  It is shown here that in neutral ion gases the thermal energy transport can
occur in the form of new types of thermal soliton waves. The solitons can form
under a vanishing net heating function, and for a quadratic net heating. It is
predicted that these solitons play an important role in a diversity of
terrestrial and astrophysical phenomena. We claim that the reported soliton
waves can be observed under ordinary laboratory conditions.
