We report interstellar C ii column densities or upper limits determined from weak absorption of the \lambda 2325.4029 Å intersystem transition observed in six translucent sightlines ( A _ { V } \gtrsim 1 ) with STIS .
The sightlines sample a wide range of interstellar characteristics including total-to-selective extinction , R _ { V } = 2.6 - 5.1 ; average hydrogen density along the sightline , < n ( H ) > = 3 - 14 cm ^ { -3 } ; and fraction of H in molecular form , 0 - \sim 40 \% .
Four of the sightlines , those toward HD 37021 , HD 37061 , HD 147888 and HD 207198 , have interstellar gas-phase abundances that are consistent with the diffuse sightline ratio of 161 \pm 17 carbon atoms in the gas per million hydrogen nuclei .
We note that while it has a gas-phase carbon abundance that is consistent with the other sightlines , a large fraction of the C ii toward HD 37061 is in an excited state .
The sightline toward HD 152590 has a measured interstellar gas-phase carbon abundance that is well above the diffuse sightline average ; the column density of C in this sightline may be overestimated due to noise structure in the data .
Toward HD 27778 we find a 3 \sigma abundance upper limit of \leq 108 C atoms in the gas per million H , a substantially enhanced depletion of C as compared to the diffuse sightline value .
The interstellar characteristics toward HD 27778 are otherwise not extreme among the sample except for an unusually large abundance of CO molecules in the gas .