  In this note we construct an integral boundary condition for the Kohn
Laplacian in a given domain on the Heisenberg group extending to the setting of
the Heisenberg group M. Kac's "principle of not feeling the boundary". This
also amounts to finding the trace on smooth surfaces of the Newton potential
associated to the Kohn Laplacian. We also obtain similar results for higher
powers of the Kohn Laplacian.
