  The light elements Li, O, Na, Al, and Mg are known to show star to star
variations in the globular clusters 47 Tuc and NGC 6752. Such variations are
interpreted as due to processing in a previous generation of stars. In this
paper we investigate the abundances of the alpha-element sulphur, for which no
previous measurements exist. In fact this element has not been investigated in
any Galactic globular cluster so far. The only globular cluster for which such
measurements are available is Terzan 7, which belongs to the Sgr dSph. We use
high resolution spectra of the S I Mult. 1, acquired with the UVES spectrograph
at the 8.2m VLT-Kueyen telescope, for turn-off and giant stars in the two
globular clusters. The spectra are analyzed making use of ATLAS static plane
parallel model atmospheres and SYNTHE spectrum synthesis. We also compute 3D
corrections from CO5BOLD hydrodynamic models and apply corrections due to NLTE
effects taken from the literature. In the cluster NGC 6752 sulphur has been
measured only in four subgiant stars. We find no significant star to star
scatter and a mean <[S/Fe]> = +0.49 +- 0.15, consistent with what observed in
field stars of the same metallicity. In the cluster 47 Tuc we measured S in 4
turn-off and 5 subgiant stars with a mean <[S/Fe]> = +0.18 +- 0.14. While this
result is compatible with no star to star scatter we notice a statistically
significant correlation of the sulphur abundance with the sodium abundance and
a tentative correlation with the silicon abundance.
