  We discuss the possibility of extraction of energy from a single heat bath in
a cyclic process, under some special initial conditions. We give an explicit
example in which a system initially prepared in a microcanonical ensemble, is
able to perform such operation. The example is similar to the Szilard engine,
but the microcanonical initial condition allows us to design a protocol where
measurement is not necessary. We also discuss the limitations and possible
extensions of this microcanonical Szilard engine.
