170 $\mu$m, if they are colder [@popescu]. The diffusion of large archives of observations at the above wavelengths (except for molecular lines) allowed in the last years the compilation of catalogues containing a huge number of galaxies. Using these catalogues and the works presented in the literature, we collected fluxes in FIR, 21 cm, CO(0-1) line and soft X-ray for two wide samples of normal [@normal] and interacting [@interacting] galaxies. Joining together these samples, we have data for a total of 2953 galaxies, not all observed in the four above wavebands. The fluxes measured with the different tracers allow now a study of the link existing between dust, gas and stars based on hundreds of galaxies.

It is known that the fluxes emitted by a galaxy at very different wavelengths may be linked together by means of the star formation mechanism (see @david [@ranalli]). For instance, the formation of massive stars generates the heating of the dust clouds in which they are embedded, by absorption of their UV radiation, and produces a re-emission of this energy in the far infrared. This process links the current star formation rate to the IR emission at 60 and 100 $\mu$m [@thronson]. The ionizing 