  The magnetostatic and magnetocapillary instability problems of isothermal
incompressible and inviscid non--conducting liquid jets in a uniform magnetic
field, is considered. The equivalence between static and dynamic approaches at
the onset of instability and cut--off wavelength is shown. It is established
that in the absence of electric currents the stability of permeable jets can be
changed by the magnetic field. A new dispersion relation for magnetocapillary
instability in such jets is derived. This relation differs from that given by
Chandrasekhar. The existence of critical magnetic field which stabilizes jets
with finite susceptibility is established. It is shown that the jet is
stabilized by the field irrespective of its being para-- or diamagnetic, but
the extent of stabilization is different.
