  By a spherical gravitating condenser we mean two concentric charged shells
made of perfect fluids restricted by the condition that the electric field is
nonvanishing only between the shells. Flat space is assumed inside the inner
shell. By using Israel's formalism we first analyze the general system of N
shells and then concentrate on the two-shell condensers. Energy conditions are
taken into account; physically interesting cases are summarized in two tables,
but also more exotic situations in which, for example, the inner shell may
occur below the inner horizon of the corresponding Reissner-Nordstr\"om
geometry or the spacetime is curved only inside the condenser are considered.
Classical limits are mentioned.
