  It is supposed that while neutrino passing through the matter a resonance
enhancement of neutrino oscillations in the matter appears. It is shown that
Wolfenstein's equation, for neutrino passing through the matter, contains a
disadvantage (does not take into account the law of momentum conservation). It
leads, for example, to changing of the effective mass of neutrino by the value
of $0.87 \cdot 10^{-2} eV$ from the very small value of the energy polarization
of the matter caused by neutrino which is equal to $5 \cdot 10^{-12} eV$. After
removing this disadvantage (i.e., taking into account this law) we have
obtained a solution of this equation. In this solution a very small enhancement
of neutrino oscillations in the matter appears due to the smallness of the
energy polarization of the matter caused by neutrino.
