  We investigate some properties of balayage, or, sweeping (out), of measures
with respect to subclasses of subharmonic functions. The following issues are
considered: relationships between balayage of measures with respect to classes
of harmonic or subharmonic functions and balayage of measures with respect to
significantly smaller classes of specific classes of functions; integration of
measures and balayage of measures; sensitivity of balayage of measures to polar
sets, etc.
