We report photometry with ISO between 60 and 200 mu m of six galaxies.
Three of them are active and the extension of their spectra beyond th
e IRAS bands up to 200 mu m confirms our previous conception that most
of the dust there is warm and has a fairly uniform temperature of sim
ilar to 30 K. In the other three galaxies which are inactive, we detec
t a very cold component (similar to 10 K and less) that could hitherto
at best be surmised. The most dramatic consequence is a threefold inc
rease in the mass of interstellar material over what one would calcula
te without the ISO data.