  Attention is drawn to recent observation of a fluid phase of hydrogen nucleii
in transition metal hydrides. It is suggested that phonon exchange processes
might be responsible for the phase transition since bound pair states,
analogous to Cooper pairs, would possess the required mobility and might
moreover render the phase transition energetically favourable. A generic
formula for the ground state binding energy based upon the results of numerical
calculations is presented and a special test of the theory is proposed.
