We propose SWS and LWS spectroscopy of selected lines in cD
 galaxies with cooling flows to determine the amount and
 physical conditions of cool (300-1000 K) atomic/molecular gas.

 Ground based observations of near IR H2 and [FeII] lines show that
 these are the galaxies with the largest column densities of warm gas
 (2000-7000 K) compared to bolometric luminosity and stellar mass.
 The ratio L(H2)/Lbol is 1-2 orders of magnitudes larger than
 Seyferts and a factor >4 larger than in the most extreme starbursters.
 Several arguments suggest that these galaxies should have considerably
 larger column densities of cool (300-1000 K) gas, so they should be
 bright, and have the largest equivalent widths of all galaxies, in
 the major coolants of this phase: [OI], [CII], [SI], [FeI],
 [FeII] and H2 0-0 lines.

 From these observations we will estimate the physical conditions
 (column density, temperature) of the cool gas component and compare
 the results with model predictions for molecular clouds excited by
 shocks, X-rays, and thermal conduction. The unusually large column
 densities of warm H2 may be related to the large amount of thermal
 energy in the hot gas, which can be tapped through its X-ray emission
 or thermal conduction. These observations also offer a direct test
 of cooling flow models, which postulate large reservoirs of cool gas
 in cooling flow clusters.

 It should be noted also that, in contrast to starbursters and
 Seyferts, cD galaxies are little represented in the GT proposals.
 Our observations will therefore guarantee that these potentially
 bright extragalactic line emitters are not overlooked by ISO
 spectrometers.