  Electrons densities in different locations of our galaxy are obtained in
pulsar astronomy by dividing the dispersion measure (DM) by the distance of the
pulsar to Earth. The properties of the interstellar plasma are related to its
heating. Following the present analysis DM measurements are obtained with
different properties for different temperatures in three regions:1)For
relatively low temperatures the state of molecular, atomic and ionized Hydrogen
was analyzed by the interstellar medium (ISM) model with partially ionized
plasma. In this region various spectroscopic effects are obtained. 2) For
temperatures approximately above 20000 (K) the interstellar gas was found to be
completely ionized medium and this plasma is defined as warm ionized medium
(WIM) where this plasma is transparent. This property is obtained from solution
of Saha equation in which the index of refraction is real, but the plasma can
be observed by dispersion measurements.3)For very high temperatures defined as
hot ionized matter (HIM), X-rays are obtained by the plasma. We concentrate in
the work on the analysis of the WIM plasma. We calculate the mass densities of
such plasma and compare it with dark matter densities which are found to be
larger. But some factors which can reduce this difference are discussed,
