L134N is a cold, starless cloud, very high above the galactic plane,
close to us and well delineated in continuum dust emission maps. This
cloud is considered to be representative of oxygen rich dark clouds
(with the presence of SO, SO2, NO, ...). It is thus a good
reference together with TMC-1 to test astrochemical models. Thanks to
ISO, SCUBA and near IR wide field cameras, the detailed study of the
dust has become possible in such cold and dark clouds. In parallel,
progress in radiotelescope receiver sensitivity now allows to map weak
lines on large surfaces. We have thus started a project to study both
dust and a few gaseous key species (CO, CS, SO and N2H+) to
address several questions. We want to assess the quantity of dust and
gas all over the cloud, study possible C18O and/or C17O
depletion towards dense cores, evaluate the structure of the gas, the
abundance of CS and SO to possibly estimate the chemical age of the
cloud (time dependent models show that the CS/SO ratio diminishes with
time) and evaluate the rare isotope abundances, especially 17O
and 34S in a first step. To constrain the molecular abundances
with the highest possible confidence, we have observed several
transitions for each species and each isotopomer. Though we have
observed far less species than Dickens et al. [1], we
have done it on a larger area, including thus the strongest C18O
peak and two other peaks, with a better signal-to-noise ratio. Most of
the data are already acquired. We present here preliminary results.