  We comment some recent unexpected experimental results on proton/deuteron
deep inelastic scattering off water molecules in H2O-D2O mixtures (C.A.
Chatzidimitrou-Dreismann et al. Phys. Rev. Lett. 79, 2839 (1997)) where a
strong dependence of the ratio of proton/deuteron cross sections on the
composition of the mixture was observed. We propose an explanation of this new
effect based on the two-fluid picture of water which arises from the theory of
QED coherence in condensed matter.
