of each type of grains.
  In preceding papers I have shown that the standard theory cannot explain UV
observations of nebulae, and is contradicted by the UV spectra of stars with
very low reddening: for how long shall the standard theory be considered as the
interpretation of the extinction curve?
