  We investigate the question whether the (I)-envelope of any subset of a dual
to a Banach space $X$ may be described as the closed convex hull in a suitable
topology. If $X$ contains no copy of $\ell^1$ then the weak topology generated
by functionals of the first Baire class in the weak$^*$ topology works. On the
other hand, if $X$ contains a complemented copy of $\ell^1$ or $X=C([0,1])$ no
locally convex topology works. If we do not require the topology to be locally
convex, the problem is still open. We further introduce and compare several
natural intermediate closure operators on a dual Banach space. Finally, we
collect several intringuing open problems related to (I)-envelopes.
