Observations at many wavelengths have revealed the important rôle
of interstellar gas in the evolution of systems of interacting galaxies.
Being highly dissipative, the gas reacts irreversibly to perturbations.
It is generally believed that it looses
its angular momentum and is driven towards the central region of the galaxy because of the gravitational
torques produced by the interaction. Atomic gas 
from the outer parts sweeps in, is converted into the
molecular phase (H2), and forms new stars.
Powerful starbursts and nuclear activity can be triggered
in one or both of the colliders, giving rise to enhanced H
, far-infrared and radiocontinuum
emission (e.g., Kennicutt et al. 1987;
Xu & Sulentic 1991; Hummel et al. 1990).
Strongly interacting galaxies also have enhanced CO emission which suggests that a larger supply of
molecular gas is available for star-formation (e.g., Braine & Combes 1993).
Observations of infrared-luminous galaxies have revealed an 
deficiency
(e.g., Martin et al. 1991). However,
the existence of such a conversion from gas into H2 is far from
being established for less infrared-luminous objects since
most work to date has focused on the extreme examples (through
far-IR selection) rather than on the interactions themselves.
Indeed, not all interacting galaxies are luminous in the far-infrared,
and studies of unbiased samples of interacting galaxies are necessary to
clarify the relation between dynamics, gas content and induced star-formation.
A complete sample of interacting galaxies
does exist in the literature. It has been compiled by Bergvall (1981) and
contains all interacting galaxies in a well-defined region of the Southern sky with
a blue magnitude lower than 14.5 (see below).
In contrast to most existing samples, the galaxies in the Bergvall sample
have not been selected on their far-infrared emission.
The optical and near-infrared properties
of this sample have been studied (Johansson & Bergvall 1990;
Bergvall &
Johansson 1995, hereafter JB90 and BJ95).
Our work has been to add
to the extensive existing database, where possible,
information about the neutral gas content of these galaxies by observing the two main
transitions of atomic and molecular gas: at 
21 cm and the J=1-0
rotational line of the CO molecule at 2.6 mm.
In the following we present the sample and the already existing datasets.
We show the 12CO(1-0) and spectra along with optical images
of the galaxies and list the parameters of the CO and lines as well as
the derived molecular and atomic gas masses.
The molecular gas masses 
) have been computed from the
12CO(1-0) line intensities using a standard conversion factor
established for our own galaxy (Strong et al. 1988).
The use of this conversion factor may be meaningful only for massive
galaxies such as the Milky Way.
This is discussed in Sect. 4.3.
The analysis of the data and a study of the relationship between gas
content and star-formation indicators will be presented in a forthcoming paper.