In this paper we show that
if X is a Banach algebra and X0 is its Gelfand subalgebra, then the set X0∗ of the
elements in X0 with compact spectrum is a Gelfand algebra whose maximal ideal
space is compact in the Gelfand topology. We also give a representation
theorem for X0∗, which we use to derive the Van der Put characterization of
C-algebras.