  We investigated a hydrostatic equilibrium model of the Milky Way following
Parker (1966), to constrain the large scale properties of the interstellar
medium. In our approach we found an excellent agreement between our simple
hydrostatic equilibrium model of the Milky Way and the recent all-sky survey
data rangeing from the gamma-ray to the radio regime. On large scales the
galactic disk-halo system is found to be stable against Parker-instabilities.
Pressure support from the Galactic disk is essential to stabilise the halo. In
particular the diffuse ionised gas layer acts as a disk-halo interface.
Assuming that the distribution of the soft X-ray emitting plasma traces the
gravitational potential, we derived the dark matter content of the Milky Way to
be about M ~ 2.8 10^11 M_o. Our findings are consistent with the rotation curve
of the Galaxy.
