  We consider the experimental properties of superconductors with a gap which
is an odd function of energy $\bepsk=\epsk - \mu$, i.e.\ , a gap which vanishes
everywhere on the Fermi surface; this is done within a in a BCS framework.
Apart from the standard phenomenology (density of states, penetration depth,
NMR, $C_V(T)$, $B_{c2}(T)$), we also look at the stability of the
superconducting state. It is stable to finite supercurrents (although with a
normal fluid density which increases with the supercurrent density), and is
also very weakly affected by non-magnetic impurities. We find two classes of
odd-gap superconductors, which strongly differ in their low-energy properties.
For a certain parameter range, most of the results resemble those for d-wave
superconductors (except for the effect of impurities).
