We propose to use ISOCAM and PHOT to measure the spectral energy
distribution of dust emission in the direction of background
stars for which the extinction curve of dust is known.
The stars have been selected from a sample of stars located
behind nearby molecular clouds (Chamaeleon and Taurus) and high
latitude cirrus clouds. We have also included two stars in the
outer edges of the SMC. The stars have been choosen so that the
the same dust is sampled in emission and absorption.
The data will be used to correlate the emission and extinction
properties of dust. We will look for the contribution of
small particles to the UV extinction. This information will
help to characterize the different components of interstellar dust
and to understand their evolution in interstellar clouds.
This is the follow-up of a work we started with the IRAS data.
 The ISO observations will help us to get make the comparison
 with more specific signatures of interstellar grains such as
the infared feature emission in the near-IR and the cold grains
emission in the far-IR. The higher angular resolution provided
by ISO will also help in reducing the difference in agular
resolution between the emission and extinction measurements.