  The high temperature limit of the 3-graviton vertex function is studied in
thermal quantum gravity, to one loop order. The leading ($T^4$) contributions
arising from internal gravitons are calculated and shown to be twice the ones
associated with internal scalar particles, in correspondence with the two
helicity states of the graviton. The gauge invariance of this result follows in
consequence of the Ward and Weyl identities obeyed by the thermal loops, which
are verified explicitly.
