  Recent experiments have proved that the response to short laser pulses of
common optical media, such as air or Oxygen, can be described by focusing Kerr
and higher order nonlinearities of alternating signs. Such media support the
propagation of steady solitary waves. We argue by both numerical and analytical
computations that the low power fundamental bright solitons satisfy an equation
of state which is similar to that of a degenerate gas of fermions at zero
temperature. Considering in particular the propagation in both $O_2$ and air,
we also find that the high power solutions behave like droplets of ordinary
liquids. We then show how a grid of the fermionic light bubbles can be
generated and forced to merge in a liquid droplet. This leads us to propose a
set of experiments aimed at the production of both the fermionic and liquid
phases of light, and at the demonstration of the transition from the former to
the latter.
