Using the HST Goddard High Resolution Spectrograph ( GHRS ) , we have obtained high S/N echelle observations of the weak interstellar N I \lambda \lambda 1160,1161 absorption doublet toward the stars \gamma Cas , \lambda Ori , \iota Ori , \kappa Ori , \delta Sco and \kappa Sco .
In combination with a previous GHRS measurement of N I toward \zeta Oph , these new observations yield a mean interstellar gas-phase nitrogen abundance ( per 10 ^ { 6 } H atoms ) of 10 ^ { 6 } N/H = 75 \pm 4 ( \pm 1 \sigma ) .
There are no statistically significant variations in the measured N abundances from sightline to sightline and no evidence of density-dependent nitrogen depletion from the gas phase .
Since N is not expected to be depleted much into dust grains in these diffuse sightlines , its gas-phase abundance should reflect the total interstellar abundance .
Consequently , the GHRS observations imply that the abundance of interstellar nitrogen ( gas plus grains ) in the local Milky Way is about 80 % of the solar system value of 10 ^ { 6 } N/H = 93 \pm 16 .
Although this interstellar abundance deficit is somewhat less than that recently found for oxygen and krypton with GHRS , the solar N abundance and the N I oscillator strengths are too uncertain to definitively rule out either a solar ISM N abundance or a 2/3 solar ISM N abundance similar to that of O and Kr .