  In this poster, we present an investigation of a new, preferred diagnostic
tool for the determination of the sulphur abundance of disk stars, see also
Ryde A&A (2006). We are in the process of analyzing a large set of stars both
in the galactic disk and halo (Ryde et al. 2007, in prep.). This diagnostics,
the forbidden sulphur line at 10821 A, is less sensitive to the assumed
temperatures of the stars investigated and less prone to non-LTE effects than
other tracers. It is an intercombination line, an M1 transition between the
triplet ground-state and the first excited singlet state. The E2 transition is
two orders of magnitude weaker. In the investigation presented here, we have
studied a homogeneous set of sub-giant and giant stars ranging from spectral
types of G5 to K4 (effective temperatures of 4000 - 5000 K). The reason why the
[SI] has not been use before is that it lies beyond the reach of normal CCDs.
