We report on the abundance of interstellar neutral nitrogen ( NI ) for 30 sightlines , using data from the Far Ultraviolet Spectroscopic Explorer ( FUSE ) and the Hubble Space Telescope ( HST ) .
NI column densities are derived by measuring the equivalent widths of several ultraviolet absorption lines and subsequently fitting those to a curve of growth .
We find a mean interstellar N/H of 51 \pm 4 { \ > ppm } .
This is below the mean found by Meyer et al . of 62 ^ { +4 } _ { -3 } { \ > ppm } ( adjusted for a difference in f -values ) .
Our mean N/H is similar , however , to the ( f -value adjusted ) mean of 51 \pm 3 { \ > ppm } found by Knauth et al . for a larger sample of sightlines with larger hydrogen column densities comparable to those in this study .
We discuss the question of whether or not nitrogen shows increased gas-phase depletion in lines of sight with column densities { \log { { N { ( H _ { tot } ) } } } } \gtrsim 21 , as claimed by Knauth et al . .
The nitrogen abundance in the line of sight toward HD 152236 is particularly interesting .
We derive very small N/H and N/O ratios for this line of sight that may support a previous suggestion that members of the Sco OB1 association formed from an N-deficient region .