  We suggest in this Letter that the Bekenstein-Hawking black hole entropy
accounts for the degrees of freedom which are excited at low temperatures only
and hence it leads to the negative specific heat. Taking into account the
physical degrees of freedom which are excited at high temperatures, the
existence of which we postulate, we compute the total specific heat of the
quantum black hole that appears to be positive. This is done in analogy to the
Planck's treatment of the black body radiation problem. Other thermodynamic
functions are computed as well. Our results and the success of the
thermodynamic description of the quantum black hole suggest an underlying
atomic (discrete) structure of gravitation. The basic properties of these
gravitational atoms are found.
