  We used a torsion pendulum containing $\approx 10^{23}$ polarized electrons
to search new interactions that couple to electron spin. We limit CP-violating
interactions between the pendulum's electrons and unpolarized matter in the
earth or the sun, test for rotation and boost-dependent preferred-frame effects
using the earth's rotation and velocity with respect to the entire cosmos, and
search for exotic velocity-dependent potentials between polarized electrons and
unpolarized matter in the sun and moon. Finally, we find that the gravitational
mass of an electron spinning toward the galactic center differs by less than
about 1 part in $10^{21}$ from an electron spinning in the opposite direction.
As a byproduct of this work, the density of polarized electrons in Sm$ $Co$_5$
was measured to be $(4.19\pm 0.19)\times 10^{22} {\rm cm}^{-3}$ at a field of
9.6 kG.
