  In order to confirm the strong Van der Waals force in the nucleon-nucleon
interaction, it is proposed to measure precisely the angular distribution of
the cross section of the low energy ($T_{lab}=20 \sim 30MeV.$) proton-proton
scattering. By using the spectrum of the long range interaction obtained from
the analysis of the phase shift data of the S-wave of the p-p scattering, a
characteristic interference pattern, which arises from the repulsive Coulomb
and the attractive strong Van der Waals forces, is predicted. The pattern has a
dip at $theta_{c.m.}=14^{\circ}$ with the depth around one per cent.
