  We observed comets 122P/1995\,S1 (deVico) and C/1995\,O1 (Hale-Bopp) with
high spectral resolving power in order to determine the ratio of N$_2^+$/CO$^+$
in their comae. While we clearly detected the CO$^+$ in both of these comets,
no N$_2^+$ was detected in either comet. From these spectra, we derive
sensitive upper limits for N$_2^+$/CO$^+$. These upper limits are substantially
below other reported detections of N$_2^+$/CO$^+$ in other comets. We discuss
the prior N$_2^+$ detections and compare them with our observations. The
abundance of N$_2$ in comets is important to our understanding of the
condensation of ices in the solar nebula. In addition, N$_2$ is a tracer of Ar
so study of N$_2$ allows an understanding of the role of comets for delivering
volatiles to the terrestrial planets. It appears that many, if not most, comets
are depleted in N$_2$ and it will be necessary to search for a mechanism for
depleting this molecule in order to be consistent with current models of the
solar nebula.
