Far Ultraviolet Spectroscopic Explorer observations of interstellar gas toward the Small Magellanic Cloud star Sk 108

We discuss the interstellar absorption lines found in Far Ultraviolet Spect roscopic Explorer spectra of the Wolf-Rayet binary Sk 108, which is located in the northeastern part of the main "bar" of the Small Magellanic Cloud. The spectra cover the 988-1187 Angstrom wavelength range at a resolution of about 12,000 and a signal-to-noise ratio of 20-40. We use detailed compone nt information from higher resolution near-UV and optical spectra to model the far-UV lines of similarly distributed species. Both the Galactic and SM C gas toward Sk 108 seem to be predominantly neutral, although a significan t fraction of the SMC gas is ionized. The column densities of P II, S II, a nd Ar I are consistent with essentially solar ratios, relative to N(Zn II), in both the Galactic and SMC gas; the column density of N I remains somewh at uncertain. Molecular hydrogen is present in the Galactic gas, with prope rties similar to those found in low mean density Galactic lines of sight an d in the Galactic gas toward several other LMC and SMC stars. We report a t entative detection of H-2 in the SMC gas for J = 1 and 3, with rotational l evel populations consistent with an excitation temperature on the order of 1000 K-similar to the H-2 found in diffuse Galactic gas toward zeta Puppis. Strong absorption from N III, S III, and Fe III has revealed a significant ionized component, particularly in the SMC; O VI is present, but relativel y weak, especially in the Galactic gas. The N(C IV)/N(O VI) ratio varies so mewhat within the SMC, suggesting that several processes may contribute to the observed high ion abundances.