  We make new Non-LTE calculations to deduce abundances of neon from
visible-region echelle spectra of selected Ne I lines in 7 normal stars and 20
HgMn stars. We find that the best strong blend-free Ne line which can be used
at the lower end of the Teff range is 6402 A, although several other
potentially useful Ne I lines are found in the red region of the spectra of
these stars. The mean neon abundance in the normal stars (log A =8.10) is in
excellent agreement with the standard abundance of neon (8.08). However, in
HgMn stars, neon is almost universally underabundant, ranging from marginal
deficits of 0.1-0.3 dex to underabundances of an order of magnitude or more. In
many cases, the lines are so weak that only upper limits can be established.
The most extreme example found is upsilon Her with an underabundance of at
least 1.5 dex. These underabundances are qualitatively expected from radiative
acceleration calculations, which show that Ne has a very small radiative
acceleration in the photosphere and is expected to undergo gravitational
settling if mixing processes are sufficiently weak, and there is no strong
stellar wind. According to the theoretical predictions of Landstreet et al.
(1998), the low Ne abundances place an important constraint on the intensity of
such stellar winds, which must be less than $10^-14 M_sun per yr if they are
non-turbulent.
