We report preliminary results of the first heat capacity measurements
on atomically layered He-3-He-4 mixture films adsorbed on the surface
of graphite. The He-4 film consists of two solid and two superfluid at
omic layers. The heat capacity has been investigated over the range 1
- 70mK as a function of the surface density of He-3 atoms added to the
film. At cover ages n(3) < 4 nm(-2), the He-3 forms a uniform two dim
ensional Fermi system. The coverage dependence of the linear coefficie
nt of the heat capacity, gamma, allows a determination of the hydrodyn
amic effective mass and F-1(s). At higher coverages a step-like increa
se in gamma is observed, interpreted as the formation of a second two
dimensional Fermi system.