  The 3.1 micron absorption feature of water-ice has been observed
spectroscopically in many molecular clouds and, when it has been observed
spectropolarimetrically, usually a corre- sponding polarization feature is
seen. Typically on these occasions, and particularly for the BN object, a
distinct position angle shift between the feature and continuum is seen, which
indicates both a fractionation of the icy material and a changing alignment
direction along the line of sight.
  Here the dependence of circular polarimetry on fractionation along the line
of sight is investigated and it is shown that the form of its spectrum,
together with the sign of the position angle shift, indicates where along the
line of sight the icy material lies. More specifically a coincidence between
the sign of the position angle displacement in the ice feature, measured north
through east, and that of the circular polarization ice feature means that the
icy grains are overlaid by bare grains. Some preliminary circular polarimetry
of BN has this characteristic and a similar situation is found in the only two
other cases for which relevant observations so far exist.
