  This paper presents follow-up observations of the mid-Infrared dark clouds
selected from the ISOGAL inner Galaxy sample. On-the-fly maps of 13CO, C18O and
the 1.2 mm continuum emission have been obtained a the IRAM 30-m telescope. A
preliminary analysis of the physico-chemical conditions at works in the clouds
is given and molecular depletion onto cold grains is discussed.
