  We present FUSE spectroscopy of SBS 0335-052, the second most metal-deficient
blue compact dwarf (BCD) galaxy known (log O/H = -4.70). In addition to the H I
Lyman series, we detect C II, N I, N II, O I, Si II, Ar I and Fe II absorption
lines, mainly arising from the extended H I envelope in which SBS 0335-052 is
embedded. No H2 absorption lines are seen. The absence of diffuse H2 implies
that the warm H2 detected through infrared emission must be very clumpy and
associated with the star-forming regions.The clumps should be denser than ~
1000 cm^-3 and hotter than ~ 1000 K and account for > 5% of the total H I mass.
Although SBS 0335-052 is a probable young galaxy, its neutral gas is not
pristine. The metallicity of its neutral gas is similar to that of its ionized
gas and is equal log O/H ~ -5. This metallicity is comparable to those found in
the H I envelopes of four other BCDs with ionized gas metallicities spanning
the wide range from log O/H = -4.8 to log O/H = -3.8, and in Ly-alpha
absorbers, fueling the speculation that there may have been previous enrichment
of the primordial neutral gas to a common metallicity level of log O/H ~ -5,
possibly by Population III stars.
