  We are involved in a program to derive properties of broad absorption line
(BAL) winds in quasars using combined UV and X-ray observations.
  A major obstacle is large uncertainties in the derived BAL column densities
because of partial coverage of the background light source. In this preliminary
report, we circumnavigate those uncertainties by making a simple assumption --
that the relative metal abundances are roughly solar. In this case, the PV
1118,1128 multiplet should have at least 500 times lower optical depth than CIV
1549,1551. Nonetheless, a PV BAL is present in at least half of the
well-measured BALQSOs we studied. We conclude that the strong lines of abundant
species like CIV are typically very optically thick. The total BAL column
densities are N_H > 10^22 cm^-2 (for solar overall metallicity), and they might
be comparable to the X-ray absorbers, of order 10^23 cm^-2, if the BAL gas is
sufficiently ionized. If the column densities in outflowing BAL gas are, in
fact, as large as the X-ray absorbers, it would present a serious challenge to
models of radiatively-driven BAL winds.
