  Collisions of ice particles play an important role in the formation of
planetesimals and comets. In recent work we showed, that CO$_2$ ice behaves
like silicates in collisions. The resulting assumption was that it should
therefore stick less efficiently than H$_2$O ice. Within this paper a
quantification of the latter is presented. We used the same experimental setup
to study collisions of pure CO$_2$ ice, pure water ice and 50\% mixtures by
mass between CO$_2$ and water at 80K, 1 mbar and an average particle size of
$\sim 90 \mu$m. The results show a strong increase of the threshold velocity
between sticking and bouncing with increasing water content. This supports the
idea that water ice is favorable for early growth phases of planets in a zone
within the H$_2$O and the CO$_2$ iceline.
