  X-ray diffraction, electrical resistivity, magnetization, specific heat, and
thermoelectric power measurements are presented for single crystals of the new
filled skutterudite compound {\CeOsAs}, which reveal phenomena that are
associated with f - electron - conduction electron hybridization. Valence
fluctuations or Kondo behavior dominates the physics down to $T$ $\sim$ 135 K.
The correlated electron behavior is manifested at low temperatures as a
hybridization gap insulating state. The small energy gap $\Delta$$_1$/k$_B$
$\sim$ 73 K, taken from fits to electrical resistivity data, correlates with
the evolution of a weakly magnetic or nonmagnetic ground state, which is
evident in the magnetization data below a coherence temperature $T$$_{coh}$
$\sim$ 45 K. Additionally, the low temperature electronic specific heat
coefficient is small, $\gamma$ $\sim$ 19 mJ/mol K$^2$. Some results for the
nonmagnetic analogue compound {\LaOsAs} are also presented for comparison
purposes.
