  We measured the electrical resistivity, $\varrho(T)$, of superconducting
CaC$\_6$ at ambient and high pressure up to 16 GPa. For $P \leq$8 GPa, we found
a large increase of $T\_c$ with pressure from 11.5 up to 15.1 K. At 8 GPa,
$T\_c$ drops and levels off at 5 K above 10 GPa. Correspondingly, the residual
$\varrho$ increases by $\approx$ 200 times and the $\varrho(T)$ behavior
becomes flat. The recovery of the pristine behavior after depressurization is
suggestive of a phase transition at 8 GPa between two superconducting phases
with good and bad metallic properties, the latter with a lower $T\_c$ and more
static disorder.
