  New optical spectra of Ca II and Na I toward HD 72127AB provide additional
evidence for both spatial and temporal variations in the complex interstellar
absorption along the two sight lines; archival UV spectra yield information on
the abundances, depletions, and physical conditions in the gas toward HD
72127A. Similarities in the strengths of various tracers of interstellar
material in the two lines of sight suggest that the total hydrogen column
densities [N(H) ~ 2.5 x 10^{20} cm^{-2}] and the depletions and ionization in
the main components at low LSR velocities also are similar. Toward HD 72127A,
the main components are relatively cool (T < 900 K), but with depletions
resembling those found in warm, diffuse disc clouds; the generally weaker
components at higher velocities have much milder depletions, more like those
found in halo clouds. Several trace neutral species -- Ca I, Cr I, and Fe I --
are much stronger toward HD 72127B, however. The column density of Cr I, for
example, is about 30 times the value determined toward zeta Oph (the only
previous detection of that species in the ISM). Dielectronic recombination in
warmer gas (T > 5000 K) may be largely responsible for the enhanced abundances
of those trace neutral species toward HD 72127B. If the main components toward
HD 72127AB are associated with material in the Vela SNR, the differences in
abundances and physical conditions occur on scales of about 1100 AU.
